Differences in Surface Color, Flesh Firmness, Physiological Activity, and Some Components of Loquat Fruits picked at Various Stages of Maturity

Abstract

To study the compositional and physiological difference of 'Mogi' loquat fruits, the fruits harvested at different maturity stages were analyzed for surface color, flesh firmness, sugar content, acid content, phenolic compounds content, carotenoids content, re-spiration rate, and ethylene production. The index of maturity was 1 (green, small)7 (yellowish orange, harvest maturity) and 8 (slightly over ripe).1. Changes of surface color of loquat fruit expressed by Hunter color value indicated that the green color faded out and yellow color appeared over maturity stages 14, the reddish color appeared over the stages 58.2. Flesh firmness decreased between stage 4 and 5, but there was no detectable softening of the flesh afterwards to full ripe.3. Fructose, glucose and sucrose were the dominant sugars; sorbitol was the minor sugars. Sucrose content decreased from the stage 5 to 8, fructose as the dominant sugar at maturity stage 8.4. Malic acid was the dominant organic acid; citric, fumaric and succinic acids were the minor ones. Malic acid content decreased through fruit maturation, while citric acid content remained nearly constant.5. Phenolic compounds content and ratio of orthodiphenol to total phenolics increased during fruit maturation.6. β-Carotene was the dominant carotenoid in stage 2; cryptoxanthin became predominant in maturity stage 7. Cryptoxanthin was seemed to exist mainly as 4 esters.7. Respiration rate of loquat fruit decreased during maturation. Ethylene production of the fruit increased simultaneously with the decrease of green color and the appearance of reddish color.8. Our results indicated that stage 7 is the optimum harvest maturity.