摘要
本试验旨在探究不同热处理对棉籽蛋白质营养价值、瘤胃降解特性与小肠消化率和分子结构的影响,并探讨棉籽蛋白质分子结构与其营养价值、瘤胃降解特性与小肠消化率之间是否存在相关性。试验分别采用干热(140、150和160℃分别加热1 h)、微波(700 W分别加热1、2和3 min)和γ辐照(剂量分别为30、45和60 kGy)的加热方式处理棉籽。采用常规化学分析法、康奈尔净碳水化合物-净蛋白质体系(CNCPS)、尼龙袋法和改进的三步体外法对不同热处理棉籽中蛋白质营养价值、瘤胃降解特性和小肠消化率进行评定,结合傅里叶变换红外光谱(FTIR)技术分析棉籽蛋白质的分子结构,并对棉籽蛋白质分子结构与其营养价值、瘤胃降解特性与小肠消化率之间的相关关系进行分析。结果表明:1)不同热处理对棉籽中蛋白质成分和CNCPS组分无显著影响(P>0.05)。2)不同热处理极显著影响瘤胃可溶部分、瘤胃可降解部分、瘤胃不可降解部分、蛋白质的瘤胃有效降解率以及小肠可消化蛋白质与总可消化蛋白质含量(P<0.01)。随着热处理时间的延长或强度的增加,棉籽蛋白质瘤胃有效降解率、总可消化蛋白质的含量和瘤胃非降解蛋白质的小肠消化率逐渐降低,小肠可消化蛋白质的含量逐渐升高。3)不同热处理对棉籽蛋白质分子结构酰胺Ⅰ带峰高、酰胺Ⅰ带峰面积、酰胺Ⅱ带峰高、酰胺Ⅱ带峰面积、α-螺旋峰高、α-螺旋与β-折叠峰高比产生了极显著影响(P<0.01)。除微波加热3 min外,其他热处理均显著升高了棉籽蛋白质分子结构中酰胺Ⅰ带峰高、酰胺Ⅰ带峰面积、酰胺Ⅱ带峰高、酰胺Ⅱ带峰面积(P<0.05),同时45和60 kGyγ辐照还显著升高了α-螺旋峰高、α-螺旋与β-折叠峰高比(P<0.05)。4)棉籽中蛋白质分子结构与其营养价值、瘤胃降解特性和小肠消化率之间存在相关性,并能建立回归方程,其中预测中性洗涤不溶蛋白质、可溶性蛋白质、快速降解真蛋白质、中速降解真蛋白质、慢速降解真蛋白质的回归方程的R^2均在0.9以上,但部分回归方程的R^2<0.6。综上所述,3种热处理方式均对棉籽中蛋白质的瘤胃降解特性、小肠消化率和分子结构产生了影响。热处理能够增加过瘤胃蛋白质和小肠可消化蛋白质的含量,以辐照剂量为60 kGy时效果最佳。棉籽蛋白质分子结构与其营养价值、瘤胃降解特性和小肠消化率存在相关性,并能够建立回归方程,但部分变量回归方程的R^2<0.6,仍需做进一步的研究。
The objective of this experiment was to explore the effects of different heat treatments on nutritional value,rumen degradation characteristics,small intestinal digestibility and molecular structure of cottonseed protein,and to discuss whether there was a correlation between protein molecular structure and protein nutritional value,rumen degradation characteristics or small intestinal digestibility in cottonseed.Cottonseed was treated by dry heat(heating at 140,150 and 160℃ for 1 h,respectively),microwave(heating at 700 W for 1,2 and 3 min,respectively)andγ-irradiation(doses were 30,45 and 60 kGy,respectively),respectively.The protein nutritional value,rumen degradation characteristics and small intestinal digestibility of different heat-treated cottonseeds were determined by traditional chemical analysis combined with Cornell net carbohydrate-net protein system(CNCPS),nylon bag method and modified three-step in vitro method.Fourier transform infrared spectroscopy(FTIR)technology was used to analyze the protein molecular structure of different heat-reated cottonseeds,and then to analyze the correlation relationships between protein molecular structure and protein nutritional value,rumen degradation characteristics or small intestinal digestibility in cottonseed.The results showed as follows:1)different heat treatments had no significant effects on protein composition and CNCPS protein components of cottonseed(P>0.05).2)Different heat treatments extremely significantly affected the rumen soluble part,rumen degradable part,rumen undegradable part,rumen protein effective degradation rate and the contents of small intestinal degradable protein and total degradable protein(P<0.01).With heat treatment time or strength increasing,the rumen protein effective degradation rate and total degradable protein content and the small intestinal digestibility of rumen undegradable protein were gradually decreased,while the small intestinal degradable protein content was gradually increased.3)Different heat treatments extremely significantly affected amideⅠband peak height and peak area,amideⅡband peak height and peak area,α-helix peak height andα-helix and β-sheet peak height ratio(P<0.01).Except microwave heating at 3 min,other heat treatments all significantly increased the amideⅠband peak height and peak area,amideⅡband peak height and peak area(P<0.05),and 45 and 60 kGy γ-irradiation also significantly increased theα-helix peak height andα-helix andβ-sheet peak height ratio(P<0.05).4)The molecular structure of cottonseed protein was correlated with its nutritional value,rumen degradation characteristics and small intestinal digestibility,and regression equations could be established.The R^22 of regression equations for neutral detergent insoluble protein,soluble protein,rapidly degradable true protein,intermediately degradable true protein and slowly degradable true protein all exceed 0.9,but the R^2 of part regression equations lowed 0.6.In summary,three heat treatments have effects on the rumen degradation characteristics,small intestinal digestibility and molecular structure of cottonseed protein.Heat treatment can increase the contents of ruminal protein and small intestinal digestible protein,and the effect is the best when the irradiation dose is 60 kGy.The molecular structure of cottonseed protein has a correlation with its nutritional value,rumen degradation characteristics and small intestinal digestibility,and can establish regression equations.However,the R^2 of some regression equations is less than 0.6,still need further research.
作者
徐文彬
高博兰
祝全超
戚丹杰
高悦
李浩然
孙满吉
XU Wenbin;GAO Bolan;ZHU Quanchao;QI Danjie;GAO Yue;LI Haoran;SUN Manji(College of Animal Science and Technology of Northeast Agricultural University,Harbin 150030,China)
出处
《动物营养学报》
CAS
CSCD
北大核心
2020年第3期1272-1283,共12页
CHINESE JOURNAL OF ANIMAL NUTRITION
基金
国家奶牛产业技术体系(CARS-36)
