Characteristics of mung bean starch isolated by using lactic acid fermentation solution as the steeping liquor

Physicochemical properties of commercial mung bean starch isolated with lactic acid fermentation solution (LFS) and starches laboratory-prepared by using NaOH, Na2SO3 and distilled water as steeping liquors were examined with the aim of elucidating the effect of different steeping liquors on the properties of starches. Results indicated that the amylose content, granular morphology and X-ray diffraction pattern of starches isolated with different steeping liquors did not show obvious differences. However, the LFS-isolated starch had significantly (p < 0.05) higher weight percentage of longer B chains and B1 chains, a lower weight percentage of A chains and a lower ratio of short-to-long chains in amylopectin than those of the other preparations. Moreover, the LFS-isolated starch showed significantly (p < 0.05) lower pasting viscosity, a higher onset temperature, a narrower temperature range and a lower enthalpy of gelatinization than the other preparations. No significant differences on the physicochemical properties mentioned above were found among the laboratory-prepared starches. The results suggest that mung bean starch is degraded during isolation with lactic acid fermentation solution, which leads to the loss of starch granules with less integrity.