Juice, Food & Beverage

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African Palm

April 24, 2007

An industry exists for extracting vegetable oil from the nuts of the African Palm. We have visited factories doing this in Costa Rica, and plants in Mexico, Nicaragua, and Colombia have been heard of. The oil is high value, and it seems to be used mostly for cosmetics or blending with other oils.

Bunches of berries, or seeds, grow on the African palm, which is a tall and very bushy palm tree, usually with ferns growing on the trunk. Thousands of acres of banana plantation have been put to palms. The bunches are about 12" to 16" in diameter; the berries are about the size of large grapes.

The 14" bunches are first cooked in long steam tunnel cookers. The main plant we visited has four, each holding half a dozen short gondola rail cars full of bunches. This blanching operation is to loosen the berries from the stems. (The plant we were at processed 1,000 tons per day.)

Once steamed, the bunches are tumbled in huge trommel screens, to separate the berries. Sometimes the berries are called fruit. They have an outer pulpy mass with a hard seed inside. Both the pulp and the seed contain oils, of different qualities.

The waste stems go to a big hammer mill and then into a smallish sugar cane roller drum press (three 32" diameter rolls, 36" wide). The material from the shredder looks and acts like hemp cushion or mattress stuffing. We could never get a drop of liquid out by hand squeezing. They add some water to this material at the inlet to the roller drum press. The oil and water outflow (press liquor) is a good 5 gpm; it is sent to a Sweco filter, along with the press liquor from the pulp presses. Thus, some oil is recovered from the stems and mixed with the oil from the pulp.

The press cake from the roller drum has a damp or oily feeling, with about 55% moisture they said. Typical of a drum press, some of the cake comes out very dry, and some is dampish. They want to press it to a lower moisture content in order to get out more oil and to be able to burn it. The bulk density is very low, so they cannot get any capacity out of their existing 12" twin screw presses. The material is too wet to burn, so it is used as mulch. A Vincent Series VP press might work in this application, although a couple more stands of roller drum presses, like at a sugar cane mill, would be a better bet.

Once de-stemmed, the berries are stirred, with steam addition, mushing them. This is done in a vertical shaft agitator-cooker (100 psi steam, 120° C), referred to as a digester.

The cooked berries fall into very heavy duty screw presses, such as a Stork, Vetter, or Columbian knock-offs. These are all twin screw presses. There is an exceptionally large flow into these 12" machines, 12 MTPH each. The cake produced is tremendously dry, only 40% moisture. Despite the extremely high pressure, the seeds in the press cake are hardly broken at all. The oil, red, comes from berry pulp; it is mostly made into oleo margarine, some is sold for industrial cooking oil. None goes to consumers. (Vincent does not offer a screw press for this application.)

The press liquor is an oil/water emulsion which is separated in hydraclones, followed by centrifuges.

The press cake from these presses is blown to cyclone classifiers or separators. The nuts drop out of the first cyclone and then go to a Ripplemill (soft grinder; they have three). In the Ripplemills they crack the nuts into kernels and into shells. The shells go to the boilers, for fuel.

The second cyclone separates out the pressed pulp, which also goes to B&W boilers for use as fuel.

They have flakers, one each, French and Davidson (?). These are three-high drum machines, 48" wide, 12" drums, each feeding the next lower drum. Each has a pair of 25-hp 1200-rpm motors, pulley driven at 260 rpm. These grind the seeds into powder. That powder goes to rather large steam pre-heaters, and then into three Anderson Expellers®. (These are ~1935 Anderson presses, used first on sunflower seeds, then cotton seeds in Nicaragua, now for palm oil in Costa Rica.)

The press liquor (oil) is filtered, in either a drum filter or a plate and frame filter press. The oil is premium quality, sold for cosmetics and pharmaceuticals.

The press cake from the kernels goes to a hammer mill (this press cake from the Anderson's is hard as a rock), and then it is bagged and sold as animal feed.

They have 60 m3/h going to the WWTP, about 260 gpm. The Vincent FF-12 Fiber Filter was used to separate suspended solids from this flow, in order to reduce pond odor. This was relatively successful, although a small screw press was needed to dewater the sludge from the Fiber Filter. There was the potential for oil recovery in this application.

A better application for the Fiber Filter was in filtering oil and water emulsions ahead of centrifuges. Keeping fiber solids out of the centrifuges would greatly increase the service life of the components subject to abrasive wear. Once again, a small screw press was needed to dewater the sludge from the Fiber Filter.

Issue 186

Apple Juice

September 19, 1995
Rev. July 1998
Rev. Aug 2013

In 1995 a series of trials were run pressing apples in the Tampa Works.  Two drums of crushed and chilled apples were flown in from Pennsylvania for the tests.

The apples came from Wentzler Apple Farms, a regional apple cider producer.  They are known for producing a high quality, natural product that is free of preservatives and sediment.  Apple cider is typically a fresh juice product that is not filtered or clarified following pressing.  Since a clear juice is desired, bag or filter presses are used to make apple cider.  All of the apple juice made in the trials was definitely too murky or hazy, with too many suspended solids, to be used as apple cider.

Commercial apple juice is made by filtering the juice that comes from the press.  This is typically done with diatomaceous earth (DE) drum filter presses.  More recent technology uses microfiltration and reverse osmosis (RO).  Centrifuges are of limited use because of their high cost and the small differential in density between the solids and the juice.

A great deal was learned in the tests.  Without the addition of a press aid, the pressing of crushed apple was almost impossible.  The screens blinded, the material slipped in the press, and press capacity went down to a tiny fraction of rated output.

Two presses aids were used, rice hulls and Weyerhaeuser Silvacel (ground wood).  Both appeared about equally effective.  In a commercial operation some optimum blend of the costly and inexpensive press aids could be determined.

The rotating cone option improved the operation a little.  A minor improvement in press throughput was noted.  However, it was felt that this improvement would not justify the additional cost and complexity associated with the rotating cone.

With 3% press aid blended into the apples, yields ranged from 72% to 80%.  This will vary with the variety of apples and the ripeness of the fruit.  Press through put capacity was 50% of the Blue Brochure rating.  In contrast, with 6% press aid, yield was 87% and capacity was up to 65%.

With 0.005" wedgewire screens there was a reduction in press capacity, as compared to using 0.041" perforation.  Since the juice from both screens contained large amounts of suspended solids, it was felt that the perforated screen was preferred.

July 1998 update

The new Fiber Filter may give Vincent an excellent means of penetrating the apple juice market.  Testing will be required.

This year we have supplied a VP-12 press to Cliffstar that will be used in producing apple juice.  In addition, we are rebuilding some of their older Vincent presses.

August 2013 update

Since the last update in 1998, the market has shifted to where most apple juice is produced in China.  Also, the production process has shifted from using screw presses to using enzymes to break down the fruit so that centrifuges (decanters) are used.  This method of producing juice achieves the very highest juice yields.

 

Issue 32

 

 

 

Bell-Carter Olive

April 25, 2005

Bell-Carter Olive is a very long established northern California firm that processes olives. The pitted olives are sold in whole, sliced and diced forms. The firm uses Vincent screw presses in two applications.

The sanitary application is part of the process of producing diced olives. After dicing, the olives are flumed (transported in a water stream) from various locations in the plant. A model VP-12 press, all stainless, is used to separate the water without crushing the product.

It is noteworthy that a Vincent Series KP press has been used in a nearly identical application, involving separating water from diced green chili peppers after they are flumed to a desired location.

The second press at Bell-Carter, a VP-16, is in the wastewater treatment plant. It is used to separate solid particles of olive from the waste stream. Once again, the trick is to separate and dewater the olives without pressing them so hard as to emulsify them into the press liquor. The sludgy mass of press cake is sent to landfill.

