Influence of Home-Scale Freezing and Storage on Antioxidant Properties and Color Quality of Different Garden Fruits

Banat’s University of Agricultural Sciences and Veterinary Medicine, Faculty of Food Processing Technology, Food Technology Department, Calea Aradului No. 119, 300645, Timisoara, Romania


POIANA, M. A., D. MOIGRADEAN and E. ALEXA, 2010. Influence of home-scale freezing and storage on antioxidant properties and color quality of different garden fruits. Bulg. J. Agric. Sci., 16: 163-171

The goal of this study is to investigate the influence of home freezing and storage at -18°C up to 10 months on the antioxidant properties and color indices of selected fruits species: strawberry (Fragaria ananassa), sweet cherry (Prunus avium L.) and sour cherry (Prunus cerasus L.). Samples were extracted and subjected to analyses for total phenolics content, total monomeric anthocyanins, vitamin C, antioxidant activity and color indices. The content of total phenolics was analyzed by Folin-Ciocalteu colorimetric method, total anthocyanins were evaluated using pH-differential method, vitamin C content by 2,6-dichlorophenolindophenol method, antioxidant activity using FRAP assay and color indices of extracts by bisulphite bleaching method. Sour cherries contain the highest amounts of polyphenols, anthocyanins and antioxidant activity among the investigated fruits species. The highest content of vitamin C was found in the fresh strawberries. After freezing, small losses were recorded for investigated bioactive compounds and color indices of fruits, because the home-freezing is a non destroyed preservation method. The storage up to 4 months did not significantly affect the bioactive compounds and color indices of investigated fruits. After a period of 10 months storage, phenolics content in frozen fruits decreased up to 28-47% of the initial value; the total anthocyanins is preserved in proportion of 80-91% of the initial value, the vitamin C content is kept at 62-76% of the initial value. By home-scale freezing and storage for 10 months, the smallest losses of antioxidant activity were recorded for sour cherries and the biggest for strawberries.

Key words: frozen fruits, vitamin C, polyphenols, antioxidant activity, anthocyanins, color indices

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