食品科学 ›› 2021, Vol. 42 ›› Issue (10): 8-13.doi: 10.7506/spkx1002-6630-20200324-361

• 食品化学 • 上一篇    下一篇

酸凝pH值对乳扇凝团理化特性、蛋白结构及微观结构的影响

魏光强,王钰潭,毛兴菊,廖紫玉,杨婧,黄艾祥   

  1. (云南农业大学食品科学技术学院,云南 昆明 650201)
  • 出版日期:2021-05-25 发布日期:2021-06-02
  • 基金资助:
    “十三五”国家重点研发计划重点专项(2018YFD0400102);云岭产业技术领军人才项目(云发改人事(2014)1782号); 云南省现代农业奶牛产业技术体系资助项目(2019KJTX0014)

Effect of Acid-Coagulation pH on Physicochemical Properties, Protein Structure and Microstructure of Rushan Cheese Curd

WEI Guangqiang, WANG Yutan, MAO Xingju, LIAO Ziyu, YANG Jing, HUANG Aixiang   

  1. (College of Food Science and Technology, Yunnan Agricultural University, Kunming 650201, China)
  • Online:2021-05-25 Published:2021-06-02

摘要: 研究测定不同酸凝pH值(4.2、4.5、4.8、5.1和5.4)乳扇凝团的基本组分、质构、粒径,酪蛋白分子结构和二级结构,以及微观结构,研究酸凝pH值对乳扇凝团理化特性、蛋白结构及微观结构的影响,并试图阐明酸凝pH值对乳扇拉伸成型的影响。结果表明:随着酸凝pH值的下降:κ-酪蛋白降解,乳扇凝团的粒径值先升后降,酸凝pH值为4.8时凝团平均粒径值为(26.74±0.11)μm;凝团的各组分质量先升后降,在pH 4.8时达到最高值;凝团的硬度值显著增大(P<0.05)。当酸凝pH值为4.8时,α-螺旋与β-折叠比值以及β-转角相对含量最小,分别为0.398和20.55%,乳扇凝团的柔韧性和稳定性好;微观结构表明凝团中的脂肪球分布均匀有序,且与蛋白和水分形成紧密的乳凝胶。综上,酸凝pH值通过影响乳扇凝团中酪蛋白的降解以及结构的变化,从而影响凝团的理化特性和结构。当酸凝pH值为4.8时乳扇凝团结构致密,持水性和可塑性强,乳扇易于拉伸成型。本研究可为乳扇加工参数的选择提供科学依据。

关键词: 乳扇;酸凝pH值;理化特性;蛋白结构;微观结构;拉伸成型

Abstract: In this work, the effect of acid-coagulation pH on the physicochemical properties, protein structure and microstructure of Rushan cheese curd was studied along with its effect on the stretch molding of Rushan cheese. The results showed that with the increase in acid-coagulation pH, κ-casein was degraded; the particle size of Rushan cheese curd rose initially and then declined, reaching an average of (26.74 ± 0.11) μm at pH 4.8, and so did all tested components, reaching the highest value at pH 4.8. The firmness of Rushan cheese curd increased significantly (P < 0.05). At an acid-coagulation pH of 4.8, the secondary structure of casein exhibited the smallest α-helix to β-sheet ratio and β-turn content, which were 0.398 and 20.55%, respectively. The flexibility and stability of the curd were excellent. The microstructure observation showed that the fat globules in the agglomerates were distributed in a uniform and orderly manner. It formed a dense milk gel with protein and water. In summary, the acid-coagulation pH affects the degradation and structural change of casein and consequently the physicochemical properties and structure of Rushan cheese curd. An acid-coagulation pH of 4.8 can impart a dense structure together with strong water-holding capacity and plasticity to Rushan cheese curd and make Rushan cheese easy to mold by stretching it. This study is expected to provide a scientific basis for the selection of processing parameters of Rushan cheese.

Key words: Rushan cheese; acid-coagulation pH; physicochemical properties; protein structure; microstructure; stretch molding

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