Cereal gums and their enzymolysis
Abstract
It is quite clear that in vitro experiments with pure substrates and highly purified enzyme preparations can do no more
than indicate types of possible action. Therefore, already having
a method of isolating a barley β -glucosan in a very high degree of
purity, means for obtaining enzyme preparations of enhanced purity
were sought, and it was hoped, by employing these preparations in
the degradation of initially-water-soluble β -glucosan, to provide
further evidence of the complex nature of the degradative scheme.
Included in this approach are attempts to differentially inactivate
endo- and exo- β-glucosanases and cellobiase, and it will be seen
that confirmation of an earlier assumption of the mechanism for the
degradation of β -glucosan has arisen from this study. Furthermore, chromatographic and ionophoretic analyses of the degradation
products of β -glucosan enzymolysis also offer the possibility of
deteimining tne manner in which the β -1,3- and (3-1,4- linkages
are distributed within the β-glucosan molecule.
With the realisation of the important part played by the
β -glucosanases in modification, the opportunity has been taken to
show some aspects of the behaviour of endo- and exo-β -glucosanases
and cellobiase during the course of commercial maltings. During
one such series of investigations the water-soluble and alkalisoluble
carbohydrates were isolated and analysed with the intention
of obtaining sane indication of the manner in which endospermic
cell-walls are broken down. At the same time there was the
possibility that an opportunity would arise to support or overthrow
the theories that either "cellulase" activity of a barley or its
green malt or gum content alone or a combination of both gives an
indication of the malting properties of a particular barley.
Al though the main argument is confined to enzymes of raw and
geminating barley, the opportunity has been taken to provide some
comparisons with the enzymes of other raw cereals.