Front Matter

YXYðmol%Þ¼

100 ðSrÞ 2

ð 2 þSrÞ 2 ð^7 Þ

whereSris the substrate molar ratio (Y/XXX). In practice, it should be borne in mind

that lipases are not equally specific towards different fatty acids andsn-1 andsn-3

positions, and side reactions, usually, cannot be completely avoided. Therefore,

above calculations can be used only as a theoretical guide and cannot replace prac-

tical studies or parameter optimizations. The equilibrium ormaximum incorporation

of acyl donors can also be calculated at a certain substrate molar ratio. The equation

is given below:

Incmax¼

200 3

Sr Srþ 2

¼

200 3

1 1 þ 2 S 0 r

ð 8 Þ

whereSr’¼1/Sr, i.e., the molar ratio between oil and acyl donors.

11.2.3 Alcoholysis between triacylglycerols and glycerol with

nonspecific lipases

Alcoholysis between triacylglycerols and glycerol is also calledglycerolysis, which

is one of the major methods for the production of partial acylglycerols. Lipase-cat-

alyzed glycerolysis has been studied for the production of monoacylglycerols due to

the inherent advantages such as mild temperature and better preservation of sensitive

essential fatty acids. The reaction between triacylglycerols and glycerol catalyzed by

nonspecific lipases will proceed toward randomization if the same premises of non-

specific lipases are assumed, as described in Section 12.2.1. The composition of the

products can therefore be calculated from the molar ratio between triacylglycerols

and glycerol according to the rule ofrandomization. If one triacylglycerol (LLL) is

reacted with one molar glycerol (Gly), the reaction mixture will consist of eight

compounds in equal concentration (12.5 mol%) provided hydrolysis is negligible.

The reaction is illustrated in Figure 4. Three diacylglycerol (DAG) or monoacylgly-

cerol (MAG) isomers are usually combined into one species. Therefore, the four

species of the products under different substrate molar ratios (1:n, between LLL

and Gly) can be calculated theoretically according to the following equations:

LLLðmol%Þ¼

100

ð 1 þnÞ 3 ð^9 Þ

DAGðmol%Þ¼

300 n ð 1 þnÞ^3

ð 10 Þ

MAGðmol%Þ¼

300 n^2

ð 1 þnÞ 3 ð^11 Þ

11.2 Lipase-catalyzed interesterification: compositional profiles 195