weight products. If size differences are significant, it is possible to continuously
fractionate the reaction mixture, and obtain a permeate stream which is rich in low
molecular weight products (Bouhallab et al., 1992; Figure 6.14). These type of reactions
continues to attract researchers as can be shown by the number of publications which
have appeared in the literature in the past years dealing with the hydrolysis of different
types of macromolecules in membrane reactors: proteins, peptides, cellulose, pectin,
maltodextrins and starch (Table 6.4).
Biotransformation of LipidsA significant number of the applications of membrane enzyme reactors explore the lipase
catalysed transformation of lipids such as bulk fats, oils, triglycérides, fatty acids and
esters in one or two phase systems (Table 6.5). The majority of the examples listed in
Table 6.5 deal either with the hydrolysis of lipids and fats for the production of fatty
acids, mono and di-glycerides and glycerol or with the synthesis of esters including
transesterification reactions. Although the large number of lipase applications might be a
consequence of the large scientific and economic effort that has been devoted to these
enzymes in the last few years, the particular structure and unusual mode of action of
Upases is most likely responsible for this trend. The fact that Upases are activated by and
act at interfaces probably makes them the perfect biocatalyst to use in membrane reactors,
Figure 6.14 Hydrolysis of
macromolecules and selective
separation of low MW products
Table 6.4 Hydrolysis of macromolecules
Enzyme-reaction description Reference
Hydrolysis of soy proteins catalysed by pronase Deeslie & Cheryan, 1981, 1982
Production of maltose corn syrups by -
amylase/glucoamylase
Hausser et al., 1983Multiphase bioreactor design 164