基于AOAC法对Englyst法测定粳米淀粉消化特性的优化

研究较快速、准确测定粳米淀粉消化特性的方法。以粳米淀粉为试验对象,AOAC法(AOAC Official Method 2002.02)测定结果为基准,对Englyst法的酶解反应时间、混合酶比例、混合酶的添加量、混合酶pH等试验条件进行优化,得到适合粳米淀粉消化特性测定的方法,并对该方法测定结果进行准确度、精密度分析。结果表明,当酶解时间为270 min、混合酶比例[α-胰腺淀粉酶(AMY):淀粉葡萄糖苷酶(AMG)]为10:1、混合酶添加量为AMY(3600 U)+AMG(360 U)、混合酶pH为6.0、样品不经糊化处理时,测得的粳米淀粉中RS含量2.13%±0.05%与AOAC法测定结果2.02%±0.06%无显著差异,并且其测定时间由AOAC法的16 h调整为270 min,大大缩短了试验时间;与原Englyst方法相比,改进后的Englyst法测得的结果2.13%±0.05%准确度和精密度高,重现性好。因此,改进后的Englyst法可以快速、准确地测定粳米淀粉的消化特性。

粳米淀粉制备中影响蛋白含量的因素研究

以优质粳米为原料,采用凯氏定氮法测定粳米淀粉中蛋白含量,通过试验研究,得到影响粳米淀粉蛋白含量的因素为:反应温度、pH值、碱性蛋白酶添加量、脱水次数;符合产品应用要求的最经济的参数为:反应温度50℃,反应pH值10.0,碱性蛋白酶添加量2%,脱水次数3次。

响应面法高纯度碎粳米淀粉提取工艺的优化及中试研究

为了优化碎粳米淀粉的碱法提取条件,采用Box-Benhnken的中心组合试验设计及响应面分析方法,研究了提取温度、碱液浓度以及提取时间3因素对碎粳米淀粉中蛋白质残留量的影响,得出了碎粳米淀粉提取效果的回归模型。结果表明,最佳工艺参数为:提取温度31.3℃,碱液质量分数0.37%,提取时间20.4 h,料液比1∶5;在此优化工艺条件下,通过中试放大试验,粳米淀粉产品指标为:淀粉纯度达91.04%,蛋白质残留量仅为0.212%,淀粉得率达59.2%,为碎粳米淀粉的工业化生产提供了理论依据。

粳米重组米的制备工艺优化及性能研究

以碎粳米粉为原料,添加一定量的抗性粳米淀粉,采用双螺杆挤压技术制备重组米,考察了模头温度、水分含量和螺杆转速对重组米品质的影响。在单因素基础上,采用响应面优化了挤压工艺条件,测定了重组米的糊化、流变、蒸煮和消化性能。结果表明,当模头温度100℃、水分含量28%、螺杆转速96 r/min时,重组米的综合得分达到70.7±0.5。重组米糊化特性的各项指标均低于市售粳米,而黏度、回生值和糊化温度略高于空白重组米;重组米G'、G"低于市售粳米,略高于空白重组米;重组米的吸水率、体积膨胀率和蒸煮损失率均高于空白重组米和市售粳米;相比于空白重组米和市售粳米,重组米的SDS和RS含量较高,RDS含量较低,分别为51.62%、9.37%和39.01%。本研究结果可为低消化性重组米产品的开发提供实验依据。

