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Title: Quality and drying characteristics of infra-red dried mango-sweetpotatoes leathers
Authors: Asumeng, Liticia
Issue Date: 28-Sep-2012
Abstract: The highly perishable nature of mangoes and sweetpotatoes due to high moisture content has resulted in high postharvest losses in Ghana. Thus the need to exploit their potential in fruit leathers production, sweetpotatoes were dextrinized (to increase sugars) at different temperatures in an oven, mashed and added to fresh mango pulp for drying. The amount of dextrins formed, dextrose equivalents and the physico-chemical parameters (pH, acidity, water activity and vitamin C) of the pulp and leathers were determined. The proximate and colour of leathers dried using the oven and the infra-red dryers were compared. The tray load, amount of dextrinized sweetpotato and temperature of drying were randomized at different levels and the drying characteristics in the infra-red dryer studied. Consumer acceptability test was also conducted. The optimal temperature for obtaining high amount of dextrin was 190-200 oC. Water activity ranged from 0.61-0.63 and the pH from 4.2-4.33. The overall acceptability was high (1.58-1.63) and was not significantly affected (P < 0.05) by the amount of sweetpotato added. Generally, all the drying processes occurred in the falling rate period. The Henderson and Pabis model best described the thin layer drying characteristics of infra-red dried mango-sweetpotato leathers. The frequency factors (Ko) for temperatures 45 oC, 50 oC and 55 oC were 4.032 × 106, 4.20 × 106 and 4.342 × 106 ( h-1) and corresponding activation energies respectively were found to be 52.829 KJ/mol, 52.831 KJ/mol and 52.837 KJ/mol. Both dryers had equal effect on proximate parameters but browning increased in oven dried leathers. Overall, the physico-chemical, sensory and proximate values obtained for infra-red dried leathers indicate that the leathers are of quality. The leathers produced compared well with a brand on the market and hence can compete when packaged properly. In order to get high quality product, save energy and time, the infrared dryer is commended for use in drying fruit leathers.
Description: A Thesis submitted to the Department of Food Science and Technology, Kwame Nkrumah University of Science and Technology in partial fulfilment of the requirements for the degree of Master of Philosophy, September-2012
URI: http://hdl.handle.net/123456789/4604
Appears in Collections:College of Science

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