该文以黑苦荞全粉为原料,采用碱法和酶法提取淀粉,对黑苦荞淀粉和普通荞麦淀粉的理化、结构特性进行分析研究。结果表明,酶法提取的黑苦荞淀粉(black tartary buckwheat starch extracted by enzymatic method, eBTBNS)有糊化迹象,颗粒表面粗糙或不规则,淀粉结构趋于更大尺寸。eBTBNS中双螺旋得到更有效的堆积,分子排列更加有序,但相对结晶度(relative crystallinity, RC)较低(P<0.05),淀粉晶型为V型。碱浸法提取的黑苦荞淀粉(black tartary buckwheat starch extracted by alkaline leaching method, BTBNS)的糊化焓值和RC最高,分别为104.50 J/g和37.18%。BTBNS和普通荞麦淀粉(common buckwheat starch, CBNS)均呈现典型的A型晶体排列,淀粉以独立的颗粒存在,尺寸较小,表面较光滑。eBTBNS、BTBNS和CBNS的直/支链淀粉分布相似,它们都包含较高数量的短支链(A和B1链,74.95%~75.70%)和较低数量的长支链(B2和B3+链,24.30%~25.04%)。2种黑苦荞淀粉均具有较高的热稳定性和更紧密的双螺旋结构。eBTBNS中的抗性淀粉含量高,对于预防和控制慢性疾病有一定的参考价值,而BTBNS和CBNS的粒径较小且分布较均匀,可能在造纸业、化妆品和包装业上有较好的应用潜力。
Black tartary buckwheat starch was isolated from the whole black tartary buckwheat flour using alkaline leaching and enzymatic methods, and its physicochemical and structural properties were investigated in comparison with common buckwheat starch (CBNS).Results demonstrated that the enzymatic extraction of black tartary buckwheat starch (eBTBNS) showed signs of pasting, the surface of the granules was rough and irregular, and the structure tended to be larger in size.The double helices stacked more efficiently in eBTBNS, and the molecular ordering was improved, while the starch crystals exhibited a V-shaped shape and lower relative crystallinity (RC) (P<0.05).Black tartary buckwheat starch (BTBNS) extracted by the alkaline leaching method presented the highest enthalpy (104.50 J/g) and RC (37.18%).Both BTBNS and CBNS exhibited a typical A-type crystal arrangement, and starch existed as separate granules with a smoother surface.eBTBNS, BTBNS, and CBNS displayed a similar distribution of branched starch, and they all contained a higher number of short chains (A and B1 chains, 74.95%-75.70%) and a lower number of long chains (B2 and B3+ chains, 24.3%-25.04%).Overall, the two black buckwheat starches showed higher thermal stability and tighter double helix structure.eBTBNS contained high levels of resistant starch, which might be useful for the prevention and control of chronic diseases, while BTBNS and CBNS showed smaller particle size and more uniform distribution, which might be used in the paper industry, cosmetics and packaging industry with better application potential.
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