What does the s/t ratio on a malt Certificate of Analysis (COA) measure?

The s/t ratio on a malt Certificate of Analysis (COA) measures the ratio of soluble protein to total protein. This metric is significant in brewing because it provides insight into the malt's quality and its contribution to the brewing process. High levels of soluble protein can indicate effective enzyme activity during the malting process, which breaks down protein into soluble forms that can contribute to the beer's flavor, mouthfeel, and overall stability.

This ratio is particularly important for brewers because an optimal balance of soluble and total protein impacts the beer's haze stability and head retention qualities. It also informs brewers about how well the malt will perform during mashing and fermentation, as excess protein can lead to off-flavors or astringency in the final product.

Overall, understanding the s/t ratio helps brewers select the right type of malt for their specific brewing needs, ensuring that they achieve the desired flavor and quality in their finished beer.