Potential of carboxymethyl cellulose and γ-irradiation to maintain quality and control disease of peach fruit.

Carboxymethyl cellulose (CMC) coatings alone and in combination with gamma irradiation were tested for maintaining the storage quality and control of post-harvest gray and black mold disease of peach. Matured green peaches were CMC coated at levels 0.5-1.0% (w/v) and gamma irradiated at 1.2 kGy. The treated fruit including control was stored under ambient (temperature 25 ± 2°C, RH 70%) and refrigerated (temperature 3 ± 1°C, RH 80%) conditions. In fruits treated with individual treatments of 1.0% (w/v) CMC; 1.2 kGy irradiation and combination of 1.0% (w/v) CMC and 1.2 kGy irradiation, no decay was recorded up to 6, 8 and 14 days of ambient storage. Irradiation alone at 1.2 kGy prevented the onset of disease incidence up to 4 days compared to 2 days by 1.0% (w/v) CMC coating following 30 days of refrigeration. Combination of CMC at 1.0% (w/v) and 1.2 kGy irradiation prevented disease incidence of peach up to 7 days during post-refrigerated storage at 25 ± 2°C, RH 70% following 30 days of refrigeration. Above combinatory treatment can be of great potential in facilitating the marketing of the fruit, thereby benefiting the growers.

Gamma irradiation induced modification of bean polysaccharides: impact on physicochemical, morphological and antioxidant properties.

In the present study starches from four bean varieties viz. red, yellow, black and white, were gamma irradiated in the dose range of 5-25 kGy to investigate the effect of radiation processing on physicochemical, morphological and antioxidant properties. Studies revealed positive correlation between gamma irradiation and solubility (r=0.91), irradiation and water absorption capacity (r=0.82) and negative correlations between irradiation and swelling power (r=-0.92), irradiation and pasting properties (r=-0.91) and irradiation and thermal properties (r=-0.89). Microscopic observation under scanning electron microscope indicated the development of surface cracking and fractures on the surface of starch granules with increase in dose. X-ray diffractometry revealed no significant change in diffraction patterns between control and irradiated starches, except a decrease in relative crystallinity. Irradiation increased the proportions of both rapidly digestible starch and enzyme resistant starch of bean starches and significantly prevented the retrogradation of bean starches during storage. Results of the DPPH radical scavenging activity and ferric reducing power indicated significant (p≤0.05) increase in antioxidant activity of all irradiated bean starches with increase in dose.