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Cheese Lab

Decent Essays

The hypothesis in this Cheese Lab was the following: if pH of milk with the enzyme, rennet, increases, then the time it takes for the curd to form would increase as well because rennet catalyzes reactions well in acidic environments. After the lab was conducted, a positive linear trend was seen between the curdling time and the varying values of pH of the milk with the rennet in Figure 4. The milk contained casein micelles, composed primarily of casein proteins, calcium and phosphate (Swinscoe, 2013). Specifically, a protein in the casein micelle named kappa casein was negatively charged, which repelled the other micelles, allowing the milk to be a liquid substance (Swinscoe, 2013). When rennet was added to milk, it caused the negative part of the kappa casein to …show more content…

Specifically, when the rennet was added to the milk solutions with pH rennet to increase and stretch (Bowen, 1996). This allowed the rennet to catalyze the reaction efficiently and therefore, the curds formed faster (Bowen, 1996). Hence, as a result of lowering pH in the milk solution with the rennet, the curds formed faster. For instance, at a pH of 6, shown in Table 4, the time it took the curd to form was 215 seconds (s) and at a pH of 8, the time it took the curds to form was 475 s. Furthermore, the pH of the milk used was about 6.7, hence slightly acidic (Guadgnolo, 2016). With the addition of drops of hydrochloric acid (HCl), the pH of the milk became lower (to values of pH 2 and 4). This was because when the hydrogen ions (from the addition of HCl) were released into the milk solution, they neutralized the negative charge on the k-casein protein, allowing the casein micelles to coagulate (Sam Adam-Day, 2015). Due to the presence of calcium, the curds could be formed in the acidic solutions, before the addition of the rennet (Sam Adam-Day,

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