Influence of cooling on the quality of autumnal apples

Abstract
Nowadays considerable proportion of apples is exposed to thermal conservation after harvesting which results in the loss of biologically active agents. Using of artificial cold for preservation of vegetable production allows keeping its nutrition value and quality as much as possible. To define the technological modes of refrigerating conservation it is necessary to consider the quality of fruits, their chemical composition, structure, intensity of the exchange processes due to activity of enzymes and also the dynamics of macro- and the micronutrients which is crucial for nutrition and biological value of fruits. The aim of this research is to study influence of low positive and negative temperatures on the change of carbohydrate fraction, content of organic acids and activity of peroxidase during storage of autumnal apples. Apples of Antonovka and Autumn striped varieties grown up in the collection garden at Pavlovsk experimental station of Vavilov Institute were chosen as objects of research. The indicators of quality in question were defined by the standard physical and chemical and biochemical methods of the analysis. Apples were stored in the cooled and frozen state at temperatures of 3±1 degC and –18deg C respectively. After blanching apples were frozen at the temperature of –24deg C and –35 deg C up to the temperature of –18 deg C. On changing peroxidase enzyme activity technological parameters of blanching before freezing were chose: 0.5% of lemon acid solution is recommended at the temperature of 95±1 degСfor 90 seconds. Dependences of changes in mono - and disaccharide content, pectinaceous substances, the sum of free organic acids on cooling conditions and storage duration are estimated. The regression equations for these dependences are received. Duration of apple storage at low positive and negative temperatures is proved by quality indicators.