Biomedical Engineering Reference
In-Depth Information
Table 14.1 Enzymes and their industrial applications.
Catalyzed Reactions
Lipids, esters
esterification and
Food, effluent treatment,
detergents, fine chemicals and
Clarification of fruit juices
Food and beverage
Detergents, food, pharmaceutical,
chemicals synthesis
Food, feed additives, pulp and
paper, sugar, textiles, detergents
Pulp, textile, feed, detergents
Food and feed additives
This process generates 15 kg of waste per kg product, in comparison to the conventional
approach which generates 50 kg of waste per kg product (Gavrilescu and Christi, 2005).
Progress in non-aqueous biocatalysis opens up new opportunities for enzyme technology
to penetrate the well established chemical industry. For example, acrylamide is convention-
ally produced chemically from acrylonitrile by sulfuric acid or copper-catalyzed hydrolysis.
This process is high in cost, low in selectivity and product quality, and results in environ-
mental pollution. Mitsubishi Rayon Co. Ltd (Japan) developed an enzymatic acrylamide
process using immobilized nitrile hydrase for the production of acrylamide. About 100 000
tons of acrylamide has been produced annually by this process with greater single-pass
conversion, higher final product concentration, near quantitative conversion and 400%
energy saving (Gavrilescu and Christi, 2005).
Biofuels are produced from renewable resources, such as biomass, which are constantly
replenished as a sustainable alternative energy source to conventional fossil fuel. Enzymes
such as cellulase can be used to hydrolyze cellulosic biomass, which can be converted to
bioethanol. Meanwhile, lipase can be used in a similar manner for the production of fatty
acids' alkyl esters of the lipids/oils used as the feedstock. Currently, intensive investigations
are being carried out to develop efficient protocols for enzymatic production of biofuels.
The aforementioned are brief examples of successful industrial applications of biocata-
lysts. In the following section, four detailed case studies of enzymatic processing of lipid-
based bioproducts, namely partial acylglycerols, bioactive compounds, phospholipids and
fatty acid alkyl esters are presented.
14.4.1 Enzymatic processing of partial acylglycerols
Partial acylglycerols (PG), namely MAG and DAG, are esters of glycerol (GLY) with either
one or two of the hydroxyl groups esterified with fatty acids, respectively (Yasukawa and
Katsuragi, 2004). With hydroxyl groups in the structure, partial acylglycerols have marked
surface activity, which enables them to reduce the surface tension at the oil-aqueous inter-
face. Thus, they are prominently used as emulsifiers in the food industry. Besides that, par-
tial acylglycerols have also been used as basic building blocks for various organic compounds
in the pharmaceutical and nutraceutical industries (Cheong and Lai, 2009). In the late 1990s,
DAG has attracted attention for its' potential as a healthful form of oil, capable of reducing
postprandial lipid level, increasing
-oxidation of fat, as well as managing and preventing
obesity (Takase, 2007). Due to their promising applications in various industries, there has
been a surge in research on enzymatic processing for the synthesis of partial acylglycerols.
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