View Full Version : Hop to malt ratio: preservative value

The Gooch
04-05-2005, 10:49 AM
Does anyone out there have any information on the Preservative Value method of hop rate that the Peter Austin / Pugsley brewers often use? It is a hop to malt ratio called Preservative value.

DeClerk has one formula that may be related but does not seem practical nor self evident in its application. It is mentioned only briefly. In his book it is a ratio between alpha and beta acids. We never used beta acids in our hop calculations, which leads me to believe it is a seperate formula.

The PV (preservative value) method is a practical hands on balance between malt and hops and is good when used along side IBU calculations. However, material regarding this method is hard to find. The only brewers I have known to use it have worked on a Peter Austin / Pugsley system or was shown it by one those said brewers. If anyone has any helpful information on this method, I would be most curious to hear it.

Has any of the English brewers out there heard of it?

The Gooch
04-06-2005, 09:35 AM
Come on I know there are old Ringwood loving brewers out there who have used this technique. Does anyone know anything more about it?

04-06-2005, 09:59 AM
Don't have any info myself, but I'm eagerly waiting for someone who does to post!

Cheers, Tim

04-06-2005, 10:26 AM
I found the following by Mort O'Sullivan, ICBD (Edinburgh, Scotland) on the HBD by seaching Google.



In recent years, the extent to which hops actually confer biological
stability to beer has been called into question. In the past, brewers
used to talk about the preservative value (PV) of hops and quantified
it based on the resin content of the hops. It was generally agreed
that alpha acids were more preservative than beta acids and depending
on where you look you might find an equation for preservative value
that looks something like this:
PV = 10[alpha + (beta/3)]
This equation would vary among different sources, but more weight is
always given to the alpha acids.
Actually, the situation is much more complicated than simply measuring
the alpha and beta acids and plugging them into a formula. The major
growth inhibiting organisms derived from hops have been identified as
trans-humulone and related (-)-humulone and colupulone compounds.
These compounds act as ionophores that disrupt the trans-membrane pH
gradient of sensitive bacteria. Lactobacilli vary tremendously in
their sensitivity to these compounds, and successful beer spoilage
organisms are often quite resistant to hop compounds. Thus a simple
measurement of PV based on the resin content in your hops is not an
accurate gauge of the antiseptic qualities of the hops. It really
depends on what your beer is exposed to.

Regarding the storage of hops and your question about oxidation:
oxidation can occur in sealed nitrogen-purged packages due to
compounds with relatively high oxidizing potential in the hops
(granted, it will be much less than in hops exposed to air). From a
bitterness point of view, oxidation decreases alpha acid bittering
potential and increases beta acid bittering potential, but not enough
to redeem the loss of alpha acid bitterness (also, oxo-beta acid
bitterness is believed to be qualitatively inferior to iso-alpha acid
bitterness). From the aroma point of view, oxidation will give you
cheesy and other off flavors and higher levels of some desirable
epoxides of hop terpenes (this may or may not be appropriate to the
style of beer you are brewing). As far as choosing hops goes, trust
your eyes and your nose. As hops oxidize they tend to change from
green to brown in color and their aroma changes noticeably. Get to
know your hops in their fresh state and you will recognize when they
are not.

- ----------------
Mort O'Sullivan
ICBD (Edinburgh, Scotland)
tarwater at brew-master.com

The Gooch
04-06-2005, 12:12 PM
Thanks More Beer for the quote. It was interesting but not exactly what I was looking for though. It could be part of the larger picture though.

The hop rate method I used to use was called Preservation Value and could be related to the formula mentioned in your posting. The formula you posted was simular to the formula in DeClerk. But what I am looking for is some practical information on balancing hops to the amount of malt used, as is the formula that the Peter Austin / Pugley system brewers are trained to use. The name PV may be a throw back to the old days.

In the PV system the amount of malt used dictates how much hops are used. It does not deal with liquid volumes or utilization. It reminds me a little of the European method of using grams alpha acid added per hectolitre (g AA/hl) , which is a way of adding hops per volume of wort. That method does not deal with utilizations either but is a rough rule of thumb as to how much hops are used per given beer style. For example a Pilsner may get between 8-12 g AA / hl (don't quote me on that one as I do not have that exact information in front of me).

The PV method will give you a multiplier that you multiply that by how many pounds of malt used. That number will be your hopping rate. Take that number and split it up for each kettle addition. Divide those numbers with the AA content of the hops and your weight in pounds to add should come out.

I just have never seen any published information on this method.

04-07-2005, 10:03 AM
Don't know if this helps but it seems to be right along the lines of balance values - BU:GU (Bittering Units:Gravity Units) as discussed by Ray Daniels in Designing great beers. I found this on the web: http://beercolor.netfirms.com/balance.html

It discussess Ray's technique and a few others. Hope this helps.


04-07-2005, 10:08 AM
Ooops.... I meant Hop, not mop. I want my money back from Hooked on Phonics...

The Gooch
04-07-2005, 10:11 AM
Thanks Conan, some of that link was interesting. The Balance Value (BV) that was mentioned are simular to the PV units I'm searching for, but not quite the same.