【Megazyme】Cell Wall Components

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K-BGLU P-BGCFA K-MBG4 T-BGZ-200T T-BGZ-1000T I-AZBGL P-BGBM K-ARGA K-XYLOSE K-XylX6-2V K-XYLS T-XAX-200T T-XAX-1000T S-AWAXP S-AWAXL K-CellG5-4V T-CCZ-200T T-CCZ-1000T T-CAF T-CTZ-200T T-CTZ-1000T I-AZCEL megazyme

The cell walls within the barley endosperm are composed of two major polysaccharides: b-glucan and arabinoxylan. Cellulose is also present, but in far smaller quantities.

These cell walls must be broken down to allow starch hydrolases to access the starch found inside the endosperm.

The cell wall fragments also need to be broken down as completely as possible. This process is driven by specialised enzymes, which are released from grains themselves during malting.

Why do cell walls matter?

The relative presence or absence of the relevant cell wall hydrolases in malt will determine the degree of starch mobilisation.

The predicted degree of cell wall hydrolysis will have a strong influence on a brewer or distiller’s process decisions, as it has a direct impact on:

mashing programme required
wort viscosity
lautering performance
filtration
likelihood of haze

There is also a likely knock-on effect on wort fermentability since the formation of fermentable sugars depends on the extent of starch mobilisation.

In summary, understanding cell wall hydrolase activity allows brewers and distillers to correct potential problems before they occur, for example through adjusted mashing procedures or addition of appropriate exogenous enzymes.

β-Glucan & β-Glucanase

β-Glucan is the major polysaccharide of the endosperm cell walls in barley and oat grains and is also present in wheat.

Product Code

K-BGLU

P-BGCFA

β-Glucan is hydrolysed by b-glucanase. An endo-acting enzyme, b-glucanase cuts internal linkages in the polysaccharide chain. β-Glucanase is also able to hydrolyse b-glucans bound to proteins, which cause precipitates and haze formation if left unaddressed.

β-Glucanase is primarily active during the malting stage: some is denatured at kilning, while the rest becomes inactive at temperatures close to starch gelatinisation. For this reason, exogenous β-glucanase is a common additive to mashes.

Measurement of b-Glucanase Activity

β-Glucanase activity in malt, wort or commercial enzyme preparations can be measured using the following products:

Product Code

K-MBG4

K-MBGL

T-BGZ-200T

T-BGZ-1000T

I-AZBGL

P-BGBM

Arabinoxylan & Xylanase

Arabinoxylan is sometimes called pentosan and is the second most abundant polysaccharide in barley endosperm cell walls. It is also the primary component in wheat cell walls. Its structure contains two main sugars: arabinose and xylose.

Where soluble arabinoxylans persist into the wort, they can cause high viscosity, poor filterability and formation of beer hazes.

Product Code

K-ARGA

K-XYLOSE

Main Hydrolase for Arabinoxylan: Xylanase

Arabinoxylan is hydrolysed by xylanase, which acts on the xylose part of the molecule. Although xylanase is able to liberate oligosaccharides from the longer chain, it is not able to cut branch points in the arabinoxylan molecule. Xylanase is found at very low concentrations in barley malts, and becomes even scarcer by the time malts reach the mashing tun: like b-glucanase, xylanase exhibits poor thermostability, with a portion becoming deactivated during kilning.

Measurement of Xylanase Activity

Due to the potential consequences of residual arabinoxylans in the finished beverage, xylanase activity is an important parameter for brewers and distillers to measure - whether relying on endogenous xylanase or supplementing with exogenous enzymes. Xylanase activity can be measured in malts and commercial enzyme preparations using the following products:

Product Code

K-XylX6-2V

K-XYLS