Production and storage of minimally processed chips from water yam (dioscorea alata).

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Febuary, 2010
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Dioscorea alata (water or greater yam), which is the most widely distributed yam specie globally and the world’s most popular yam after the D. rotundata/ cayenensis complex in terms of consumption is less highly regarded in West Africa, because it is not suitable for the preparation of 'fufu'. Processing of the tuber into other forms either than flour and flakes would enhance its use. This study was conducted to select the best varieties of Dioscorea alata for the production of minimally processed frozen yam chips for French fries production. Fifteen varieties of Dioscorea alata samples were used for the study. French fried samples from all the fifteen samples were presented to consumer panelist to rank them in order of preference with respect to their sensory characteristics (color, appearance (sogginess), crispiness, flavor (smell and taste), mouth feel and overall acceptability). Two of the best four samples were selected at random, steam blanched (10mins.), French fried at different times (5, 10,15mins.) and analyzed for the effect of the blanching periods on the sensory parameters. Two of the best four samples were selected at random; steam blanched and frozen at a temperature of -18 oC for storage studies over a period of twelve weeks. Sensory evaluation by trained panelists, Instrumental texture analysis and microbiological evaluation of frozen French fried samples was conducted every four weeks for twelve weeks. Steam blanching time had no significant effect on the sensory characteristics of French fried chips. Samples TDa 98/01176, TDa /001168, TDa 291 and “Matches” were the best for fried chips. sensory characteristics of TDa 291 fries were similar to that of potato fries. The two yam samples were safe for consumption in terms of microbial load over the twelve week storage period.
A thesis submitted to the Department of Biochemistry and Biotechnology, Kwame Nkrumah University of Science and Technology. in partial fulfillment of the requirements for the degree of Master of Science.