The Preservation Of Foods Essay Research Paper — страница 2

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occur in foods. The life of many foods may be increased by storage at temperatures below 4 C (40 F). Commonly refrigerated foods include fresh fruits and vegetables, eggs, dairy products, and meats. Some foods, such as tropical fruits (e.g., bananas), are damaged if exposed to low temperatures. Also, refrigeration cannot improve the quality of decayed food; it can only retard deterioration. One problem of modern mechanical refrigeration–that of dehydration of foods due to moisture condensation–has been overcome through humidity control mechanisms within the storage chamber and by appropriate packaging techniques. Salt and Nitrites Brine is a combination of high concentration of salt, in a water solution. Brine is used as a preservative and is also used a pickling agent. In

refrigeration and cooling systems, brine is used as heat-transfer media because of the low freezing temperatures or as vapour-absorption agents. SODIUM CHLORIDE (chemical formula: NACL), mineral substance is of a great importance. The meatpacking, sausage-making, fish-curing, and food-processing industries use salt as a preservative or seasoning or both. It is employed for curing and preserving hides and as brine for refrigeration. Salt decreases the moisture in meats available to spoilage micro-organisms. Nitrite prevents microorganisms from growing and retards rancidity in meats. Nitrite also produces the pink colour associated with cured products by binding (as nitric oxide) to humyoglobin. However, the use of nitrite in meat products is controversial owing to its potential

cancer-causing activity. Sodium erythorbate or ascorbate is another common curing additive. It not only decreases the risks associated with the use of nitrite but also improves cured meat colour development. Other common additives include alkaline phosphates, which improve the juiciness of meat products by increasing their water-holding ability. Freezing Freezing and frozen storage provide an excellent means of preserving the nutritional quality of foods. At subfreezing temperatures the nutrient loss is extremely slow for the typical storage period used in commercial trade. The type of freezing process, which is commonly done now, is, flash, freezing which is found to be especially effective with certain types of food. Except for beef and venison, which benefit from the ageing

proces. The meat is frozen soon after they have been slaughtered, with best results at temperatures of 0 F (-18 C) or lower. Usually the type of preservative, which is used when the meat is being frozen, is meat curing. Sugar or Sucrose Fruits can be either frozen in a syrup or dry-sugar pack to exclude air and prevent both oxidation and desiccation. The use of sugar or sucrose inhibits oxidative degradation in the fruit. “The standard unambiguous granulated sugar has dry impurity of less than 0.1%” Preservatives in the Food, Pharmaceutical and Environmental industries, R.G Board, M.C. Allwood and J.G Banks Pages 202. The function of sucrose as a preservative relies mainly on the ability to bind water and so make it unavailable to support spoilage, organism. In fermented

sausages, sucose acts as a substrate for acid formation, which inhibits production of toxins by food poisoning bacteria. “About 1% is the normal level of addition which is below the sweet threshold which allows the mellowing of harshness caused by the added sugar” Preservatives in the Food, Pharmaceutical and Environmental industries, R.G Board, M.C. Allwood and J.G Banks Pages 202-203 Pickling Sorbic acid is primarily used in pickling of vegetable. The reason being, that it increase the acidity of the product from about 4.6 on the pH level. Pathogenic (toxin-producing) mould, yeast, or bacteria cannot survive in acidity levels of that range. There are some that can withstand that unfavourable environment. Due to this factor, a higher concentration or solution is needed in

order to kill of these toxic organisms. Hydroxybezoate has a pH 4.6 level, which remedies this problem. But because of the high acidity level. The taste of the product come in to question so a certain amount of preservative has to be added to the proportion of food. A table1 is provided below Permitted preservation in vegetables products. Preservatives in the Food, Pharmaceutical and Environmental industries. Consumer Worries Of the many health concern challenging the public trusts in the recent year, food safety is the main topic of discussion. Pesticides use is the most common issues, which is familiar to us. But a huge amount of news has been directed at food preservation. Like Salmonella bacteria in eggs causing outbreaks of illness; colour additives banned for possible