【作者】 王杰；

【导师】 吴坤；

【作者基本信息】 河南农业大学 ， 发酵工程， 2016， 硕士

【摘要】 淀粉是一种多糖,可作为食物的辅料用于增稠剂、粘合剂、保潮剂、乳化剂等来美观食物或改变食物结构。但淀粉质食品在低温条件下放置一段时间会出现老化现象,导致淀粉食品货架期短,质量变差,收益受损。γ-聚谷氨酸是一种高分子阴离子多肽聚合物,主链上大量游离的羧基赋予其很多特性。它在食品领域已有广泛应用,其中添加到面质品中能够延缓面包、面条、蛋糕等的老化。淀粉是面质品的重要组成部分,它与面质品的老化有直接关系。本研究将γ-聚谷氨酸加入到淀粉中,分析γ-聚谷氨酸对淀粉糊化和老化性质的影响,旨在为γ-聚谷氨酸应用到淀粉质制品中提供理论依据。本课题研究的主要内容及结果如下:将γ-聚谷氨酸添加到淀粉中进行糊化作用,研究其对淀粉性质的影响。研究结果显示γ-聚谷氨酸能使淀粉的溶解度、膨胀度、糊化特性、冻融稳定性、凝沉性等表观现象发生不同程度的改变。γ-聚谷氨酸对红薯淀粉、玉米淀粉和小麦淀粉性质的影响:随着γ-聚谷氨酸浓度的增加,红薯淀粉、玉米淀粉和小麦淀粉的膨胀度和溶解度都呈现先升高后降低的趋势,在γ-聚谷氨酸浓度为0.08%时淀粉的膨胀度和溶解度都达到最高值,与对照相比,淀粉膨胀度分别提高了11.11%、13.04%、14.06%,溶解度分别提高了50%、44.44%、40%,使淀粉颗粒膨胀,体积变大。结果说明γ-聚谷氨酸能促进红薯淀粉、玉米淀粉、小麦淀粉的吸水膨胀。通过快速粘度分析仪、质构分析仪、核磁共振仪的测定分析,加入γ-聚谷氨酸之后,三种淀粉糊的黏度升高,凝沉性降低;γ-聚谷氨酸也降低了淀粉凝胶的冻融稳定性、硬度、回生值和衰减值,延长了淀粉凝胶的持水性。γ-聚谷氨酸浓度为0.08%时,与对照相比红薯淀粉、玉米淀粉、小麦淀粉的回生值分别降低了52.26%、86.87%、53.07%;X-射线衍射分析淀粉衍射图谱,在添加γ-聚谷氨酸浓度为0.08%时,与对照相比,淀粉颗粒的结晶度分别由18.13%、19%、19.84%降到16.81%、17.67%和18.11%,说明γ-聚谷氨酸能够增强红薯、玉米、小麦淀粉的稳定性,降低淀粉颗粒的结晶度,延缓淀粉的老化速度。傅里叶红外光谱分析,三种淀粉的出峰图谱相似,加入γ-聚谷氨酸后淀粉的O-H和C-H（不饱和）分别由3434 cm^-1和2939 cm^-1转移到3236 cm^-1和2917 cm^-1附近,但观察不到-COOH处的峰,说明γ-聚谷氨酸的-COOH作为取代基主要与淀粉的-OH结合,改变了淀粉的分子结构。γ-聚谷氨酸对马铃薯淀粉性质的影响:γ-聚谷氨酸能降低马铃薯淀粉的膨胀度,增大淀粉的溶解度、冻融稳定性和凝沉性。与对照淀粉相比,在γ-聚谷氨酸浓度为0.08%时,马铃薯淀粉的膨胀度减少了16.25%,溶解度增大了93%,回生值增大了58.84%。通过快速粘度分析仪、质构分析仪、核磁共振仪的测定分析,γ-聚谷氨酸能降低马铃薯淀粉糊的黏度,提高淀粉凝胶的硬度、回生值和衰减值,减少淀粉凝胶的持水性。X-射线衍射分析淀粉在加入γ-聚谷氨酸为0.08%之后,结晶度由13.89%变为14.08%。结果说明γ-聚谷氨酸能增大马铃薯淀粉颗粒的结晶度,促进马铃薯淀粉的老化。由傅里叶红外光谱图分析,与淀粉混合后,添加浓度为0.08%γ-聚谷氨酸的-COOH消失,马铃薯淀粉在3498 cm^-1处的-OH转移到3454 cm^-1。结果表明γ-聚谷氨酸的-COOH主要与马铃薯淀粉的-OH发生反应。从总体结果来看,γ-聚谷氨酸可抑制红薯淀粉、玉米淀粉和小麦淀粉的老化作用,而对马铃薯淀粉的老化却表现为促进作用。更多还原

