Impact of electron-beam irradiation combined with shellac coating on the suppression of chlorophyll degradation and water loss of lime fruit during storage

Abstract

The change in the color of the lime peel from green to yellow is the main postharvest-period problem that is unacceptable to consumers. The purpose of this research was to study the effect of electron-beam (E-beam) irradiation and shellac coating on chlorophyll degradation and qualities in lime fruit. Lime fruit cv. Paan were treated with E-beam irradiation at dosages of 0 (control), 0.5 and 1 kGy and stored at 13 °C for 30 d. E-beam treatment at 1 kGy delayed the change in peel color (b* and ΔE values), total chlorophyll content and the increase of chlorophyllase activity more compared to the 0.5 kGy E-beam and control treatments. However, 1 kGy E-beam irradiation increased the respiration rate, resulting in high weight loss. Therefore, shellac coating at 10 % (w/v) applied prior to irradiation with 1 kGy E-beam could minimize the respiration rate and water loss. In addition, shellac coating combined with E-beam irradiation delayed the color change of lime peel (L*, a*, b* and ΔE values), maintained the total chlorophyll content and suppressed the activity of chlorophyll degrading enzymes (chlorophyllase, Mg-dechelatase and pheophytinase) compared to non-treated fruit. However, the combined treatments affected the reduction of titratable acidity and enhanced the accumulation of total ascorbic acid and the hydrogen peroxide (H2O2) content. The results imply that shellac coating combined with E-beam irradiation is an alternative approach to delay chlorophyll degradation and maintain the quality of lime fruit.