Assessment of physico-chemical and functional properties of native and modified “Kponan” yam (Dioscorea cayenensis-rotundata complex) cultivar starches
By: Koné Daouda, Djè Kouakou Martin, Koné Martial Fankroma, Dabonné Soumaila, Kouamé Lucien Patrice
Key Words: Yam, Cultivar, Native starch, Modified starch, Functional properties.
Int. J. Agr. Agri. Res. 8(3), 10-25, March 2016.
The starch of “Kponan” yam cultivar was isolated and was modified through oxidation, acetylation, acid modification and enzymatic modification. The various modified starches of “Kponan” yam cultivar and its native starch were characterized in terms of morphological characteristics, some proximate composition and functional properties. Results obtained showed that the starch granules were Polyhedral and Ovotriangular in shape. The granule size ranged from 7.55µm – 53.47µm. Chemical and enzymatic modifications didn’t alter the granule morphology. Proximate composition analysis revealed that moisture, protein, fat and ash contents were reduced after modification and were ranged from 08.26 % dw to 10.11% dw, 0.13 % dw to 0.18 % dw, 0.07 % dw to 0.11 % dw and 0.51 % dw to 0.83 % dw respectively. As for functional properties, WAC, OAC, LGC, syneresis and PC were determined. Our results indicated that modification such as oxidation, acetylation and enzymatic modification increased meaningfully (p<0.05) the WAC and OAC of native starch while acid modification decreased them significantly (p<0.05). It appeared significant differences (p<0.05) between the OAC values of starches, whatever the oil type is. Otherwise, the LGC of the native starch was 9% (w/v) and increased after oxidation (11%) and acetylation (10%), whereas it decreased in acid modified (8%) and enzymatic modified (6%) starches. Syneresis tendency was reduced after oxidation, acetylation and enzymatic modification but increased following acid modification. Studies conducted on paste clarity revealed that percentage transmittance (650 nm) increased after chemical modifications (oxidation and acetylation) and enzymatic modification whereas acid modification reduced it.