BarthHaas has published their latest Hop Science issue in which they talk about nitrogen – from field into beer, yeast in sour beers and hop creepiness.

Hop creep is an important phenomenon that brewers need to understand when they produce hop-forward intensive beers. It appears in direct to hops diastatic activity that appear when hops are added during fermentation or maturation, converting beer dextrins in the young beer to fermentable carbohydrates. Furthermore, yeast cells still present in the green beer can ferment these carbohydrates to carbon dioxide and ethanol, that will further lead to fermentation by-products such as acetaldehyde, diacetyl, ethyl and acetate esters, and higher alcohols, compromising beer quality. Furthermore, the fermentative activity can lead to an increased alcohol content, decreased residual extract, and an increased risk of overflowing fermentation tanks or over-carbonated bottles due to the formation of CO2, leading to even bursting of bottles or cans, in severe cases. To avoid all this, German researchers have now developed a method for quantification of the diastatic activity of hops, incubating hops with a potato starch substrate for 48 hours and using response surface methodology. 14 different German hop varieties were tested. The company is organizing a presentation on Nov 8th, to give more facts about the hop creep to all interested.