Effect of Different Pre-Treatments and Storage Conditions on Some Quality Parameters of Apple Chips Dried by Vacuum Combined Two Side Infrared Radiation

Abstract

The effect of ultrasound (0, 50, and 100% amplitude), ethanol (0, 50, and 100%), citric acid (0.75%), and their combined application on some quality parameters and microstructure of apple slices dried by novel vacuum combined two-way infrared dryer (275W, 400 mmHg) were investigated. In addition, the changes in quality parameters at 20, 30, and 40 degrees C during 8-month storage were evaluated. The different pretreatments, especially their combinations, had significantly affected the drying time, rehydration rate, color values (L*, a*, and b*), browning index, sugar content, 5-hydroxymethylfurfural (HMF), and sensory properties of the apple slices. The increasing ethanol concentration and ultrasound amplitude shortened the drying time from 110 min to 71 min. The high ethanol concentration combined with high ultrasound amplitude resulted in increased rehydration rate and decreased browning index, HMF, and general acceptance. As a result, the combination of ethanol containing (99.9%) 0.75% citric acid and 100% ultrasound amplitude was the best pretreatment method in terms of drying time, color, rehydration rate, browning index, and HMF content of apple chips.