HLP Medium

[abrix]

I'm curious if anyone has used HLP medium to check up on their sanitation practices. If so, was it worth the effort? Did you change anything in your sanitation routine as a result?

Related, does anyone have a source for HLP medium that doesn't require getting 10 x 500g cans from Siebel? Google didn't turn up anything for me. I'm guessing I'll have to get on the phone and try some sweet-talking, but curious if anyone has any leads.

If, like me, you'd never heard of it before, HLP is Hsu's Lactobacillus and Pediococcus medium (linky above) and is used to selectively culture lacto and pedio from a fermentor, keg, bottle, wort sample, etc. to monitor for contamination...with no microscope required!

 

[Kaiser]

Even with a microscope you'll need a selective growth medium to monitor beer spoilers. The problem is that even very low populations of these can leaf to of flavors. These small populations can't easily be seen under a microscope.

Many people think that one can check for infections with a microscope. But you can't. At least not reliably.

That stuff is rather expensive. I wouldn't mind some, though.


Kai

 

[bdh]

If you were really motivated to do this cheaply you might be able to make an approximate version of the media yourself. It's mainly milk solids, yeast extract, some tomato juice, and dextrose. For example (http://www.bd.com/europe/regulatory/Assets/IFU/Difco_BBL/290010.pdf) lists a formula that could be used as a starting point, but you'd probably have to play around with it a bit to get the pH and buffering correct.

I'd be surprised if you could find a cheap source of this. Almost all of the demand comes from scientific labs with high quality control needs and much larger budgets than a homebrewer.

 

[Kaiser]

Thanks bdh,

I would need to add something that inhibits yeast growth. That usually involves some toxic chemical.

Kai

 

[abrix]

According to Teri Fahrendorf, the 'active ingredient' in HLP is Actidione, a.k.a. cycloheximide. One gram is $35 from AG Scientific. According to a reference for a related medium, one would add 7ml of 0.1% cycloheximide per liter, along with 3g phenylethanol and 10ml sorbitan mono-oleate.

It is an agar or media that supports the growth of the specific bacterium, Lactobacillus and Pediococcus. HLP contains Actidione, which suppresses the growth of yeast. (It kills the yeast.)

 

[drocra]

FYI, you can buy individual bottles of HLP media from White Labs at http://www.yeastman.com. It's $119.65. Not cheap, but honestly, there are enough uncommon ingredients in there that unless you have access to a lab it's not worth it financially to make it yourself.

In addition to the yeast inhibitory properties of the cycloheximide, HLP also contains oxygen scrubbers (sodium thioglycollate) to convert the closed tube into an anaerobic environment. It's an excellent way to detect anaerobic organisms like Lactobacillus and Pediococcus without needing an anaerobic jar.

 

[drocra]

Also, if anyone is in the Colorado area, want to go half-sies?