粳米多孔淀粉制备工艺优化及性质研究

以宁夏843粳米淀粉为原料,用单因素和正交试验研究制备多孔淀粉的最佳工艺,对制备的多孔淀粉与原淀粉的主要理化性质和吸附应用进行了比较研究。最佳工艺条件为体系温度37℃、体系反应时间14 h、加酶量35%、体系pH值4.5,扫描电子显微镜图显示多孔淀粉表面略显粗糙、有孔洞,为中空结构,多孔颗粒没有塌陷现象,颗粒基本完整。由此反应条件制备的粳米多孔淀粉的比容积、膨胀率、透光率、吸油率分别为0.401 g/mL、15.2%、9.6%、99.8%,较粳米原淀粉分别增加了19.7%、34.5%、12.9%、45.3%,粳米原多孔淀粉对铜离子的吸附量较原淀粉提高了51.9%,而氨基多孔淀粉对铜离子的吸附量较原淀粉和原多孔淀粉分别提高了120.5%和45.2%。粳米多孔淀粉较原淀粉比容积、膨胀率、透光率、吸油率都有所增加。多孔淀粉经过氨基改性以后吸附铜离子的能力明显增强。

粳米多孔淀粉黄原酸酯的合成及其吸附重金属离子动力学研究

以粳米多孔淀粉为原料,采用单因素分析和正交试验研究合成粳米多孔淀粉黄原酸酯(PSX)的最优工艺,通过傅里叶红外光谱仪对所得产品进行结构表征和分析,通过吸附试验,研究了其对废水中Cu^(2+)和Pb^(2+)的吸附规律。结果表明:合成粳米PSX最优工艺条件为搅拌时间3h,二硫化碳用量2.0mL,氢氧化钠用量20mL,温度30℃,傅里叶红外光谱对PSX结构表征显示在3343cm^(-1)附近处的特征峰变窄,在2550cm^(-1)处出现新的弱吸收峰,推测是PSX单元的—SH伸缩振动产生的峰,且黄原酸酯基的形成使1085cm^(-1)处峰的位置发生了变化,说明粳米多孔淀粉添加了黄原酸基。通过吸附试验得出粳米PSX对Cu^(2+)和Pb^(2+)的吸附都在30min达到平衡,都是快速吸附的过程,且吸附过程都符合准二级动力学方程,对Pb^(2+)的吸附拟合度更高。

微波及超声-微波协同加热对大米淀粉回生特性的影响

研究了传统加热、微波加热和超声-微波协同加热对粳米淀粉和糯米淀粉回生特性的影响。结果表明:粳米淀粉对热作用的敏感性更高,在相同的贮存时间下,微波加热和超声-微波协同加热的粳米淀粉凝胶较传统加热的样品回生速率慢,凝胶强度增加和酶解力下降较小,并且微观结构上更致密平整。原因在于微波加热和超声-微波协同加热方式下淀粉颗粒膨胀破裂不充分,直链淀粉浸出的量相对较少,导致淀粉凝胶重结晶有序化程度较低,从而抑制淀粉回生过程。

改良挤压技术制备低蛋白质构米的研究

以粳米淀粉为原料,使用改良挤压技术制备低蛋白质构米,利用响应面分析法考察加工参数如物料含水率、螺杆转速和机筒温度的变化对低蛋白米质构特性的影响,并且以粳米的质构指标为参考指标,优化低蛋白质构米的制备工艺。结果表明,最优工艺参数为物料含水率35%,螺杆转速30r/min,机筒温度(糊化区温度)120℃,该工艺条件下,低蛋白质构米的硬度为(9 122±244)g,黏性为(-983±49)g.s,弹性为0.67±0.05,接近粳米的质构特性(硬度为(8 996±196)g,黏性为(-627±41)g.s,弹性为0.62±0.03)。同时,与粳米相比,其蛋白质含量非常低,为0.43%±0.01%,而且外观和色泽接近市售粳米,米粒完整,颜色均一,圆润光滑,轮廓分明,米质结构紧密。

Starch RVA Profile Properties for Cold Tolerant and Sensitive Cultivars of Japonica Rice at Different Altitudes

