A. Valdez-Fragoso

IMPREGNATION AND OSMOTIC DEHYDRATION OF SOME FRUITS: EFFECT OF THE VACUUM PRESSURE AND SYRUP CONCENTRATION

Apple, mango and melon were subjected to impregnation and osmotic dehydration at vacuum pressure (VI-VOD). The effect of the vacuum pressure (135–674 mbar) and concentration of the sucrose solutions (41–60°Brix) on the mass transfer parameters were evaluated. The lowest final aw levels in apple and mango were achieved with 50°Brix syrup and vacuum pressure of 674 mbar and in melon with 57°Brix and 593 mbar. Water loss of similar magnitude was observed in melon and mango, and there was water gain in the case of apple. The solids gain (SG) in apple was higher than in melon and mango. Minimal values of SG were detected in mango, and a maximum SG value was observed in apple. Melon and mango presented weight losses of up to 8.9% while the weight of apple increased. Results indicated that the impregnation phenomena predominated in the combined VI-VOD process of apple and osmotic dehydration phenomena in melon and mango.

Impregnation properties of some fruits at vacuum pressure

Abstract The effects of vacuum pressure and its application time on the volume of isotonic solution (IS) impregnated in slices of mango, apple, papaya, banana, peach, melon, and mamey were studied using response surface methodology. Fruits were subjected to vacuum impregnation (VI) treatments using sucrose IS. VI times between 3 and 45 min and vacuum pressures (VP) between 135 and 674 mbar were applied. Second order polynomials were developed to estimate the volume of IS impregnated in each fruit (R2⩾0.870). VP had a significant effect (p⩽0.10) on the volume of IS impregnated in fruit slices of all the studied fruits. The impregnation also depended significantly (p⩽0.10) on the VI time, except for apple. Under the studied conditions, the effective porosity values of the fruits varied from 0.016 for mamey to 0.330 for apple.

Coating of Puffed Wheat by a Tumbling Method a Fluidized Bed Technique

Puffed wheat, traditionally consumed as a ready-to-eat breakfast cereal, is normally covered with sweet coatings. To make it more appealing to different tastes and consumers, the coating may also have colored ingredients added. Due to the rugged surface of puffed wheat, colored coats do not totally cover the particulate, causing problems of appearance that may affect overall quality. There is a need to develop uniform coats in order to improve physical properties, such as color and texture. Puffed wheat was coated with sweetened chocolate syrups by tumbling and a fluidized bed. Different proportions of sugar, cocoa, and starch were used to develop the cover and obtain an optimum formulation. The coated wheat was characterized by instrumental techniques. The developed product using the fluidized bed technique presented a firmer consistency and a more uniform color than the tumbling-coated and the commercial wheat.