Enzymes as Biocatalysts for Lipid-based Bioproducts Processing - Food and Industrial Bioproducts and Bioprocessing - page 324

14 Enzymes as Biocatalysts for
Lipid-based Bioproducts Processing
Ling-Zhi Cheong, Zheng Guo, Sergey N. Fedosov,
Bena-Marie Lue, Ram C.R. Jala, Gündüz Güzel,
and Xuebing Xu
14.1 INTRODUCTION
Bioproducts are materials that are derived from renewable biological resources such as
agriculture, forestry, and biological waste. The use of enzymes as biocatalysts for lipid-
based bioproducts processing has been discussed and reviewed both in the academia and
industry over the last five years (Hou, 2005; Xu et al ., 2006 , 2007a , 2008 ; Divakar and
Manchar, 2007 ; Naik et al ., 2010 ; Fernandez-lafuente, 2010 ). This chapter provides insights
into distinct enzyme characteristics essential in industrial processing, including enzyme
kinetics. A brief review of the industrial applications of enzymes is also given with special
focus on enzymatic processing of four different lipid-based bioproducts, namely: partial
acylglycerols, bioactive compounds, phospholipids and fatty acid alkyl esters.
14.2 ENZYME CHARACTERISTICS
Biocatalysis refers to the applications of either isolated enzymes or whole cells as catalysts
(Schmid et al ., 2001). One of the remarkable characteristics of enzymes is their chemical
precision or selectivity. Enzymes selectivity can be categorized into substrate, stereo, region
and functional group selectivity. Enzymes with substrate selectivity, such as lipases, can be
used to selectively remove, separate or enrich specific fatty acids for nutritional and
pharmaceutical applications (Xu, 2004a). Stereoselectivity is the enzyme's capability to
selectively act on a single enantiomer or diastereomer. Aspartase has been used industrially
to stereoselectively add ammonia to fumarate producing highly pure L-aspartic acid at low
cost (Fusee, 1987). Regioselectivity refers to the enzyme's ability to act on one location in
a molecule. This has been widely used for preparation of structured lipids (Xu, 2004a).
Meanwhile functional group selectivity is defined as enzyme selectivity towards a certain
functional group in the presence of other equally or more reactive functional groups. For
example, Nitrilase is capable of selectively hydrolyzing nitrile group in the presence of ester
or amide, which is almost impossible through traditional chemical means (Rozzell, 1999).
Another remarkable characteristic of enzymes is their high catalytic efficiency. Enzyme-
catalyzed reactions usually display high reaction rate accelerations from 10 5 to 10 17 fold,