Enzymes are organic catalysts produced by living organisms which aid in the progression of specific biochemical reactions without undergoing any permanent chemical changes themselves. They are complex, conjugated proteins necessary and required to sustain life. Today, enzymes are also used world-wide in a variety of different industrial applications such as the production of paper, wine fermentation, and bio-remediation.
One of the most important industrial applications enzymes are used in worldwide is the production of paper. Paper is one of the most important, used and recycled material used worldwide. It is used in many different applications such as crafts, art, printing, etc. Since man first appeared on earth, they sought ways to record their thoughts in some permanent form. They went through stone and bones to brass and copper. Today, humans use paper for a variety of reasons. Without paper, books wouldn’t exist; history wouldn’t have been recorded, and the movement of art and literature wouldn’t have been able to develop at all.
The use of enzymes in the production of paper wasn’t discovered until recently. And since then, the use of enzymes in the pulp and paper industry has grown since 1980.
The process of paper production occurs in five important steps: (1) the creation of pulp, (2) deinking, (3) bleaching, (4) pitch control, and (5) coating.
The raw material, wood, is first acquired from trees. Wood is a natural polymer composed of cellulose, hemicellulose and lignin. Cellulose is the principle, structural material which makes of the cell walls in plants. Hemicellulose is a polysaccharide in plant cell; and lignin is an organic material which binds all these fibers together. There are two methods used to create pulp from wood: mechanical pulping and chemical pulping.
Mechanical pulping is the process in which all the fibres in the wood are separated mechanically with the input of large amounts of energy. Mechanical pulping is less expensive than chemical pulping, but the produced product becomes darker when exposed to sunlight. Mechanical pulping is usually used in the manufacturing of newsprint paper. During chemical pulping, wood chips are soaked and cooked in chemical solutions until the lignin dissolves and the wood fibers are released. As a result, the wood chips yield a dark color, and must be beached.
Deinking is the process of recycling and removing the ink from the fibers of the pulp. This is an area with a large potential for enzymes, namely cellulase and hemicellulase. Cellulase is a class of enzymes which attack cellulose, the principal material of the cell walls of plant cells. And hemicellulase is a class of enzymes closely linked to cellulose that cleave lignin. Together, these enzymes work to hydrolyze and remove the micro fibrils from waste paper. Deinking usually occurs in a neutral or alkaline environment which improves pulp cleanliness and brightness.
Xylanase enzymes are used to cleave the hemicelluloses in fiber in order to make the bleaching process more effective by reducing the chemicals by up to 30%, and can also improve the brightness of the paper. The bleaching process is done with chlorine or other forms of toxic compounds.
The next step is enzymatic pitch control. During production, pitch agglomerates from the felts and rollers can cause holes in the paper which has to be recycled or downgraded in quality. As a result, the enzyme, lipases, are used to control pitch during the process. Lipases attack long-chain fatty acids, and thus are able to convert the tri-glycerides within the wood resin of the pulp to fatty acids which are more stable in water. Lipases act immediately and do not reduce the brightness of the paper.
The final step of the production of paper is called the starch modification for paper coating applications. A starch-based coating formula is used to coat the surface of the paper, as raw starch is unsuitable,...