不同米淀粉精细结构对其回生特性的影响

选用4种不同的淀粉，通过考察回生特性，探究相对分子质量、链长分布、短程有序性、相对结晶度及半结晶层状结构等精细结构影响回生特性的机理。结果表明：与糯米淀粉和粳米淀粉相比，小米淀粉和黑米淀粉回生值、硬度和热焓值较大，糯米淀粉储藏前后硬度和回生后的热焓值均较小，具有较好的抗回生特性。研究发现，这是由于小米淀粉和黑米淀粉的直链质量分数较高(小米淀粉15.55%、黑米淀粉11.22%),支链淀粉峰M_w较大(小米淀粉M_w=2.12×10⁷ g/mol、黑米淀粉M_w=2.25×10⁷ g/mol)、半结晶层厚(小米淀粉d=6.978 4 nm、黑米淀粉d=6.698 6 nm),且中长链占比大(小米淀粉B1链占比40.91%),易形成稳定的双螺旋结构，具有更高的表面有序度(小米淀粉0.76、黑米淀粉0.70),回生后2种淀粉分子重排更有序稳定。

Effects of Different Rice Starch Fine Structure on Retrogradation Characteristics

In this paper, four different kinds of starch were selected to explore the mechanism of fine structure affecting the regenerative properties, such as relative molecular weight, chain length distribution, short-range order, relative crystallinity and semi-crystalline layered structure. The results showed that, compared with glutinous rice starch and japonica rice starch, millet starch and black rice starch had higher recovery values, hardness and enthalpy values, while glutinous rice starch had lower hardness and enthalpy values before and after storage, which showed better resistance to recovery. The study found that this was due to the high amylose content of millet starch and black rice starch (millet starch 15.55%, black rice starch 11.22%), The amylopectin peak Mw was large (millet starch Mw=2.12×107 ^{g/mol, black rice starch M}w=2.25×10⁷ g/mol), the semi-crystalline layer was thick (millet starch d=6.9784 nm, black rice starch d=6.6986 nm), and the proportion of medium-long chain was large (millet starch B1 chain accounted for 40.91%). It is easy to form a stable double helix structure, with higher surface order degree (millet starch 0.76, black rice starch 0.70), and the molecular rearrangement of the two kinds of starch is more orderly and stable after backheating.