The Preservation Of Foods Essay Research Paper

The Preservation Of Foods Essay, Research Paper

The preservation of food.

Different government organisation, such as the world Health (WHO) and the United Nations Foods and Agriculture Organisation (FAO) have different definitions of food additives.

In laymen terms, a food additive is any substance added to food.


” Any substance the intended use of which or may reasonably be expected to result directly or indirectly in its becoming a component to otherwise affect the characteristics of any food ” Mechanisms of action of food Preservation procedures, G.W.Gould. page 2

The food Protection committee of the institute of medicine’s Food and Nutrition Board Defines and additive as a ” substance or mixture of substance, other than a basic foodstuff, which is present in a food as a result of any aspect of production, processing storage, or packaging “.

Types or different form of food preservatives

Food preservatives are classified into two main groups: antioxidants

and antimicrobials,

+ Antioxidants are compounds that delay or prevent the deterioration of foods by

oxidative mechanisms. For example, enzymes called phenolases catalyse the oxidation of certain molecules (e.g., the amino acid tyrosine) when fruits and vegetables, such as apples, bananas, and potatoes, are cut or bruised. The product of these oxidation reactions, collectively known as enzymatic browning, is a dark pigment called melanin. Antioxidants that inhibit enzyme-catalysed oxidation include agents that bind free oxygen (i.e., reducing agents), such as ascorbic acid (vitamin C), and agents that inactivate the enzymes, such as citric acid and sulphites.

+ Antimicrobial agents inhibit the growth of spoilage and pathogenic micro-organisms

in food. Antimicrobials are most often used with other preservation techniques, such as refrigeration, in order to inhibit the growth of spoilage and pathogenic microorganisms. Sodium chloride (NaCl), or common salt, is probably the oldest known antimicrobial agent. Organic acids, including acetic, benzoic, propionic, and sorbic acids, are used against micro-organisms in products with a low pH. Refer to the fig 1 in appendix to see a list of common preservatives used in the food industry.

What are the main reasons for food preservatives?

Food Preservatives are used in food for four main reasons.

1. To maintain Product consistency.

Emulsifiers give a product a consistent texture and prevent them from separating. Stabilisers and thickeners give smooth uniform texture. Anti-caking agents help substance such as salt to flow freely.

2. To maintain palatability and wholesomeness.

Preservatives retard product spoilage caused by mould, fungi or yeast. Bacterial contamination can cause foodborne illness, including life-treating botulism. Antioxidants are preservatives that prevent fats and oil in baked and other good from becoming rancid or development an off flavour. They also prevent cut fresh fruits such as apples from turning brown when exposed to air.

3. To provide controlled acidity.

Some food preservatives like sorbic acid help modify the acidity and alkalinity of foods for proper flavour, taste and colour.

4. To enhance flavour or impact desired colours.

Many spices and natural and synthetic flavour enhance the taste of foods. Colours like wise enhance the appearance of certain foods to meet customer expectations. In addition, many substances added to foods may seem unheard of when listed on the ingredient label, but are actually quite familiar. For example, ascorbic acid is another name for vitamin C, alpha is another name for vitamin E and beta-carotene is another source of vitamin A

Types of food Preservation techniques

Low-temperature preservation

Storage at low temperatures prolongs the shelf life of many foods. In general, low temperatures reduce the growth rates of microorganisms and slow many of the physical and chemical reactions that 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 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


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 carcinogenicity (cancer – causing ability): and possible risk from hormones given to cows to increase milk production. Another major issue, which has come into the public light, is the debate on natural additives versus man made additives.

The primary threat of cancer from food is the food itself, not pesticides and other contaminants. ” The nation’s food supply carcinogens that dwarf all the synthetic preservative.” Richard Doll and Richard Petro published a 117 page report in the journal of the national Cancer Institute on The cause of cancer: quantitative Estimates of Avoidable Risk of Cancer in the United States Today,1981. Carcinogens are found naturally in many spices, in smoked or salted fish, pickled vegetable, corn, peanuts and boiled or fired protein-rich foods such as beef, pork, eggs and chicken, for example. On the other hand, “many foods contain substance such as vitamins A, C and E that seem to have protective affects against cancer.” Richard Doll and Richard Petro published a 117 page report in the journal of the national Cancer Institute on The cause of cancer: quantitative Estimates of Avoidable Risk of Cancer in the United States Today, 1981. And if not for the use of some preservatives like nitrates cured into meats, Clostridium Botulism would be forever prevalent in all types of foods products. But the dilemma starts here, because it has been proved that some forms of nitrates cause carcinogenic cancer. Where do you draw the line? If you use it, it stops one thing, but creates another problem. In my opinion, if the good out weigh the bad then use this type preservative.

In 1981, British investigators, Richard Doll and Richard Petro published a 117 page report in the journal of the national Cancer Institute on “The cause of cancer: quantitative Estimates of Avoidable Risk of Cancer in the United States Today”. In their report, commissioned by the US congress, the researchers attributed about 35 % of cancer deaths to diet habits.

From this report, the dietary guidelines issued by the National Cancer Society, and the British Department of Health is similar in their conclusion about the roles of food in promoting or helping to prevent cancer. Emphasis is reducing fat intake, increasing fibre intake, avoiding obesity and limiting consumption of alcoholic beverages and salt-cured, salt pickled and smoked fish.

But the government still does not explicitly point out these facts to the consumer.

Consumerism is very strong and if the consumer is not properly informed about this, how are the consumers themselves truly going to trust a government? In my eyes the government know that if consumers were truly aware, a lot of industries involved in the food sector would lose a lot of capital as well as the government losing a huge amount of investment, themselves.


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