Efficacy of Hexanal Treatment on the Physical and Biochemical Attributes and Shelf Life of Mango

Abstract

Mango is a perishable fruit with a limited shelf life once ripe, resulting in significant postharvest losses. The objectives of this study are to determine the efficacy of hexanal treatment in prolonging the shelf life of mango fruits and to determine the effects of hexanal treatment on the physical and biochemical attributes of mango. A laboratory experiment was performed to determine the efficacy of hexanal treatment in different concentrations as a postharvest dip on the physical quality and extension of storage life of mangoes and its interaction with variety and agro ecological zone of production. Further studies were carried out to determine the effects of hexanal treatment on the biochemical attributes of mango. The study was done at two agro ecological zones namely Machakos (AEZ IV) and Meru (AEZ II) and on two varieties namely Apple and Tommy atkins. Fruits were harvested at mature green stage, cleaned, sorted and divided into several batches. A formulation of hexanal also known as Enhanced Freshness Formulation (EFF) was used at two concentrations 2% and 3% as a postharvest dip to treat the mangoes in the laboratory and observed under ambient room temperatures throughout the ripening process. The study also included untreated fruits which were only dipped in plain water to act as control. Various ripening parameters were evaluated at 3 day intervals to determine the effects of the EFF treatments. These parameters include: physiological loss of weight, colour, firmness, ethylene evolution rate and respiration rate. Additionally, Samples from all treatments were taken and refrigerated and later evaluated for several ripening biochemical parameters measured namely, brix, ascorbic acid content, total titratable acidity, Beta carotene and simple sugars (glucose, fructose and sucrose).The results showed that fruits treated with the EFF exhibited slowed ripening rate as compared to untreated fruits by 3 days in the Apple variety and 5 days in the Tommy Atkins variety. Hexanal treatment slowed down the rate of 10 cumulative weight loss by 5% -6%. It also delayed the drop in hue angle by 3-6 days as well as delayed drop in both peel and flesh firmness. This is indicative of slowed down ripening process resulting to prolonged shelf life. It was also observed that mangoes treated with 3% EFF had a longer shelf life by 3 days than those treated with 2% EFF indicating that 3% EFF was highly effective in prolonging the shelf life of the fruits. Hexanal formulation applied as a postharvest dip can therefore be adopted as a solution to reduce postharvest losses and prolong the shelf life of mango fruits for both domestic and commercial use. In all the ripening parameters measured in this study, hexanal treatment was observed to slow down the rate at which the ripening process progressed but did not significantly change the quality of the fruits compared to the untreated fruits. Hexanal treated fruits exhibited a slower ripening rate as well as a higher retention for sugars, vitamin C, Beta carotene and acidity. In some parameters such as TSS, Beta carotene, glucose and fructose content there was no significant difference between fruits from different varieties or even harvested from different zones. However, in parameters such as TTA differences were noted between varieties with Tommy atkins variety recording a higher TTA than apple mangoes. The varietal difference was also noted in sucrose content where apple mangoes had a higher level of sucrose content as compared to the Tommy atkins variety. It was concluded that hexanal treatment indeed prolonged the shelf life of mango fruits without altering the quality and biochemical attributes. Hexanal has been recommended for further studies and later commercialization.