Both presses use the rotating cone option. This is key to the soft pressing of a slippery material that would otherwise channel out of the cake discharge of the press.

Today we would recommend the Series KP "soft squeeze" presses for these applications. The recent incorporation of a rotary cone feature in these presses has expanded their market potential.

Issue 160

Chicory

June 16, 2011

Chicory is a vegetable that grows throughout Europe and North America, especially where sugar beets are grown.  New Zealand is leading producer.  The roots are bigger than carrots, about the size of a turnip.  During the Civil War, the Great Depression, and WWII England, chicory root was used as a substitute for coffee.  The flours and leaves have been used since ancient times in human consumption foods (mostly salads), animal forage, and home remedies.

Today the commercial interest of chicory lies in inulin.  Inulin is a food additive or dietary supplement.  It is used in many of the products where pectin, Xanthan gum, and carrageenan are used:  yogurt, ice cream, power bars, milk products, bread. The inulin is sold either in liquid concentrate form or in powder produced in a spray dryer.

Chicory can be processed in the very same manner as sugar beets.  The chicory is sliced into wafers, thinner than cossettes, probably 1/8" thick.  These are fed into a diffuser.  The liquid from the diffuser is filtered and then concentrated.   The inulin is in the dissolved solids, although it is referred to as a dietary fiber.  It is a polysaccharide.  The root contains about 20% inulin by weight, which is 68% of the dry solids by weight.

Inulin is produced in Europe, in the same places that sugar beets grow.  To date it is not produced in the United States.

The spent chicory from the diffuser is made into animal feed, much like sugar beet pulp.  This residue, at 85% moisture, is fed into a screw press at 140° F.  The resulting press cake can be sold moist (as is), or it can be run through a rotary drum dryer for further moisture reduction.

In an alternate extraction process, the fresh root was fed into our screw press.  It had 72% moisture, which was reduced to 62% in the press cake.  

When pressing the spent chicory, relatively few fines go through the 0.015" wedgewire screen of the press.  However two sources have reported a puree coming through the screen of the press.  This occurred when dehydrated chicory, which they had re-hydrated, was pressed.  (Dehydrated chicory is about 98% inulin.)

To date Vincent Corporation's activities with chicory have been limited to laboratory testing and trials.

Issue 234

Coconut Coco Lopez

August 30, 1995
Rev. March 2012

The best known coconut product is cooking oil. This is extracted from copra (dried coconut meat), either with Anderson Expellers® or, much less commonly, in a solvent extraction process. The Anderson screw press exerts sufficient pressure to liquify the fat in the coconut; over five hundred have been sold for this purpose in the Philippines alone. Alternatively, hexane is the solvent used to dissolve the fat in the copra. The industry producing this high cholesterol cooking oil is centered in Southeast Asia.

Vincent machines do not have anything to do with producing coconut cooking oil. None of our presses will squeeze tight enough. However, there is a coconut product, Coco Lopez, which is produced with Vincent screw presses.

Coco Lopez was started with a government grant to the University of Puerto Rico. The project was funded in an effort to develop a new industry for the island commonwealth. The project was headed by a staff member (or student) by the name of Lopez, and in 1970 a Vincent VP-6 press was purchased and shipped to the University. Vincent’s Tampa sales representative, Art Lund, was instrumental in the project.

The product developed is known as Cream of Coconut. The most popular brand, Coco Lopez, is used as a cooking ingredient for a variety of main dishes and desserts; it is found on the shelves of most supermarkets. Also, pina colada mix is a very popular product.

Coco Lopez is produced from fresh shredded coconut meat. The coconuts are harvested, shucked, and shelled. The water in the coconut, especially from mature coconuts, is discarded. However, recently a strong market has been developed for this natural drink.

In the Americas the meat is removed from the shells either with a machete or, following boiling, with a spoon. In Asia the coconuts are shelled with a snag-tooth ripper.

The brown peel is removed from the meat, after which it is shredded or grated to a size similar to that of the flakes that are spread on cookies and cakes. At that point the meat is ready to be pressed in Vincent presses.

Generally, double pressing is employed, although the most progressive processors use triple pressing to obtain the highest yield. Usually hot water is added to the press cake after the first pressing. Large 16" presses are used for first pressing, while smaller 12’s and 10’s are used for second and third pressings. The rotating cone option is used to maximize yield.

Recently Series KP presses have been supplied with tapered shaft screws. The goal is to match the yield performance of the traditional Series VP and CP presses.

The white juice extracted from the coconut is referred to as coconut milk. It is screened and homogenized. Sometimes it is centrifuged and/or concentrated in an evaporator. With the addition of a great deal of sugar, Coco Lopez is produced.

The original project was so successful that Lopez left the University and commercialized the product. The industry was moved to the nearby Dominican Republic because the labor is cheaper and both coconuts and sugar cane are plentiful. Today there are half a dozen firms producing Cream of Coconut on the island. Ironically, the largest of these import their sugar from Guatemala because of lower cost and higher quality.

The greatest volume of coconut cream is produced in the Philippines. There a plant will run 400,000 to 500,000 coconuts a day. In the Dominican Republic, 60,000 a day would be a more typical figure.

 

Issue 31

 

 

Cranberry Processing

December 23, 2005

Vincent recently participated in testing at a cranberry processing plant. Many years ago we had sold screw presses for juicing cranberries, and it was interesting to see how the industry has evolved.

At the plant where we were, the cranberry juice was recovered in an extractor, without the use of the traditional screw press.

The plant can hold 1.5 million barrels of cranberries in frozen storage, and can process 900,000 barrels a year (100 pounds per barrel). Thus the plant runs year round. Bins of frozen berries are dumped into a sizer that blows out the trash, drops the unders, and screens out the overs. Then the berries are pneumatically conveyed to where they are separated from the air stream and dropped into Urschel slicers. This produces pieces much like sliced olives in a salad, about 1/16" thick. Then they are fed into the juice extractor.

The extractor looks like a 4' diameter screw conveyor in a 30' long trough. The screw rotates slowly 120 ° in the forward direction and then backs up 90°, then forward again, all at low rpm. The action, controlled by a VFD, is extremely smooth. The screw is inclined about 10°, and the flights of the screw are covered with slots that are smaller than the cranberry slices. The result is that water put in at the high end flows down, going through the cranberries that are being screwed uphill. Thus, the machine is a true counterflow diffuser, without need for separation between various stages.

The berries are 8° Bx to start, and they are under 0.5 o Bx at the discharge of the extractor.

The sliced berries from the discharge of the extractor were landspread ten years ago. Instead, now they are sent to an infuser, where they are made into "sweet & dry". This is a diffuser running backwards. Sugar solution with flavoring concentrate is added to the slices. Cranberry, orange, cherry, and other flavors can be used.

The pieces are then dried in Sanvik bakery-style band dryers, to make Craisins and similar products. The markets in snack foods and breakfast cereals have shown excellent growth. The two leading cranberry processors, Ocean Spray and Decas, have distinct methods of diffusing cranberries, each covered by its own process patent.

Issue 168

Food Grade

September 18, 2011
 

Sometimes screw presses are used to squeeze material destined for human consumption.  Typically this is a fruit or berry juice, or nutraceuticals.  For these applications our screw press construction is modified from the usual sludge, waste, and manure configurations.

Most Vincent presses are made with all liquid contact parts made of 304 grade stainless.  This stainless steel is sandblasted before shipping the press.  For food grade applications it is necessary to go further, to an alternate finish.

