Impact of power ultrasound on the quality of fruits and vegetables during dehydration

摘要

In the present work, the influence of power ultrasound (US) on the quality of fruits and vegetables during both the pre-treatment and drying has been evaluated. Chemical indicators such as pectinmethyl esterase and peroxidase enzymes, vitamin C, carbohydrates, proteins, polyphenols and 2-furoylmethylamino acids (indicators of the early stages of Maillard reaction) have been studied. In addition, rehydration capacity, leaching losses and shrinkage and organoleptic characteristics of the final product have also been assessed. During blanching, similar leaching losses and enzyme inactivation were found in low temperature and prolonged conventional treatments and in US processes, but with a significant reduction in the time for the latter. Finally, application of US in drying of carrots and strawberries originated significant reductions in processing time, while providing high quality end-products. The quality was higher as compared to marketed products and superior or equivalent to samples obtained under similar conditions in a prototype convective dryer, and, in the case of some indicators, similar to that of freeze-dried samples.