玉米品种和淀粉老化处理对其红外光谱结构与体外发酵参数的影响

Effects of Corn Variety and Starch Retrogradation on Infrared Spectroscopy Structure and in Vitro Fermentation Parameters

本试验旨在研究不同玉米品种[普通玉米和高直链淀粉玉米(简称高直玉米)]和淀粉老化处理对其营养成分、傅里叶变换红外光谱(FTIR)分子结构以及体外发酵参数的影响,并探索玉米FTIR分子结构参数与体外发酵特征的相关关系。结果表明,玉米品种和淀粉老化处理对部分FTIR结构参数、体外发酵总挥发性脂肪酸(VFA)含量和丁酸占比存在显著交互作用(P<0.05),老化前高直玉米β-葡聚糖峰高、纤维化合物面积和峰高以及碳水化合物Ⅲ区面积显著高于普通玉米(P<0.05);老化后高直玉米的丁酸占比显著低于普通玉米(P<0.05),老化后高直玉米总VFA含量和丁酸占比显著低于老化前普通玉米(P<0.05),但是老化后高直玉米与普通玉米在FTIR分子结构方面没有显著差异(P>0.05)。高直玉米丙酸占比显著高于普通玉米(P<0.05),而总产气量、甲烷产气量和氢气产气量显著低于普通玉米(P<0.05);淀粉老化处理显著降低了总产气量、甲烷产气量、氢气产气量、干物质降解率和丙酸占比(P<0.05),而显著提高了乙酸占比(P<0.05)。相关性分析结果显示,总产气量与酰胺Ⅰ区峰高、酰胺Ⅰ区与酰胺Ⅱ区峰高比、纤维化合物峰高以及总碳水化合物区域结构呈显著负相关(P<0.05),与酰胺Ⅱ区面积和峰高呈显著正相关(P<0.05);干物质降解率与酰胺Ⅱ区峰高、酰胺Ⅰ区与酰胺Ⅱ区峰高比、纤维化合物峰高、碳水化合物Ⅰ区面积、碳水化合物Ⅰ区与Ⅱ区峰高呈显著负相关(P<0.05);乙酸占比与酰胺Ⅰ区峰高、酰胺Ⅰ区与酰胺Ⅱ区峰高比、纤维化合物峰高和总碳水化合物区域结构呈显著正相关(P<0.05),与β-葡聚糖面积和峰高呈显著负相关(P<0.05);总VFA含量与酰胺Ⅱ区面积和峰高呈显著正相关(P<0.05),与酰胺Ⅰ区峰高、酰胺Ⅰ区与酰胺Ⅱ区面积比和峰高比、纤维化合物峰高以及总碳水化合物区域结构呈显著负相关(P<0.05)。综上所述,不同玉米品种和淀粉老化处理改变了FTIR分子结构以及体外发酵参数;体外发酵总VFA生成、干物质降解率和气体产气量与FTIR分子结构(除酰胺Ⅱ区外)呈负相关,而与酰胺Ⅱ区呈正相关。

The experiment was conducted to analyze different corn varieties(normal corn and high amylose corn)and starch retrogradation on feed nutrients,Fourier transform infrared spectroscopy(FTIR)molecular structure and in vitro fermentation parameters,and to explore the correlation between FTIR molecular structure parameters and in vitro fermentation characteristics of corns.The results showed that there were significant in⁃teractions between corn variety and starch retrogradation on sectional FTIR structure parameters,total volatile fatty acid(VFA)content and the butyrate proportion in in vitro fermentation(P<0.05).Compared with the normal corn,theβ⁃glucan peak height,the area and peak height of cellulosic compounds and carbohydrate peakⅢarea in the high amylose corn before retrogradation were significantly increased(P<0.05),but the bu⁃tyrate proportion in the high amylose corn after retrogradation was significantly decreased(P<0.05).Com⁃pared with the normal corn before retrogradation,total VFA content and the butyrate proportion in the high am⁃ylose corn after retrogradation were significantly reduced(P<0.05),but there was no significant difference in FTIR molecular structure between the normal corn and the high amylose corn after retrogradation(P<0.05).Compared with the normal corn,the propionate proportion in the high amylose corn was significantly increased(P<0.05),but the total gas production,methane production and hydrogen production were significantly re⁃duced(P<0.05).Starch retrogradation significantly reduced the total gas production,methane production,hy⁃drogen production,dry matter degradation rate and propionate proportion(P<0.05),and significantly in⁃creased the acetate proportion(P<0.05).The correlation analysis results showed that the total gas production was negatively correlated with the amideⅠpeak height,peak height ratio of amideⅠto amideⅡ,cellulosic compound peak height and total carbohydrate domain structure(P<0.05),while it was positively correlated with the area and peak height of amideⅡ(P<0.05).The dry matter degradation rate was negatively correlated with the amideⅡpeak height,peak height ratio of amideⅠto amideⅡ,cellulosic compound peak height,carbohydrateⅠarea,peak height of carbohydrateⅠand carbohydrateⅡ(P<0.05).The acetate proportion was positively correlated with the amideⅠpeak height,peak height ratio of amideⅠto amideⅡ,cellulosic compound peak height and total carbohydrate domain structure(P<0.05),while it was negatively correlated with the area and peak height ofβ⁃glucan(P<0.05).The total VFA content was positively correlated with the area and peak height of amideⅡ,while it was negatively correlated with the amideⅠpeak height,area and peak height ratio of amideⅠto amideⅡ,cellulosic compound peak height and total carbohydrate domain structure(P<0.05).In conclusion,there are differences in FTIR molecular structure and in vitro fermentation parameters as affected by different corn varieties and starch retrogradation.The total VFA produce,dry matter degradation rate and gas production in vitro were negatively correlated with the FTIR molecular structure except for amideⅡ,but were positively correlated with amideⅡ.