Octover 20th, 2012
Assignment 1: Cellular Biology furthers technology-Enzymes in the Dairy Industry
Since ancient times, enzymes have played an important role in food production. Especially in the diary industry, some enzymes are required for the production of cheese, yogurt, and other dairy products, while others are used in a more specialized fashion such as improving texture or flavour of the product. Enzymes are used to catalyze the desirable reactions in industrial processes. Today, enzyme applications in such processing get more difficulties because of the rare occurrence and high costs. The aim of using the microbial enzymes is to achieve this problem. Five of the more common types of microbial enzymes involved in the dairy industry involve: Rennet, Proteases, Lactase, Catalase, and Lipases. Milk contains proteins, especially caseins which maintain its liquid form. Proteases are enzymes that are added to milk during the process of cheese production, to hydrolize caseins, like kappa caseins, which stabilizes micelle formation and thus preventing milk coagulation. On the other hand, rennet and rennin are general terms for enzymes used to coagulate milk. The Chymosin enzyme which can be obtained from animal, microbial, or vegetable sources, is responsible for up to 70% of cheese production. It is now possible to produce chymosin in genetically modified fungi. These modified microorganisms contain the gene derived from the stomach of calves that is responsible for producing chymosin. When grown in a bioreactor, they release chymosin into the medium. Afterwards, the enzyme is extracted and purified, yielding a product that is 80%-90% pure. Natural rennin contains only 4%-8% active enzyme. Chymosin produced by genetically engineered microorganisms is now used to produce cheese in many different countries. Rennet (Chymosin) has owed to an increase in demand for cheese production worldwide. Rennin acts on milk in two stages, by enzymatic and by nonenzymatic action, resulting in the coagulation of milk. In the enzymatic phase, the resultant milk becomes a gel due to the influence of calcium ions and the temperature used in the process. Many microorganisms are known to produce rennet-like proteinases, as mentioned above, which can substitute the calf rennet. Good yields of milk-clotting protease may be obtained in a medium containing 4% potato starch, 3% soybean meal, and 10% barley. During growth, lipase is secreted together with the protease. Therefore, the lipase activity has to be destroyed by reducing the pH, before the preparation can be used as cheese rennet. Protease is another notable enzyme. Cow milk contains a number of different whey proteins such as lactoglobulin and lactalbumin. The denaturing of these whey proteins, using proteases as catalysts, results in a creamier yogurt product. The denaturing of whey proteins is also essential for cheese production. In addition, proteases reduce allergic properties of cow milk products for infants, which produce healthier milk for them. Lactease is a glycoside hydrolase enzyme that decomposes lactose into its constituent sugars of galactose and glucose. Lactose intolerant individuals can result from insufficient production of lactase enzyme in the small intestine. Feeding lactose-containing milk to lactose-intolerant individuals can result in discomforts such as: cramps, gas, dehydration, diarrhoea in the digestive tract upon ingestion of milk products, or maybe even death. Lactase provides relief for lactose and tolerant individuals because it can be used commercially to prepare lactose-free products, particularly milk by the process of hydrolysis of the lactase into glucose and galactose. In addition, lactase enzymes can be used in preparation of ice cream to make a creamier, sweeter-tasting product and improving digestibility. Finally, this reduces sandiness due to crystallization of lactose in concentrated preparations....
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