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Throughout the history of mankind science has searched into the realms of the unknown. Along with it bringing new discoveries, allowing for our lives to become healthier, more efficient, safer, and at the same time, possibly more dangerous. Among the forces driving scientists into these many experiments, is the desire to preserve the one fuel that keeps our lives going; FOOD. As early as the beginning of the 19 th century, major breakthroughs in food preservation had begun.
Soldiers and seamen, fighting in Napoleons army were living off of salt-preserved meats. These poorly cured foods provided minimal nutritional value, and frequent outbreaks of scurvy were developing. It was Napoleon who began the search for a better mechanism of food preservation, and it was he who offered 12, 000 -franc pieces to the person who devised a safe and dependable food-preservation process. The winner was a French chemist named Nicolas Appert. He observed that food heated in sealed containers was preserved as long as the container remained unopened or the seal did not leak. This became the turning point in food preservation history.
Fifty years following the discovery by Nicolas Appert, another breakthrough had developed. Another Frenchman, named Louis Pasteur, noted the relationship between microorganisms and food spoilage. This breakthrough increased the dependability of the food canning process. As the years passed new techniques assuring food preservation would come and go, opening new doors to further research. FOOD PROCESSING Farmers grow fruits and vegetables and fatten livestock. The fruits and vegetables are harvested, and the livestock is slaughtered for food.
What happens between the time food leaves the farm and the time it is eaten at the table? Like all living things, the plants and animals that become food contain tiny organisms called microorganisms. Living, healthy plants and animals automatically control most of these microorganisms. But when the plants and animals are killed, the organisms yeast, mold, and bacteria begin to multiply, causing the food to lose flavor and change in color and texture. Just as important, food loses the nutrients that are necessary to build and replenish human bodies. All these changes in the food are what people refer to as food spoilage.
To keep the food from spoiling, usually in only a few days, it is preserved. Many kinds of agents are potentially destructive to the healthful characteristics of fresh foods. Microorganisms, such as bacteria and fungi, rapidly spoil food. Enzymes which are present in all raw food, promote degradation and chemical changes affecting especially texture and flavor.
Atmospheric oxygen may react with food constituents, causing rancidity or color changes. Equally as harmful are infestations by insects and rodents, which account for tremendous losses in food stocks. There is no single method of food preservation that provides protection against all hazards for an unlimited period of time. Canned food stored in Antarctica near the South Pole, for example, remained edible after 50 years of storage, but such long-term preservation cannot be duplicated in the hot climate of the Tropics. Raw fruits and vegetables and uncooked meat are preserved by cold storage or refrigeration. The cold temperature inside the cold-storage compartment or refrigerator slows down the microorganisms and delays deterioration.
But cold storage and refrigeration will preserve raw foods for a few weeks at most. If foods are to be preserved for longer periods, they must undergo special treatments such as freezing or heating. The science of preserving foods for more than a few days is called food processing. Human beings have always taken some measures to preserve food.
Ancient people learned to leave meat and fruits and vegetables in the sun and wind to remove moisture. Since microorganisms need water to grow, drying the food slows the rate at which it spoils. Today food processors provide a diet richer and more varied than ever before by using six major methods. They are canning, drying or dehydration, freezing, freeze-drying, fermentation or pickling, and irradiation. Canning The process of canning is sometimes called sterilization because the heat treatment of the food eliminates all microorganisms that can spoil the food and those that are harmful to humans, including directly pathogenic bacteria and those that produce lethal toxins.
Most commercial canning operations are based on the principle that bacteria destruction increases tenfold for each 10 C increase in temperature. Food exposed to high temperatures for only minutes or seconds retains more of its natural flavor. In the Flash 18 process, a continuous system, the food is flash-sterilized in a pressurized chamber to prevent the superheated food from boiling while it is placed in containers. Further sterilizing is not required. Freezing Although prehistoric humans stored meat in ice caves, the food-freezing industry is more recent in origin than the canning industry. The freezing process was used commercially for the first time in 1842, but large-scale food preservation by freezing began in the late 19 th century with the advent of mechanical refrigeration.
Freezing preserves food by preventing microorganisms from multiplying. Because the process does not kill all types of bacteria, however, those that survive reanimate in thawing food and often grow more rapidly than before freezing. Enzymes in the frozen state remain active, although at a reduced rate. Vegetables are blanched or heated in preparation for freezing to ensure enzyme inactivity and thus to avoid degradation of flavor.
Blanching has also been proposed for fish, in order to kill cold-adapted bacteria on their outer surface. In the freezing of meats various methods are used depending on the type of meat and the cut. Pork is frozen soon after butchering, but beef is hung in a cooler for several days to tenderize the meat before freezing. Frozen foods have the advantage of resembling the fresh product more closely than the same food preserved by other techniques.
Frozen foods also undergo some changes, however. Freezing causes the water in food to expand and tends to disrupt the cell structure by forming ice crystals. In quick-freezing the ice crystals are smaller, producing less cell damage than in the slowly frozen product. The quality of the product, however, may depend more on the rapidity with which the food is prepared and stored in the freezer than on the rate at which it is frozen.
Some solid foods that are frozen slowly, such as fish, may, upon thawing, show a loss of liquid called drip; some liquid foods that are frozen slowly, such as egg yolk, may become coagulated. Because of the high cost of refrigeration, frozen food is comparatively expensive to produce and distribute. High quality is a required feature of frozen food to justify the added cost in the market. This method of preservation is the one most widely used for a great variety of foods. Drying and Dehydration Although both these terms are applied to the removal of water from food, to the food technologist drying refers to drying by natural means, such as spreading fruit on racks in the sun, and dehydration designates drying by artificial means, such as a blast of hot air. In freeze-drying a high vacuum is maintained in a special cabinet containing frozen food until most of the moisture has sublimed.
Removal of water offers excellent protection against the most common causes of food spoilage. Microorganisms cannot grow in a water-free environment, enzyme activity is absent, and most chemical reactions are greatly retarded. This last characteristic makes dehydration preferable to canning if the product is to be stored at a high temperature. In order to achieve such protection, practically all the water must be removed. The food then must be packaged in a moisture-proof container to prevent it from absorbing water from the air. Vegetables, fruits, meat, fish, and some other foods, the moisture content of which averages as high as 80 percent, may be dried to one-fifth of the original weight and about one-half of the original volume.
The disadvantages of this method of preservation include the time and labor involved in re hydrating the food before eating. Further because it absorbs only about two-thirds of its original water content, the dried product tends to have a texture that is tough and chewy. Drying was used by prehistoric humans to preserve many foods. Large quantities of fruits such as figs have been dried from ancient times to the present day.
In the case of meat and fish, other preservation...
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Research essay sample on Food Processing And Preservation
