Evaluation of the mechanical and biochemical composition of rare citrus taxa fruits in the Russia’s humid subtropics

Abstract

In the present study, an assessment was made of the mechanical and biochemical composition of the fruits of rare citrus taxa grown in the humid subtropics of Russia. The studies were carried out on the basis of the bioresource collection of citrus crops of the Federal Research Center "Subtropical Scientific Center of the Russian Academy of Sciences" (Sochi). The objects were 13 taxa of the genus Citrus belonging to the rare category: C. aurantiifolia Sw. (cv. ‘Tahiti’, cv. ‘Foro’), C. × aurantium var. myrtifolia Ker Gawl. cv. ‘Cinotto’, C. × bergamia Risso Poit., C. × ichangensis Sw., C. limon L. ‘Del Brasil’, C. × limonelloides Hayata, C. × limetta Risso cv. ‘Chontipico’, C. maxima Burm. Merr. cv. ‘Sambokan’, C. medica L. (var. sarcodactylus Sw.), C. × meyerii Yu. Tanaka. Measurement of the mass concentration of organic acids, sugars and vitamin C was carried out by capillary electrophoresis using the Kapel-105M system. The results showed that the studied taxa have fruits with different mechanical and biochemical composition. All studied rare taxa were divided into three groups according to fruit weight: small-fruited, medium-fruited and large-fruited. Taxa C. × meyeri, C. maxima cv. ‘Sambokan’, C. aurantifolia, C. aurantifolia had a high juice yield from 51.3 to 57.2%. The maximum levels of vitamin C were noted in C. × aurantium var. myrtifolia ‘Cinotto’, C. × limetta ‘Chontipico’ and C. medica. Among the organic acids identified, citric and malic acids were the most common, followed by tartaric and succinic acids, although other acids predominated for some taxa. Most samples have the highest amount of sucrose, followed by fructose and glucose. The least amount of sucrose was found in C. aurantifolia ‘Foro’, C. × aurantium var. myrtifolia ‘Cinotto’ and C. × limetta ‘Chontipico’ Fruits of C. × aurantium var. myrtifolia ‘Cinotto’, for C. maxima ‘Sambokan’, for C. × limetta ‘Chontipico’. For all the studied objects, a high assessment was given to the appearance of the plant, fruits, which indicates their decorative properties.