This set of Enzyme Technology Questions and Answers for Aptitude test focuses on “Large Scale Use of Enzyme – Enzymes in Fruit Juice, Wine, Brewing and Distilling Industry”.
1. In the preparation of fruit juices and wines, enzymic hydrolysis becomes necessary.
a) True
b) False
View Answer
Explanation: In the preparation of fruit juices and wines, enzymic hydrolysis becomes necessary so as to remove the cloudiness due to the presence of pectins. Pectins are a-1,4-anhydrogalacturonic acid polymers, with varying degrees of methyl esterification. Hence the above statement is true.
2. Which of these is not an additional benefit produced by enzymic hydrolysis in preparation of fruit juices and wines?
a) Solution viscosity
b) Volume increase
c) Scoopability improvement
d) Shorter fermentation times
View Answer
Explanation: Along with removal of cloudiness in preparation of fruit juice and wines, enzymic hydrolysis have the following benefits.
• Solution viscosity
• Volume increase
• Beneficial changes in flavor
• Shorter fermentation times in wineries
Scoopability improvement is required in ice-creams and skimmed milk powder, and is done by lactases.
3. Which of the following is not a part of enzyme preparation produced from Aspergillus Niger?
a) Polygalacturonase
b) Pectinesterase
c) Cellulase
d) Hemicellulase
View Answer
Explanation: Cellulase is used to cellulose to glucose and is part of enzyme preparation obtained from Trichoderma Reesei. Enzyme preparation produced from Aspergillus Niger consist of the following:
• Polygalacturonase hydrolyzes 1,4-a-D-galactosiduronic linkages randomly.
• Pectinesterase releases methanol from the pectyl-methyl esters.
• Pectin lyase which cleaves pectin without the necessity of pectin methyl esterase action.
• Hemicellulase which is a mixture of hydrolytic enzymes.
4. Which of the following enzyme hydrolyzes 1,4-a-D-galactosiduronic linkages randomly?
a) Polygalacturonase
b) Pectinesterase
c) Pectin lyase
d) Hemicellulase
View Answer
Explanation: Polygalacturonase (EC 3.2.1.15 hydrolyzes of 1,4-a-D-galactosiduronic linkages randomly. Pectinesterase (EC 3.2.1.11) releases methanol from the pectyl methyl esters. Pectin lyase (EC 4.2.2.10), cleaves the pectin without the necessity of pectin methyl esterase action. Hemicellulase is a mixture of hydrolytic enzymes.
5. ____________ releases methanol from pectyl-methyl esters.
a) Pectin lyase
b) Pectinesterase
c) Cellulase
d) Hemicellulase
View Answer
Explanation: Pectinesterase releases methanol from the pectyl methyl esters. Pectin lyase cleaves the pectin without the necessity of pectin methyl esterase action. Hemicellulase is a mixture of hydrolytic enzymes which includes xylan endo-1,3-b-xylosidase, xylan 1,4-b-xylosidase and a-L- rabinofuranosidase. Cellulase is used to cellulose to glucose and is part of enzyme preparation obtained from Trichoderma Reesei.
6. Which of the following enzymes are not a part of hemicellulase?
a) xylan endo-1,3-b-xylosidase
b) xylan 1,4-b-xylosidase
c) Pectinesterase
d) L- rabinofuranosidase
View Answer
Explanation: Pectinesterase is not a part of hemicellulases and releases methanol from the pectyl methyl esters. Hemicellulase is a mixture of hydrolytic enzymes which includes xylan endo-1,3-b-xylosidase (EC 3.2.1.32), xylan 1,4-b-xylosidase (EC 3.2.1.37) and a-L- rabinofuranosidase (EC 3.2.1.55). Hemicellulase is not a pectinase strictly, but its presence helps reduce hemicellulose levels.
7. Which of the enzyme acts on elimination reaction which releases oligosaccharides with non-reducing terminal 4-deoxymethyl-a-D-galact-4-enuronosyl residues?
a) Pectin lyase
b) Cellulase
c) Hemicellulase
d) Pectinesterase
View Answer
Explanation: Pectin lyase acts on elimination reaction which releases oligosaccharides with non-reducing terminal 4-deoxymethyl-a-D-galact-4-enuronosyl residues. These enzymes cleave pectin without the necessity of pectin methyl esterase action. Pectin lyase cleaves the pectin without the necessity of pectin methyl esterase action. Hemicellulase is a mixture of hydrolytic enzymes. Pectinesterase releases methanol from the pectyl methyl esters.
8. Which of the following enzyme is not used in the brewing industry?
a) Fungal α-amylase
b) β-glucanase
c) Papain
d) Pectinesterase
View Answer
Explanation: The enzymes used in brewing industry are as follows:
• Bacterial and fungal α-amylase are used in Saccharification of starch.
• β-glucanase is used in the breakdown of barley β-1,4- and b-1,3- linked glucan.
• Neutral proteases are used in hydrolysis of protein to increase the fermentation rate in the production of high gravity beer.
• Cellulases help in breakdown the barley β-glucans.
• Papain is used to prevent the occurrence of protein- and tannin-containing ‘chill-haze’ otherwise formed on cooling the beer.
Pectinesterase and not used in the brewery industry and releases methanol from the pectyl methyl esters.
9. Rum is prepared from __________
a) grapes
b) barley malt
c) molasses
d) corn
View Answer
Explanation: Carbohydrate sources are used world-wide to produce distilled alcoholic drinks. Rum is prepared from molasses and grapes to produce brandy (fermentable sugar). Barley malt is used to produce whiskey and scotch. Corn is used to produce whiskey (starch and hence requires saccharification throughout the fermentation).
10. Light beers of low calorific value have become popular in recent times.
a) True
b) False
View Answer
Explanation: In recent times, light beers of low calorific value have become popular. Light beers require a higher degree of saccharification at lower starch concentrations to reduce the alcohol and total solids contents of the beer and is achieved by the use of glucoamylase and fungal α-amylase during the fermentation. Hence the statement is true.
11. Whiskey cannot be prepared from ___________
a) barley malt
b) grapes
c) corn
d) rye
View Answer
Explanation: Grapes are used to produce brandy and not whiskey. Whiskey is prepared from barley malt, corn and rye. These require saccharification throughout the fermentation period as the starting point is starch.
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