Biochemical and physiological changes of star apple fruit ( Chrysophyllum cainito) during different “on plant” maturation and ripening stages

Abstract

Abstract This study aimed to determine the respiration rate, ethylene production, total reducing sugars, total phenolic compounds, chlorophylls, color and firmness of green and purple varieties of star apple fruit (Chrysophyllum cainito) during “on-plant” maturation and ripening in order to contribute determining a ripening index for appropriate harvesting time. Respiration rate (RRCO2) and ethylene production decreased significantly during ripening, although an increase in ethylene was noted at mature stage of the purple variety. Total reducing sugars increased significantly during the three stages, while total phenolic compounds decreased, and skin showed higher level of total phenolics compared to pulp. Similarly, chlorophylls (a + b) and carotenoids in skin decreased during ripening, however, the decrease in carotenoids was less significant compared to the decrease of chlorophylls. Overall, color changed from darker to lighter and duller due to ripening. Firmness also decreased significantly during ripening causing softening of the fruit. Results also showed that color and firmness might be considered as a good ripening index for star apple. Conclusively, star apple does not seem to have a climacteric pattern, and its behavior during maturation and ripening was similar to most of non-climacteric fruits.