Two cultivars of tomato (Lycopersicon esculentum Mill.), Selection-7 (shelf life 7-8 d) and ARTH-3 (shelf life 14-15 d) were analyzed for oxidative stress and the antioxidant enzyme system at different stages of fruit ripening. The results presented here suggest that during the early stages of fruit ripening, efficient antioxidant system protects the tomato fruits against the damaging effect of progressive oxidative stress. At later stages, however, oxidative damage occurs due to decreased activities of the ROS scavenging enzymes.

Changes in chemical composition and the activities of hydrolytic enzymes during four different stages of maturity, viz. mature green (MG), color turning (CT), ripe (R), and overripe (OR), have been studied in guava fruits cv. Banarsi Surkha. Chlorophyll content decreased while carotenoid content increased during ripening. Starch content decreased with concomitant increase in alcohol-soluble sugars. Cellulose, hemicellulose, and lignin also decreased up to ripe stage, while pectin continued to decrease up to OR stage. PG (polygalacturonase) and cellulase exhibited progressive increase in activity throughout ripening, whereas pectin methyl esterase (PME) activity increased up to CT stage and decreased at R stage. The activities of alpha-amylase and beta-amylase decreased significantly with ripening. The most notable metabolic changes occurred between MG and CT stage, implying that for improved postharvest handling, guava fruits may be harvested at CT stage.

Changes in chemical composition and hydrolytic enzyme activities in guava fruits cv. Lucknow-49 have been reported at four different stages of maturity, viz., mature green (MG), color turning (CT), ripe (R) and over ripe (OR). Chlorophyll content decreased, while carotenoid content increased with advancement of ripening. Starch content decreased with concomitant increase in alcohol soluble sugars. The cell wall constituents viz., cellulose, hemicellulose, and lignin decreased up to R stage, while the pectin content decreased throughout up to OR stage. Among the cell wall hydrolyzing enzymes, polygalacturonase (PG) and ceUulase exhibited progressive increase in activity throughout ripening, while pectin methyl esterase (PME) activity increased up to CT stage and then decreased up to OR stage. The maximum increase in the activities of cell wall hydrolysing enzymes was observed between MG and CT stages. The activities of starch hydrolyzing enzymes, a-amylase and [~-amylase decreased significantly with advancement of ripening. These changes in the activities of hydrolyzing enz y m e s could be considered good indicators of ripening in guava.

Six chickpea strains were analysed for their protein content and various protein fractions. The protein content ranged from 20.9-25.27%. Albumin, globulin, prolamin and glutelin contents ranged from 8.39-12.31%; 53.44-60.29%; 3.12-6.89% and 19.38-24.40% respectively. Salt soluble proteins (albumin + globulin) and globulins resolved into 19-23 bands whereas albumin proteins resolved into 30-34 bands. The molecular weights of various polypeptides ranged from 10-91 kD. Amino acid analysis of total proteins revealed that glutamic acid was present in maximum concentration followed by aspartic acid and arginine. Just like other pulse proteins, chick pea proteins were also found deficient in sulphur containing amino acids.

Tomato varieties ARTH‐3 (long shelf‐life; 14–15 days) and Sel‐7 (short shelf‐life; 5–7 days), harvested at color turning stage, were stored in open trays at 10, 25 and 35C and sampled at two day intervals until complete deterioration. Variety ARTH‐3 could be stored at all the temperatures for ten days, while Sel‐7 could tolerate 35C only for four days. However, at 10 and 25C, it could be stored for six days. In both varieties, lipoxygenase (LOX) activity, malondialdehyde (MDA) value and H2O2 content increased during storage. Increase in storage temperature further enhanced the activity of LOX, and also increased MDA value and H2O2 content. Sel‐7 had higher values for these parameters than ARTH‐3. Activities of enzymes responsible for scavenging reactive oxygen species (ROS) viz., superoxide dismutase, peroxidase, ascorbate peroxidase, glutathione reductase and catalase decreased continuously during storage. With increase in temperature, the activities of these enzymes further decreased significantly in both varieties. Sel‐7 had significantly lower activities of ROS scavenging enzymes than ARTH‐3 throughout the storage period. These results suggest that fruits stored at higher temperature are subjected to severe oxidative damage leading to extensive membrane damage and loss of tissue structure.