Question: 1. Describe the physical changes that occur during frying hen eggs temperature 180°C? at
2. Discuss how nitrites can be used to preserve cured meat products.
Ans 1 Deep frying is an ancient process commonly used in food industry. It is a lost cost and highly demanding process which involves oil-food interaction at high temperature. When food is cook at high temperature dehydration occurs and food gets completely cooked because of which physical and chemical changes take place. There are vareity of examples such as starch gelatinization, protein denaturation, caramelization, maillard reaction ( giving food an aromatic and mouth watering aroma, which occurs when amino acids and sugar breaks down). Similarly deep frying of hen egg involves protein denaturation. The protein is a three dimensional arrangement of atoms in amino acid chain molecules and fold into spatial conformations via non colent interactions such as hydrogen bonding, ionic interactions and vanderwall forces. When the whole egg i.e yolk and white( albumen-major source of protein) is heated it turn into solid. This solidification of protein is known as coagulation. The heat causes the protein structure to lose water molecules and hence shrink them. Different proteins denature at diiferent temperature, similarly egg white starts denaturing at 61 degree celcius. As the protein changes its shape, it changes its taste and texture also.
Ans 2 Salts ( sodium chloride) are used as preservatives for meats from a long time.It was accidently found that nitrite salts increases the shelf life of meats by preventing rancidity( spoilage of food) and also the growth of bacteria. So now a days nitrite salts such as sodium nitrites are being used as preservatives and purified nitrites are commercially manufactured for this purpose. Pure nitriles if consumed at levels of 3-5 gm can be dangerous and may result in death also as it binds with oxygen in body stronger than heamoglobin thus not allowing oxygen to reach the organs. So it is added to meat according to level(0.01-0.02% depending on type of meats) set by USDA. It helps in improving meat quality , when added at allowed levels set by USDA it inhibits the growth of almost all bacteria such as Clostridium botulinum, Clostridium perfringens, Listeria monocytogens.that caauses food spoilage and sickness.