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- Title
Proteolytic activity of the Carpathian traditional liquid milk coagulant.
- Authors
Yukalo, Volodymyr; Krupa, Olha; Datsyshyn, Kateryna; Storozh, Liudmyla
- Abstract
Introduction. In the Ukrainian Carpathians, a special Carpathian liquid milk (CLM) coagulant is used for the production of traditional soft cheeses such as brynza and budz. Since CLM coagulant has not been studied before, the aim of the work was to characterize its milk coagulant and proteolytic properties. Materials and methods. Milk coagulants were obtained from farms in Vorokhta, Carpathians. Milk-clotting activity was examined by the Soxhlet method. The content of proteins was determined using the Kjeldahl method. Homogeneous αS1-, β- and ϰ-casein substrates were separated by preparative electrophoresis. The concentration of the products of casein substrates proteolysis was determined spectrophotometrically. The specificity of casein fractions proteolysis was established by analytical electrophoresis. Results and discussion. CLM coagulant has high milk coagulant activity, which is slightly lower than of the standard rennet enzyme and is close to the solid milk coagulant preparation Glek. It was found that the activity of CLM coagulant increases during its storage, which is apparently achieved through the proteolytic enzyme extraction from calf's stomach cells. The milk clotting time for fresh CLM coagulant is 159 min, and after 18 months of storage it is reduced to 49 min. Milk-clotting activity of the fresh CLM coagulant is 2515 Soxhlet Units (SU), whereas after storage during 18 months the milk-clotting activity increased to 8100 SU. In the production of Carpathian brynza and budz, it is recommended to use the amount of CLM coagulant, which provides the beginning of milk coagulation at 33-35 °C after 20-25 min. The analysis of the casein substrates proteolysis products by electrophoretic and spectrophotometric methods shows the high specificity of CLM coagulant to ϰ-casein. Such specificity is characteristic for the purified natural milk coagulant enzyme - chymosin. Along with that, CLM coagulant, unlike pepsin and, to a lesser extent, standard rennet, practically does not cleave αS1- and β-casein substrates. Conclusions. Milk-clotting activity of CLM coagulant during its storage for 18 months increases 3 times. According to the specificity of αS1-, β- and ϰ-casein substrates proteolysis, CLM coagulant is close to chymosin.
- Subjects
COAGULATION; COAGULANTS; CASEINS; PROTEOLYTIC enzymes; LIQUIDS; MILK; RENNET; PEPSIN
- Publication
Ukrainian Food Journal, 2023, Vol 12, Issue 2, p240
- ISSN
2304-974X
- Publication type
Article
- DOI
10.24263/2304-974X-2023-12-2-7