The Relation between Enzymatic Reaction and Solid Fat Index

Abstract

In contrast to the usual lipase reactions which are carried out on liquid oil (below 40°C) as a substrate, unstirred reactions of solid fats have now been investigated. The solid fat index (SFI) was used as a solid fat content in the substrates. The enzymes employed here were Candida cylindracea lipase (CC), Mucor miehei lipase (MM) and Geotrichum candidum lipase (GC). When lipases CC and GC were used, the hydrolysis rates decreased with the increase of SFI of the substrates. Lipase MM showed an opposite behavior. The trends became less clear in the prolonged reactions or in high hydrolysis conversion in these three lipases. The positional and substrate specificities of the lipases were high in the lower conversion. Lipase reaction sequences were found to differ depending on the origin of the enzyme and on SFI of the substrates for a given lipase. The amount of the monoglycerides accumulated in the reaction product became as high as 6-s7% in contrast to 1-2% in stirred reaction. Lipase MM with the specificity at the 1- and 3-position did not show any reactivity towards the ester bond at the 2-position of the glyceride. Since the reaction sequence was controlled by positional migration, it was different from those of the other lipases. This was confirmed by lower hydrolysis rates and higher accumulation of mono- and diglycerides than in other lipase reactions.