Guava (Psidium guajava L.) sugar components and related enzymes at stages of fruit development and ripening.

Abstract

Guava contained fructose, glucose, surcrose, and inositol in the decreasing order. Reducing sugars mainly composed of fructose and glucose increased slowly during the period of immature and mature stages, and increased sharply at ripening upto full ripe stage. Although the concentrations of both fructose and glucose were higher in white, C-1-16 seedling variety than in pink, C-1-40 seedling variety in either of the immature and mature stage, only with the exception of fructose at maturation where it was higher in pink. At full ripe the pink variety contained more fructose and glucose than the white and at ripening the concentrations of froctose and glucose were almost nearing to equal to each other but at full ripe fructose comprised 55.93% of total sugars in the white variety and 58.28% in the pink. Sucrose and inositol constituted the minor sugar components and also increased gradually with insignificant rise of concentration during ripening. Activity of invertase began to develop during ripening and attained the maximum at full ripe. This enzyme showed a maximum activity at pH 3.5-4.0. Amylase activity started to increase as the fruits reached the maturation and increased upto full ripe and showed the optimum pH 7.0. Although, at ripening the white variety had higher invertase activity than the pink, amylase activity of the pink variety was 2.1 times higher than the activity of the white.