Chemistry Reference
In-Depth Information
Fig. 8.4
Effect of
β
-glucanase on beer filtration. (Also see Colour Plate 1.)
a level of 0.025%, the filtration performance of the green beer was restored. Similarly, the
filtration rates were improved further at higher dose rates. Likewise, with this approach the
effects of proteases, hemicellulases and amylases can be demonstrated.
8.5.3 Low carbohydrate beer production
Low carbohydrate beer, commonly referred to as 'lite' beer, can be produced through the
application of enzymes. In this case, enzymes can be applied during wort production or
during fermentation. The α-1,6 bonds in amylopectin are not hydrolyzed by the α-amylase
or β-amylase. Although malt is able to produce all the enzymes needed to break down starch
into fermentable sugars, the malt limit dextrinase is unable to break down ungelatinized intact
granules. As the limit dextrinase is temperature labile, it is degraded easily during kilning and
also during mashing. This means that in normal beers the maximum fermentability is 70-82%
(apparent degree of fermentation). Together with other beer components like proteins and
tannins, this unfermentable dextrin material is mainly responsible for the mouthfeel, fullness
and sweetness of beer. Together with the alcohol component, it contributes to the caloric value
of beer. A small increase in fermentability can be achieved by adding a fungal α-amylase
to ensure the complete breakdown of the α-1,4 links. A greater increase in fermentability
can be obtained by adding an amyloglucosidase. This preferentially hydrolyzes the α-1,4
linkages and also slowly hydrolyzes the α-1,6 linkages to produce glucose. Low caloric or
