摘要
【目的】研究超声波对肌原纤维蛋白凝胶化学作用力与保水性的影响,并探讨化学作用力与保水性之间的内在联系。【方法】取活AA鸡屠宰,提取肌原纤维蛋白(myofibrillar proteins,MP),用不同超声时间处理MP并制成热诱导凝胶,运用凝胶中总巯基含量的变化来反应二硫键的形成;凝胶的表面疏水性S0和Zeta电位值来表征疏水作用力和静电斥力;用拉曼光谱的I850/I830比值大小反映凝胶氢键的变化;凝胶保水性用高速离心机测定。【结果】超声波处理0—6 min时,MP凝胶的总巯基含量随时间的增加而减少,活性巯基含量显著增加;处理6—15 min时,MP凝胶的总巯基以及活性巯基均随时间延长而显著减少,而对MP原料进行同样处理时,处理时间在0—6 min内,MP总巯基和活性巯基变化趋势与MP凝胶相同;超过9 min后,活性巯基和总巯基没有显著变化,且二者含量逐渐接近。表明短时间超声波处理促进了MP分子内部巯基转变成二硫键,长时间超声波处理和加热成胶的共同作用促进了活性巯基转变成二硫键。MP凝胶的表面疏水性先随超声时间延长从1 194.1显著上升到1 489.5(6 min),随后逐渐降至1 230.8,表明超声波产生的空穴效应能够使MP分子内部疏水基团暴露到分子表面,但超过6 min后,增加的蛋白表面疏水性又被包裹在凝胶网络中。MP凝胶的Zeta电位绝对值随超声时间的增加从6.03显著增加到7.68(P<0.05),超过6 min后显著减少,表明超声波处理使MP分子逐渐展开,蛋白质分子间静电作用增强,但过度展开后对其形成凝胶的静电作用力不利。适度的超声时间(0—6 min)使MP凝胶的归一化强度I850/I830比值从0.9805增加至1.023(P<0.05),表明MP与水分子形成的"蛋白-水分子"氢键增多,6 min过后比值减少,蛋白与水分子之间的氢键减弱;超声波处理0—6 min后的MP凝胶保水性从47.5899%快速升至72.9855%(6 min)(P<0.05),之后随时间延长,凝胶的保水性减少至44.356%。相关性分析结果表明,保水性与总巯基的相关性不大(P>0.05),与活性巯基显著相关(P<0.05),与表面疏水性、电位绝对值和氢键都极显著相关(P<0.01)。【结论】超声波显著影响肌原纤维蛋白凝胶化学作用力与保水性;疏水作用力、静电斥力和氢键是决定保水性的主要作用力,而二硫键次之;超声波处理时间为6 min时为最优条件,在此条件下,凝胶的疏水作用力、氢键和静电斥力均达到最大,致使凝胶网络结构均匀致密,能最大限度的保留水分。
[ Objective ] The influences of ultrasound on chemical forces and water holding capacity of myofibrillar protein （MP） gel were studied. The relationship between MP gel chemical forces and WHC was revealed. [Method] AA type broilers were slaughtered. The MP was extracted from breast muscle. The MP solution and heat induced gel in different ultrasound times were prepared. Total sulfhydryl group （SH） content changes of gel were used to reflect the formation of disulfide bond. Surface hydrophobicity and Zeta potential value of the gel were employed to present the hydrophobic interaction and electrostatic repulsion, respectively. The ratio of I850/I830 was used to show the hydrogen bonding changes of gel. Water holding capacity （WHC） of MP gel was calculated by high-speed centrifuge. [ Result] As the ultrasonic time （UT） increased （0-6 min）, the total SH contents of the MP gel decreased and reactive SH content significantly increased, at stronger UT （6-15 min）, the total SH and reactive SH contents all decreased. At short time （0-6 min）, the changing trends of MP and MP gel about the total SH and reactive SH content were the same, while the total SH and reactive SH contents of MP all had no significant changes （P〉 0.05） over 6 rain, suggesting that UT promoted internal SH of MP into disulfide bond for shorter time, and UT and heating gel for longer time work together to promote reactive SH into disulfide bond. Surface hydrophobicity of MP gels increased from l 194.1 to 1 489.5 （P〈0.05） and decreased from 1 489,5 to 1 230.8 at last, for the cavitation phenomenon induced by UT could bring the hydrophobic regions into the surface, while at UT〉6 min, the hydrophobic group was wrapped in the gel network. Zeta potential value of the gel changed from 6.03 to 7.68 （P〈0.05） （0-6 min） , and then decreased over 6 min, which showed that ultrasonic wave made protein molecular chain unfolding, negatively charged by exposure, resulting in the stronger electrostatic repulsion, while excessive expansion of MP molecules were not conducive to the electrostatic force of the gel. After moderate UT （0-6 min）, the normalized intensity of 1850/I830 ratio increased from 0.9805 to 1.023 （P〈0.05）, which indicated that more phenolic hydroxyl groups of tyrosine were exposed to the aqueous environment, generating hydrogen bonds with water molecules, while the ratio decreased at UT〉6 min, hydrogen bonds between water molecules and protein were weaken. At UT ~〈6 min, the WHC of samples increased sharply from 47.5899% to 72.9855% （6 rain） （P〈0.05）, while at 9 min and above, WHC dropped gradually to 44.356%. Results of the correlation analysis showed that WHC of MP gel was unrelated to total SH content （P〉0.05） and was significantly related to reactive SH content （P〈0.05） and had a significantly correlation with Zeta potential absolute value, the surface hydrophobicity and hydrogen bonding （P〈 0.01）. [ Conclusion ] Ultrasound has significant impacts on both chemical forces and water holding capacity of the MP gel. Hydrophobic force, electrostatic repulsion and hydrogen bonding play important roles in holding water in MP gels, disulfide bonds not. Thus a value of 6 min is the optimum time for the water holding capacity of MP gel, under this condition, hydrophobic force, hydrogen bonding and electrostatic repulsion of the gel are maximum, resulting in the gel network structure of uniform density, and retaining water at best.
作者
王静宇
杨玉玲
康大成
汤晓智
张兴
马云
倪文溪
WANG JingYu YANG YuLing KANG DaCheng TANG XiaoZhil ZHANG Xing MA Yun NI WenXi(College of Food Science and Engineering~Collaborative Innovation Center for Modern Grain Circulation and Safety~Key Laboratory of Grains and Oils Quality Control and Processing, Nanjing University of Finance and Economics, Nanjing 210023 College of Food Science and Technology, Nanjing Agricultural University~Collaborative Innovation Center for Meat Production and Processing, Quality and Safety Control, Nanjing 210095)
出处
《中国农业科学》
CAS
CSCD
北大核心
2017年第12期2349-2358,共10页
Scientia Agricultura Sinica
基金
国家自然科学基金(31371798)
江苏省高校优势学科建设工程资助项目
关键词
肌原纤维蛋白凝胶
二硫键
疏水作用力
静电斥力
氢键
保水性
myofibrillar protein gel
disulfide bond
hydrophobic force
electrostatic repulsion
hydrogen bond
water holdingcapacity
microstructure