We refer to the alternate finish as Vincent Food Grade.  For this case, after the first sandblasting, we fill, by welding, pits and undercuts which the sandblasting has made visible.  These new welds are ground, and any weld splatter that has been missed is also ground off.  Next the parts are blasted with glass bead.  This gives a finish that has a slight luster, an improvement over sand blasting. 

We passivate (swab down) the stainless with acid to remove carbon steel inclusions.  These inclusions come from using chipping hammers, wire brushes and other carbon steel tools.  Without passivating, rust streaks are apt to appear on the press.

During assembly, food grade grease is used in the cone bushings, shaft bearings, and seal housing.  If requested, the gearbox can be filled with food grade grease; people do this where they absolutely do not permit any non-food grade lubricants in their facility.

An alternate finish just coming into play is electro-polishing.  So far this is limited to our smaller presses.

Vincent does not offer the highly polished equipment used in creameries and factories handling milk products like ice cream, yogurt, and cheese.

Optional CIP accessories are offered with presses for food applications.  These include both internal and external CIP.  There is a recent newsletter describing these.

In all cases pasteurization is required for food materials from screw presses.

Issue 237

Free Run Grape Juice

November 17, 2003

There is an interesting application for the Series KP screw presses in the grape juice and wine industry. This involves improving the yield of free run juice at a minimum capital cost.

Successful testing was conducted over a harvest season. Three model KP-16 presses were utilized to increase the proportion of free run juice while at the same time increasing the throughput capacity of downstream presses.

The normal flow was to process the grapes through destemmers, followed by crushers. Free run juice from this mass was removed in rotary drum screens. The remaining solids, called "must", were pressed for maximum yield in traditional Le Coq and Diemme screw presses.

The quality of the juice from the high yield presses is lower than that of free run juice. This is because of impurities that are pressed into the juice in presses designed and operated for maximum yield.

Installing the "soft squeeze" KP presses after the rotary screens allowed additional yield of free run juice. At the same time, the physical volume of must was reduced. This in turn increased the capacity of the Le Coq and Diemme presses.

One innovation was to use the cake discharge cone as an adjustable fixed orifice device, rather than the normal floating constant pressure door. This was achieved by replacing the air pressure regulator controls on the discharge air cylinder with a linear positioner. With this the operator was able to set (and vary) a discharge opening that resulted in the best yield without over-pressing the must.

Since this testing was performed, the larger capacity Models KP-24 and KP-30 have been introduced. It is expected, should industry conditions improve, that the large scale presses will find application in large volume grape juicing.

Issue 145

Ginger

Originally published January 12, 2005 (updated July 1, 2014)

Ginger is a tropical Asian tuber plant, whose hot, spicy root has a pungent aroma. This root is somewhat like an agglomeration of radishes, except white in color. These can be found in the produce section of the supermarket. It is used primarily in cooking or as a medicine. Powdered root is sold as a spice, and we are familiar with its flavor in Ginger Ale.

Some years ago, we almost sold a screw press to Charles Jacquin et Cia. for extracting juice from Ginger. They use the juice in the production of a fine liqueur. Unfortunately, a large amount of suspended solids were present in the press liquor, and the cost of clarification precluded an economic operation. The machine was to have been sent to China.

Another customer, Royal Pacific Foods, in California, has since built a successful ginger product line. They import cargo containers of the root from China. The material arrives washed and packed in 30# net bags like those used for onions and potatoes.

Royal Pacific first shreds the root in a Corenco M12A angle shredder. The shredded material falls directly into a standard Vincent Model CP-6 screw press with a profile bar screen and 5-hp drive.

In pressing, ginger produces an extremely high yield of juice. Normally 75 to 80% by weight is converted into press liquor. (The press cake is discarded.) The press liquor is pasteurized and packaged in 5-gallon pails, which are frozen solid. The product is sold predominately to producers of oriental cuisine.

One set of operating data gave 1.5 gpm of press liquor and 500 pounds per hour of press cake, for a total feed into the press of 1,250 pph. That was with well-ground material being fed into a CP-6 press. The air pressure on the discharge cone was 80 psi and screw speed was 17 rpm.

 

Issue 156

 

 

 

Grape Juice

May 18, 1993

Recently we had a chance to visit fruit juice producers in western New York, along the shore of Lake Erie. This is an area known for growing grapes and deciduous fruit. The plants we visited are using Vincent screw presses in the production of grape, cranberry, prune and apple juice. They both bottle and can these juices, operating on a year-round basis.

To make grape juice they dump one ton bins of grapes into a screw that feeds into a de-stemmer. This is a horizontal drum about 5' in diameter with 7/8" perforations. The grapes and some juice fall through the perforations. The stems and trash come out the far end of the drum. From there a screw takes the stems to a dumpster; these are land-spread in the orchards.

From the de-stemmer the grapes are pumped, by a piston pump, to a heat exchanger where they are heated to about 160ºF. From there they go to a trough where "paper" press-aid is added.

This press aid comes in the form of sheets of pulp board. They use a high shear agitator to tear up the paper and mix it in with the grapes. They use 100# of paper per 1000 gallons of juice (if a gallon weighs around nine pounds, that is about 1%).

Rice hulls (a second, cheaper press aid), along with pectin and enzymes, are added. The material is agitated in a cook tank and then pumped to a screen cage de-juicer. It is about three feet in diameter and has a fairly fine screen.

Pomace from end of the screen cage de-juicer is fed with a screw conveyor to the hopper of the Vincent press. They have variable speed presses in order to switch from one type of fruit to another. Also, they have their presses equipped with the rotating cone option because of the slippery nature of the material they are pressing. This material tends to channel, and the rotating cone counteracts this tendency.

The press liquor is pumped, along with the juice from the screen cage de-juicer, to the next stages of juice clarification and bottling.

The cake from the press is sent to landfill.

Issue 3

Infused Oil

January 11, 2008

We had an interesting visit to SpringThyme Oils, a firm specializing in producing infused oils.  They buy approximately 400 tons per year of either sunflower or virgin olive oil.  This oil is infused with herbal flavorings prior to sale to commercial accounts in the restaurant trade and in bulk to bottling firms.  The most popular herbs are basil, chili pepper, garlic and mint.  Others being prepared include coriander, parsley, rosemary, spring onion, and thyme.

The processing involves placing each herb in an infusion kettle with three kilos of oil to each kilo of herb.  Diffusion is controlled with a combination of temperature and time factors.

The task for Vincent is to separate the oil from the herb once the herb’s essential flavors have been infused into the oil.  This separation must be achieved with conflicting requirements:

 

  1. Squeeze out every drop of oil and
  2. Minimize the suspended solids flowing out with the oil.

We found that pressability varied greatly.  Parsley pressed like a charm!  On the other hand, both basil and spring onion were very slimy:  they tended to channel (spit) past the cone and press capacity was reduced because they blinded (covered over) the openings in the screen of the press.

Because of the wide range of herbs involved, the screw press being built has lots of bells and whistles.  The screw is notched in order to collect fiber; these fibers will wipe (brush) the screen during operation.  The rotating cone feature is included to break up channeling of the cake as it discharges.  A VFD is being programmed both for automatic reversing pattern operation and for slow variable speed in the forward direction.  Both perforated and slotted screens are being supplied.  These will have the No Tools hinged mechanism to facilitate cleaning between batches.  The tight screw-to-screen clearance on the SpringThyme press will also help keep the screen clear and improve throughput.

We hope that it will be possible to use press aid to further improve both press capacity and the clarity of the oil.  High quality bleached cellulose fiber as well as less expensive rice hulls will be tested.  The larger fibers in press aid are known to scour the surface of the screen, while the fibers themselves both retain fine particulate and give the press something to bite on.

