Reducing postharvest losses using modified atmosphere packaging bags for African nightshade (Solanum scabrumMill.) leaves

Abstract

African nightshade (Solanum scabrum Mill.) is important for its nutrition, health promoting compounds and its contribution in providing a secure food supply and livelihood for smallholder farmers in rural, peri-urban and urban areas in Kenya. However, inadequate postharvest handling practices result in high losses. To address this issue, studies were conducted to evaluate the effect of modified atmosphere packaging (MAP) on improving storability, nutritional and health promoting compounds of 'Olevolosi' African nightshade. Plants were cultivated in a climate chamber for four weeks and three weeks under greenhouse conditions. Leaves were harvested and either packaged in MAP (Xtend®) or left in the open (control). The leaves were stored for 8 days to simulate retail conditions (20°C and RH 56%) and 15 days in cold storage (7°C and RH 86%). Fresh weight loss, leaf colour, antioxidative compounds (i.e., β-carotene, lutein, lycopene, vitamin E, and vitamin C), chlorophylls, protein, microbial counts, and gas composition within MAP were evaluated. The results showed that leaf colour was retained by MAP, more so at 7°C. MAP reduced weight loss by 76.4-83.9% at 20°C and 71.0-84.8% at 7°C compared with the control. Moreover, MAP maintained or even increased the content of protein, vitamins C and E, β-carotene, lutein, lycopene and chlorophylls in both storage conditions in comparison to the control. During storage, the concentration of CO2 increased to 0.7-3.3%, while O2 was reduced by 0.9-3.3% being more pronounced at 20°C, compared to ambient conditions. However, the use of MAP did not reduce microbial counts. The findings indicate the potential of using MAP to improve shelf life and preserve bioactive quality compounds of African nightshade. This could be a vital step to improve nutrition, health and the economic status of smallholder farmers in developing countries such as Kenya.