Physicochemical properties of buckwheat starch of Shaanxi Province.

[Objective] The study was done in order to get physicochemical properties of starch from buckwheat mainly cultivated in Shaanxi Province,and provide basis for the processing of buckwheat starch and buckwheat food.[Method] Main buckwheat varieties planted in Shaanxi Province,such as Yuqiao 1,Yuqiao 2,Japanese autumn buckwheat and red flower buckwheat,are taken as materials,and checked with maize and potato starch. Buckwheat starch is separated by water extraction and the granular structure,composition,gelatinization characteristic,gel texture characteristics of buckwheat starch are determined in the paper. [Result] The buckwheat starch granule is commonly polygonical or round shaped.The particle size scope is 1.4-14.5 μm,and the size is consistent.The polarization cross is clear.Its X-ray diffraction pattern is A-type.The amylose content of 4 buckwheat varieties is 258.2-326.7 g/kg,the solubility is low,situating between the potato starch and the maize starch.The peak viscosity of buckwheat starch,the viscosity at the beginning of holding period,the viscosity at the beginning of coolinging period,the viscosity of final cooling period,and the viscosity at the end of 50 ℃ holding period are higher than those of maize starch.The starch paste has stronger thermo stability,cold stability and gel formation ability.As well,the acid and the alkali resistance,and bear cutting ability are strong.The transparency of buckwheat starch paste is low,the freeze-thaw stability and the gel formation ability are a bit strong.The hardness,resilience and cohesiveness of gel are high.The characteristic of gel texture is fine.[Conclusion] The granule shape,micro-crystal structure,starch composition of the buckwheat starch are similar to those of cereal starch.The gel texture characteristic has both yam and legume starch merits.The buckwheat starch can be used as ideal raw material of thickening agent,cementing agent and the starch gel product in the food industry.