Milk coagulation : impact on cheese

Abstract: Cheesemaking origins from “The fertile crescent”, nowadays southern Turkey, some 8000 years ago. Curd was found in young, still suckling, ruminants’ stomachs after slaughter. All characteristic cheese properties that we think of today, are thought to have evolved through accidents, unlike nowadays, where cheese production rather is planned, designed and centralized to big factories. The purpose of the essay is to, through literature, understand the correlation between; raw milk composition and coagulation properties, which milk coagulating enzymes are available and how they differ, and their joined impact on cheese properties. The most important parameters of milk composition, in cheese perspective, is protein and fat. Animal rennet, which is most used historically, consists of two proteolytic enzymes, chymosin and pepsin, where chymosin have the most specific activity towards the κ-casein of milk. The available animal rennet cannot provide for the increased demand of cheese, substitutes are therefore necessary. Generally, the substitutes have a higher proteolytic activity, resulting in lower cheese yield and production of bitter flavoured peptides. Plant extracts from Cynara cardunclulus have been used historically for cheeses from sheep milk in Spain and Portugal. Microbial substitutes can be either naturally occurring proteases or produced through recombinant DNA-technology. The production of the substitutes needs to be optimized in order to produce consumer approved cheese. Several aspects are important to control during the design of a specific cheese. It is important to be able to match a specific milk with a correct coagulant under the right conditions, effective breeding programmes are important for all species in order to influence the milk composition. In mail correspondence with an innovation group, working on developing Swedish goat rennet, the need of rennet from Swedish animals is emphasized as there might be an economical boost of farm produced cheeses.