SHELF-STABLE PINEAPPLE SLICES PRESERVED BY COMBINED METHODS

Pineapple slices were treated by two combined methods, packaged and st ored at room temperature. The first preservation method consisted of b lanching pineapple slices at 100 degrees C for two minutes followed by a cooling period of 1.5 minutes at room temperature. The slices were then immersed in a 50% sucrose solution with 1,000 ppm of potassium so rbate and 150 ppm of sodium bisulfite. The osmotic treatment was done at room temperature (28.5 +/- 1.5 degrees C) for 24 hours. The treated slices were removed from the osmotic solution, the excess syrup from the slices was removed, and the product was later packaged in sealed p lastic bags. The final water activity values ranged between 0.95 and 0 .97 for the packaged product. For the second preservation method, the pineapple slices were blanched in saturated steam for 12 minutes and s tored at 12 degrees C until processing by combined methods. Sucrose so lutions (55 and 60 degrees Brix) with four different concentrations of potassium sorbate (100, 200, 300, or 500 ppm) were used as osmotic so lutions. The water activity was 0.91 after the osmotic process and 0.8 8 after hot air drying. A shelf life of at least 30 days was observed for product prepared with both preservation techniques, and the sensor y characteristics noted were similar to those in a commercially canned product (Del Monte canned slices). The inhibitory effect of potassium sorbate on yeast and mold growth was significant for concentrations a bove 300 ppm.