Issue 195

 

Liquid Smoke

November 2, 2012

Vincent has extended from steak sauce into BBQ sauce during its ninth decade.  Our involvement is through an ingredient in char which is used by sauce producers to add smoke flavor.  Char presses surprisingly well, yielding a 15% percent moisture drop from an original moisture content near 55%.  We have only one installation at this time, but it is a niche application which has proven easy to master.

Char is used in a number of industries and applications.  There are three main uses for char:  it is concentrated to make liquid smoke; compressed to make briquettes; and dried to harvest activated carbon.  This issue of “Pressing News” will focus on the use and production of liquid smoke.

The liquid smoke produced by our client is sold to barbeque sauce producers and meat processing companies.  To treat a meat with liquid smoke requires a “smoke house” and atomizers (very fine misters).  The meat is hung in the “smoke house”, and the atomizers create a fine cloud of liquid smoke.  This cloud interacts with the meat in much the same way as actual smoke, even leaving a “smoke ring” in the meat.  After the meat has hung for an allotted time, it is deemed smoked, and is ready for distribution. 

The production of liquid smoke requires a supply of saw dust.  This saw dust is screened to select the right particle size.  (The temperatures and timing in the continuous production of liquid smoke require a specific particle size.)  The screened sawdust is then carbonized by heating in an oxygen-free environment.  This creates the char.  The char is then soaked with water.  Water soluble elements in the char enter into solution.  The water is filtered in a screen and then concentrated by evaporation, leaving behind the liquid smoke.  

It is important to note that char is different from ash.  Char is essentially elemental carbon, but it holds some of its original cellular morphology and organic content.  In contrast, ash’s organic compounds have been combusted, and its cellular morphology no longer resembles its original makeup.

The gasses from producing the char are burned as a heat source.

The char sludge from the screen is run through a Vincent screw press.  The press liquor from the press is liquid smoke, water, and char fines.  This press liquor is sent back over the same screen mentioned earlier, to remove the fines.  Thus the liquid smoke in the press liquor adds to the yield of the production process.

The press cake is sold to charcoal briquette companies.  These firms compress the char to produce their own products.

In the case of our client, Vincent was able to increase their production of liquid smoke by 50%.  That result speaks for itself.

 

Issue 250

 

 

Oat Bran - Screw Press

August 8, 2007

SunOpta markets special flour additives that are produced from oat bran. Their oat bran raw material is a low value by-product that results from processing oats.

Milling the oat bran and heating it, with a hot acid solution, converts the bran into a valuable food ingredient. An outstanding characteristic is that its inclusion improves the palatability of breads that are microwaved just prior to consumption. Heating releases the moisture. The result is a special, fresh-from-the-oven flavor. As a result, fast food chains are a key market for the product.

Part of the manufacturing process requires that the wet bran, following acid treatment, be dried. Over ten years ago Vincent supplied a screw press for this purpose to the SunOpta Kentucky plant. As the manufacturing process was refined, the press failed to dewater the material. The bran definitely wants to hold water.

Press aid, in the form of dried flour, was tried, to no avail.

Bridging in the inlet hopper was addressed by gluing Teflon panels to the sides of the hopper. Unfortunately, solving the bridging problem did not solve the dewatering problem.

The inlet hopper was pressurized in order to evaluate the Supercharger effect. If anything, this blinded the screen even more. In the end the press was abandoned.

Years later, we again tried dewatering this material, this time with a twin-screw press. Periodically opening the cone to discharge accumulated solids showed promise, as did programming the press' VFD to periodically swing through a reversing cycle. Improved performance was achieved, to the extent that large scale testing is justified.

Issue 189

Oat Bran Fiber Filter

September 14, 2006

It was at the Minnesota SunOpta plant that our first commercial success was finally achieved with oat bran by-products. The dewatering technology used at the facility involves a belt press. The filtrate flow from this belt press contains a significant amount of bran fibers. These were overloading the Waste Water Treatment Plant (WWTP).

A Fiber Filter was installed to filter the flow from the belt press. Using a medium range 43-micron sleeve, a significant amount of fiber was recovered. This resulted in an important reduction in the loading at the WWTP.

Financial justification became possible by making this a sanitary installation. The belt press operates under sanitary conditions, and these same conditions were applied to the Fiber Filter. As a result, the fiber sludge that is separated by the Fiber Filter can be salvaged. This fiber is added to the cake from the belt press. The improved yield that results is sufficient to justify the Fiber Filter.

As with our work at pumpkin canneries, reducing load at the WWTP was justified only because the commercial value of the by-product fiber was recognized.

Issue 178

Palm Oil

March 9, 2004

Some interesting work was done in the palm oil industry. A Vincent Fiber Filter machine was used to filter suspended solids from the hot oil flow that subsequently goes to centrifuges. The objective is to improve separation performance, to reduce plugging, and to reduce abrasive wear of these centrifuges.

The testing was conducted in Costa Rica where there are a number of palm oil extraction facilities. The oil comes from the berries of the African palm, a tall and very bushy palm tree, usually with ferns growing on the trunk. Thousands of acres of banana plantation have been put to palms. The bunches at the crown of the tree are about 12" to 16" in diameter; the berries are about the size of large grapes.

Truck loads of bunches are delivered the processing plant and loaded into gondola railcars. Strings of half a dozen gondolas are pushed into long steam cooking tunnels. This loosens the berries from the stems. Next the gondolas are dumped into huge rotating drums where the bunches are tumbled so that the berries break loose, separating from the stems.

The berries are next cooked and crushed in vessels called digesters. These vessels, positioned over powerful screw presses, operate with 150 psi steam.

From the digester the berries go to twin 12" screw presses. These presses were made by Vetter (Germany) and Stork (Holland); one, and maybe both, of these firms have since left the market. The presses are of high capacity (12 MTPH) and torque. The press cake produced is extremely dry, only 40% moisture.

The press liquor from these presses contains oil, water, and sludge. The oil is separated and clarified in decanter tanks. Solids and water are removed with centrifuges and, in the tests, a Fiber Filter. The oil is mostly made into oleomargarine, although some is blended with soybean oil for commercial cooking.

The press cake goes through two cyclone separators or classifiers. In the first separation the hard kernels are separated from the pulp of the berry. In the second cyclone the pulp is separated and subsequently fed as fuel into B&W boilers.

The hard kernels are cracked in Ripplemills. The outer shell joins the flow to the boilers, while the inner seed is flaked in French and Rosscamp vertical roller mills. The seed, now a powder, is conveyed to digesters where it is cooked with 150 psi steam. From there it is fed into Anderson Expellers which, to Vincent at least, exert unimaginably high pressures. The solid fat in the seeds is converted to an oil that flows from the screens of the presses. This oil is of a higher quality than the oil extracted from the pulp of the berries. Rather than being made into oleomargarine, it is sold to the pharmaceutical and cosmetic industries.

It was found that a simple Series KP screw press was needed to squeeze liquid from the sludge produced by the Fiber Filter.

Issue 147

Pectin Production

February 7, 2006                                                                                                                                                                                                  ISSUE #170

The Series VP ("Vincent Press") screw presses came out in 1952. The latest addition to this series is the Model VP-24. This machine is for applications where the Model VP-22 is borderline in capacity. The VP-22, introduced in 1973, was to have double the capacity of a Model VP-16. Over the years we have found that it generally falls short of this mark. In contrast, the VP-24 is expected to easily double the capacity of a VP-16. 

The attached photo shows the first VP-24 that we have produced. This machine was done in vapor tight construction because it will be used to expel aqueous alcohol solution from citrus pectin. The machine is being installed in the Danisco plant in Mexico.

