36E-53 |
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W. YUENYONGPUTTAKAL, Dept. of Product Development, Faculty of Agro-Industry Kasetsart Univ., 50 Phahonyothin Rd, Chatuchak, Bangkok, 10900, Thailand, K. Niranjan, School of Food Biosciences, The Univ. of Reading, Whiteknights Po Box 226, Reading, RG6 6AP, England, and P. Wuttijumnong, Dept. of Product Development, Faculty of Agro-industry, Kasetsart Univ., 50 Phahonyothin Rd., Chatuchak, Bangkok, 10900, Thailand. Persimmon (Diospyros kaki) is a tropical and subtropical fruit. In recent year, persimmon has become a familiar fruit in many countries. The leading non-astringent persimmon cultivars grow in Thailand is P2 that contains highly soluble tannin which has to be removed before consumption. P2 is desirable when a product that can be preserved for a long period of time is to be made. Osmotic dehydration enables the partial removal of water by direct contact of a fruit with a hypertonic medium. This gives rise to two major counter current mass transfer fluxes, namely water flow from the product to the surrounding solution and solute infusion into the product. This method can be used as a pre-treatment step prior to further processing. In this work, a ternary aqueous system consisting of sucrose and NaCl was used to elucidate the effects of the concentrations of two solutes on mass transfer from persimmon fruit. The mass transfer parameters were experimentally determined by measuring Weight Reduction (WR), Water Loss (WL) and Solid Gain (SG).The mathematical models as a function of osmotic solution concentration were fitted to 2nd order polynomial. Sucrose and NaCl were shown to have synergistic effect on mass transfer. WL/SG ratio was a good indicator of the extent to which the osmotic solution condition succeeds the maximisation of water loss and minimisation of solid gain. There were increase in WL/SG with increase sucrose concentration in the absence of NaCl, in the same side, trend to higher WL/SG by the increasing of NaCl with the lower sucrose concentration. The response surface plotting of WL/SG ratio were shown the optimise for maximum water loss and minimised incorporation of solids.
Session 36E, Fruit & Vegetable Products: General
2005 IFT Annual Meeting, July 15-20 - New Orleans, Louisiana |