What is a Vegetarian? Write down your ideas (2 mins)

Lesson 3 Objectives: To describe the production of the enzyme chymosin To recall the role of chymosin in the manufacture of vegetarian cheese To describe microbial products used in food, including vitamin C, carrageen extract, enzymes such as invertase, citric acid, amino acids such as glutamic acid, monosodium glutamate

Rennet comes from the stomach of slaughtered cows. Rennet contains two protein digesting enzymes, one of which is called CHYMOSIN. These enzymes cause milk to form WHEY CURDS: This raw cheese. We can now genetically modify bacteria to produce CHYMOSIN. What is the advantage of this? Acceptable to vegetarians, AND GM free. CHYMOSIN is GM free, only the bacteria used to make it are genetically modified. Making Cheese

1Bacteria in milk ferment the sugar it contains. aName the sugar. bName the acid produced when bacteria ferment milk sugar. 2Describe what happens when milk is curdled. 3Why does curdled milk taste sour? 4Chymosin is a vital part of the process of making cheese. aWhat is chymosin? bWhy is chymosin a vital part of the process of making cheese? 5In the UK most of the chymosin used to make hard cheese is produced by genetically modified (GM) microorganisms. However, the cheese is rated as ‘GM free’. aWhy is the cheese rated as ‘GM free’? bSuggest reasons why the makers of cheese might think it important that their product is rated as ‘GM free’. Bacteria are responsible for curdling the milk. They get into the milk and ferment the lactose sugar it contains. As the fermentation proceeds, the pH of the milk is lowered (the milk becomes acid) to the point where the milk proteins coagulate forming curds.

Task Use the textbooks to complete worksheet B3.1 3b – Microorganisms and food. Micro-organisms break down protein

Body Mass Index = Body Mass (Kg) (Body Height) 2 (m 2 ) Can you think of any situations where the BMI is not the best way to determine obesity?

Size 0 – BMI<18

Obesity

Exam Question Describe the stages in the commercial production of soy sauce. (4 marks) Any four in correct sequence from: 1. cook soya bean; 2. mix with (ground) roasted wheat; 3. ferment with Aspergillus ; 4. brine is added; 5. yeast and/or Lactobacillus added; 6. second fermentation/refermentation; 7. filtered; 8. pasteurisation; 9. use sterile bottle; [Ignore sterilising] Max 3 marks if any points in wrong sequence.