Our knowledge of how our press performs in pineapple is very limited. We know of installations in Honduras, Brazil, Venezuela, the Philippines, and Japan where a Vincent screw press is used in making pineapple juice, but we have had almost no significant contact with any of them for many years. Many of the sales were made through the late Art Lund, a sales agent, and we have no data as to the actual operations. As recently as 1998 we supplied a VP-16 for use in a pineapple operation in Costa Rica.
Some notes indicate we should expect a 42% to 48% juice yield, and that the press should have the rotating cone option. Other notes show 50% yield and that the rotating cone is not necessary.
The process in Honduras involves first trimming the pineapple and then crushing it in a Vincent shredder. Next the crushed material is run through a Vincent screw press. We are not sure but we believe they add water to the press cake and then press it again. In any case, the press liquor is run through Brown or FMC finishers.
In Okinawa they have two presses. One VP-12 is fed the culls and odd pieces of pineapple for juicing. The second, a smaller VP-10 press, is used to press the pulp wash. It is likely that the press cake from the VP-12 is washed to diffuse the remaining sugars, and then re-pressed.
One press in Brazil has been in service for almost 30 years, and it is operating successfully to this day. Benedito Jorge, now a director of Citrosuco, has been involved with this press from the very start.
The Ginaca machine is used to core and skin the pineapple; the plug of fruit produced is sliced into the familiar canned fruit salad item. We have observed that the Ginaca works best on green fruit, and the skins and trims from such fruit are relatively slimy and do not press well. Consequently, when pressing trim from Ginaca machines it is common to de-rate the brochure capacity figures of our presses.
With FMC Italy's help we did a process chart in 1996 where 20 MT/HR of topped, skinned and cored pineapple are run through an FMC Paddle Finisher. Free running juice and the juice that can be easily separated are recovered.
The pulp (pomace) discharged from the Paddle Finisher is further squeezed in a Screw Finisher. The pomace discharged by this Finisher still contains juice. The moisture content is 78% to 80%.
Next the pomace is pressed, without the addition of water, in a Vincent screw press. Normally 8% of the juice recovery is obtained in this press.
There is a letter from the 1970's where we wrote that we had two 10" units, with non-rotating cones, running twelve years in Venezuela (24 hour day during a six month season). Whole mature fresh Spanish Reds, at 85% moisture, less tops, produced juice at 10Âº to 13Âº Brix. They used 3/32 perf screens, and reportedly the press met its 10,000 pph capacity rating and ran consistently with a 50/50 split between juice and cake, with some runs of 60% juice when at 13Âº Bx. The speed was increased from the normal 21 rpm up to 30 rpm, taking the motor from 5 hp up to 7-1/2 hp. The cone pressure was nominal, 40 psi.
Frequently we find that pineapple plants make use of old Jones screw presses. These are vertical machines, a dated version of the Vincent horizontal interrupted screw design.