Ca(OH)_(2)对大米淀粉凝胶特性的影响

Effects of Ca(OH)_(2) on gelling properties of rice starch

该研究从大米中提取大米淀粉,向其中添加不同质量分数(0%~1.6%)的Ca(OH)_(2),研究大米淀粉的结晶度、热特性、糊化、流变、质构、淀粉短程有序性以及淀粉凝胶中水分状态的变化。结果表明,Ca(OH)_(2)使大米淀粉的相对结晶度和糊化焓降低,添加量小于0.8%时,冷糊黏度提高、回生性能改善,添加量为0.8%时,冷糊黏度和回升值达到最大值,分别为对照组的1.31倍和3.93倍。Ca(OH)_(2)可改善大米淀粉凝胶的流变和质构特性,添加量为0.8%时,大米淀粉凝胶的贮能模量、硬度和咀嚼性达到最大值。通过比较傅里叶红外光谱上1047 cm^(-1)/1022 cm^(-1)和1022 cm^(-1)/995 cm^(-1)比值可知,随着Ca(OH)_(2)添加量增加,大米淀粉的短程有序性呈先增加后降低的趋势。通过低场核磁共振测定大米淀粉凝胶的横向弛豫时间T_(2),发现Ca(OH)_(2)使自由水的比例显著增加,一部分不易流动的水转化为自由水,但总体上水的流动性有所下降。以上结果表明,Ca(OH)_(2)以剂量依赖方式影响大米淀粉的凝胶特性。该研究可为Ca(OH)_(2)在淀粉凝胶食品加工中的应用开发提供参考。

In this study,rice starch was extracted from rice,and Ca(OH)_(2) of different mass fractions(0%-1.6%) was added to the rice starch.The crystallinity,thermal properties,gelatinization,rheology,texture,short-range order of starch,and the change of water state in the starch gel were studied.Results showed that the addition of Ca(OH)_(2) decreased the relative crystallinity and the gelatinization enthalpy,and the final viscosity and the retrogradation characteristics of the rice starch were improved when the addition of Ca(OH)_(2) was less than 0.8%(mass ratio).As the addition amount of Ca(OH)_(2) was 0.8%,the final viscosity and the setback of the paste achieved the highest value,which were 1.31 times and 3.93 times of the control samples,respectively.Ca(OH)_(2) could improve the rheological and texture properties of rice starch gel,and the storage modulus,hardness,and chewability of rice starch gel reached the maximum when the addition amount of Ca(OH)_(2) was 0.8%.By comparing the ratios of 1 047 cm^(-1)/1 022 cm^(-1) to 1 022 cm^(-1)/995 cm^(-1) in Fourier-transform infrared spectra,the short-range order of rice starch first increased and then decreased,as the steadily increased Ca(OH)_(2) addition amount.The transverse relaxation time T_(2) of rice starch gel was measured by low-field nuclear magnetic resonance technology and the results demonstrated that the overall fluidity of water decreased,the proportion of free water significantly increased with the addition of Ca(OH)_2,and the proportion of the water that was not easy to flow partially decreased by converting to free water.It was suggested that the gelling properties of the rice starch were affected by Ca(OH)_(2) in a dose-dependent manner.This study could provide a reference for the application of Ca(OH)_(2) in the processing of starch gel food.