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PRESENTATION OUTLINE
IRRADIATION PROCESS
- Food irradiation is a promising new food safety technology that can eliminate disease-causing microorganisms such as E. coli O157:H7, Campylobacter, and Salmonella from foods.
- The process involves exposing the food, either packaged or in bulk, to carefully controlled amounts of ionizing radiation for a specific time to achieve certain desirable objectives.
- Gamma rays are emitted from radioactive forms of the element cobalt (Cobalt 60) or of the element cesium (Cesium 137). Gamma radiation is used routinely to sterilize medical, dental and household products and is also used for the radiation treatment of cancer. X-rays are produced by reflecting a high-energy stream of electrons off a target substance (usually one of the heavy metals) into food. X-rays are also widely used in medicine and industry to produce images of internal structures. Electron beam (or e-beam) is similar to X-rays and is a stream of high-energy electrons propelled from an electron accelerator into food.
Photo by Matt. Create.
DEHYDRATION PROCESS
- Why dry? Drying (dehydrating) food is one of the oldest and easiest methods of food preservation. Dehydration is the process of removing water or moisture from a food product. Removing moisture from foods makes them smaller and lighter. Dehydrated foods are ideal for backpacking, hiking, and camping because they weigh much less than their non-dried counterparts and do not require refrigeration. Drying food is also a way of preserving seasonal foods for later use.
- How dehydration preserves foods Foods can be spoiled by food microorganisms or through enzymatic reactions within the food. Bacteria, yeast, and molds must have a sufficient amount of moisture around them to grow and cause spoilage. Reducing the moisture content of food prevents the growth of these spoilage-causing microorganisms and slows down enzymatic reactions that take place within food. The combination of these events helps to prevent spoilage in dried food.
- The basics of food dehydration Three things are needed to successfully dry food at home: Heat — hot enough to force out moisture (140°F), but not hot enough to cook the food; Dry air — to absorb the released moisture; Air movement — to carry the moisture away. Foods can be dried using three methods: In the sun— requires warm days of 85°F or higher, low humidity, and insect control; recommended for dehydrating fruits only; In the oven; Using a food dehydrator — electric dehydrators take less time to dry foods and are more cost efficient than an oven.
Photo by NathanF
CANNING PROCESS
- Raw Packing - also called "cold packing" is the practice of filling jars tightly with freshly prepared, but unheated food. Such foods, especially fruit, will often float in the jars. The entrapped air in and around the food may also cause discolorati
- Hot-packing is the practice of heating freshly prepared food to boiling, simmering it 2 to 5 minutes, and promptly filling jars loosely with the boiled food. Whether food has been hot-packed or raw-packed, the juice, syrup, or water to be added to the foods should also be heated to boiling before adding it to the jars. This practice helps to remove air from food tissues, shrinks food, helps keep the food from floating in the jars, increases vacuum in sealed jars, and improves shelf life. Preshrinking food also permits filling more food into each jar. Many fresh foods contain from 10 percent to more than 30 percent air. this is important because how long canned food retains high quality depends on how much air is removed from food before jars are sealed. Hot-packing is the best way to remove air and is the preferred pack style for foods processed in a boiling-water canner. At first, the color of hot-packed foods may appear no better than that of raw-packed foods, but within a short storage period, both color and flavor of hot-packed foods will be superior.
Photo by karenandbrademerson
FREEZING PROCESS
- Freezing, in food processing, method of preserving food by lowering the temperature to inhibit microorganism growth. The method has been used for centuries in cold regions, and a patent was issued in Britain as early as 1842 for freezing food by immersion in an ice and salt brine. It was not, however, until the advent of mechanical refrigeration that the process became widely applicable commercially. In 1880 a cargo of meat shipped from Australia to Britain under refrigeration accidentally froze, with such good results that the process was at once adopted for long-distance shipments and other storage. In the 20th century quick, or flash, freezing was found to be especially effective with certain types of food. Except for beef and venison, which benefit from an aging process, meat is frozen as promptly as possible after slaughter, with best results at temperatures of 0 °F (−18 °C) or lower. Fruits are frozen in a syrup or dry sugar pack to exclude air and prevent both oxidation and desiccation. Most commercial freezing is done either in cold air kept in motion by fans (blast freezing) or by placing the foodstuffs in packages or metal trays on refrigerated surfaces (contact freezing).
Photo by webheathcloseup
FERMENTATION PROCESS
- Fermentation in food processing is the conversion of carbohydrates to alcohols and carbon dioxide or organic acids using yeasts, bacteria, or a combination thereof, under anaerobic conditions. Fermentation usually implies that the action of microorganisms is desirable. The science of fermentation is also known as zymology or zymurgy. The term "fermentation" is sometimes used to specifically refer to the chemical conversion of sugars into ethanol, a process which is used to produce alcoholic beverages such as wine, beer, and cider. Fermentation is also employed in the leavening of bread (CO2 produced by yeast activity); in preservation techniques to produce lactic acid in sour foods such as sauerkraut, dry sausages, kimchi, and yogurt; and in pickling of foods with vinegar (acetic acid).
- When studying the fermentation of sugar to alcohol by yeast, Louis Pasteur concluded that the fermentation was catalyzed by a vital force, called "ferments," within the yeast cells. The "ferments" were thought to function only within living organisms. "Alcoholic fermentation is an act correlated with the life and organization of the yeast cells, not with the death or putrefaction of the cells,"[8] he wrote. Nevertheless, it was known that yeast extracts can ferment sugar even in the absence of living yeast cells. While studying this process in 1897, Eduard Buchner of Humboldt University of Berlin, Germany, found that sugar was fermented even when there were no living yeast cells in the mixture,[9] by a yeast secretion that he termed zymase.[10] In 1907 he received the Nobel Prize in Chemistry for his research and discovery of "cell-free fermentation."
Photo by Christian Collins
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- Garrett Moore
- Santiago Flores
- Jon Garcia
