- 18th century-fermentative activity of microorganisms discovered
- 1833- enzyme diastase in alcohol precipitate of malt extract, now called amylase, converts starch to sugar
- First application –use of renin isolated from calf or lamb stomach in cheese making
- 1914- first commercial enzyme production started in Germany
- Real breakthrough of enzymes- introduction of microbial proteases in washing
- Pectinases used in food industry since 1930 in fruit juice manufacturing.
- Plant derived commercial enzymes include proteolytic enzyme papain, bromelain and ficin.
- Animal derived enzymes include proteinases like pepsin and rennin.
- Most of the enzymes are, however, produced by microorganisms in submerged cultures in large reactors called fermentors.
- Criteria for enzyme selection include: specificity, reaction rate, pH andtemperature optima and stability, effect of inhibitors and affinity to substrates
- Paper industry enzymes should not contain cellulose degrading activity as a side activity
- Animal feed industry enzymes must be thermo tolerant to survive in the hot extrusion process used in animal feed manufacturing
- These enzymes must have maximal activity at the body temperature of the animal
- Enzymes used in industrial applications must usually be tolerant against various heavy metals and have no need for cofactors
- They should be maximally active already in the presence of low substrate concentration
- Industrial enzymes are produced by a relatively few microbial hosts like Aspergillus, Trichoderma, Streptomyces & Bacillus.
- Happens in many bulk enzyme applications like liquefaction of starch with amylases, bleaching of cellulose pulp with xylanases or use of enzymes in animal feed.
- Lipases decompose fats into more water-soluble compounds by hydrolysing the ester bonds between the glycerol backbone and fatty acid. Most important lipase in the market was originally obtained from Humicola lanuginose. It is produced in large scale by Aspergillus oryzae host after cloning the Humicola gene into this organism.
- Amylases are used in detergents to remove starch based stain hydrolyse gelatinised starch, which tends to stick on textile fibres and bind other stain components.
- Cellulases have been part of detergents since early 90s.
- Cellulase is actually an enzyme complex capable of degrading crystalline cellulose to glucose.
- In textile washing cellulases remove cellulose microfibrils, which are formed during washing and the use of cotton based cloths can be seen as colour brightening and softening of the material.
- Alkaline cellulases are produced by Bacillus strains and neutral and acidic cellulases by Trichoderma and Humicola fungi.
2 Starch hydrolysis and fructose production:
- Starch degrading enzymes was the first large-scale application of microbial enzymes in food industry.
- Mainly two enzymes carry out conversion of starch to glucose: alpha-amylase cuts rapidly the large alpha-1,4-linked glucose polymers into shorter oligomers in high temperature
- This phase is called liquefaction and is carried out by bacterial enzymes
- In the next phase called saccharification, glucoamylase (fungal enzyme) hydrolyses the oligomers into glucose.
- Beta-amylase is commercially produced from barley grains and used for the production of the disaccharide maltose
- Another enzyme used in milk industry is beta-galactosidase or lactase, which splits milk-sugar lactose into glucose and galactose.
- Enzymes are used also in fruit juice manufacturing.
- Fruit cell wall needs to be broken down to improve juice liberation.
- Pectins are polymeric substances in fruit lamella and cell walls.
- Addition of pectinase, xylanase and cellulase improve the liberation of the juice from the pulp.
- Pectinases and amylases are used in juice clarification.
- Additional enzymes can be used to help the starch hydrolysis (typically Alpha-amylases), solve filtration problems caused by beta-glucans present in malt (beta-glucanases), hydrolyse proteins (neutral proteinase), and control haze during maturation, filtration and storage (papain, alpha-amylase and beta glucanase).
- Enzymes are widely used in wine production to obtain a better extraction of the necessary components and thus improving the yield hydrolyse the high molecular weight substances like pectin.
4 Animal feed:
- First commercial success was addition of beta-glucanase into barley base feed diets.
- Enzymes were tested later also in wheat-based diets.
- Xylanase enzymes were found to be the most effective ones in this case.
- Addition of xylanase to wheat-based broiler feed has increased the available metabolizable energy 7-10% in various studies.
- Usually a feed-enzyme preparation is a multienzyme cocktail containing glucanases, xylanases, proteinases and amylases.
- Enzyme addition reduces viscosity, which increases absorption of nutrients, liberates nutrients either by hydrolysis of non-degradable fibres or by liberating nutrients blocked by these fibres
- Alpha-amylases have been most widely studied in connection with improved bread quality and increased shelf life
- Use of xylanases decreases the water absorption and thus reduces the amount of added water needed in baking glucose oxidase has been used to replace chemical oxidants and lipases to strengthen gluten, which leads to more stable dough and better bread quality.
6 Pulp and Paper:
- Major application is the use of xylanases in pulp bleaching.
- Xylanases liberate lignin fragments by hydrolysing residual xylan, reduces considerably the need for chlorine based bleaching chemicals.
- Other minor enzyme applications in pulp production include the use of enzymes to remove fine particles from pulp – facilitates water removal.
- In paper making, enzymes are used especially in modification of starch which is used as an important additive.
- Starch improves the strength, stiffness and erasability of paper
- Leather industry uses proteolytic and lipolytic enzymes in leather processing.
- The use of these enzymes is associated with the structure of animal skin as a raw material.
- Enzymes are used to remove unwanted parts.
- Alkaline proteases are added in the soaking phase. This improves water uptake by the dry skins, removal and degradation of protein, dirt and fats and reduces the processing time.
- In dehairing and dewooling phases enzymes are used to assist the alkaline chemical process. Results in a more environmentally friendly process and improves the quality of the leather
8 Enzymes in analytics:
- Enzymes are widely used in the clinical analytical methodology these enzymes need to be free from side activities- elaborate purification processes are needed.
- The detection of the antibody-antigen complex is usually based on enzymes linked to the antibodies.
- This enzyme is either an alkaline phosphatase, which can be detected in colour forming reaction by p-nitrophenyl phosphate or peroxidase, which is detected in the presence of H2O2 with a colour forming substrate.
9 Chirally pure amino acids and aspartame:
- Natural amino acids are usually produced by microbial fermentation.
- Novel enzymatic resolution methods have been developed for the production of L- as well as for D-amino acids.
- The concept is based on the specificity of enzymes to detect only one of the two chiral molecules of amino acid derivatives.
- Aspartame, the intensive non-calorie sweetener, is synthesized in non-aqueous conditions by thermolysin, a proteolytic enzyme, from N-protected aspartic acid and phenylalanine methyl ester.