Effect of hot water and calcium chloride treatment on the shelf-life of 'Keitt' mangoes and 'Cavendish' bananas from Mozambique

Abstract

Mango (Mangifera indica L.) and Banana (Musa acuminata L.) are important tropical fruits ripen quickly and have a short postharvest life and commercialization window. In Mozambique, about 40 % of these fruits have been lost. In order to recommend small and medium enterprises in post-harvest fruit preservation, there is a need to develop appropriate alternative techniques for the post-harvest handling of fruits. In this work, the extension of the shelf-life of fresh mango and banana fruits by delaying ripening using hot water dipping and calcium treatment was studied. Although hot water and calcium chloride as post-harvest losses reduction treatments and shelf-life prolong were already studied, reports on the effects of optimized hot water dipping and calcium chloride on the ripening and other physiological aspects in mangoes and bananas from Mozambique are scarce or totally missing. For representation of whole country, the fruits were collected from Gaza, Manica and Nampula provinces of south, central and north parts of Mozambique, respectively. The banana (variety Cavendish) and mango (variety Keitt) samples were collected Mid-August 2016 and in January 2017, respectively. Three hundred and six fruits collected were at three different maturity stages (green, green-yellowish and yellow) and transported to the Instituto Superior Politécnico de Manica (ISPM). The raw material was characterised according to their proximate composition, size, weight, firmness and colour. Analyses of soluble solids and ascorbic acid were also performed. Sensory attributes of flavour, sweetness, astringency and overall acceptance and visible chilling injury were assessed. The optimal hot water dipping temperature and calcium chloride concentration was determined using Rotational Composite Design (RCD). The bananas and mangoes ripening and shelf-life after the postharvest treatment were determined using Randomized Complete Block Design (RCBD). The results of fruit characterization showed that mango fruits with low moisture (green with 83.62%), and fibers (0.44%), high ash (2.05%) crude lipids (0.29%), protein (0.85%) and carbohydrate (13.81%), high total soluble solids (24.60%), and high vitamin C content (14.83mg/100g) were collected in Nampula. However, banana fruits with low moisture (73.18%) and fibers (0.27%), high crude proteins (3.44%), ash (0.58%), and crude lipids content (4.92%), high total soluble solids (24.50%) and vitamin C content (2.40mg/100g) were collected in Manica. The results showed that the optimal conditions of the process stabilized with the desirable function was obtained at 55ºC of hot water temperature dipping and 3% of calcium chloride concentration. The results indicated that, as the chilling injury scores increased, fruit firmness was maintained, total solid soluble increased, vitamin C content decreased and high shelf-life in samples treated with calcium chloride and kept on refrigerator storage conditions. These qualities were reported in green-yellow bananas from Manica and green-yellow mangoes from Nampula where the shelf-life time reached 25 and 27 days, respectively. The researcher concluded that calcium chloride treatment and refrigerator storage conditions better fit. This is the first time that Mozambique mangoes and bananas fruits were characterized and assessed in the postharvest treatment and storage conditions providing valuable information to extend shelf-life of bananas and mangoes. The researcher recommends that stakeholders working in the postharvest treatment area should take advantage of the calcium chloride treatment and refrigeration storage conditions initiatives to improve the fruit shelf-life. Mozambique policy formulation process should embrace an all-inclusive formulation to achieve a positive and sustainable policy impact on the fruit post-harvest sector. Stakeholders should promote use of calcium chloride to improve fruit post-harvest productivity in the target area sustainably.