| 1. |
- Glantz, Maria, et al.
(författare)
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Impact of protease and lipase activities on quality of Swedish raw milk
- 2020
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Ingår i: International Dairy Journal. - : Elsevier BV. - 0958-6946. ; 107
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Tidskriftsartikel (refereegranskat)abstract
- An increasing demand for dairy products with long shelf-life is foreseen. A limiting factor for maintaining high quality of these products is the activity of spoilage enzymes during storage. Lipase and protease activities in Swedish raw milk at farm and dairy level were investigated, analysing milk samples from three geographical regions and two seasons. Lipase activity in milk at farm level was affected by regional and seasonal variations, whereas at dairy level only season had an effect. Lipase activity was positively correlated with ionic calcium. For protease activity, no effect of either region or season was seen. Degradation products, e.g., free fatty acids, peptides and plasmin proteolysis products, varied differently between season and geographical origin at both farm and dairy level. The results indicate that lipase and protease activities are important for raw milk quality, while ionic calcium might be a future indicator for milk fat stability.
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| 2. |
- Nilsson, Kajsa, et al.
(författare)
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An investigation of the enzymatic cleavage of κ-casein in non-coagulating milk
- 2020
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Ingår i: International Dairy Journal. - : Elsevier BV. - 0958-6946. ; 109
-
Tidskriftsartikel (refereegranskat)abstract
- Non-coagulating milk is unwanted in cheese production because it impairs chymosin-induced coagulation properties in bulk milk. Milk samples were analysed to investigate the coagulation process in non-coagulating milk for comparison with milk samples that have a high coagulation ability. This was done by measuring two peptides after chymosin cleavage, namely para-κ-casein and caseinomacropeptide, in all the milk samples using capillary electrophoresis. The results showed that cleavage of κ-casein into para-κ-casein and caseinomacropeptide occurred in both coagulation groups, suggesting that the aggregation stage is the cause of non-coagulating milk. Non-coagulating milk had lower content of para-κ-casein after chymosin addition compared with coagulating milk, which might be the result of a lower content of available κ-casein. Furthermore, this study indicates that there are different mechanisms that explain good coagulation ability and lack of coagulation ability of milk. The results can be useful in understanding the potential chemical mechanisms behind non-coagulating milk.
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