I have dry hopped cold.... did not love it. My results corresponded with info below. I do all dry hopping at room temperature. I wonder if the cold beer temps/dry hops could also be some of the issues people have with "keg hopping" that have talked about. Here is some good info from NHC this summer - YCH Hops presenting
Presentation - Temperature starts around 17-18 minutes in..... lots of other good info in here in addition:
https://s3-us-west-2.amazonaws.com/homebrewassoc/wp-content/uploads/Dry-Hopping-Effectively-1.m4v
Power point - scroll down - there is a slide on effects seen at different temperature dry hopping:
https://s3-us-west-2.amazonaws.com/homebrewassoc/wp-content/uploads/Dry-Hopping-Effectively.pdf
Dryhop Temperature
Lots of options on this, really depends on what you want to achieve. 3 categories to discuss:
1) 60F to 70F- Emphasis on fruity, juicy, citrus compounds. Increased efficiency and increased VDK...need longer secondary rest.
2) 50F to 60F- Balance between Fruity, Juicy, grassy, piney, earthy aromas and flavor. Decent Efficiency and moderate VDK
3) Below 50F- Emphasis on harsher grassy, vegetal flavor and aroma
A couple common problems that people do have with these beers (besides oxygen) are harshness of hops (dry hopping too low on temp perhaps). Another problem is Diacetyl - perhaps as a result of late dry hop and pulling off yeast too fast to not take up the VDK from dry hopping which can jump start small fermentation that goes unfinished at the end and carries diacetyl over to final beer.
My dry hop is all at room temp which gives me the fruity emphasis...... It is also on day 2-3 which gives biotransformation and it also gives active yeast time to deal with the VDK while they are active, plus I am not taking the beer to the keg until 10 days later as well. Not that all of that was by design - but, reflecting on my process vs. the above observations on the slide - might be part of the reason I have had good success with these beers.
