Effect of storage conditions on physico-chemical properties of cowpea leaves

Abstract

Cowpea leaves are highly perishable thus to improve their utilization, there’s need for proper postharvest management. This study sought to determine the physicochemical changes of cowpea leaves during storage. The cowpea leaves were sorted and packaged using three main packaging materials; sacks, modified atmosphere packaging (cling film) and perforated trays which imitated storage in open crates. Samples were stored at different storage temperatures 30±2℃, 25±2℃ and 10±2℃. The samples under storage were observed for physiochemical changes every two days for a period of eight days. Physico-chemical parameters were significantly (p<0.05) affected by the period and temperature of storage and packaging material. Storage in high and ambient temperatures, extended storage, and tray and sack showed higher deterioration in physicochemical properties as compared to low temperatures and modified atmosphere packaging. There was a significant difference in visual appearance, aroma and the overall acceptability of cowpea leaves stored under different conditions (p< 0.05). Storage conditions had an influence on the sensory quality, nutritional quality and the shelf life of cowpea leaves. Modified atmosphere packaging at 10℃ was seen to preserve sensory with an overall acceptability mean score of 5.22 and nutritional attributes best as compared to modified atmosphere packaging, sack and tray packaging at ambient and extreme temperature storage where moisture (36.21±26.28a and 33.28±26.20a respectively), ascorbic acid (198.7±276.75a and 169.1±254.31a respectively), beta carotene (46.77±58.66a and 48.59±65.04a respectively) and color degradation (∆E 11.89±5.99a and ∆E 11.29±5.27a respectively) was higher. A combination of low temperature and modified atmosphere packaging for storage would be recommended to extend the shelf life and in turn combat post-harvest losses and increase the utilization of the vegetable. Storage temperatures, packaging materials and duration of vegetable storage are vital when it comes to extending the commercial life of fresh cowpea leaves.