The objective of this paper was to determine the influence of different types of drying methods and of the apples drying temperatures on the antioxidant activity of extracts made from those dried apples. The highest capacity to neutralize free radicals was stated in the case of an extract produced from freeze-dried apples. A statistically significantly lower antioxidant activity of them, comparing to raw apples (the antioxidant activity was by 9% lower) was found only when a drying temperature at a shelf was 40°C. At the same time, the content of polyphenols in the dried apples, though irrelevantly decreased, did not statistically significantly differ from their content in the raw apples prior to drying. During the convective process of drying, the antioxidant activity of apples significantly decreased, and reached a level of 60 to 80% of the raw material activity. Similarly, the decrease in the content of polyphenols was approximately 30-35%. A low temperature drying process also caused a decrease in the antioxidant activity, as well as in the content of polyphenols, however, this decrease was not as significant as in the case of drying at high temperatures, though, it was higher than in the case of a freeze- drying process. The antioxidant activity was reduced by about 8 to 27%, and the content of polyphenols by 5 to 9%. No unambiguous influence of the drying temperature level on the dried apples’ quality factors was determined, irrespective of a drying method applied.
convective drying, freeze-drying, low-temperature drying, antioxidant activity, polyphenols