45F-22 |
Accelerated shelf-life studies of dehydrated strawberries pretreated by vacuum impregnation with nutraceuticals |
J. Xie, Y. ZHAO, and C. Han. Dept. of Food Science & Technology, Oregon State Univ., 100 Wiegand Hall, Corvallis, 97331-6602 Vacuum impregnation (VI) is considered as a useful method to decrease moisture content and introduce desired solutes into the porous structure of food and to conveniently formulate the product without destroying its structure. VI may be used as a pretreatment before drying to improve quality, save energy during the final drying stage, and develop nutrtionally fortified products. The objective of this study was to study the shelf-life of dehydrated strawberries pretreated by VI using calcium and zinc for improving quality and enhancing nutrtional value of dried strawberries. Strawberry was vacuum impregnated in 50% w/w diluted high fructose corn syrup with or without 12% w/w calcium gluconal and 0.04% w/w zinc lactate for 15 min, then osmotic dehydration for 2 hr in the same solution. After pretreatment, strawberries were dried in a freeze dryer for 96 hr and then vacuum packaged in polymer bags. The shelf-life of dehydrated strawberry was studied by using accelerated shelf-life method at 5ºC, 21ºC and 38ºC. Changes in color, weight loss and rehydration of dried samples were mornitored during 11 weeks of storage. Arrhenius equation was used to establish a theoretical shelf-life as a function of temperature. Our results showed that VI pretreatment with calcium and zinc did not change water loss and rehydration capacity of dried berries during storage. VI pretreatment with zinc improved color stability, and high concentraiton of cacluium may darken the surafce color of dried berries depending on the storage temperature as high temperature speeded up surface brown discoloraiton. VI prerteratmen with calcium and zinc fortified calcium and zinc content to 15% and 20% DRI value, respectively in 200 g of dried strawberries. Vacuum impregnation using nutraceuticals as a pretreatment of drying could be an effective way to produce high quality and nutritionally fortified dried strawberries.
Session 45F, Fruit & Vegetable Products: Fruits (Fresh)
|