Dry hopping is the process of adding hops to beer at any point after the boiling step.  This late hop addition contributes to beer flavor with minor changes to the bitterness.  The current market trend is towards hop-forward beers.  There is a lack of systematic data on how the hopping protocol influences the final product.  In this research, IPA-style beers were brewed with three different alcohol levels (4, 8, 12%) using three post-fermentation hopping protocols.  The following hopping protocols were used:  single hop addition at a rate of 3.5 g/L with a 10-day hop extraction period, five additions of hops, spaced every 2 days over a 10-day period, with a cumulative hop addition equaling 3.5/L, and a single hop addition at a rate of 3.5 g/L after filtration of the beer, followed by a 10-day extraction.  All beers were filtered and carbonated after dry hopping.  International bitterness units, total phenolics, and total protein content were measured, and no differences were observed between hopping protocols within an alcohol level. Total phenolics increased with alcohol level, with 12% ABV beer containing approximately double the phenolic content of 4% ABV beers.  Preliminary flavor analysis indicates high levels of isoamyl acetate, as well as many other esters.  A consumer panel was used to determine the overall liking of the samples and descriptive terms using check-all-that-apply.  Banana was more frequently selected as an attribute as the alcohol content increased.  As with the chemical analysis, alcohol level was found to be a bigger driver of differences than dry hopping protocol.  This initial study indicates that dry hopping protocol has a limited impact on final IPA flavor, although future work should explore dry hopping at a higher rate and using different hop varieties.

Dry hopping protocol has a limited influence on the chemical and sensory properties of India pale ale (IPA) beers

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