{"title":"Enzymatic Sol-Gel Transition in Milk","authors":"I. T. Smykov, D. S. Myagkonosov","doi":"10.1134/s1061933x23601385","DOIUrl":null,"url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>The objective of this study is to enhance the comprehension of the mechanism of enzymatic gelation in milk by investigating statistically significant changes in milk viscosity and carrying out corresponding electron microscopic studies of the process of structure formation at the enzymatic stage of coagulation using various enzyme preparations. Employing a non-destructive method (Hot-Wire) to monitor viscosity, we were able to confirm a decrease in viscosity during the middle of this stage and identify a previously undescribed peak in viscosity change at the end of the enzymatic stage. By conducting parallel studies utilizing transmission electron microscopy and various methods of specimen preparation, it was possible to discover that a hierarchical transformation process in the protein component of milk started at the end of the enzymatic stage of gelation in milk. This process is triggered by a cooperative conformational transition in casein micelle clusters, which leads to a series of increasingly energy-intensive reactions resulting in the transformation of loosely bound micelle clusters into denser aggregates. The final structure of the milk gel primarily consists of the previously formed individual micelle aggregates. It was noted that no changes in the microstructure of the milk gel were observed during the enzymatic stage of gelation when milk-clotting enzymes (MCEs) of animal, plant, and microbial (GMO) origins were used. Furthermore, investigations into the molecular weight distribution of soluble protein substances in samples generated with different types of MCEs revealed that the enzyme derived from the fungi of <i>Rhizomucor miehei</i> had a greater proteolytic effect on milk proteins compared to other variants of MCEs.</p>","PeriodicalId":521,"journal":{"name":"Colloid Journal","volume":null,"pages":null},"PeriodicalIF":1.4000,"publicationDate":"2024-05-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Colloid Journal","FirstCategoryId":"92","ListUrlMain":"https://doi.org/10.1134/s1061933x23601385","RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q4","JCRName":"CHEMISTRY, PHYSICAL","Score":null,"Total":0}
引用次数: 0
Abstract
The objective of this study is to enhance the comprehension of the mechanism of enzymatic gelation in milk by investigating statistically significant changes in milk viscosity and carrying out corresponding electron microscopic studies of the process of structure formation at the enzymatic stage of coagulation using various enzyme preparations. Employing a non-destructive method (Hot-Wire) to monitor viscosity, we were able to confirm a decrease in viscosity during the middle of this stage and identify a previously undescribed peak in viscosity change at the end of the enzymatic stage. By conducting parallel studies utilizing transmission electron microscopy and various methods of specimen preparation, it was possible to discover that a hierarchical transformation process in the protein component of milk started at the end of the enzymatic stage of gelation in milk. This process is triggered by a cooperative conformational transition in casein micelle clusters, which leads to a series of increasingly energy-intensive reactions resulting in the transformation of loosely bound micelle clusters into denser aggregates. The final structure of the milk gel primarily consists of the previously formed individual micelle aggregates. It was noted that no changes in the microstructure of the milk gel were observed during the enzymatic stage of gelation when milk-clotting enzymes (MCEs) of animal, plant, and microbial (GMO) origins were used. Furthermore, investigations into the molecular weight distribution of soluble protein substances in samples generated with different types of MCEs revealed that the enzyme derived from the fungi of Rhizomucor miehei had a greater proteolytic effect on milk proteins compared to other variants of MCEs.
期刊介绍：
Colloid Journal (Kolloidnyi Zhurnal) is the only journal in Russia that publishes the results of research in the area of chemical science dealing with the disperse state of matter and surface phenomena in disperse systems. The journal covers experimental and theoretical works on a great variety of colloid and surface phenomena: the structure and properties of interfaces; adsorption phenomena and structure of adsorption layers of surfactants; capillary phenomena; wetting films; wetting and spreading; and detergency. The formation of colloid systems, their molecular-kinetic and optical properties, surface forces, interaction of colloidal particles, stabilization, and criteria of stability loss of different disperse systems (lyosols and aerosols, suspensions, emulsions, foams, and micellar systems) are also topics of the journal. Colloid Journal also includes the phenomena of electro- and diffusiophoresis, electro- and thermoosmosis, and capillary and reverse osmosis, i.e., phenomena dealing with the existence of diffusion layers of molecules and ions in the vicinity of the interface.
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