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The practical application of scientific principles to the art of hop agriculture and brewing science
3 thoughts on “#7: Cat Pee and Old Lady Perfume”
Hi James and Greg.
great podcasts here. James you have already helped my hop growing venture heaps in aus. Can you explain in more detail the science of hopping rates and scheduling with regard to whole flowers being used in commercial brews. my brewer hates grassy notes and dry hops too much.
I love the punchy fruity notes with fresh hops wet or dried.
If I understand correctly you’re asking about whole hop cone usage and if there are any special considerations when using them. Additionally what are the aroma impacts of whole hops wet or dry?
That’s probably more than I can answer in this format but Gregg and I can dedicate an episode to cover in more detail. In general there is little to no difference between pellet and whole cone hops…IF…the hops are processed correctly. Assuming proper drying and storage we see more oxidation on whole cone hops mainly due to the fact that there is more air contact around the lupulin glands and you will never get all the O2 out of a barrier bag of whole cones. That means potentially more off-flavors from whole dry cones than pellets Alpha/beta oxidation is also increased in whole cone for the same reasons.
Grassy notes come from a group of chemicals responsible for the aroma of “cut grass” and oftentimes is called grassy or “green”. This is not chlorophyll as that accounts for a flavor of cooked greens. The grassy aroma is easily removed by placing the hops closer to the hot side to flash off the volatiles responsible.
If the brewer is dry hopping at rates higher than 0.8kg/hectaliter (1.8lbs/bbl for the NA gang) then he is over-hopping since the maximum rate in most beer is the 0.8 number. the beer simply can’t take any more hop aroma compounds that we LIKE. He is likely pulling in other less desirable compounds especially if he is allowing the hop material to sit in the beer longer than 3 days at room temperature.
More is definitely not better. In fact if you want more impactful, fruity floral hop notes cutting back to something more like 0.65kg actually will allow for more of the hop character to dissolve into the beer.
Hi guys, awesome info! I just found your podcast while trying to diagnose some weirdness in my year 1 hop yard, talk about perfect timing.
Can you speak to the inverse relationship to cohumulone levels and disease resistance that early/mid-20th century breeders focused on? If lupuloides/pubescens varieties have poor resistance, high thiol/terpene alcohols, and high cohumulone, but continental lupulus varieties have higher resistance, lower thiols, and lower cohumulone, is that just epigenetic expression or genetic limitation? I’m curious about a correlation between specific metabolite production, it’s nutritional/environmental stimulus, and the variability of expression based on climate and cultural practices. I heard you say that Chinook was the only variety demonstrated to express significant epigenetic differences based on terroir, could you elaborate on that? Also, wouldn’t you say that Brewer’s Gold parentage spurred the higher oil and thiol content in modern hops, as opposed to humulene/caryophyllene? Those are more concentrated in the continental hops (as well as farnesene), though the oils are lower v/w.
Interesting research on the dry hopping rates, but if you aren’t getting more aroma from more dry hops, why do higher dry hopped beers so often smell more pungent? Not arguing that you’re not getting lots of unpleasant compounds too, but isn’t that more of a qualitative distinction? Even if solubility rate and substrate concentration are inverse, 50% of 44# is still more than 80% of 22#
How do you balance the solubility of a compound with its volatility? As you mentioned, humulene epoxide is very dense, low volatility, but only soluble to about .5g/L in water. Compare that to the highly volatile linalool, which is soluble to about 1.5g/L. Are enthalpy of vaporization, flash point, vapor pressure, or boiling point a suitable metric to compare against solubility to better evaluate addition timing? Also, could the heavy minerality of Burtonized water accentuate hop character not only by the sulfur note, but also by reducing the vapor pressure of solution through increased solute concentration? Lastly, could small amounts of extremely dense fixative compounds such as those in orris root serve to prevent CO2 scalping of dry hops by similarly decreasing vapor pressure of solution?