Question

1. What compound in the grape juice is fermented? What other major product is produced during fermentation? 2. What is the purpose of sealing the flask with a balloon? What product is captured in the balloon? 3. What group of microorganisms is responsible for producing fermented beverages? What microorganism was used in this exercise? 4. Why is hydrogen sulfide production monitored during fermentation? Why is this end product undesir able in wine production? 5. What process in the microorganism used for wine production contributes to the formation of hydrogen sulfide? 6. Fermentation is a means of food preservation. What end products produced in fermentation are antago nistic or inhibitory to spoilage organisms?

Answer 1

1. glucose and fructose are found in high concentration in grape juice. it is fermented to form ethanol and carbon dioxide. Fermentation is anaerobic respiration in which glucose is broken down to Alcohol and CO2.

2. the main purpose of sealing the flask with baloon is to prevent the entry of Oxygen to the system that may stop fermentation. the ,main gas that is captured in the baloon is CO2 which is a byproduct of fermentation. trace amount of Hydrogen Sulfide may also be formed as the byproduct.

3. Fermentation is carried uot by microorganisms like fungi (yeasts- saccharomyces cerevisaie) and bacteria such as Lactobacillus, Streptococcus, Bacillus etc.

4.  Hydrogen Sulfide may be formed by the natural breakdown of sulfur-containing amino acids in grape during fermentation. Hydrogen Sulfide should be monitored carefully because a trace amound of Hydrogen Sulfide can can cause off flavors, change in colour and rotten egg smell in the wine.

5. the synthesis of aminoacids. Hydrogen Sulfide may be formed by the natural breakdown of sulfur-containing amino acids in grape during fermentation. cysteine is the main source of sulfur in grapes.

6. fermentation lower the PH of the medium. the acidic condition is unfavorable to spoilage organisms. alcohol also a key role in preventing the growth of spoilage organisms in fermented foods