Change of the main components of a chemical composition of frozen strawberries under previous treatment in solutions with structure-retaining properties

Abstract

The objective of the research lies in the study of the main indices of the chemical composition of strawberries during freezing and storage under its previous treatment in solutions with structure-retaining properties. The main indices of the chemical composition of strawberries during freezing and a six-month storage under previous treatment in the solutions with structureretaining properties were studied, namely in 1 %, 2 % and 3 % solutions of potato starch and 1 % and 2 % sugar-pectin solution. The main components of the chemical composition were identified. The content of soluble solids was determined using refractometer, sugar content was measured by means of ferricyanide method, organic acids were identified by alkali titration, ascorbic acid content was determined by iodometric method. It has been found that during freezing and storage of frozen strawberries there are losses of the main components of chemical composition, the amount of which considerably depends on the type and concentration of the solution for treatment. Application of the previous treatment of strawberries before freezing helps to retain the main components of chemical composition of strawberries during freezing and storage. Losses of soluble solids of previously treated strawberries during freezing were by 0,9-1,2 % lower compared to control. Sugar content went down to1,8-3,3 % as the result of freezing. Previous treatment of berries before freezing promotes their preservation by 0,1-0,7 %. Organic acids content in strawberries remained practically unchanged. Ascorbic acid content during freezing of strawberries suffered essential losses that made up 43,8-50,3 % under the lowest in the sample that were previously treated in 2 % sugar-pectin solution and by 13 % lower than in control. During storage the losses of ascorbic acid in strawberries without previous treatment were by 4,4-7,6 % higher.

Quality Investigation of Frozen Garden Strawberries at Partial Dehydration Before Freezing

“…For stabilizing a quality of frozen strawberry, there are recommended solutions with antioxidizing, antiseptic properties that favor preservation of С-vitamin value, among which aqueous extracts from oak bark, birch, tutsan grass and green tea infusion [4], concentrated solutions of saccharose with cryoprotective properties [5]. The positive influence on preservation of the strawberry tissue microstructure is made by solutions of calcium chloride (CaCl 2 ) and pectin methyl esterase, 0.3 % guar gum and 2 % sugar-pectin [6][7][8]. But at these methods of preliminary processing of strawberries before freezing, there appears a necessity to buy auxiliary materials, not always easily accessible.…”