柠檬酸钾与TG酶对牛乳酸凝胶形成的协同作用

The Combined Effect of Potassium Citrate and Transglutaminase on the Texture and Microstructures of Acid-Induced Milk Gels

分别将0,5,10,20,30,40和50 mmol/L柠檬酸钾与TG酶加入脱脂牛乳中,在42℃的条件下放置1 h,然后添加1.5×10^(6) CFU/g的复配菌种(W_(保加利亚乳杆菌):W_(嗜热链球菌)=6:4)使乳蛋白形成凝胶,旨在分析柠檬酸钾对凝乳颗粒尺寸、凝胶强度、持水力、硬度和微观结构的影响。结果表明,在0~40 mmol/L范围内,随着柠檬酸钾浓度的升高,乳蛋白凝胶强度从36.70 mN增加到812.60 mN,弹性模量G’从16.28 Pa增加到108.14 Pa,持水力从28.20%增加到90.27%,当柠檬酸钾的浓度达到50 mmol/L时,乳蛋白无法形成凝胶。扫描电镜的结果表明,在0~40 mmol/L范围内,随着柠檬酸钾浓度的升高,凝胶的网络结构的致密程度显著提高,柠檬酸钾和TG酶协同处理可显著提高酸乳凝胶的质构特性和稳定性。

Various concentrations(0,5,10,20,30,40 and 50 mmol/L)of potassium citrate were added to the skim milk.followed with transglutaminase(mTGase)treatment.After being incubated for 1 h at 42℃,1.5×10^(6) CFU/g mixture culture(W_(Lactobacillus bulgaricus):W_(Streptococcus thermophilus)=6:4)was added into the samples.The changes in particle size caused by potassium citrate were investigated.The acid-induced milk gel was evaluated in terms of firmness,water-holding capacity(WHC),rheological behavior and microstructure.The result indicated that,under the premise concentration of potassium citrate from 0 to 40 mmol/L,the firmness increased from 36.70 mN to 812.60 mN;The storage modulus(G’)rosed from 16.28 Pa to 108.14 Pa;WHC increased from 28.20%to 90.27%.The skim milk gel would not be formed when the concentration of potassium citrate was 50 mmol/L.Furthermore,cryo-scanning electron microscopy images showed that more interconnected networks and smaller pores were present in the gels at higher concentrations of potassium citrate,thus the texture properties of skim milk gel was significantly improved.The synergistic treatment of potassium citrate and mTGase could significantly improve the texture and stability of acid-induced milk gels.