(7/7) Bio HL IA: CaCl2 concentration and cheese coagulation

본 문서는 2021 May session에 제출한 IB Bio HL Internal Assessment입니다.
Research Question은 How does different mass (g) of calcium chloride (g) affect time (s) required for milk to coagulate facilitated by the enzyme rennin?입니다
식품 가공 혹은 enzyme denaturation을 주제로 하고 싶으신 분에게 도움이 될 것입니다

[본문내용]

Research Question

How does different mass (g) of calcium chloride (g) affect time (s) required for milk to coagulate facilitated by the enzyme rennin?

Background Information

Often I make homemade cheese using milk and rennet. When I first tried to make cheese at home, I failed making cheese several times because curd did not formed. However, when I used high calcium milk, with higher calcium in it compared to ordinary milk, I succeed to get enough curd and therefore could make homemade cheese for the first time. This made me to guess that calcium has significant effect on milk coagulation process, and I became curious about the relationship between calcium content and milk coagulation process. Therefore, I conducted an experiment to investigate about how different calcium concentration affects clotting time of rennet while coagulating milk.

Enzyme is a protein, which acts as a biological catalyst by lowering activation energy for reactions, and therefore speeding up reactions. Catalysis of reaction by enzyme occurs due to the interaction between substrate and active site. Active sites are cracks on the surface of the enzyme caused by the way the protein folds itself up into its tertiary structure (Jim C, 2007). Binding of substrate on enzyme’s active site cause conformational change of enzyme’s active site, and this is called induced fit, meaning that the precise orientation of the enzyme required for catalytic activity can be induced by the binding of the substrate (Department of Biochemistry and Molecular Biophysics University of Arizona, 2004). There is a precise substrate interaction that occurs at the active site stabilized by numerous weak interactions such as hydrogen bonds, electrostatic interactions, and disulphide bonds (Department of Biochemistry and Molecular Biophysics University of Arizona, 2004). Enzymes are used widely in food industry like dairy and brewing industry. For example, enzyme called rennin is used in cheese production.

Rennin is a protease, a group of enzymes that break the long chainlike molecules of proteins into shorter fragments of peptides and amino acids (Encyclopedia Britannica, 2015), which is used to coagulate milk. It is added to milk during cheese production to hydrolyze caseins, specifically kappa casein, which stabilizes micelle formation preventing coagulation (Theresa P, 2017). Rennin is a gastric protease synthesized by chief cells in neonatal stomach of ruminants such as cattle, goats, camels, and pigs (Richard B, n. d.). Its role is to change milk to a solid or semisolid state in the stomach to allow milk to be retained for longer periods in the stomach, so that proteins in the milk can be digested (Richard B, n. d.). In the past, rennin was extracted from dried calf stomachs, but now rennin can be obtained from several different animals, microbial or vegetable sources (Theresa P, 2017)…

• 총페이지수: 17 pages
• 과목명: Biology
• 주제: IB Biology HL Internal Assessment – How does different mass (g) of calcium chloride (g) affect time (s) required for milk to coagulate facilitated by the enzyme rennin?
• The file is in Word format.