Drying kinetics and quality characteristics of green apple peel (Mallus communis L. var. “Granny Smith”) used in herbal tea production

摘要

Green apple peels, (25.06 ± 0.06 g) with the moisture content of 3.05 ± 0.02 [kg(moisture) kg~(–1) (dry matter)], were dried using two dehydration methods, microwave,and natural drying until moisture content of apple peels was reduced to 0.092 ± 0.001[kg (moisture) kg~(–1) (dry matter)]. Microwave drying periods at 1,000, 800, 600, and400 W lasted for 17, 21, 27, and 33 min, respectively; whereas, natural drying lastedfor 66 hr. The scope of this study, a comparison of measurements of moisture withthat of the predicted results was made, obtained from 21 thin layer drying models.For both 600 and 800 W microwave drying, Modified Henderson and Pabis's model;whereas, at 1,000 W, Alibas's model, and at 400 W, Modified Jena and Das's modelwere considered to be the most appropriate models. The most suitable drying processaccording to color parameters, chlorophyll content, and nutrients was obtainedat 400 W microwave drying.Practical applicationsThe herbal tea industry is growing globally and it is constanrly looking for new flavorsthat can attact consumers' attention. Herbal teas, in addition to being delicious, arerequired to meet the daily nutritional needs of the consumers. One of the drawbacksof drying is the loss of aroma and nutrients, moreover, drying operations carried outin open fields, such as sun drying, leads to contamination and can cause more harmthan benefit. Thus, for food safety, it is very essential for herbal tea production facilitiesto use appropiriate methods to produce high-quality products. The present studyon drying of apple peels for herbal tea contains important data on the selection of themost suitable drying method for the preservation of nutrients.