CHANGES OF ACTIVE COMPOUNDS IN APRICOT FRUITS CAUSED BY STORAGE DEPEND ON CHARACTERISTIC FEATURES OF VARIETIES

Abstract

Apricots (Armeniaca vulgaris Lam.) contain a wide variety of nutrients such as sugars and acids, and preventive bioactive compounds such as vitamins, polyphenols and pectins which possess antioxidant activity and affect shelf life of fruits. Like other biological features, these properties are hereditarily determined. Therefore, proper selection of varieties, in addition to the optimal mode of storage, can help to reduce losses in commercial properties and deterioration of the chemical composition of apricots during storage because of rots, physiological diseases, and natural attrition. The article presents a comparative evaluation of the chemical composition and keeping quality of fruits in most common apricot varieties from Krasnodar region that are well adapted to the local conditions of growing. They are the Pineapple, Emerald, Red-Cheeked, Sunny, Amber, ripening in the second ten days of July, and the Krasnodar late, ripening in the third week of July. The differences in many chemical components of fruits peculiar to varieties have been found. An amount of soluble solids in the fruit ranged from 13.5 in Emerald variety to 18.8 % in Pineapple, and the sugars varied from 9.5 to 13.6 %, respectively. Apricot is a high acidic culture with fruits which can contain from 1.4 to 2.0 % organic acids. The high content of pectin at more than 1.0 % was also observed. Pineapple and Sunny varieties accumulated a significant amount of ascorbic acids which was superior to an average value of 14.0 mg/100 g for the central zone of the Krasnodar region. P-active catechins were detected in fruits at 45.6 to 155.9 mg/100 g. The high content of catechins at more than 100.0 mg/100 g was observed in Emerald, Red-Cheeked and Amber varieties. In the Pineapple variety the vitamin PP level of 0.6 mg/100 g was detected. According to L.V. Metlitskii (1976) vitamin PP is a component of many enzymes involved in cellular respiration, metabolism of proteins, and regulation of nervous activity. For full assessment of the biochemical peculiarities of apricots we investigated the content of -carotene (provitamin A). In fruits with light yellow color of the pulp such as the Pineapple fruits the -carotene content was 1.66 mg/100 g, in case of intense yellow color, particularly in Red-Cheeked and Krasnodar late varieties, it was 3.05 and 3.52 mg/100 g, respectively. The activity of polygalacturonase (PG) before computation of fruit for storage and during storage was also tested. The PG activity affecting fruit shelf life was the lowest at fruit harvesting. After 5 days of storage no PG activity was found in Sunny and Red-Cheeked varieties, while in Amber variety it increased slightly, indicating the varietal specificity. After 10 days of storage the PG activity increased and reached the maximum value by the day 15 being at peak in Sunny variety. Soluble pectins during storage were spent more intensively than protopectin, and in fruits with lower keeping quality, particularly in the Sunny variety, these processes were more active than in fruits with higher keeping quality, for instance in Amber variety. A 3.7 % decrease in sugars during storage was detected in Sunny and Emerald varieties. The acid level decreased by 10.0 % on average, and vitamin C and Pactive catechin content became lower by 15.5 to 20.7 %. In Amber, Krasnodar late and Emerald plants the C vitamin activity remained relatively high. In Krasnodar late and Emerald apricot trees the carotene level did not change during storage. In the Sunny and Red-Cheeked varieties it decreased while in Amber increased slightly due to continuing maturation. At the end of storage a natural loss reached 6.8 % in Amber and Emerald varieties and 10.2 % in the Sunny variety. The best marketable quality at 60.0 and 57.4 % rate of fruits of the highest commercial grade were observed in Amber and Krasnodar late varieties. The Sunny variety which annually accumulated ascorbic acid at a high level is recommended as a parental form in breeding for high vitamin C content.