Resource-saving technologies of refrigeration preservation for the apples of autumn grades
Annotation
Technological parameters of pretreatment and freezing of standard and non-standard fractions of autumn varieties of apples and semi-finished products based on them were investigated and substantiated. The objects of research are selected the high-yielding autumn grades of "dushistoe", "shtrifel" and "kitaika" apples grown in the collection garden at Pavlovsk experimental station of N.I. Vavilov Research Institute of Plant Industry. In the process of blanching and freezing the enzyme peroxidase activity was determined by spectrophotometric method, content of ascorbic acid – by Tilmans, mono- and disaccharides – by cyanide method, organic acids – by titrometric method in terms of malic acid, and the amount of pectin substances – by carbazole method. Safety indicators were determined by standard methods. For blanching apples with an activity of thermostable peroxidase enzyme more than 0.5 mg of guaiacol/g it is recommended 0.5% solution of citric acid, the temperature of 95°C, the time – 120 s. It is shown that the content of mono- and disaccharides, ascorbic acid, pectin substances, free organic acids in standard and non-standard fraction are identical and the number of these compounds decreases during the blanching and freezing by 18–30% depending on the variety and technological parameters of the processes. To freeze the standard and non-standard fractions of apples it is recommended the temperature of minus 35°C, which allows to increase the duration of their storage to 9 months at the temperature of minus 18°C. Using non-standard fraction of apples for production of the frozen apple semi-finished product is an important resource-saving factor and it allows to reduce losses of apples at processing by 6–7 times. Frozen fractions of apples are recommended to be used as an independent product as well as in confectionery production, technology of dairy products, and bakery products, which is of great practical importance.
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