EFFECT OF TEMPERATURE ON THE GROWTH OF YEAST

Project Abstract

Yeast cells respire aerobically if there is enough oxygen supply. If there is not enough oxygen present then fermentation will take place as the yeast cells have to respire anaerobically. Fermentation makes energy that is used for cell growth. When yeast cells ferment they also produce ethanol (alcohol) which is important to brewers. The yeast cells need sugar to ferment as without sugar, the yeast cells would not be able to respire at all. The sugar supply provided is called sucrose, Enzymes in the yeast cells break down the sucrose into glucose. Yeast reproduces by budding in other words when the yeast cell grows too big. It splits to make two metical copies of itself. This form of reproduction is called asexual as it only involves one parent cell. Yeast needs amino acids to build into proteins so it cans growth. Anion acids are supplied by malt extract.

Project Overview

IntroductionThe word “Yeast” comes to us from the old English gist, gyst and from the indo-European root yes-meaning boil, from or bubble.Yeast microbes are probably one of the earliest domesticated organizing. People have used yeast for fermentation and baking throughout history.Archaeologists digging in Egyptian ruins found early grinding stones and baking chambers for yeasted bread, as well as drawings of 4,000. years- old bakeries and breweries. (Phillips 2012) in 1680, the Dutch naturalist Anton van leeuwenhock first microscopically observed yeast but at the time he did not consider them to be living organisms but rather globular structures (Huxley, 1871) in 1857 French microbiologist louis Pastear. Proved in the paper “memire sur la fermentation alcoolique” that alcoholic fermentation was conducted by living yeasts and not by a chemical catalyst. (Barntt 2003). Pasteur showed that by bubbling oxygen into the yeast broth, cell growth could be increased but fermentation was inherited as an observation cater called the “Pasteur effect”YEASTYeast is any of various one called fungi that can cause the fermentation of carbondydrates producing carbon dioxide and alcohol. Bakers put it in bread to make it rise. Yeast is also used for the production of beer and wine. Yeast that are used commercially consist of masses of microscopic yeast organism.TYPES OF YEASTYeats is a very interesting little organism. It is neither a plant nor an animal but a single called fungus. As such there are several different species and varieties of yeast. And just like the apples you choose to make year cider, each one will make the end product taste a bit different. The difference in come is because of the rate of sugar consumption and carbon dioxide and other waste product creation as well as temperature and PH needed for fermentation.The two main types of yeast are baker’s and brewer’s yeast. White both are saccharomyces cererisiae, they are different strains (Like the difference between red delicious and Macintosh applies). The active dry yeast that you can get in grocery store is bakers yeast and is used for baking bread. To brew hard cider you want brewers yeast. This comes in dry and liquid forms.IMPORTANCE OF YEASTYeast is important because it is used for making food which people eat.Yeast is used in the making of bread beer and wine. Bread in particular is an extremely important part of people diets world wide.HOW YEAST IS USEDYeast lack chlorophyll. The lack of chlorophyll in yeast means that yeast has to rely on other things for food. Fruit grain, nectar and molasses are the things yeast feeds on for sugar. Yeast break down its food by producing a chemical called ferments or enzymes. Some species of yeast break down their food into alcohol and carbon dioxide. That process is called fermentation. Fermentation is important in making bread, beer and wine.Temperature: Temperature is the measurement in degrees of how hot or cold a thing or place is (Oxford dictionary 6th edition 2000).