The initial research was apparently carried out at KUL in Belgium, but it was a paper by Grady Hull of the New Belgium Brewing Co. that really brought the concept to the attention of the English-speaking homebrew realm.
The basic concept is that “oleic acid in the olive oil will provide the UFAs necessary for yeast growth and proper fermentation, eliminating the need for wort aeration.” Commercial breweries (and home brewers) are interested in minimising oxygen contact with beer at all stages of brewing in order to extend flavour stability.
The catch is that, at home brewing scale, the amounts of olive oil used in the paper are unfathomably small – 0.0000833mL per 5 US gallons.
Several other questions also remain. Oleic acid only provides fatty acids, so there is still a need for a sterol source (the paper mentions the possibility of “adding a combination of ergo sterol and oleic acid”) and the paper reports increased ester levels by this method, which may or may not be appropriate for the beer you’re brewing. There’s also a big question over exactly how much olive oil is optimal. Two other people came up with rates as high as 3mL or 15gm per 5 US gallons.
Of course, in their own inimitable fashion, home brewers around the world have jumped in head-first to test it out. And the funny thing is that several people are reporting positive results!
I guess it’s worth pointing out that most of the ‘results’ refer to measurable/observable fermentation characteristics, and not necessarily flavour. I find it interesting that in the home brewing world the use of olive oil is seen primarily as an easy alternative to oxygenation of wort or yeast, not as a means of minimising oxygen contact, which was the initial intention of the paper.
To be honest, I’m still quite sceptical. But I’m a grumbly old stick-in-the-mud anyway. Depending on how much stock you put in random people on the internet, it may still be reasonable to state that, a) you aren’t likely to ruin your beer with a small addition of olive oil; and b) it doesn’t appear to affect head retention.
I’m not aware of anyone saying that adding olive oil ruined their beer, so there doesn’t seem to be too much to lose by experimenting. Olive oil is one of my favourite foods anyway, so maybe I should give it a go. It might be a good addition to pizza beer!