What does curd taste like?

am Puls Biologie 5, textbook

160 No cheese without bacteria or fungi You probably know that: you leave the milk in the kitchen for a few days and suddenly it tastes sour and looks crumbly. Microorganisms that you are already familiar with are responsible for this: lactic acid bacteria. Their acidity causes the milk protein casein to coagulate by destroying its structure. This is used to advantage in cheese production. First, cream is added to the raw milk or separated from it, depending on how fat the cheese should be later. To make cream cheese, lactic acid bacteria are now added to the liquid milk. Because unlike forgotten milk, the coagulation of the casein is desirable here. For the production of soft cheese (eg Brie and Camembert) or hard cheese (eg Emmentaler and Parmesan) rennet is used for coagulation. This is a mixture of the enzymes pepsin and especially chymosin. In the past, rennet was obtained from the stomachs of young ruminants, especially calves. Without the rennet enzymes, they would not be able to digest milk. Similar to antibiotics, rennet is now mainly produced using biotechnology, because the amount produced from calf stomachs would not be sufficient by far. These rennet substitutes come from certain fungi or bacteria that are grown in fermenters. Genetically modified microorganisms, to which a gene has been used to synthesize the desired enzyme, are increasingly being used. When the coagulation process is complete, a greenish-yellow liquid remains, the whey. It is not necessary for the cheese-making process to proceed (unless you want to make whey cheese such as ricotta). There are now a number of other products to which whey is added, such as soft drinks. In alpine dairies, the whey is squeezed out through towels (k Fig. 19, left). The remaining whey-free mass is called curd cheese. It is crushed into curd cheese. The stronger the end product, the smaller the fragments have to be (k Fig. 19, right). Fig.19: Left: squeezing out the whey through a cloth. What remains is curd. Right: The curd cheese is still broken up by hand in this dairy. The curd is then gently heated and stirred and poured into molds while further removing the remaining whey. For mold cheese (e.g. Roquefort, Gorgonzola), mold is added to the curd. These are mushrooms that are harmless to humans and that give the cheese a special flavor. If you want to make hard cheese, this mass still has to be pressed in order to really get rid of all the whey. With many types, the resulting cheese wheel is placed in a salt bath (k Fig. 20). This removes water, gives flavor and contributes to the formation of the rind. Fig. 20: Salt bath of the cheese wheels. Now the cheese is allowed to mature. Depending on the cheese, this takes a few days or several months. During ripening, some of the fat and casein are broken down by bacteria and fungi. Hard cheese is often covered with a layer of wax to increase its shelf life. In 2015 Austria produced 190,782 tons of cheese. The average per capita consumption of cheese in Austria is around 12 kg per year. Lactic acid bacteria or rennet make the milk solid. Tasks W 1 Humans have an enzyme similar to chymosin. It just means something different with us. Find the right name and describe where it is formed and how it works. W 2 Consideration: Why do the rennet enzymes work best at 36–37 ° C? E 3 Carries out a cheese tasting in the class: everyone brings a cheese and presents it. Arranges the cheese you have brought with you according to how it was made (microorganisms, temperature, etc.). For testing purposes only - property of the publisher öbv

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