Effect of aloe (Aloe vera) leaf extract coating on quality and shelf life of mango (Mangifera indica l.) fruits at two controlled temperature levels

Abstract

Mango (Mangifera indica L.) is a popular and economically important tropical fruit throughout the world due to its excellent visual and eating qualities and nutritional composition. But the fruit is highly perishable and utmost care is required in handling to reduce postharvest losses. Trade in mangoes has been limited because of its highly perishable nature and its susceptibility to low temperature injury, physical injury and post-harvest diseases. Approaches to extending fresh fruit shelf life have included reducing storage temperature, use of surface coatings, and modified and controlled atmospheres; yet no studies have demonstrated the use of aloe gel natural plant extract based on its antifungal properties on enhancement of shelf life and quality of mango fruits. This study was done to evaluate the effects of aloe leaf extract coating on quality and shelf life of mango fruits at two temperature levels. Two experiments were conducted at Egerton University laboratories. The objectives were: (1) to determine the effects of aloe leaf extract surface coatings on shelf life, quality and anthracnose disease incidents on mango fruit, (2) to determine the effect of varying storage temperature on shelf life, quality and anthracnose disease incidents on mango fruit and (3) to determine the interaction effects of aloe leaf extract surface coating and varying storage temperature on shelf life, quality and anthracnose disease incidents on mango fruit. The experimental design was a 5 by 2 factorial experiment embedded in complete randomized design with three replications. The fruits were randomly divided into 5 lots of twenty fruits each. The first lot constituted the positive control and was coated with chitosan. The second, third, fourth and fifth lots were coated with Aloe vera gel at concentrations 0%, 25%, 50% and 75% respectively and stored at room temperature and at 13ºC. The parameters which were assessed included: percentage weight loss, peel and flesh colour change, pH, titratable acidity, total soluble solids (TSS), firmness, Vitamin C content, and degree and anthracnose incidents. The data collected was subjected to Analysis of Variance (ANOVA) at P ≤ 0.05, using SAS (version 9, 2005) and means for significant treatments separated using the Tukey’s Honestly Significant Difference Test at P ≤ 0.05 and t- Test at P ≤ 0.0001.The results showed that at both temperatures 50 and 75% aloe concentrations significantly increased the shelf life evidenced by reduced percentage weight loss, reduced decrease in Titratable acidity and ascorbic acid. Fruit firmness, fruit colour and total soluble solids concentration and pH were also maintained for longer periods in these treatments. However, Aloe vera gel coating did not have effect on anthracnose disease. Thus A. vera gel at 50% can be used as a coating for improved by twelve days postharvest shelf life and maintaining quality of mango fruits hence reduced postharvest losses.