European Union Risk Assessment Report

Bacterial 1,3-1,4-β-glucanases: structure, function and protein engineering

This review covers the physiology and molecular biology of the plant β-glucanases possessing either endo-1,3-β-D-glucanase (EC 3.2.1.39) or endo-1,3;1,4-β-D-glucanase (EC 3.2.1.73) activity. These β-glucanases are structurally related enzymes that are believed to be involved in many important aspects of plant physiology and development, such as germination, growth, defense against pathogens, flowering, cellular and tissue development and differentiation, and probably other roles. They also are regulated by numerous plant hormones, biotic and abiotic elicitors and stresses, and they exhibit complex tissue- and developmental-specific gene expression.

The Physiology and Molecular Biology of Plant 1,3-β-D-Glucanases and 1,3;1,4-β-D-Glucanases

Size-exclusion chromatographic determination of β-glucan with postcolumn reaction detection

A new form of the mixed-linked (1→3),(1→4)-β-d-glucan has been obtained from barley grains using a new extraction and purification process that involves two key steps. A hot-water extraction of the β-glucan from the grain followed by a freeze and thaw of the extract. The commercial product from this process, called Glucagel, forms as a gelatinous or fibrous precipitate, which can be dried. Glucagel has novel functional properties. It forms soft thermoreversible, translucent gels that melt and set at temperatures of ≈60°C.

Glucagel, A Gelling β‐Glucan from Barley

The FIA-fluorimetric methods for the determination of β-glucan in worts and beers have been investigated, modified and improved. Fluorescence is excited by using a mercury lamp and a 338 nm band-pass excitation filter, and detected using a 425 nm long-pass emission filter. It has been found that an increase of the ionic strength of the eluent, up to a maxium of 1% Sodium Chloride, increases the range of β-glucan molecular weights effectively bound by Calcofluor. The influence of the low molecular weight components of wort and beer: dextrins, aminoacids, etc, has been studied and found that their effect is negligible. The interference of wort and beer colour on the measurement of β-glucan has been quantified and several approaches are given to overcome it. Thirty-six European beers have been analyzed for β-glucan content. The possible detection of the addition of exogenous β-glucanases to wort and beer is discussed.

https://onlinelibrary.wiley.com/doi/pdf/10.1002/j.2050-0416.1989.tb04639.x

Determination of β-glucan in wort and beer by its binding with Calcofluor, using a fluorimetric flow-injection-analysis (FIA) method

Three commercial β-glucanases, two fungal (Biobeta P-100 and Filtrase AM) and one bacterial (Finizym 200L) have been studied with regards to the β-glucan hydrolysis in beer. At the temperature (0°C) and enzyme concentrations (5–20 ppm) tested, β-glucan degradation takes place in two stages: the first one consisting of an initial induction period of short duration (ca. 4 hours) and slow degradation rate, and the second following a first order kinetics, the rate constant of which is directly proportional to the enzyme dose. The enzyme doses recommended by the manufacturers are somewhat higher than the enzyme doses needed to lower the β-glucan content of beer, after the usual lagering time, below the filtering troublesome levels. No evidence for synergic or competitive effects between fungal and bacterial β-glucanases have been found.

https://onlinelibrary.wiley.com/doi/pdf/10.1002/j.2050-0416.1990.tb01018.x

KINETICS OF β-GLUCAN DEGRADATION IN WORT BY EXOGENOUS β-GLUCANASES TREATMENT

Determination of monohaloacetic acids in beer has been carried out by: 1) percolation of the beer through a C-18 Sep-Pak in order to eliminate the less polar components; 2) acidification of the eluate (pH=0.5) and extraction of the monohaloacetic acids with ethyl acetate; 3) removal of the organic solvent by rotary evaporator and vacuum; 4) methylation of the residue with BFMeOH; 5) extraction of the methyl ester derivatives with hexane; and 6) separation, detection and quantitation by gas-liquid chromatography, using a fused-silica BP-1 (12m × 0.53 mm) microbore column, and electron capture detection. Recovery yields are nearly 100% for all monohaloacetic acids. Detection limits are lower than 0.1, 0.05 and 0.01 ppm for chloroacetic acid, bromoacetic acid and iodoacetic acid, respectively. Seventeen European beers have been analyzed for monohaloacetic acids content, and negative results have been found in all cases.

https://onlinelibrary.wiley.com/doi/pdf/10.1002/j.2050-0416.1990.tb01019.x

Determination of chloroacetic acid, bromoacetic acid and iodoacetic acid in beer by microbore gas-liquid chromatography and electron capture detection.

Victoria Todo

Papers

Determination of β-glucan in wort and beer by its binding with Calcofluor, using a fluorimetric flow-injection-analysis (FIA) method

KINETICS OF β-GLUCAN DEGRADATION IN WORT BY EXOGENOUS β-GLUCANASES TREATMENT

Determination of chloroacetic acid, bromoacetic acid and iodoacetic acid in beer by microbore gas-liquid chromatography and electron capture detection.