A second VP-24 is expected to ship to China later this month. It, too, has the vapor-tight design as it will be used to separate alcohol solution from apple pectin. The drives of these two machines differ because the applications are different: the Danisco machine is 40 horsepower, while Yantai Andre Pectin requires only 20 hp.

Both presses will be driven by VFD's. The Baldor explosion-proof motors that were selected are rated for operation from 9 to 90 Hertz.

The discharge cone of the VP-24 is actuated by dual air cylinders. This simplification is now appearing in almost all Series VP presses. It is especially good in vapor-tight applications as it puts the air cylinders and thrust bearing outside of the vapor-tight compartment.

The design of the covers on these presses has been improved as a result of work with CP Kelco in Denmark. There is a 1/2" O-ring of solid Silicone mounted in a pocket that follows the perimeter of the cover. The cover itself is a thick honey-comb structure that minimizes warpage. This simple design provides reliable sealing while greatly reducing the number of clamps required.

Vapor-tight presses must use direct coupled drives to avoid the fire hazard associated with belt drives. Direct-coupling is used in many other applications where the length of the machine is not an issue. A belt drive allows shortening the machine by approximately the length of the motor.

A much-simplified mechanism is being used to drive the discharge cone when the rotating cone feature is specified. This has greatly reduced the cost of this option.

 

 

Peel Juice

May 23, 2005                                                                                                                                                                                                       ISSUE #161

A popular orange-flavored soft drink in Australia is labeled Peel Juice.  Much like Sunny Delight in the States, it is a sweet, non-carbonated drink with cloud added for appearance.

Adding water to fresh orange peel is the first step in making Peel Juice.  Once the sugars in the peel are diffused into the water, the mass is pressed to separate the liquid.  This step is repeated three times (three stage washing) until the Brix of the peel is reduced to below 1o Bx.  

Converting this bitter liquid into a soft drink requires only a few steps.  First, enzymes are used to break down the pectin.  Next, resins are used to de-bitter the liquid.  Finally, the liquid is concentrated in an evaporator in order to facilitate transportation and storage.  Subsequently it is blended and packaged into a range of consumer products.

Specialty resins are supplied by Bucher Unipektin through their Citrus Division in Chittaway Bay in Australia.

The press cake (washed peel solids) from the final pressing is sold as fresh animal feed.  The sheep love it.

An interesting variation of this technology has been pursued in Sicily.  Several citrus plants on the island produce pectin peel.  More than one of these is experimenting with peel juice made from their used wash water. 

Pectin peel is the raw material that companies like CP Kelco and Danisco use to produce pectin, the food ingredient.  Pectin peel is produced by washing the sugars from the peel.  This is done by diffusing the sugars out of the peel in counterflow wash systems.

A major problem faced by pectin peel producers is the disposal of the used wash water, as this water contains the sugar from the peel.  Large amounts of solids are involved:  by weight, the amount of sugar approaches the weight of pectin peel being produced.  In the last fifteen years all of the pectin peel plants in the United States have shut down, at least partly because of this environmental problem.  Thus, the Italian technology for converting the used wash water into a by-product may someday become widespread.

Vincent screw presses are an important part of these processing systems.

 

 

Pomegranate

December 31, 2006
(Rev. Dec. 2011)

The popularity of pomegranate juice has risen dramatically in Europe and North America. This demand arises at least partly from the medical benefits of the anti-oxidants present in the juice.

In one test, a large number of commercial juices were acquired at local markets. Large differences in color, suspended solids, and, especially, flavors were noted. Overall, the juice tastes somewhat like bitter cranberry juice. It is apparent that the flavor is affected adversely by the presence of tannin in the juice.

A pomegranate is a very round fruit, about the size of an orange. It has a hard, red outside skin. Inside are arils that grow attached to either a thin membrane or a pulpy mass of yellowish-white material.

The arils are a watery red color, about the size of half a pea. These arils are juice sacks with a tough outer membrane, containing a seed and a lot of juice. When the tough outer membrane is burst, juice flows freely. Juice yield of 90% was obtained when pressing arils. Overall, two-thirds of the weight of a pomegranate is made up of arils.

The juice from the arils of mature fruit is high Brix, up to 18o. The pH is very low, someplace between 2 and 4 pH.

The problem with pomegranate juice is separating the arils from the skin and white membrane. Bitter off-flavor is added to the juice by the tannin in the membrane. Hand picking the arils from the fruit is too slow a process to be commercially viable.

Investigation revealed a number of methods employed to separate arils. Tumbling the fruit in a machine like a grape destemmer reportedly works in India. In Georgia (ex-USSR) the fruit was lightly crushed and squeezed between rollers, prior to removing a patch of skin so that the juice could be expelled by hand squeezing. One juicer slices the fruit in half and then uses a hemispherical reamer, much like a Brown orange juice extractor. Similarly, the FMC orange juice extractor has been used, with limited results so far. In addition, experiments have been run with vibratory screens and flotation. (The arils sink but the membrane floats.)

A number of tests were run using the Vincent screw press. Everything from pure arils to whole fruit was fed into the press. The results, especially in terms of juice yield, were excellent.

It would appear that to produce consistent, high-quality juice, the use of debittering technology should be considered.

 

Issue 182


 

Pumpkin Cannery

September 10, 1998

Our first Fiber Filter installation is at the Nestle pumpkin cannery in Morton, Illinois. This cannery operates at rates of up to one hundred tons per hour each year during a season that lasts only fifty days (68 days this year due to California weather). During the entire season employees work 12 hour shifts, 7 days a week. The Libby's brand pumpkin is produced for retail sale, while larger containers are canned for institutional customers.

In a pumpkin cannery the pumpkins are first washed. Then the pumpkins are sliced into chunks and conveyed to Wilter cookers (or blanchers). These are stacked screw conveyors, about 20' long, 4 high, heated with steam. In operation each Wilter drains 50 gpm of 5º Bx liquid. This liquid is mostly juice blanched from the pumpkin, along with steam condensate.

There is a faint percentage of fiber in this drain water. Two years ago a rental CP-6 press was used in an effort to capture the material. The operation was marginal because all of the fiber was forced through the screen of the press at anything above a minimal cone air pressure. Nevertheless Nestle purchased a Model VP-12 screw press.

The installation was not acceptable. The press lacked capacity, and too much fiber went through the screen. The 500 gpm (maximum) flow was way too dilute for a screw press.

The situation has been salvaged by substituting a Model FF-12 Fiber Filter for the screw press. The sludge produced is in the desired range of 8% to 9-1/2% solids. It is noteworthy that since the dissolved sugars are 5º Bx, this means that the insoluble fiber solids in the sludge are actually in the range of 3% to 4-1/2%.

The customer has installed a pressure booster pump for use with the cleaning system. This provides 400 psi at the spray nozzles of the Fiber Filter. It was found advisable to spray the fabric sleeves of the Fiber Filter once a shift.

The sludge from the Fiber Filter is pumped back into the flow of good product to be canned. A progressive cavity (Moyno) pump is used to pump the sludge to an FMC finisher.

The fabric sleeves being used have a relatively large rating of 130 microns. This was selected so that grit, which comes embedded in the pumpkin skin, will pass through the screen and into the wastewater flow.

Issue 83

Seaweed

June 10, 1998

Last year we rented three machines to a seaweed processing factory in southern Chile.  Our client, Danisco Ingredients, uses carrageen seaweed as a raw material.  They produce carrageenan, a food additive that is extracted from the seaweed.

