英文名：Beta-Glucan (Barley;Med Viscosity) 5g
1. Which barley beta-glucan do you recommend for the glucanase assay? There are three kinds of barley beta-glucan availabale from Megazyme – high viscosity, medium viscosity and low viscosity.
For glucanase assay, we recommend the medium viscosity beta-glucan. We now offer low, medium and high viscosity wheat arabinoxylans, and we think that the low viscosity material will be best (easiest) to use in the reducing-sugar assay.
2. Both substrates; barley beta-glucan and wheat arabinoxylan, are standardised to a specific viscosity, e.g. 23-24 cSt. Are the substrates adjusted to give this viscosity?
The substrates are enzymically treated to yield the required viscosity (20 ~ 30 cSt). Modification of the viscosity of beta-glucan is required for IOB viscometric malt beta-glucanase test (which works well).
3. I would like to vacuum dry the standards instead of measuring the moisture content. I wish to dry them at a temperature lower than used in the preparation in Megazyme. Would you please give me some suggestions?
We suggest that you dry the β-glucan powders further in a vacuum oven at about 50˚C. This will lower the moisture content to approximately 1-2%.
4. I understand a specific polymer can be used for the assay of malt β-glucanase and celluloses. I would very much like to know which polymer this β-glucan is?
The polymer you require is barley beta-glucan (medium viscosity). The beta-glucan that we supply is pure 1,3:1,4-beta-D-glucan. Barley β-glucan is also susceptible to hydrolysis by cellulase.
5. Although not specified on the beta-glucan data sheet, is the ratio of 1-3 to 1-4 bonds measured? If so, what is the ratio and would you expect it to remain standardised over a number of different batches?
The content of 1,3 bonds in barley beta-glucan is about 32% (from literature). We would not expect this to change much (if at all) over different batches.
6. We have measured the molecular weight of beta-glucan originating from barley ordered from your company. Can you please tell us which method have you used for measuring molecular weight?
The MW’s were determined by Multiangle laser light scattering technique.
7. I have purchased barley beta-glucan (lot 30108) and carob galactomannan low viscosity (lot 30702) and would like to know what else there might be in these substrates.
Barley beta-glucan lot 30108 would contain about 3-4% arabinoxylan (this was produced in 1993). Material supplied post 1995 contains < 0.5% arabinoxylan. Carob galactomannan is quite pure (> 96%).
8. Low, Medium, High Viscosity β-Glucans, are they naturally occurring at these MW’s or are the MW fractions obtained by some other process?
The high molecular weight beta-glucan is the naturally occurring; this is enzymically modified to give the other viscosities.