Industrial Application of Enzyme in Agro-industries
Uses of Enzymes in Solution:
Enzymes have a wide variety of applications in industry, medicine research etc. Some of the important applications are briefly discussed under the following headings:
(i) Uses of enzymes in solution,
(ii) Use of bi-phasic systems,
(iii) Uses of immobilized enzymes, and
The various uses of enzymes in solution are briefly described below.
Detergents represent the largest industrial application of enzymes amounting to 25-30 % of the total sales of enzymes. The enzymes used in detergents must be cost effective, safe to use and be able to perform the task in the presence of anionic and non-ionic detergents, soaps, oxidants etc. at pH between 8 and 10.5. Enzymes constitute only 0.4 – 0.8 % crude enzyme by weight (about. 1 % by cost) of detergents. The chief enzymes used are proteases, α-amylase and, sometimes, cellulase.
1. Proteases: Proteases are used to digest away proteins present in blood stains, milk, grass etc. and also in association with dirt; therefore, they help in removal of dirt as well. Only serine proteases are suitable for use in detergents. These enzymes are produced by Bacillus licheniformis and Bacillus amyloliquefaciens. Proteases are packed inside dust-free granules coated with wax materials made from Paraffin oil or PEG plus hydrophilic binders; the granules disperse in wash releasing the enzyme. This strategy protects uses from hypersensitivity to the enzymes.
2. α Amylase: Amylase is used to digest away starch present in association with dirt and stains; they are produced by B. licheniformis.
3. Celluloses: Celluloses, produced by fungi, are used for washing cotton fabrics. The enzyme digests away the small fibers raised from the fabric without damaging the major fibers of the fabric.This restores the fabric to ‘as new’ condition, and also removes soil particles by digesting the associated cellulose.
4. Lipases: Lipases suitable for detergent use have been identified and are used for digestion lipids present in stains and/or dirt.
II) Leather Industry:
Alkaline proteases (0.1-1 % w/w) are used to remove hair from hides; this is safer and more pleasant than the traditional method using sodium sulphide. De-haired hides are processed or bated often using pancreatic enzymes to increase their suppleness and softness in appearance. Bating is necessary for the production of soft leather clothing.
III. Wool Industries:
Wool fibers are covered with overlapping scales pointing towards the tip this favors problem is successfully overcome by a partial digestion of the scales by papain (protease); this process also gives the wool a silky appearance and adds to its value. However, the process is no more in use due to economic reasons (mainly high cost of papain), but is likely to be initiated again with the availability of cheaper enzymes.
IV. Food, Dairy, Juice and Beverages Industries:
Several processes in the production of food, beverages etc. utilize enzymes e.g. production of glucose syrup, maltose syrup and sucrose industry for preparation of invert syrup.
V. Use in Medicine:
Enzyme applications in medicine are as extensive as in industry. Pancreatic enzymes have been used in digestive disorders since nineteenth century. Most enzymes are used extra cellularly for
(i) Topical applications, e.g. collagenase,
(ii) Removal of toxic substances, e.g. rhodonase,
(iii) Disorders within blood circulation system, e.g., streptokinase, urokinase etc.
The enzyme preparations must be of high purity and free from unwanted contamination; therefore, they are generally from animal sources and very costly. For example, urokinase is isolated from human urine and costs nearly $ 200/mg; the annual market for this enzyme is nearly $150 million. Enzymes have a major potential application in treatment of cancer, e.g. asparagenase in the treatment of lymphocytic leukemia. Tumor cells are unable to synthesize L-asparagine due to an enzyme deficiency, and obtain this amino acid from body fluids. Asparaginase drastically reduces the levels of free L-asparagine in the food stream, creating starvation in tumor cells for this amino acid; normal cell are not affected since they can synthesize L- asparagene. Asparaginase is injected intravenously, slows half-life of about 1 day (in dog), and may lead to complete recovery in 60% of the cases.
VI. Aspartame Synthesis:
Aspartame is a dipeptide containing one residue each of L-aspartic acid and methyl ester of L-phenylalanine. It is 180 times sweeter than sucrose, and is used as low level amino group is protected by a reaction with, usually, benzyl chloroformate and methyl ester of L-phenyalanine by the protease thermolysin. D-phenylalanine methyl ester is also added in a quantity equal to that of the L-isomer; the D-isomer forms an addition complex with aspartame which forms a precipitate. This removes aspartame from the reaction mixture and gives high yields at concentrations above 1 M. Later, aspartate is recovered from the precipitate by suitably changing the pH, and finally the benzyl chloroformate (attached to the amino group of L-aspartic acid) is removed by a simple hydrogenation process.
* L Aspartic acid + L- phenylalanine methyl ester
↓ D-Phenylalanine methyl ester
(Aspartame addition complex)
↓ pH alteration
* Aspartame + D-phenylalanine methyl ester
Aspartame + Benzyl chloroformate
Figure: Synthesis of aspartame by thermolysin. * The amino group of L-aspartic acid is protected by a reaction with benzyl chloroformate