Changes in the Biochemical Components in Kiwi Fruits Due to the Period of Their Collection

Abstract

On the basis of the Institute of Agriculture of Academy of Sciences of Abkhazia (Sukhum) there is a collection of sweet Actinidia, research on the introduction and selection of kiwi is actively being conducted, the forms of trellises, planting schemes, crown formation, optimal harvest times, etc. are being studied. Since 2003, research has been conducted to obtain varieties of sweet Actinidia, characterized by less pubescence of the fruit or its complete absence. This article discusses the changes in the biochemical composition of kiwi fruits, depending on the timing of their collection. Objects of research are promising kiwi varieties with hairless skin grown in number lecture plantation IAASA Gulripshyi district of the Abkhazia Republic: Pobeditel, Otchara, Apsny, Gulripshskyj. The fruits were selected in two terms – during the physiological maturity period (the second decade of November) and during the consumer maturity period (the first decade of January). The research was carried out in the Laboratory of Plant Physiology and Biochemistry (Subtropical Scientific Centre, Sochi, Russia Federation) using classical methods. The fruits of the new varieties of kiwi without pubescence skin were characterized by a more pronounced dark color of the peel (compared to the classic varieties), small-fruited (no more than 6.0 cm in size), multi-seeded and lack of pubescence. The flesh of the fruit is greenish-yellow in color with a rich sweet taste and a delicate consistency, different from the pubescent varieties of kiwi. Among the studied varieties cv. Pobeditel was distinguished by a light green and sweet-tasting pulp, with a large number of seeds. The Otchara variety was distinguished by a slightly noticeable pubescence of the fruit and a very thin skin. The flesh of the fruit is light green, loose, with a large number of seeds. In the variety of the fruits are larger, with a large number of seeds. The flesh is light green with a brownish tinge compared to the Gulripshskyj variety, which has a lighter flesh, also with more seeds. It is shown that valuable biochemical components (soluble solids, sugars and organic acids) accumulate more than others in the fruits of the Pobeditel variety. The variation (V, %) of these traits in fruits depends on the variety and the harvest period. By the second harvest period (January), all fruits showed a decrease in the content of ascorbic acid, in the varieties Apsny, Otchara and Gulripshskyj to 40–47 % of the November amount, in the Pobeditel variety by January, the amount of vitamin C was 23 % of the original. The content of ascorbic acid is most dependent on the harvest period, the coefficient of variation depending on the variety is 12.03 % (Gulripshskyj) – 42.31 % (Pobeditel). Fruits taken at a later date (January) contain a higher amount of dry matter, which indicates that the assimilation processes in the fruit continue until January. In the fruits taken in January, synthetic maturation processes continue, as a result of which there is an active consumption of organic acids, and the sugar-acid index leaf towards increasing the sweetness of kiwi fruits. According to the content of ascorbic acid, November fruit removal is more preferable, since fruits contain more ascorbic acid, therefore, have a greater nutritional value.