Effects of Gum Arabic Surface Treatment on Nutritional Quality of Whole Mango (Mangifera Indica) in Makueni County and Evaluation of Canned Mango Chunks

Abstract

Mango production in Kenya has been on the rise. In 2013 about 581,290 MT were produced of which 40% were lost due to lack of proper postharvest management practices. The greatest loss was through pest and microbial spoilage and chemical deterioration of nutrients. The study aimed at developing methods to preserve the nutritional quality and reduce post-harvest losses in the mango value chain. Using a structured questionnaire, randomly administered to 40 mango farmers, post handling practices were assessed along the entire value chain. Whole mature mango fruits were sampled at farm, transport and market levels for nutrient deterioration assessment. A method that involved coating of whole mangoes with 0%, 10%, 15% and 20% gum arabic was developed for nutrient preservation. Another method involving canning of mango chunks packed in different sugar syrup concentrations (0, 30, 40, 50 and 60oBx) for mango preservation and shelf life was developed to reduce post-harvest loss. The survey data collected was analysed using statistical package (SPSS. Version 20.0). Laboratory analysis for nutrient content was conducted at Egerton University, Kenya Agricultural and Livestock Research Organization (KALRO) laboratories and Njoro Canning Factory. Changes in weight, ascorbic acid, β-carotene, total soluble solids (TSS), titratable acidity (TA) and pH of the fruits were evaluated using standard methods. Data was arranged in a complete randomized design in a factorial arrangement and analyzed using SAS (Version 9.3). Means were separated using Tukey’s HSD (P<0.05). From the survey, the main mango varieties grown were Apple (74.5%) followed by a combination of Apple and Ngowe (12.7%). Storage at farm level was by heaping of mangoes in ventilated stores. Draining mango latex after harvesting was practiced to reduce deterioration. Laboratory analysis revealed that gum arabic coating could extend the shelf life of mangoes up to 15 days by reducing percentage weight loss by 20% while maintaining the fruits’ nutritional composition. A coating concentration of 10% gum was the most efficient. Canning process extended the shelf life of canned mango chunks up to three months. Higher concentration of sugar syrup (60oBx) was efficient in maintaining the nutritional composition of the canned chunks. There was significant (P<0.05) increase in TSS during storage, significant decrease (P<0.05) in weight, titratable acidity, vitamin C, β-carotene and pH in coated mangoes while canned mango chunks, showed no significant (P>0.05) difference on the pH during storage, TSS increased significantly (P<0.05), titratable acidity, β-carotene and vitamin C decreased significantly (P<0.05) during storage. The study concluded that mangoes could be extended by coating with edible gum arabic. Similarly, mango chunks could be canned in sugar syrup for extended storage.