Danisco purchases red, black and narrow leaf carrageen.  The red is harvested by underwater divers using helmets and lead boots.  The black washes up on the beaches, and the narrow leaf is picked by women and children from rocks at the ocean's edge.

The rental machines on test are a Vincent triple pass rotating drum dryer, a Vincent horizontal shredder with narrow blades, and a "soft squeeze" KP-6 press.

The VS-35 Shredder has worked very well, both on baled dry material and on seaweed fresh from the fishing boats.  Initial plugging was overcome by going to a discharge screen with large 2-1/4" holes.  The one remaining problem has been blade damage arising from rocks to which the seaweed is attached.

The dryer has also worked very well.  The seaweed goes through a sticky stage as it is dried from 82% down to 18% moisture. However, it has not adhered to the inside of the dryer, so the product recirculation feature does not appear necessary.

Most tests were run feeding two to four pounds per minute into the dryer.  Gas recirculation was not used in order to keep down the wet bulb temperature.  The highest temperature material can reach in the dryer is the wet bulb temperature (dew point), and it is felt that the viscosity of the carrageenan produced might be adversely affected by exposure of the carrageen to high temperature.

It is not possible to remove any moisture at all from the seaweed with a screw press.  We tried shredding, macerating, and adding lime; nothing worked.  However, the press worked well at removing free water from previously dried seaweed that was later washed to remove sand and rocks.  In one test moisture content was reduced from 68% to 60%.

A full scale wash/shred/dry/bale process has been proposed.

[February, 2009  A couple years ago Danisco relocated an old Vincent dryer to this factory.  The engineer we worked with in 1998, Alejandro Martinez, is now the plant manager.]

Issue 78

 

Seaweed Pressing

December 12, 2010


Pressing News #78 describes our failure in 1997 to dewater seaweed with a screw press.  Off and on since then we have worked with seaweed, always with about the same poor results.

Processors who work with seaweed work with red, brown, green, and black varieties. These have come to Vincent from the Philippines, the Canadian Maritimes, Chile and Ireland. The products manufactured from seaweed are food additives (carrageenan), alginate (a gum), pharmaceuticals, and agricultural fertilizer.

Seaweed, a range multicellular alga, has moisture contents of 79% to 82% when harvested fresh. Processing generally requires that the seaweed first be dried to 18% moisture content. Mechanical removal of the moisture (as with a screw press) has the obvious thermal advantage over using a rotary drum dryer.

Recently we ran tests on brown seaweed from Nova Scotia. This material was sent to us by Eurocan Bio-Marine. It had been diluted to 11% solids in a grinding process. First we ran our sample through a Fiber Filter in an effort to remove the water that had been added. The results were disappointing, but they did show promise: the solids were increased to 13%.

This material with 13% solids was fed into a CP-4 laboratory press. As with our previous efforts, nothing was achieved. The seaweed cake came out still at 13% solids.

Next we injected steam through the resistor teeth of the press. Temperatures of 165° F were achieved at the inlet; 155° F at the cake discharge; and 145° F press cake temperature. The solids content of the press cake increased to 16%.

Our next effort was to wash the 13% solids material with 70% isopropyl alcohol. The seaweed was mixed with a 1:1 ratio of alcohol. It was not practical to go through a three stage counterflow wash system. So the mixture of ground seaweed with an equal proportion of alcohol was run through the press. During this testing we continued the steam injection. The result was press cake with 25% solids content.

This is the best we have ever done with seaweed. And it is probable that even better results are feasible. We have experience that indicates that an alcohol counterflow wash system may allow a higher solids content to be achieved. We look forward to another round of testing.

Issue 228


Soybean Protein Concentrate

March 28, 1995
Rev. September 2012

Vincent has screw presses in Holland, Israel, France, China, Russia, and the United States in an alcohol washing process.  The process is used to produce protein concentrate from soybeans.

Following harvest, vegetable oil is extracted from soybeans.  This is done by flaking the beans and then running them through a solvent extraction process.  A final step involves low heat hexane removal systems of "flash desolventizing" or "Down Draft Desolventizing", which leave an oil-free and hexane-free material.  This material is known as "white flake".  (Vincent is not involved in any part of this industrial process.)

SPC (Soybean Protein Concentrate) can be separated from white flake.  The solubles (mainly sugars) in the white flake are removed (diffused) through washing with aqueous alcohol.  Vincent screw presses remove as much of the remaining alcohol, water, and sugar as possible.  Finally the product is run through desolventizing equipment to remove all traces of alcohol and to reduce the moisture to around 8%.  The product produced in this manner, SPC, is rich in protein.

The screw presses used in this application are special.  Since the soybean material performs much like sawdust or ground corncob, very low press cake moisture (in the range of 50% to 56%) can be achieved.  However, it takes more horsepower than normal, and an unusual screw is required in the press.  This screw design was developed by Daniel Chajuss of Hayes General Technology Company, a pioneer in the industry.

Furthermore, because of the alcohol that is present, the machines are made in an explosion-proof configuration.  Bolted vapor tight covers are used throughout.  Under safety codes, V-belt drives cannot be used, so in-line drives are necessary.  As a result, vapor tight presses are longer than normal.

European ATEX (“Atmosphères Explosibles”) standards for vapor-tight presses have required the addition of features such as the use of RTD's (resistance temperature detectors) and ATEX certified motors and gearboxes.  Vincent presses meet these requirements.

In the 1900's, most SPC presses were Model VP-16's.  These are used for processing 50 metric tons per day (MTPD) of white flake, which results in an output of 1.5 metric tons per hour (MTPH) of SPC.   More recently, the wider adoption of SPC as an animal feed, especially for commercially grown fish, has led to the use of Model VP-24 presses.  These will handle 100 MTPD of SPC or more.  Larger scale projects are being designed which are likely to use twin screw presses in order to achieve the higher capacity requirements.

Originally SPC was used primarily as a premium ingredient in the food processing industry.  Because of its blandness, palatability, and freedom from deleterious and antigenic components, as well as its ability to take flavorings, it is used to extend, and substitute for, many foods.  It is used in meat, poultry, fish and milk products.  It is also important as a milk replacement in feed for calves and piglets, as well as being used in pet foods.  Soy protein concentrate is used in powder, textured, and highly functional and soluble "refolded" forms.                                        

A by-product of this process is a molasses.  When the alcohol is recovered from the press liquor of the screw press, there is residual water and sugars.  This flow is concentrated in an evaporator, producing molasses suitable for animal feed.

This is an unusual market niche in which Vincent has specialized.  While we are experts on the screw presses that are required, we refer broader technical inquiries to Hayes General Technology in Israel.

Model VP-30 Screw Press Vapor Tight Configuration Model VP-30 Screw Press Vapor Tight Configuration

MODEL VP-30 SCREW PRESS -- VAPOR TIGHT CONFIGURATION

Model VP-30 Screw Press Vapor Tight Configuration Model VP-30 Screw Press Vapor Tight Configuration

 

Issue 24

 

 

Sugar Beet Chips

March 15, 1993
(Rev. Sept. 1996)

The press order most recently booked by Vincent Corporation involves a new application for the Company. A VP-12 press will be used to dewater pulp made from sugar beet chips.

Sugar beet chips are small pieces of sugar beets. These pieces are knocked of the fresh beets as they are shipped to, delivered, washed and culled at factories that produce sugar from sugar beets.

The press will be installed at one of the beet processing plants of Western Sugar Company. Until this time, the plant has dumped the chips in a pond where they have been a malodorous nuisance.

