Hop Steeping - a debate

[alikocho]

Some might find this adds an interesting contribution to the debate - http://www.mrmalty.com/late_hopping.php

[alikocho]

Hi All
Just to add a few bits of info to this interesting debate. The boiling points (at 760 mm Hg or our atmospheric pressure) of what I consider to be the most siginificant and pungent "aroma" compounds (Terpenoid compounds and their derivatives) of hops are as follows:

Myrcene 166 degrees C
Humulene 166 degrees C
Linalool 194 degrees C
Geraniol 229 degrees C
Caryophyllene 256 degrees C
Farnesene 260 degrees C
Selinene 260 degrees C

So although there will be losses of these important aroma compounds for sure, it may be actually less than you think at say an 80 degrees C steep. I always as a Flavour Chemist think also in terms of "polarity" and hence "solubility" of chemicals in their "solvent" enviroment (water in this case). These terpenes are very non polar (and hence very oil solubility) and their solubility will generally also increase in water as the temperature increases. Certainly they will be less soluble in 20 degrees C water than 80 degrees C.

I believe there is a difference between flash point and boiling point.

Flashpoints for the oils:

Myrcene - 103F
Farnesene = 79F
Myrcene = 104F
Humulene = 110.2°F
Caryophyllene =200F

This makes some interesting reading - http://www.ahaconference.org/wp-content ... ltweis.pdf

[Dr. Dextrin]

I believe there is a difference between flash point and boiling point.

Yes, flash point is where you can set fire to the vapour above the pure liquid in air. I don't think it has any particular relevance here.

[dcq1974]

For sure - yes Flashpoint is important! So is vapour pressure

It is a measure of the minimal temperature that we will start to see losses of volatile chemicals not just to ignite them

I need to convert from F to C




Thanks for the link - appreciate it.

[alikocho]

I believe there is a difference between flash point and boiling point.

Yes, flash point is where you can set fire to the vapour above the pure liquid in air. I don't think it has any particular relevance here.

Aside from the fact that the vapor is potentially being lost from a volatile oil? Which might well prove to be relevant here.

[dcq1974]

Flashpoints for the oils:

Myrcene - 39 degrees C
Farnesene = 26 degrees C
Myrcene = 40 degrees C
Humulene = 43 degrees C
Caryophyllene =93 degrees C

Although in practice and from observation - these guys can stand quite a bit of heat in the kitchen

[gregorach]

Flashpoints for the oils:

Myrcene - 103F
Farnesene = 79F
Myrcene = 104F
Humulene = 110.2°F
Caryophyllene =200F

Or, in sensible units:

Myrcene - 39.4C
Farnesene = 26.1C
Myrcene = 40.0C
Humulene = 43.4C
Caryophyllene = 93.3C

(Sorry, I hate Fahrenheit, but that's a whole other argument.)

The flash point of a volatile material is the lowest temperature at which it can vaporize to form an ignitable mixture in air. Measuring a flash point requires an ignition source. At the flash point, the vapor may cease to burn when the source of ignition is removed.

[http://en.wikipedia.org/wiki/Flash_point]

For comparison, the flash point of petrol is -43 C (note the minus sign there). I hope that no-one would suggest that an open container of petrol will rapidly evaporate to nothing at any temperature above that. Similarly, the flash point for ethanol is 16.6 C, but you can enjoy a dram at room temperature without worrying about all the alcohol evaporating away as you drink it.

[gregorach]

Ah, I see dcq1974 beat me to it...

[dcq1974]

Hey Dunc
Speed Up

[alikocho]

For comparison, the flash point of petrol is -43 C (note the minus sign there). I hope that no-one would suggest that an open container of petrol will rapidly evaporate to nothing at any temperature above that. Similarly, the flash point for ethanol is 16.6 C, but you can enjoy a dram at room temperature without worrying about all the alcohol evaporating away as you drink it.

But both will evaporate, right? And give off a smell from their aroma compounds, yes?

And how fast does gasoline evaporate at 80C? And ethanol?

It's worth bearing in mind (I suspect) that we are talking about tiny quantities of hop oils...

[weiht]

Hey Ali - Its interesting that you mentioned layering effect, I realise it makes alot of difference in dry hopping, ie the sequence of the hops additions. However, it seems some of the famed ipa/dipa homebrewers are saying that for kettle additions, they are starting not to do those 20mins 15 10 5 3 1 0 additions, and are migrating to just a simple 60 30(Optional) 15/10 and a BIG flame out instead. Any views?

[Capn Ahab]

Capn - U said the people u talk to mentioned that Jamil had to adjust his process to fit the commercial brewing, BUT he did mention on CYBI that u can scale down the commercial to homebrew and clone the beers, BUT u cant scale up the homebrew and clone it at the commercial level without making necessary changes.

This is the point I was trying to make. I 100% agree with the 'use more' mantra (especially for hops), but the point is that the longer they sit in hot wort, the more you will need. This seems to be borne out by this flashpoint issue.

[alikocho]

Hey Ali - Its interesting that you mentioned layering effect, I realise it makes alot of difference in dry hopping, ie the sequence of the hops additions. However, it seems some of the famed ipa/dipa homebrewers are saying that for kettle additions, they are starting not to do those 20mins 15 10 5 3 1 0 additions, and are migrating to just a simple 60 30(Optional) 15/10 and a BIG flame out instead. Any views?

I can tell you emphatically that a lot (and many of the pros in the US) are doing 60 (30) 15-10 and a heap of hops on flameout and a heap dry hopped. I do the same - I brewed a session IPA last night (5g - 1.042 - 65 IBU) which I hopped at 60 (1oz), 30 (1oz), 10(2oz), and then dropped 4oz of hops on at flameout. I'll dry hop with at least four ounces, if not twice that. This isn't unusual for me, and I have an IPA recipe that uses 140g of Simcoe, 70g of Ahtanum, 70g of Centennial as the dry hops for a five gallon batch.

More hops is the secret to big aroma. Don't worry about the cost. Just think of them as little green cones of awesome.

[dcq1974]

It's a combination of all these factors - nothings ever that simple

[weiht]

Ali, i reckon u lose at least 3L to hops and trub!!!