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olive oil as O2 alternative
Hey folks - I've been contemplating using olive oil as an alternative to oxygenating my wort at the time I pitch my yeast. I've read articles in Zymurgy and BYO and have also seen posts on AHA TechTalk about this technique. Just curious if the trusted and revered BKB group has tried using olive oil. If so, how much? How were the results (lag time, foam retention, taste, etc.)? Cheers!
I have been waiting for you to try it first. 
Havent heard too much about this recently, it was the rage a couple of years ago, and I think it was New Belgium that did a whole trial with it. If I remember correctly the amount needed when scaled down to a homebrew level was to stick the tip of a pin into a puddle of oil, then shake it off, what sticks to the pin is plenty.
I've never heard of this before. Any links to an article explaining it?
Try it and tell us how it works out...
never heard of this before but did about an hour of research and for a 5 gallon batch its like you boil a quart of water and put in a drop of olive oil boil it and then add between a drop and a teaspoon of the original mixture. I actually may try this as my aeration techniques are not the greatest. I'm brewing next week we will see. From what I read the problem is if you use too much it can add some fusel flavor and you will have 0 head retention.
When I say 1n1m3g's name attached to this I had hoped that he had done a study on this already and had some great definative result to share. Knowing he is a yeast guy and all.
Alas, this olive oil thing remains an enigma.
I think the DeStruise brewery uses olive oil in their yeast preps, but that is totally unconfirmed.
I looked around some and found a couple brewing forums that had also discussed using olive oil as an oxygenation alternative.
One of the members used the 'pin head' method for measuring out the amount, which was calculated at being " ~20µL olive oil for a 300mL " yeast slurry.
http://www.homebrewtalk.com/f13/high-gr … oil-55404/
And here is a published thesis documenting an experiment.
http://www.brewcrazy.com/hull-olive-oil-thesis.pdf
Hopefully this helps.
Thanks for posting the olive oil thesis, Guy. This is exactly the kind of stuff I was looking for.
So, according to the results of Grady Hull's tests the best results were obtained by adding 1mg olive oil for every 25 billion cells in cold storage 5 hours before pitching into the fresh wort. If one assumes that there are roughly 250 million cells per ml of a 1L saturated, oxygenated starter culture, then the appropriate amount of olive oil would be 10mg. This might be slightly less for an unoxygenated culture due to lower cell density.
One thing that I noticed in this thesis was that they were reusing yeast from a previous fermentation. This is a common practice in commercial breweries and they might reuse a healthy population of yeast for 10 or so fermentations before starting afresh. This is a very different technique used compared to what most home brewers use; a fresh starter culture for every brew session. Grady mentioned in the introduction that stored yeast harvested from a fermentation for reuse are depleted in key cell wall components (i.e. sterols and unsaturated fatty acids) and that the traditional technique of oxygenating wort during pitching provided the yeast to resynthesize these components during the lag time when they are in contact with the dissolved oxygen. Obviously, a healthy fermentation requires healthy yeast and the added oxygen, or in the case of this study the addition of olive oil, provided the necessary precursors for harvested yeast to become "healthy" for the subsequent fermentation.
It would seem then that both oxygenation and olive oil addition would both be unnecessary for us home brewers who are building up our yeast in an oxygenated starter culture (i.e. on a stir plate). I interpret the addition of olive oil to the stored yeast without any further oxygenation of the wort as the same thing we do in our starters, but in our case I'm sure we all also oxygenate our cooled wort as well.
What do you all think of conducting an experiment? I say anyone willing should do one of the following on one of their next batches and report back on the results. Splitting the batch and doing two for a comparison using the same wort would be even better.
1. Create an unoxygenated starter (i.e. just add yeast and let set without stirring) days before the brew session and cool it down a day or two before brewing to settle the yeast and to mimic the harvested and cold storage technique of breweries. Add olive oil 5 hours before pitching, swirl around to get the yeast in contact with the olive oil and let settle until pitching.
2. Create an unoxygenated starter days before the brew session and pitch into oxygenated wort.
3. Create an unoxygenated starter days before the brew session and pitch into unoxygenated wort.
4. Create an oxygenated starter on a stir plate and pitch into oxygenated wort.
5. Create an oxygenated starter on a stir plate and pitch into unoxygenated wort.
Obviously we can't do as thorough of an analysis as Grady did but we can take measurements such as amount olive oil added, lag time, fermentation time, original gravity, final gravity, and taste after bottling or kegging.
I will definitely do some of these comparisons the next time I brew. Any other takers? Cheers!
Sounds like a good idea!
The only problem with having multiple people do it is that your going to end up with many uncontrolled variables that will effect the outcome person to person, yeast type, o.g, fermentation temperature, percentage of fermentable sugars, ect, so the results will vary greatly and may not be too very conclusive.
I would love to do a comparison, by making several 1/2 to 1 gallon mini-batches, all from the same boil. I would be unable to do it directly though to due to school, and some equipment issues (stir plates and aerators, might be able to borrow stir plate from chem lab though), and my lack of brewing experience. I could however brew it ( all-grain or extract), ferment it, document the entire process, and send bottles out to members that would be able to pick up on subtle taste variations ect.
Could also try adding dead yeast cells as they contain up to 2% ergosterol by weight, because the olive oil is not in itself replacing O2, but by adding some unsaturated-fatty acids you are reducing the amount of O2 needed to produce ergosterol (cell wall membrane). Ergosterol is required in part for the anaerobic growth of yeast, to produce more yeast you need to be able to produce more cell-membrane.
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