In the test installation the beet chips will be run through a miniature diffuser where some of the sugar content will be extracted. The beet pulp that is removed from this process will be pressed in the Vincent press. The press liquor, with its sugar content, will be returned to the diffuser. The press cake will be sold to a feed milling operation where it will be blended with other feedstuffs.

The throughout of beet chips is expected to be about 3,000 pounds per hour. This quantity could be handled adequately with a small VP-6 press. However, the Western Sugar operation will do the job with a VP-12 press. The reason for the oversize press is that the machine was selected primarily to process alfalfa into leaf protein concentrate during the off season. The larger fifteen horsepower VP-12 was required for pressing alfalfa. To make the same machine operate satisfactorily on the small quantity of beet chips, a conversion kit is being provided to cut the horsepower down to five and to cut the speed of the machine approximately in half.

We will look forward to reporting actual performance results of this machine later this year.

ADDENDUM, SEPTEMBER 1996  This press is currently in service at Western Sugar dewatering waste vegetation that is received at the sugar mill.  The press cake is mixed with sugar beet pulp that remains after the sugar is removed. All of this material is dried in a rotating drum dryer and pelted for sale as animal feed.

Issue 1

 

Sugar Cane

May 17, 1995
Rev. February 1998

Vincent presses are not used to squeeze the juice out of sugar cane. The presses that are used for this application are quite different: they consist of huge rollers that crush the cane between them, like immense steam rollers.

On the other hand, Vincent presses found service in two different sugar cane applications in 1995.

One application was part of a University of Florida project funded by the DOE. It involved an effort to reclaim the lands left from phosphate strip mining operations. Dr. Ashley Vincent, through Savant Vincent, the consulting firm that he heads, was retained for a portion of the project.

Four different varieties of sugar cane were grown on the reclaimed lands. These canes, complete with leaves and tassel, were harvested, shredded, and run through a Vincent VP-6 screw press. The inbound material was split roughly 50/50 into press cake and press liquor. It was hoped that the press liquor could be economically further processed into ethanol. The press cake is suitable for animal feed.

A second application involving sugar cane started with a telephone call from a research scientist who saw our ad in a trade journal. His project required testing with 10" and, later, 16" presses at a sugar plantation in southern Florida. Pilot operations were conducted by a joint venture formed between a large growers' co-op and an even larger flavors and fragrance firm.

Their efforts are directed at extracting certain essential molecules from the leaves on the top of the cane. After harvesting and shredding, these leaves are run through a Vincent press. The characteristic 50/50 split is achieved. The duty is heavy, requiring extra horsepower. Currently the site has one VP-22 is in service on a semi-commercial basis.

Pilot operations such as these are exciting because of the potential they represent. Should the processes prove economic, there would be a need for multiple, large capacity presses.

Issue 26

Tequila

October 24, 2004

Vincent has been working with tequila distilleries in the Guadalajara area of Mexico.

Tequila is produced by fermenting the juice from the agave plant. Agave is a leafy cactus, like the yucca, aloe vera and century plants. It takes seven years to grow. At maturity there is a central fibrous ball from which the leaves grow. The leaves are discarded at harvest, and the central ball is transported to the distillery.

These balls are heavy and large, about two feet in diameter. There are two ways in which they can be processed.

Traditional processing calls for cooking the balls for 24 to 36 hours. This is done in steam chambers. Following cooking, the balls are run through large hammer mills, or hog mills. These shredders resemble those that is used at paper mills to chop tree trunks into chips.

The chipped agave is run through three or four stands of roller mills. These mills are small versions of the roller mills that are used for pressing sugar cane. Juice is forced from the agave in these roller mills. The juice is filtered, fermented and tequila whiskey is produced.

The largest tequila producer is Jose Cuervo. Their Los Camiches Distillery in La Laja uses diffuser technology instead of roller mills. The agave is not cooked. Instead it is simply shredded and fed through the diffuser. The diffuser is similar to a Crown Iron Works extractor, with the material conveyed by drag flight conveyers instead of trays. Hot water is sprayed from above. In its passage through the diffuser, Brix (dissolved sugars) in the agave are reduced from typical 20º degrees Brix to about 2° Bx. Upon leaving the diffuser, the agave is fed to screw presses, where the last moisture and dissolved solids are recovered.

The liquid from the diffuser, plus the press liquor, is filtered, cooked, and then fermented. The remaining fiber (press cake) is either composted or used as animal feed.

Testing with the Fiber Filter has proven unsuccessful due to the very fine nature of the fiber particles in the flows. However, screw press operations show much more promise.

Issue 166

Vapor Tight Screw Presses

February 18, 2002

Recently a very successful start-up of two Model VP-22 screw presses was accomplished. These machines are unusual in that they were made in vapor tight construction. The presses are being used to separate aqueous alcohol solution from pectin.

The customer is CP Kelco, formerly Copenhagen Pectin. Their factory in Denmark is the world's largest producer of pectin, a food ingredient which is extracted from dried citrus peel. The raw material, dried lime, lemon, grapefruit, and orange peel, is purchased from citrus processors around the world.

The pectin is extracted from the peel with acid followed by isopropyl alcohol (IPA) precipitation. The product goes through various wash stages before final pressing ahead of drying. Vapor tight covers contain the IPA fumes, which can be explosive.

Currently Vincent has another vapor tight press under construction. It is a VP-16 that will be used in the production of Soybean Protein Concentrate (SPC). This is a traditional application for Vincent screw presses. In the process aqueous ethanol is pressed from the soybean protein ahead of a steam dryer. The installation will be in Haifa, Israel, with start-up scheduled for later this year. (See Pressing News #24, Solvent Extraction.)

Another machine, a CP-6, is being designed for Crown Iron Works of Minneapolis. This press is proposed to be used to separate methanol solution from a material similar to pine needles. This installation will be on Prince Eduard Island, Canada.

The machines reflect safety concerns because of the alcohols that are present. Explosion proof motors are supplied. Another feature is the use of bronze fasteners to prevent sparking. Because of the potential for fire, V-belt drives cannot be used, so in-line drives are necessary. Bolted vapor tight covers are used throughout, usually with Pyrex portholes that include manually operated wipers. These design features assure compliance with safety codes.

Issue 125

Vapor Tight Screw Presses II

June 28, 2007

The production of many food ingredients requires the separation of aqueous alcohol solution from the product. This is accomplished in a screw press of vapor tight construction. The design and construction of such presses is a specialty of Vincent Corporation of Tampa, Florida.

Machines used in potentially explosive atmospheres require careful consideration of safety factors. Use of explosion-proof motors and vapor-tight covers, as well as avoidance of belt drives, are obvious items. More importantly, the design must avoid the possibility of metal-on-metal rubbing. The European ATEX regulations are very demanding.

The final moisture content of the press cake is controlled by the air pressure on the discharge cone of the screw press. The discharge cone of modern Vincent presses is actuated by dual air cylinders. This design is especially good in vapor-tight applications as it puts the air cylinders and thrust bearing outside of the vapor-tight compartment.

The design of the covers for vapor-tight presses has been improved as a result of work with CP Kelco in Denmark. A 3/4" O-ring of solid Silicone is mounted in a pocket that follows the perimeter of the cover. The cover itself is a honey-comb structure that minimizes warpage. This simple design provides reliable sealing while greatly reducing the number of clamps required.

In some applications there is a need to strip the press cake away from the discharge. This is done by having the discharge cone rotate along with the screw of the press. A much-simplified mechanism is being used to drive the discharge cone when the rotating cone feature is specified. This has greatly reduced the cost of the option.

The key markets for vapor-tight screw presses include the production of pectin and soybean protein concentrate. Pectin is extracted from citrus peel, apple waste, as well as sugar beet pulp. Some work has been done with facilities producing Xanthan gum.

