CERTIFICATETHIS IS TO CERTIFY THAT Kshitij Navet HAS SATISFACTORILY COMPLETED THE CHEMISTRY PROJECT FOR THE YEAR 2012-2013INTERNALEXAMINER, SIGNATURE EXTERNAL EXAMINER, SIGNATURE PRINCIPAL SCHOOL STAMP
I would like to acknowledge the contributions of our Chemistry teacher Mrs. Mrinal Agarwal and our Principal Mr: John Dinakaran for sharing their greatest knowledge with us
| Page No.
| Experiment 1
| Experiment 2
The Objective of this project is to study the rates of fermentation of the following fruit or vegetable juices.
1. i. Apple juice
2. ii. Carrot juice
Fermentation is the slow decomposition of complex organic compound into simpler compounds by the action of enzymes. Enzymes are complex organic compounds, generally proteins. Examples of fermentation are: souring of milk or curd, bread making, wine making and brewing. The word Fermentation has been derived from Latin (Ferver which means to ‘boil’).As during fermentation there is lot of frothing of the liquid due to the evolution of carbon dioxide, it gives the appearance as if it is boiling. Sugars like glucose and sucrose when fermented in the presence of yeast cells are converted to ethyl alcohol. During fermentation of starch, starch is first hydrolysed to maltose by the action of enzyme diastase. The enzyme diastase is obtained from germinated barley seeds. Fermentation is carried out at a temperature of 4–16 °C (40–60 °F). This is low for most kinds of fermentation, but is beneficial for cider as it leads to slower fermentation with less loss of delicate aromas. Apple based juices with cranberry also make fine ciders; and many other fruit purées or flavorings can be used, such as grape, cherry, and raspberry. The cider is ready to drink after a three month fermentation period, though more often it is matured in the vats for up to two or three years.
Louis Pasteur in 1860 demonstrated that fermentation is a purely physiological process carried out by living micro-organism like yeast. This view was abandoned in 1897 when Buchner demonstrated that yeast extract could bring about alcoholic fermentation in the absence of any yeast cells. He proposed that fermenting activity of yeast is due to active catalysts of biochemical origin. These biochemical catalyst are called enzymes. Enzymes are highly specific. A given enzyme acts on a specific compound or a closely related group of compounds. Fermentation has been utilized for many years in the preparation of beverages. Materials from Egyptian tombs demonstrate the procedures used in making beer and leavened bread. The history of fermentation, whereby sugar is converted to ethanol by action of yeast, is also a history of chemistry. Van Helmont coined the word iogaslt in 1610 to describe the bubbles produced in fermentation. Leeuwenhoek observed and described the cells of yeast with his newly invented microscope in 1680. The fruit and vegetable juices contain sugar such as sucrose, glucose and fructose. These sugars on fermentation in the presence of the enzymes invertase and zymase give with the evolution of carbon dioxide. Maltose is converted to glucose by enzyme maltose. Glucose is converted to ethanol by another enzyme zymase
C12H22O11 + H2O C6H12O6 + C6H12O6 Sucrose Glucose Fructose Zymase
C6H12O6 + C6H12O6 2C2H5OH + 2CO2
Please join StudyMode to read the full document