ABSTRACT

The aim of the study was to determine the effect of sugar, pectin preparation, and L-ascorbic acid addition on selected physicochemical traits and organoleptic properties of frozen raspberries. Dry sugar or in the form of 60 % syrup at a dose of 10 g/100 g of fruit was used with pectin or 0.5 % L-ascorbic acid. A 1.5 % solution of the pectin preparation was applied at a dose of 10 g/100 g of fruit alone or with a 0.5 % addition of L-ascorbic acid. Sorted fruits in 500 g samples treated with additives were frozen in plastic containers at -40 C, the storage temperature of -28 - -30 С being reached after about 90 min. The evaluation was conducted at a stage of raw material, directly after freezing, and after 3-, 6-, 9-, and 12-month storage. Fresh fruit contained 13.4 % of dry matter, 4.1 % of total sugars, 2.12 % of acids as citric acid, 48.3 mg/100 g of vitamin C, and 60.8 mg/100 g of anthocyanins. The additives contributed to the differentiation of frozen fruit samples in the level of dry matter, sugars, and vitamin C, and brought about some dilution of the remaining components. Freezing and 1-year storage of fruit not treated with any additives decreased the content of vitamin С in 100 g to 21.6 mg and of anthocyanins to 45.5 mg. In the samples with the additives these values were 23.4-29.2 mg /the samples of an enriched vitamin С content not being taken into consideration/ and 47.1-56.3 mg, respectively. The organoleptic quality of frozen raspberries without additives evaluated in a 5-score scale was 3.78 and that of fruit with the additives 4.21- 4.74. Of the analyzed variants of the additives used in freezing raspberries for direct consumption the 60 % syrup of sucrose may be recommended on account of high organoleptic quality and simple application. The 1.5 % solution of pectin preparation may be used in freezing raspberries for diabetics and the other groups of people who do not tolerate sugar in their diet.