两种分子质量大豆可溶性膳食纤维对大米淀粉老化性质的影响

Effect of Soybean Soluble Dietary Fibers of Different Molecular Weight on Retrogradation Properties of Rice Starch

采用动态流变仪、X-衍射仪、FTIR、差示扫描量热仪(DSC)和扫描电镜(SEM)等手段研究两种分子质量(HSSDF,27.8 ku和LSSDF,9.3 ku)大豆可溶性膳食纤维(SSDF)对大米淀粉(RS)短期(4 h)及长期老化(14 d)的影响。结果表明:SSDF可显著降低淀粉体系弹性模量的增加,提供淀粉凝胶的黏性;HSSDF对RS短期老化的抑制效果更为显著。4℃老化14 d,RS-SSDF体系的△Hr显著低于RS,而HSSDF与LSSDF对△Hr的影响未见显著差异。RS老化7 d形成B型结晶,SSDF可降低大米体系的相对结晶度,其中HSSDF的效果更为显著。相较于RS老化形成的致密结构,RS-SSDF体系中形成明显的空腔,呈蜂窝状结构。两种分子质量的SSDF(27.8 ku和9.3 ku)均可抑制RS的短期老化和长期老化,其中HSSDF对RS老化的抑制效果更为显著。

The effect of soybean soluble dietary fibers(SSDF)with molecular weight of 27.8 ku for HSSDF and of 9.3 ku for LSSDF on short-term retrogradation(4 h)and long-term retrogradation(14 d)of rice starch(RS)were inves tigated by employing dynamic rheometry,X-ray diffraction,Fourier transform infrared spectroscopy(FTIR),differential scanning calorimetry(DSC)and scanning electron microscopy(SEM).The result showed that the addition of SSDF could significantly reduce the increase of elastic modulus of starch system during short-term retrogradation and increase the viscosity of starch gel.The inhibition effect of HSSDF on short-term retrogradation of RS was more pronounced.The△Hr values of RS-SSDF system was significantly lower than RS.The effect of HSSDF and LSSDF on the△Hr values of rice starch showed no significant difference.The typical B-type crystallinity of rice starch formed when stored at 4℃for 7 d.Results of FTIR and XRD indicated that the relative crystallinity of rice system was decreased by adding SSDF,especially the HSSDF.Compared with the compact structure of rice starch formed in the aging process,obvious cavity structure was formed in RS-SSDF blends,showing a honeycomb structure.Different molecular weight SSDF(27.8 ku and 9.3 ku),especially the HSSDF,had a inhibition effect on short-term retrogradation and long-term retrogradation of RS.