Front Matter

11.1 Introduction

Enzymatic modification of fats and oils has long been of great interest (Yokozeki et

al., 1982; Macrae and Hammond, 1985). The idea was initiated in the early 1980s for

the production of cocoa butter equivalents (CBE), which were patented individually

by two companies, Unilever (Coleman and Macrae, 1980) and Fuji Oil (Matsuo et

al., 1980). Extensive progress and increasing interest continued until the late 1980s,

at which time major advances in fundamental microaqueous enzymology had been

achieved. One of the great advances was the elucidation of lipase structures through

the study of protein engineering (Brady et al., 1990), and another was the develop-

ment of enzymatic catalysis in microaqueous media (Zaks and Klibanov, 1984). It is

established now that lipase, if optimally applied, works as well in microaqueous

media as in an aqueous system (Klibanov, 1997). Thermodynamic predictions for

biocatalysis and functions of water activity in organic media were also extensively

investigated in relation to this nonaqueous enzymology (Halling, 1994). The wide

applications of lipase technology in the lipids industry require stable, pure, and spe-

cific commercial lipases to be available at low cost. The major progress in genetic

production has made this requirement possible.

Most lipase applications in the lipid field lie in lipid hydrolysis, synthesis and

modification, and these have been reviewed and discussed recently (Mukherjee,

1990; Eigtved, 1992; Akoh, 1996; Bornscheuer and Kazlauskas, 1999). As yet,

the applications have concentrated on value-added products such as CBE, human

milk fat (HMF) substitutes, structured lipids (SL), and polyunsaturated fatty acid

(PUFA)-enriched products. Other applications such as monoacylglycerols, diacyl-

glycerols, and other esters, and margarine fats have also been widely investi-

gated. The typical reactions for the production of these materials include hydroly-

sis, esterification, and interesterification (acidolysis, alcoholysis, and ester – ester

exchange). The typical reactions for the lipase applications in lipid modifications

are included in Figure 1.

A large number of reviews have been published focusing on lipase-catalyzed hy-

drolysis and esterification, including the general state of the art (Yahya et al., 1998;

Gandhi, 1997; Lortie, 1997; Eigtved et al., 1988), kinetics (Malcata et al., 1992;

Jansen et al., 1996), processes and bioreactors (Buhler and Wandrey, 1987; Ya-

mane, 1987; Hirano, 1988; Kloosterman et al., 1988; Linfield, 1988; Malcata et

al., 1990; Balcao et al., 1996b; Vaidya, 1996), media (Bozeix et al., 1992), and pro-

ducts (Bornscheuer, 1995). Therefore, this chapter focuses on enzymatic interester-

ification including ester – ester exchange, acidolysis, and alcoholysis.

The fundamental enzyme technology has been well established throughout text-

books (Gacesa and Hubble, 1987; Chaplin and Bucke, 1990), monographs (Wingard

et al., 1976; Kennedy, 1987), and review papers (Pitcher, 1978; Buchholz, 1982). It is

not the intention of this chapter to re-describe some of these details; rather, the chap-

ter focuses on several engineering aspects of the lipase-catalyzed interesterification

for the modification of oils and fats, i.e., special features of the reaction or micro-

aqueous systems, applications of fundamental enzyme technology in lipase-cata-

lyzed reactions, etc. Although a list of reviews has been published since the early

1980s (as mentioned earlier), a discussion on engineering has not yet been published

on the modification of oils and fats by lipase-catalyzed interesterification.

11.1 Introduction 191