Comparison of three drying processes to obtain an apple peel food ingredient

Apple peel, a waste product from dried apple manufacture, has a high content of bioactive phenolic compounds. In Chile ca. 9000 ton of apple peel are generated each year. To obtain a novel food ingredient, we compared three drying processes on Granny Smith apple peel: oven (60°C), drum dryer (110°C), and freeze drying. The influence of each drying technology on the chemical characteristics and antioxidant capacity on fresh and dried peel fractions were determined. The results indicate that all the drying processes affected the chemical characteristics and the color of the ingredient. Total phenolics content and antioxidant capacity decreased significantly in all the products during drying. The preservation of phenolics in apple peel was higher using freeze drying (92%). The drum-drying process retained over 70% putatively healthy phenolics. In addition, this is the most economical system suitable to obtain the apple peel ingredient.