Influence of freezing and drying on phytochemical properties of various fruit

Gennadiy Vyacheslavovich Semenov, Irina Stanislavovna Krasnova*, Oleg Aleksandrovich Suvorov, Irina Dmitrievna Shuvalova and Nikita Dmitrievich Posokhov

Moscow State University of Food Production, Talalikhina Street 33, Moscow 109316, Russia

DOI : http://dx.doi.org/10.13005/bbra/1786

ABSTRACT: Initially the total antioxidant activity, the total flavonoid contents, the total phenolic contents and the ascorbic acid were measured in fresh fruits. Then samples for freezing and vacuum freeze-drying were frozen what led to a decrease in total antioxidant activity by 11% (persimmon) - 28% (kiwi fruit), a reduction of total phenolic and total flavonoid contents for about 10% and the content of ascorbic acid decreases by 8% (kiwi fruit) - 30% (apple). The remaining frozen purees were subjected to vacuum freeze-drying at the temperature plus 25-27 ºC and a chamber pressure of 80 Pa in the primary drying and the temperature plus 38-40 ºC and a chamber pressure of 80 Pa at the secondary drying. The total antioxidant activity of freeze dried samples in comparison with fresh fruit decreased by 20% (persimmon) - 50-55% (apple), the total content of flavonoids and phenolic compounds decreased by 20-30%, reduction of the ascorbic acid ranged from 23-29% (apple and persimmon) to 55% (pear). The other part was subjected to convective drying and as a result the total antioxidant activity decreased by 46% (persimmon) to 68% (pear and apple), the total content of flavonoid contents compounds decreased by 42% (apple, kiwi, persimmon) - 56% (pear). The total content of phenolic compounds in all samples decreased by 40-45% and the content of ascorbic acid reduced by 45-55%. The study results demonstrated that the antioxidant properties of the fruits studied in the following order: fresh fruit> frozen fruit> freeze-dried fruit> convective dried fruit.

KEYWORDS: Total antioxidant activity; total phenolic contents; total flavonoid contents; sensorial analyses; apples; pears; kiwi; persimmon; coulometry; freeze-drying

[ HTML Full Text]