Some methods exist for detecting H2S in the lab by reaction with lead acetate, but these methods are non-quantitative and are typically not sensitive enough to detect trace quantities of H2S in finished beer. For these reasons, these methods are not widely used in breweries.
Humans have developed a hypersensitivity to sulfur compounds, including H2S and mercaptans. The presence of copper ions in the nasal mucus increases the binding affinity of sulfur compounds to receptors in the nose and increases the sensory threshold by up to 1000x. Sulfur compounds, in comparison to other common off flavors/defects in beer, are much easier to detect. For example, the average sensory thresholds for diacetyl (0.15 mg/L), acetic acid (90 mg/L) and lactic acid (140 mg/L) are much higher compared to H2S (0.01 to 0.02 mg/L).
Train your nose and flavor palate
A trained sensory panel is the most effective tool for detecting H2S in the brewery. Brewers can train their palates to be more sensitive to specific off-flavors and other aromas, including H2S and mercaptans.
Commercial sensory panel management courses and kits are available, which allow brewers to “spike” their beer sample with specific chemically pure flavor compounds.
Using this approach, a sensory panel can be trained to become increasingly sensitive to H2S, mercaptans, other sulfur compounds, and more.
Is it on-brand or an off-flavor? Train your sensory panel well to determine if H2S levels are within acceptable limits for the style (i.e. lagers). Early detection of H2S allows for the brewer to take corrective action if required.
Ensure the quality and consistency of beer by learning how to build and manage proficient sensory panels with the Siebel Institute of Technology Sensory Panel Management course and at-home sensory training kits.
Learn more by visiting: shop.siebelinstitute.com
For more information about H2S download the full dedicated paper from Lallemand Brewing.