Brewing with enzymes - Enzymes in Food Technology - page 167

Main enzyme types involved in the barley malting process. a

Table 8.2

Enzyme Substrate Activity Source Significance

Carboxypeptidase
(commonly referred
to as β -glucan
solubilase)

Endosperm cell
walls

Removes the outer
layer of protein in
the endosperm cell
wall

Detectable in raw
barley

Makes β -glucan
more accessible to
glucanase enzymes

Also produced by
the aleurone

Xyloacetylesterase Endosperm cell

walls

Releases acetate
from arabinoxylan

Detectable in raw
barley

Plays a role in
releasing β -glucan
and making it more
accessible to
glucanase enzymes

Also produced by
the aleurone

Feruloyl esterase Endosperm cell

walls

Releases ferulate
from arabinoxylan

Detectable in raw
barley

Has a limited effect
on making β -glucan
more accessible to
glucanase enzymes

Also produced by
the aleurone

Xylanse Endosperm cell

walls

Responsible for
hydrolyzing the [c3]

Detectable in raw
barley

Hydrolyzes
pentosans
surrounding the
glucan layer in the
barley cell walls,
releasing the glucan
and making it more
accessible to
enzymic attack

Also produced by
the aleurone

α - L -
arabinofuranosidase

Endosperm cell
walls

α - L -
arabinofuranosidase

Detectable in raw
barley

Hydrolyzes
pentosans
surrounding the
glucan layer in the
barley cell walls,
making the glucan
layer more
accessible to
enzymic attack

Also produced by
the aleurone

Endo- β ,1-3
glucanase

Solubilized
β -glucan

β 1-3 linkages

Aleurone Reduces wort

viscosity. Improves
mash filtration and
final beer filtration

Endo- β ,1-4
glucanase

Solubilized
β -glucan

β 1-4 linkages Aleurone Reduces wort

viscosity. Improves
mash filtration and
final beer filtration

(Continued)