Evaluation of shelf-life, antioxidant activity and nutritional quality attributes in carnauba wax coated eggplant genotypes

Abstract

Eggplant genotypes of white, green and violet are very popular in the specific regions of sub-tropics and tropics. These possess enormous health benefits as having high antioxidant activity. Due to limited shelf life i.e. 3 days at ambient storage, wholesalers and retailers apply many unhygienic practices. They use petroleum based oil to make the fruit surface shiny and attractive. In the present study, Eggplant genotypes, viz. violet, green and white, were assessed after carnauba wax (CW) emulsion containing additives such as 2.5% polyethylene glycol (PEG) and 0.5% sodium alginate (SA) as T1, 0.5% SA as T2, 2.5% PEG as T3 and non-coated eggplant fruits as control fruits (T4) for shelf life extension and retention of nutritional quality attributes at ambient condition (20 ± 2 °C and RH 52–54%) for 7 days. The additives mixed CW coatings were effective in extending the shelf life and retaining the nutritional quality attributes than control genotypes. Sodium alginate (SA) mixed CW coating resulted in maximum shelf life extension of white eggplant genotypes by 7 days as compared to 3–4 days in control eggplant genotypes at ambient storage. However, 6.9%, 1.83% and 6.04% decrease in physiological loss in weight was obtained in 0.5% SA based CW coating after 5 days of ambient storage of violet, green and white eggplant genotypes, respectively in comparison to fully control eggplant genotype. The firmness level of eggplant genotypes in 0.5% SA based CW coating was more (85.1%, 50% and 45%) after 7 days of ambient storage of violet, green and white genotypes, respectively in comparison to fully control eggplant genotype. Similarly, total phenol content was also increased (26.1%, 37.5% and 180.9%) in 0.5% SA based CW coated eggplant genotypes of violet, green and white, respectively after 7 days of ambient storage in comparison to fully control eggplant genotype. Initially there had been increase in antioxidant activity in white genotype up to 5 days of storage which thereafter decreased on 7 days of storage in all the treatments. However, violet and green genotypes had not followed any trend during storage.