[Objective] By investigating of change rule rice starch RVA profile properties and the influence of cold tolerance on rice quality,the aim was to provide scientific references to the breeding of new cold-tolerant japonica rice varieties with high quality in the Yunnan plateau.[Method] Four cold-tolerant and five cold-sensitive japonica rice cultivars were grown at three locations with different altitudes in Yunnan plateau to investigate rice starch RVA profile characteristics.[Result] The results showed that with increasing altitude,the setback viscosity in cold-sensitive cultivars increased significantly,while the peak viscosity and breakdown viscosity decreased significantly.However,the peak viscosity and breakdown viscosity in cold-tolerant cultivars initially decreased and then gradually increased with rising altitude,whereas the setback viscosity initially increased and then decreased.[Conclusion] The starch RVA parameters of cold-tolerant cultivars were less sensitive to different environments than those of cold-sensitive cultivars.Cooking and eating quality of cold-tolerant cultivars had relatively stable trends with rising altitude,whereas cooking and eating quality of cold-sensitive cultivars had a trend toward inferior.

Effects of Different Sowing Dates and Sites on Starch RVA Profile Characteristics of Different Ecotypes of Rice (Oryza sativa, L. japonica)

[Objective] This study aimed to investigate the effects of different sowing dates and sites on starch RVA profile characteristics of different ecotypes of japonica rice. [Method] Five different ecotypes of japonica rice were sown at seven different dates in four rice planting regions in Jiangsu Province to analyze the differences in starch RVA profile parameters among different rice varieties. [Result] Among eight parameters of rice starch RVA profile, peak time exhibited no significant differences among different sites, while other seven parameters varied significantly or extremely significantly among different sites, sowing dates and varieties. Specifically, rice variety exerted the most significant effects on rice starch RVA profile parameters. Starch RVA profile characteristics varied significantly among different ecological conditions but exhibited no significant differences among different latitudes. To be specific, in different sites, peak viscosity （PKV）, hot paste viscosity （HPV） and breakdown viscosity （BDV） demonstrated a descending order of Huai＇an 〉 Suzhou 〉 Lianyungang 〉 Yangzhou. Cool paste viscosity （CPV） and consistence viscosity （CSV） were higher in the north than in the south; specifically, CPV and CSV were significantly higher in Lianyungang and Huai＇an than in Yangzhou and Suzhou. Setback viscosity （SBV） showed an increasing trend with increasing latitude; specifically, SBV was significantly lower in Suzhou than in other three sites. Pasting temperature （PAT） and peak time （PET） changed slightly among different latitudes. With the postponing of sowing date, peak viscosity （PKV）, hot paste viscosity （HPV）, cool paste viscosity （CPV） and peak time （PET） showed a decreasing trend, setback viscosity （SBV） and consistence viscosity （CSV） increased, breakdown viscosity （BDV） increased first and then decreased, whereas pasting temperature （PAT） decreased first and then increased. Furthermore, rice starch RVA profile parameters showed the same variation trend with sowing date in different sites; early sowing within suitable sowing dates could effectively improve the parameters of rice starch RVA profile. However, different parameters exerted different variations among different sites and most parameters were higher in the north than in the south, which indicated that starch RVA profile parameters were significantly affected by sowing date in the north of Jiangsu Province. Among eight starch RVA profile parameters, setback viscosity exhibited the maximum variation coefficient, while peak time exhibited the minimum variation coefficient. Among five rice varieties, Nanjing 46 exhibited the highest peak viscosity and breakdown viscosity and the lowest setback viscosity and consistence viscosity, suggesting that Nanjing 46 had the most appropriate starch RVA profile characteristics and the best cooking and eating quality. Lianjing 4 exhibited relatively high peak viscosity and breakdown viscosity, and relatively low setback viscosity and consistence viscosity, suggesting that Lianjing 4 had good starch RVA profile characteristics. Different sowing dates and sites exerted significant effects on starch RVA profiles of different eco- types of japonica rice. Rice starch RVA profile characteristics varied significantly among different sites but exhibited no significant variations among different latitudes. In addition, starch RVA profile characteristics varied significantly among different sowing dates. Therefore, early sowing of the same variety was conducive to improving starch RVA profile characteristics in appropriate planting regions. [Conclusion] This study provided a theoretical basis for producing high-quality rice and improving the eating quality of rice in Jiangsu Province.