Physical, Chemical and Enzymatic Changes in Amla (Emblica officinalis) Fruit during Growth and Maturation

Amla (Emblica officinalis) is one of the most prominent fruits in terms of nutritional and medicinal properties and is utilized for the preparation of many traditional processed foods and in Ayurvedic formulations.

This study aims to investigate the enzyme activity and physical and chemical quality parameters during the growth and development stages of amla fruit for the determination of proper harvesting time to get optimum nutrient contents of fruit.

The amla fruits of the chakaiya variety were harvested at 135 to 270 days after fruit set (DAFS) in 2021 and 2022 to study the various physical, chemical and enzymatic changes during growth and maturation.

The geometrical and gravimetric attributes of the fruit, viz. diameter, height, weight, volume, surface area, sphericity, aspect ratio, and radius of curvature increased. However, density decreased with the growth and maturation of the fruit. Furthermore, the rolling resistance, yellowness index and firmness of the fruit increased during the entire harvesting period of 135 to 270 DAFS. Total soluble solids and titratable acidity of the fruits increased only up to 195 DAFS and after that, continuously decreased. In contrast, ascorbic acid concentration grew in the entire growth and development period. Tannin, phenolic compounds and naringin content of the fruit steadily dropped until the final stage of harvest. Pectin Methyl Esterase (PME) activity was detected very low, 0.009 unit/ml at 135 DAFS, but as the fruit grew and matured, activity increased to 0.307 unit/ml at 270 DAFS. Polygalactouronase (PG) activity was not detected until 210 DAFS and, therefore significantly increased with maturity.

Considering the optimal value of all studied physical, chemical and enzymatic attributes of the fruit during the entire harvesting period of 135 to 270 DAFS, the optimal harvesting time of the fruit was 210 DAFS.