88E-26 |
Impregnation properties of strawberry under sub-atmospheric conditions |
W. C. JORGE, Ingenieria Quimica y Alimentos, Universidad de las Americas-Puebla, Ex Hacienda Santa Catarina Martir, Cholula, Puebla, 72820, Mexico, M. P. Hugo, Facultad de Ciencias Quimicas/Secretaria de Investigacion, Universidad Autonoma de Chihuahua, Ciudad Universitaria S/N, Chihuahua, 31170, Mexico, and V. F. Aurora, Facultad de Ciencias Químicas/ Secretaria de Investigacion, Universidad Autonoma de Chihuahua, Ciudad Universitaria S/N, Chihuahua, 31170, Mexico. Partial removal of water and impregnation of solutes through the dehydration-impregnation process is applied to improve quality and extend shelf-life of fruits and vegetables. The dehydration-impregnation process under vacuum conditions is emerging as one that has many advantages. Efficient impregnation is currently dictated by the porosity of the fruit. The aim of this study was to investigate the effect of vacuum, vacuum application time, and relaxation time on the volume of isotonic solution impregnated per unit volume in strawberries. Whole strawberries were placed in vacuum desiccators containing sucrose isotonic solution (12°Brix) in a fruit:syrup ratio of 1:10. Impregnation experiments were conducted at five vacuum levels, five vacuum application times, and five relaxation times ranging from 0 to 659 mbar, 3 to 45 min, and 3 to 45 min, respectively. A central composite design was applied. Using response surface regression analysis on the experimental data, a quadratic model was derived (R2=0.937). It was found that vacuum and relaxation time play significant roles in determining the quantity of impregnated isotonic solution (p£ 0.01). Vacuum application time, on the other hand, had no effect on impregnated isotonic solution. Effective porosity of strawberry was calculated by using the concept of the hydrodynamic mechanism. Effective porosity was 2.2 % on average. The model derived can provide a tool to predict quantitatively the impregnation levels, within the range of experimental conditions.
Session 88E, Fruit & Vegetable Products: Processing
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