【Abstract】 Starch is a kind of polysaccharide,which can be used as the auxiliary material of the food,such as thickening agent,adhesive,moisture preserving agent,emulsifier,etc,to beautify food or change the structure of the food.But the starch food at low temperature for a period of time will appear aging phenomenon which may lead to short shelf life,poor quality and impaired earnings of starch food.γ-PGA is a kind of high molecular polymer,which has a lot of free carboxyl groups in the main chain.It has been widely used in the food industry like delaying the aging of bread,noodles,cakes,etc.Some studies had pointed out that starch was an important component of the flour product,and it was directly related to the aging of the products.In this study,γ-PGA was added into the starch and the effect of γ-PGA on the pasting and aging properties of starch were analysed to lay a firm theoretical foundation for the application of γ-PGA in starch industy.The main contents and results of this research are as follows:The gelatinized mixture was obtained by adding γ-PGA into starch,to study the effect of γ-PGA on the properties of starch.The results of this study showed that the solubility,swelling power,pasting properties,freeze-thaw stability and retrogradation of starch could be changed in different degrees.Effect of γ-PGA on the properties of sweet potato starch,corn starch and wheat starch:With the increased of the concentration of γ-PGA,the solubility and swelling power of the sweet potato starch,corn starch and wheat starch showed the trend of increasing first and then decreasing.Both these two parameters reached the highest values when the concentration of γ-PGA was 0.08%,and the swelling power and solubility of starch were still greater than the control when the concentration ofγ-PGA was 0.12%.Compared with the parameters of the control,when the concentration of γ-PGA was 0.08%,the swelling power increased by 11.11%,13.04%,14.06% and the solubility increased by 50%,44.44%,40% respectively,resulting in the swelling power of the starch granules.The results showed that γ-PGA could promote the water absorption capacity of sweet potato starch,corn starch and wheat starch.After adding γ-PGA into these three starch,compared with the parameters of thecontrol,their pasting viscosity were increased while their retrogradation were reduced.Measured by RVA,TPA and NMR analysis,the addition of γ-PGA was able to reduce the freeze-thaw stability,hardness,setback and the attenuation values of those starch gel,and extend the water holding capacity of starch gel.When the concentration ofγ-PGA was 0.08%,compared with the control,the retrogradation values of starch were respectively reduced by 52.26%,86.78%,53.07%.By X-ray diffraction analyzing the starch granules,compared with the parameters of the control,the crystallinity of starch granules decreased from 18.13%,19%,19.84% to 17.67%,16.81% and 18.11% respectively.The results showed that the stability of these three kinds of starch could be enhanced by γ-PGA,the crystallinity of the particles was decreased and the aging rate of starch was inhibited at the same time.These three kinds of starch were also analysed by FT-IR spectrogram,which had similar peak patterns.After adding the γ-PGA whose concentration was 0.08% into starch,the O-H and C-H（unsaturated）of the starch were respectively transferred from3434 cm^-1and 2939 cm^-1 to 3236 cm^-1and 2917 cm^-1.However,the peak of-COOH was not observed.The pattern showed that the-COOH of γ-PGA bonded with the-OH of starch as a substituent so that the molecular structure of starch was changed.Effect of γ-PGA on the properties of potato starch:γ-PGA could reduce the swelling power of the potato starch and increase the solubility,retrogradation and freeze-thaw stability of the starch.Compared with the parameters of the control,the swelling power of potato starch decreased by 16.25%,the solubility increased by 93% and the setback value increased by 58.84% when the concentration of γ-PGA was 0.08%.Measured by RVA,TPA and NMR analysis,γ-PGA could reduce the pasting viscosity and the water holding capacity of starch gel,and could increase the gel hardness,setback and attenuation values of potato starch.In addition,by X-ray diffraction analyzing,the crystallinity of starch was changed from 13.89% to 14.08% after adding the γ-PGA whose concentration was 0.08%.The results illustrated that γ-PGA could increase the crystallinity of starch granules and inhibit the aging of potato starch.By the FT-IR spectrogram analyzing,the-COOH ofγ-PGA were disappeared after mixing with potato starch,and the-OH of potato starch in 3498 cm^-1 transferred to 3454 cm^-1.The results showed that the-COOH of γ-PGA were mainly related to the-OH of starch.Seen from the overall results,γ-PGA could inhibit the aging of sweet potato starch,corn starch and wheat starch,but the aging of potato starch was presented as afacilitating role.更多还原