Influence of the addition of increasing amount chestnut shell to bentonite/polyester composites
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Various methods were used to preserve foods since ancient times. Freezing is one of the oldest and most widely used food preservation methods, which allows preservation of taste, texture, and nutritional value in foods better than any other method. As a method of long-term preservation for fruits and vegetables, freezing has been successfully employed to provide a significantly extended shelf life by decreasing water activity, reducing chemical reactions and inhibiting microorganism growth Recently, IQF (Individual Quick Frozen) method, which assures that the better part of the vitamins, antioxidants and fibers of the natural products, is the most preferred freezing technique. The objective of this study is to investigate the effect of storage period on total phenolic contents and DPPH radical scavenging activity of frozen sweet cherry, sour cherry, fig and peaches, which are obtained from Food Freezing Plant located in Bilecik, Turkey. Besides, effect of slicing and pitting on antioxidant activity and total phenolic contents of frozen peaches and sour cherries, which have larger market share. To determine the composition of the fruits, 0Brix, refractive index, pH, titratable acidity, maturity and chemical properties were investigated, firstly. Then, the frozen fruits, which are defined samples from the same lots, were analysed for total phenolic contents by Folin Ciocaltaeu method and DPPH radical scavenging activity during 6 months. The results showed that the maximum inhibition loss% was determined 49.18% in peaches and minimum value of inhibition loss% was 15.55% in sweet cherñes. The highest loss of inhibition% was determined in the peaches and figs, which were frozen with high maturity level. The sweet cherries that have been harvested at the optimal maturity and healthiness level showed the lowest inhibition loss% during storage. Besides, it was established that pretreatments such as slicing and pitting increase loss of inhibition.