The trend is toward larger and larger screw presses. The traditional 16" press, used for many decades, lost favor to the VP-22 for soybean applications at ADM in the 1990's.

This same design was selected for citrus pectin production by CP Kelco in 2000. In 2005, 24" presses were supplied to Danisco and a Chinese firm, for citrus and apple pectin respectively. More recently, Archer Daniels Midland has selected the 30" press.

As a rule, these presses are driven by VFD's. Baldor and Siemens explosion-proof motors are now available that are rated for operation over an extremely wide range, 9 to 90 Hertz.

Issue 188

Wet Corn Milling

July 2, 2012
 

Vincent is a very old screw press company, but with only a recent entry into wet corn milling.  We only have a few installations to point to, but we definitely have our foot in the door.

Wet corn milling is the process by which corn is separated into its four basic components:  starch, germ, fiber, and protein.  Once separated, fiber and protein are made into animal feedstuffs; germ is refined into corn oil; and starch may be further refined as sweeteners, starches with specific traits, bioproducts or ethanol.

Dewatering the corn fiber left over after separation of the valuable starch and germ (which contains the oil) is our major application.  In the process of making animal food from this by-product, the fiber is dewatered ahead of a dryer.  This means that maximum moisture removal is important.   Our first installation was at Pendik Nisasta in Turkey.  This is a small mill, but a major USA firm is in it as a joint venture partner.  They replaced two worn out Vetter fiber presses with Vincent presses a couple years ago, and they have been pleased with the performance.

After that we supplied a small fiber press to GPC in Muscatine.  It replaced a Merconi C-400 bowl centrifuge.

We have had two interesting applications with Tate & Lyle.  At their Louden, Tennessee mill they put in Model KP-24 presses to dewater fiber containing 40% residual starch.  This was part of an ethanol production process likely to be modified next year.  The application was challenging because fiber with that high a starch content does not want to give up its moisture.  But the presses turned out well.

These same KP-24 "soft squeeze" presses were purchased for the Tate & Lyle mill in Ft. Dodge, Iowa, for the same process.  These were never installed, and one ended up in their Lafayette, Indiana (south) mill.  There it was placed as a pre-press ahead of existing Vetter fiber presses.  This double pressing arrangement proved very successful in allowing the mill to sustain constant peak throughput capacity.  At the same time they picked up 0.5% starch recovery.  Plus energy savings.  As a result an additional KP-24 was purchased for another line.

Most recently Vincent has booked an order for three Model VP-24 presses.  These will be used on fiber, ahead of the dryer, in the GPC Muscatine, Iowa mill.  This order followed a series of maintenance inspections and performance tests of the smaller rental press, which they purchased.

Vincent presses have proven to work well on foots.  Our experience has been mostly with soybean foots, although we did some successful testing at a major IOWA corn mill a couple years ago. 

Another area of interest has been dewatering corn germ.  Germ must be dewatered before it is sent to the oil extraction facility.  We did have success on corn germ at the Corn Products' Cardinal, Ontario mill several years ago.  But the project did not go ahead; chalk it up as one more technical success but commercial failure for Vincent.  We do expect to undertake a serious corn germ project fairly soon.  We feel that our Series KP presses will prove suitable replacements for Frannino presses in this application.

Vincent now has a rental fleet of almost 200 of our screw presses!  This gives us great flexibility for on-site testing.  This rental fleet has been invaluable in our work in wet corn milling. 

Issue 247

Hydrocolloids

September 3, 2012
 

Hydrocolloids are a major group of chemicals most people have never heard of.  They serve very important functions both as food ingredients and for industrial applications.  The three principal hydrocolloids are pectin, xanthan gum, and carrageenan.

For many years Vincent screw presses have been used in the production of pectin, a polysaccharide food ingredient used for thickening.  Since most pectin is extracted from lemon and lime peel, we probably got into this market because of our roots in the citrus industry.  What was different about the pectin presses was that they had to be manufactured in a vapor-tight configuration.

Vapor tight presses are also suitable for other hydrocolloids where flammable solvents are used, including xanthan gum.  Xanthan gum is produced using a grain (usually corn) fermentation process.  Alcohol is used to precipitate and wash the gum following fermentation.  The flow from the fermenter may or may not be pre-thickened ahead of the screw press.  If pre-thickening is used, generally this is done with a screen.

For xanthan gum, as with pectin and soybean protein concentrate, vapor-tight presses are used to separate the aqueous alcohol solution ahead of a dryer.  Safety standards for our presses, especially those built with the European ATEX certification, are very stringent.  Explosion proof motors and tightly sealed covers are just a start.  Today RTD's (remote temperature detectors) are installed on the cone bushings, bearings and other potential hot spots.  Besides temperatures, a variety of other variables should be monitored.

Inert gas, usually nitrogen, may be pumped into the press compartment containing the screens.  The system can be either slightly pressurized so that air does not leak in, or under a slight vacuum to prevent alcohol from leaking out.  An oxygen meter may be used to monitor the oxygen concentration inside he press.  The system can be designed with alarms and automatic shutdown if the oxygen concentration increases above safe levels.

The cake discharge is usually enclosed, but it works well in an "open to atmosphere" system.  Ventilation can be used to ensure that the solvent concentration stays below the lower explosive limit.

Products related to xanthan gum include welan and gellan, with gellan gum falling in the food-grade category.  It is promoted as an alternate to pectin.  Welan is used industrially in applications such as oilfield drilling mud.  Gums used in frac drilling are vital and highly specialized.

 

In Wikipedia we read (somewhat edited for brevity):

Xanthan gum was discovered by an extensive research effort by Allene Rosalind Jeanes and her research team at the United States Department of Agriculture, which involved the screening of a large number of biopolymers for their potential uses. It was brought into commercial production by the Kelco Company under the trade name Kelzan in the early 1960's.

One of the most remarkable properties of xanthan gum is its ability to produce a large increase in the viscosity of a liquid by adding a very small quantity of gum, on the order of one percent. In most foods, it is used at 0.5%, and can be used in lower concentrations. The viscosity of xanthan gum solutions decreases with higher shear rates.  This means that a product subjected to shear, whether from mixing, shaking or even chewing, will thin out, but once the shear forces are removed, the food will thicken back up.  A practical use would be in salad dressing: the xanthan gum makes it thick enough at rest in the bottle to keep the mixture fairly homogeneous, but the shear forces generated by shaking and pouring thins it, so it can be easily poured.  When it exits the bottle, the shear forces are removed and it thickens back up, so it clings to the salad.

In foods, xanthan gum is most often found in salad dressings and sauces. It helps to prevent oil separation by stabilizing the emulsion, although it is not an emulsifier. Xanthan gum also helps suspend solid particles, such as spices. Also used in frozen foods and beverages, xanthan gum helps create the pleasant texture in many ice creams. Toothpaste often contains xanthan gum, where it serves as a binder to keep the product uniform.  Xanthan gum also helps thicken commercial egg substitutes made from egg whites, to replace the fat and emulsifiers found in yolks.

In the oil industry, xanthan gum is used in large quantities, usually to thicken drilling mud. These fluids serve to carry the solids cut by the drilling bit back to the surface.  When the circulation stops, the solids still remain suspended in the drilling fluid. The widespread use of horizontal drilling and the demand for good control of drilled solids has led to its expanded use. It has also been added to concrete poured underwater, to increase its viscosity and prevent washout.

In cosmetics, xanthan gum is used to prepare water gels, usually in conjunction with bentonite clays. It is also used in oil-in-water emulsions to help stabilize the oil droplets against coalescence. It has some skin hydrating properties.

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