| Summary: | 碩士 === 國立中興大學 === 食品科學系 === 91 === It is difficult to separate yam starch from its tuber because of the presence of viscous mucin, which is a carbohydrate moiety firmly associated with protein (glycoprotein).Two varieties of yam, D. pseudojaponica Yamamoto (Keelong) and D. alata L. (Yangmingshan-native species), were used in the study. The objective of this investigation was to utilize several physical separation methods to separate mucilage and starch, and to increase the recovery yield of polysaccharides and proteins from mucilage. Methods used included sedimentation, centrifugation and adsorptive bubble separation(ABS).
The results showed that acid hydrolysis yielded , mannose (95.4 %).
Centrifugation destroyed the structure of glycoprotein, resulting in further separation of caebohydeates, proteins and ashes in different parts of starch paste and mucilage. On the method of centrifugation , the larger is centrifugal force(7263×g), lesser polysaccharide of mucilage wice be(5.96%). the small is centrifugal force(5975×g), more polysaccharide of mucilage wice be(23.7%). The crude mucilage of yam recovery rate by the way of bubble separation more than centrifugation (RCF = 7263 × g)( Yangming yam : 2.07 g﹤4.32 g ; Keelong yam : 6.54 g ﹤20.1 g ).
It is easy to separate soluble carbohydrates mucilage from two different yam (Yangming yam : 86.8% ; Keelong yam : 98.6%), but the contained of soluble carbohydrates more than protein by the separation (Yangming yam : 30.2% ; Keelong yam : 56.8%). The absorbing rate of polyaccharide is about 3.5 times than the treatment by centrifugation. This method is simple, and especially good for ingredients recovery from a dilute solution.
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