EFFECT OF TEMPERATURE ON THE GROWTH OF YEAST

TABLE OF CONTENTS

Dedication – – – – – – – – i

Acknowledgment – – – – – – – ii

Table of contents – – – – – – – iii

Overview – – – – – – – – – iv

CHAPTER ONE

Introduction – – – – – – – – 1

Yeast. – – – – – – – – – 2

Types of yeast – – – – – – – – 2

Importance of yeast – – – – – – 3

How yeast is used – – – – – – – 3

Temperature – – – – – – – – 4

CHAPTER TWO

How does temperature affect yeast? – – – 5

CHAPTER THREE

Medicinal value of yeast on human health. – – 8

CHAPTER FOUR

Conclusion and summary – – – – – 10

Reference – – – – – – – – – 11

TABLE OF CONTENTS

Dedication – – – – – – – – i

Acknowledgment – – – – – – – ii

Table of contents – – – – – – – iii

Overview – – – – – – – – – iv

CHAPTER ONE

Introduction – – – – – – – – 1

Yeast. – – – – – – – – – 2

Types of yeast – – – – – – – – 2

Importance of yeast – – – – – – 3

How yeast is used – – – – – – – 3

Temperature – – – – – – – – 4

CHAPTER TWO

How does temperature affect yeast? – – – 5

CHAPTER THREE

Medicinal value of yeast on human health. – – 8

CHAPTER FOUR

Conclusion and summary – – – – – 10

Reference – – – – – – – – – 11

OVERVIEW

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.

CHAPTER ONE

Introduction

The 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”

YEAST.

Yeast 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 YEAST

Yeats 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

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