preservatives+Nate+Holmy

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 * Preserving Food**

Table of Contents 1.Drying food 2. canning food 3. freezing food 4. importance 5. works cited

Drying This is the oldest form of food preservation. The native americans would dry apples, corn, beans.[1] Once a food was dried it was able to be kept for a very long period of time. The Native Americans would pick the fruits and dry them in their wigwams hanging on hooks. [1] The wigwam was so dry becasue of the constant fire the food looses its moisture.[1] Ways to dry the food today have a wide range of ways to do it. on of the most common ways is to put food in a oven at a high temperature. When you dry something in the oven at a high temp it is different than putting the same object in the fire with the same temperature. The oven is a confined space with more oxegen floating around in it. The Oxygen is a poor conductor of heat. This allows more molecules to be floating around which also makes less oxygen touching the fruit as it dries. [3]you can compare this concept to when you touch the blacktop on a hot day. it feels hotter than when you put your hand in the oven at 180 degrees. The oven is hotter but you have less conduction becasue of the oxygen is a poor conductor of heat. so you are able to keep your hand in the oven longer than if you put your hand on the blacktop. This is the reason that if you put your hand in the oven it just feels warm. But if you were to put your hand on the stove it will burn. The heat is interatacting in a much larger space. Less surface area of heat is touching you. This allows a higher heat to get the object to burn. So you can dry food at high temperatures without burning yourself. You can do it outside as long as you have a dry enviroment. When a food is dry however there is very little moisture making the water molecules full.[3] This causes the food to be good to eat for years. When you dry fruit the fruit tastes sweeter. the reason for this is when you dry a food you take away the water. Causing the fruit to have concentrated sugar pockets. When the water evaporates the sugar can form long bonds making pockets of crystals of sugar to form. When there is little moisture and lots of heat crystals form when it starts to cool down.[3]

Canning The way that canning works is that you put food into a container and bring it up to high temperatures. This causes the air to leave because you are exciting a already excited gas by adding more heat. When the can cools the metal stops expanding and shrinks. This causes a air tight seal. No air can get in and no air can get out. In industrial canning they put preservitives such as salt or in some items vinagar. This helps keep canned goods have a longer shelf life. Talking more about the sealling concept. When something gets hot it expands becasue the molecules are starting to get ready to jump to the next energy level. They become excited and start vibrating more and more. If they get extremly hot they turn into a gas. Then when they are taken off the heat the molecules start to cool making them transfer energy into heating up the rest of the space. They will make a new equilibrium with the room and the can will be sealed. The preservatives do slightly alter the taste and takes away some of the nutrients. But the food lasts longer. The reason for some of the nutrients is taken is because when you put cucumbers in a jar with vinegar some of the water goes into the vinager and some of the vinager goes into the pickle. This is a concept of a solution with a solute and solvent. In this case the vinegar is the solvent becasue there is more vinegar than water. When you eat the pickle you do not taste water you taste vinegar.[2] media type="custom" key="6306549" This video talks about how different foods are acidic or basic. It talks abou how the different foods need different care of canning them. Also it says that you should eat all of your foods that you can with in 2 years. It gives a visual display of how to can food and why it is important.

Freezing When you freeze food you are putting it into the freezer which should be below 0 C.[4] You are taking food that you want to store for a while (1 to 2 months). What will happen is you will rapidly freeze the water. This keeps nutrients and color with in the meat. The outer part of the meat wil rapidly freeze causing the meat to keep its freshness. When no oxygen gets in the meat is safe for up to a year. The water freezes making a insulation on the outer edge of the meat. Once this happens the liquids on the inside of the meat freeze right in place. This prevents the ability of large crystals to form since the meat can not expand if the outer edge is already solid. When no crystals form the meat does not get freezer burn or lose nutrients.[6] It keeps it flavor and the color on the outside goes a little more pale but on the inside the color stays the same. When you freeze food slowly all the moisture travels to a same general area. causing large ice crystals to form. This lowers the quality of the meat. If you freeze quickly the molecules make just as many ice crystals but the crystals are smaller and through out the enire meat. This helps when thawing the meat becasue the moisture is able to go back into the meat more evenly than if the moisture was in clumps. A common way to freeze meat quickly is using liquid nitrogen. Liquid N is extremly cold. when poored on meat it cools the meat till both the nitrogen and meat are at equilibrium. [5]this means that the meat and Liquid Nitrogen are at the same temperature. When this happens the meat gets colder and the liquid nitrogen gets warmer. The water molecules are still freezing and the meat is able to be preserved. The fast freezing also helps prevent the growth of mold and bacteria on the food. The reason is the rapid freezing changes the temperature of the meat so quickly that nothing can grow on the meat. Most bacterias need a warm climate to grow and culture to become of harmful size.[5]

importance The importance of preserving food correctly. this is extremly important becasue if you preserve food the wrong way you can effect the taste, color and bacteria may form. If there is bacteria in your food you could become sick.[4] Some fairly common bacterias are botolism and ecoli. Both of which have been known to kill people in the most extreme cases. If you preserve food correctly you can get a shelf life of up to a year. This is important becasue there are times of the year that food is hard to grow. If we are able to preserve the food then we can get food all year round. This means that we can be full instead of hungry. This makes us more comfortable and also able to complete more tasks. Without food we would not be living here today. When food is preserved properly we still get all the nutrients that we need for our every day lives as well as the food keeps its taste and color. This helps for presentation of food so we are willing to eat more. The more food we eat the less food there is so if we preserve our excess food we can continually eat. The one that is the lightest is when you dry out the food or dehydrate it. This is good to know becasue the fact that if you ever go and live in the woods the lighter the food the better. The lightest food will last long and you will be able to go further distances before getting tired.

Works Cited [1] Berzok, Linda Murray. //American Indian Food//. Westport, Conn.: Greenwood, 2005. Print. [2]"Canning Basics For Preserving Food." //! Canning Recipes for Preserving Food//. Web. 03 June 2010. []. [3]"Drying Food." //College of Agricultural, Consumer and Environmental Sciences at the University of Illinois//. Web. 03 June 2010. []. [4]Farrell, Jeanette. //Invisible Allies: Microbes That Shape Our Lives//. New York: Farrar, Straus, and Giroux, 2005. Print. [5]"Freezing and Food Safety." //FSIS Advertisement Rotator//. Web. 03 June 2010. []. [6]McCoy, J. J. //How Safe Is Our Food Supply?// New York: F. Watts, 1990. Print