A Semi‐Quantitative Method for the Detection of Trace Amounts of Native Collagen in Beer

Concerns about the potential allergenicity of collagen proteins remaining after beverage fining have necessitated development of methods to detect collagen in beer at very low concentrations. We have developed a semi‐quantitative SDS‐PAGE/densitometer method suitable for use in brewer's laboratories, for detection of residual native collagen at levels as low as 0.03 ppm (depending on the beer). The method is based on the fibril‐forming properties of collagen molecules at elevated ionic strength. It will not detect denatured collagens so cannot be used on pasteurised beers. For a quantitative reference that compensates for significant differences in beer composition, and the different fining agents, a known amount of the acid‐soluble fraction of the fining agent is added to the test beer to set limits of detection for the test. Densitometer results from the SDS‐PAGE gels can vary with sample volume, depending on background interference but this can be reduced by careful selection of gel loading volumes. Fining out of the added collagen occurs in some beers, so less collagen is detected in the reference samples than expected. However, as long as densitometer readings for the sample are below those of the spiked reference, then collagen levels can be declared with confidence as being less than those of the reference.