Varietal response of Russian plum fruits to long-term cold storage

Cultivation of Russian plum in the humid subtropics conditions of Russia is a promising direction for industrial horticulture. The key task is the development of technologies that ensure prolongation of storage life of fruits without deterioration of their nutritional and consumer properties. Optimization of postharvest processing becomes especially important for minimizing economic losses and extending the time window for selling seasonal products. The aim of this work was to evaluate the effectiveness of a preparation based on 1-methylcyclopropene (“1-MCP “Fresh-Form”) for prolongation of cold storage of two varieties of Russian plum of medium maturity – ‘Gek’ and ‘July Rose’. The research included a comprehensive study of biochemical and organoleptic parameters of fruits to substantiate the suitability of varieties for prolonged storage and validation of postharvest processing technology. Preparation “1-MCP “Fresh-Form” is a gaseous compound 1-methylcyclopropene, which belongs to the class of ethylene inhibitors, a phytohormone regulating the cascade of biochemical reactions associated with ripening, senescence and destructive processes in the postharvest period. Experimental fruit samples after harvesting were divided into two groups: control and 1-MCP-treated. Storage was carried out in industrial chambers at a temperature of (+2 ± 0.5) °C and humidity of 85–90 %. Quality monitoring included quantitative analysis of organic acids, determination of ascorbic acid dynamics, evaluation of carbohydrate profile (sucrose, glucose, fructose), calculation of sugar-acid index and soluble solids content, quantitative determination of total polyphenols, organoleptic evaluation. The study revealed varietal specificity of biochemical response of plum fruits of ‘Gek’ and ‘July Rose’ varieties to the treatment during cold storage. A decrease in carbohydrate metabolism and degradation of ascorbic acid was found, with simultaneous active synthesis of polyphenols. The ‘Gek’ variety showed resistance to the treatment, while the ‘July Rose’ variety showed susceptibility. The treatment increased the shelf life by 46 %. Application of 1-MCP confirmed the effectiveness in prolongation of storage of Russian plum without critical loss of quality. The obtained data indicate the feasibility of technology implementation in agropractice of the region with adaptation of treatment protocols to varietal specificity of metabolism.