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Foodborne illness often shows itself as flu-like symptoms such as nausea, vomiting, diarrhea or fever, so many people may not recognize that the illness is caused by bacteria or other pathogens on food. The onset of symptoms may not occur for two or more days after the contaminated food was eaten. Thousands of types of bacteria are naturally present in our environment, but not all bacteria cause disease in humans. Some of the more familiar il nesses include E. coli and Salmonella, which are may be present in uncooked foods 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 livin 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 a reward to the person who devised a 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 air tight.
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. 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 refe 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. Early 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 of richer and more varied food than ever before by using six major methods. They are canning, drying or dehydration, freezing, freeze-drying, fermentation or pickling, and irradiation. 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. Other methods or a combination of methods may be used to preserve foods. Salting of fish and pork has long been practiced, using either dry salt or brine. Salt enters the tissue and, in effect binds the water, thus inhibiting the bacteria that cause spoilage. Another widely used method is smoking, which frequently is applied to preserve fish, ham, and sausage.
The smoke is obtained by burning hickory or a similar wood under low draft. In this case some preservative action is provided by such chemicals in the smoke as formaldehyde and creosote, and by the dehydration that occurs in the smokehouse. Smoking usually is intended to flavor the product as well as to preserve it.
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Research essay sample on Fruits And Vegetables Plants And Animals
