Notes on physiology and anatomy of unit 4 digestive system, Lecture notes of Physiology

Download Notes on physiology and anatomy of unit 4 digestive system and more Lecture notes Physiology in PDF only on Docsity! What is cooking? Navniet It can be defined as an application and withdrawal of heat to bring certain physical or chemical changes in the raw material to make it edible or more delicious. Cooks select and combine ingredients using a wide range of tools and methods. In the process, the flavor, texture, appearance and chemical properties of the ingredients can change. Cooking techniques and ingredients vary widely across the world, reflecting unique environmental, economic and cultural traditions. Cooks themselves also vary widely in skill and training. Preparing food with heat or fire is an activity unique to humans and some scientists believe the advent of cooking played an important role in human evolution. Most anthropologists believe that cooking fires first developed around 250,000 years ago. The development of agriculture, commerce and transportation between civilizations in different regions offered cooks many new ingredients. New inventions and technologies, such as pottery for holding and boiling water expanded cooking techniques. Some modern cooks apply advanced scientific techniques to food preparation. Culinary art is the art of preparing and cooking foods. The word "culinary" is defined as something related to, or connected with, cooking. Culinarian is a person working in the culinary for skillfully preparing meals that are as pleasing to the palate as to the eye. Increasingly they are required to have knowledge of the science of food and understanding of diet and nutrition. They work primarily in restaurants, fast food chains, stores, franchises, hospitals and other institutions. Why we cook food?  To make food more digestible : Food is properly absorbed by the digestive system and subsequently assimilated by the body. Cooking process breaks down the cellulose present in the vegetables, soften the connective tissue of meat and gelatinize the starch. The texture of the food is changed for easy digestion.  Makes food safer to eat : Cooking sterilizes the food as the bacterial are controlled either below 4 degree Celsius or beyond 63 degree Celsius.  Makes food palatable : Cooking process blends different flavor in food, thus improves their appearance. Helps to stimulate the digestive juices and makes it more palatable. Cooking helps in extracting of soluble compounds from various types of raw materials. This soluble compound creates flavor which forms the base for sauces, gravies and stocks. AIMS AND OBJECTIVES OF COOKING  Improves colour and texture of the food : Cooking makes the food more attractive, eg: blanching of spinach improves the color of spinach, blanching of bones changes the color of raw bones as well as it helps to improve bone marrow fast. Hard potato changes the texture after cooking and turns into cooked soft potato.  Gives balanced diet: Cooking involves mixing of variety of ingredient. Thus it automatically increases the nutritional value and deficiency of one food value is supplemented by other food material.  Changes the appearance of food : One can change as well as improve the appearance of food by blending one material to other.  Increases more variety : Cooking of food increases variety just by adding some sauce on top of bread and gratinating with some cheese can change it into a very tasty dish called "pizza".  Preservation : Cooking with different ingredients helps in preservation such as pickle with oil or a chutney with sugar. For many thousands of years, people have used heat to cook foods. However, along with the formation of the desired flavor, odour and color compounds, the process of heating can also lead to the formation of less favorable substances. One such compound that has received much scientific and media interest over recent years is acrylamide. Discovery of acrylamide in food: Acrylamide in food is a white crystalline amid of propenoic acid that can damage the nervous system and is carcinogenic in laboratory animals, they claim that acrylamide is produced when certain carbohydrates are baked or fried at high temperatures. Initially, acrylamide was only known for its uses in industrial processes such as in the production of plastics, glues, paper and cosmetics. Accidental exposure of workers to high levels of acrylamide leads to the identification of the substances as a neurotoxin. This means that acrylamide at high doses has the ability to cause damage to the nervous tissue. In animals high doses of the compound are known to cause cancer and effect reproduction. In 2002 researchers from Stockholm University, Sweden made the surprising finding of acrylamide formation in foods, and since then, acrylamide has been found in a range of foods processed at high temperatures. Acrylamide can be formed in foods during heating process that reach temperatures of 120 degree Celsius or higher example, frying, baking and roasting. French fries, potato crisps, biscuits, crackers, crisp breads, breakfast cereals, roast potatoes, bakery products and coffee were originally found to contain acrylamide. Further investigations have identified acrylamide in dried fruits, in baked vegetables, in black olives and some roasted nuts.