A bit of a side topic, but whatever happened to the talk about how a very small dab of olive oil was just as good as pure o2 prefermentation?
Here's the paper if you want to read it: http://www.brewcrazy.com/hull-olive-oil-thesis.pdf
Here's the excerpt form Experimental Homebrewing after I'd talked to Grady Hull about using OO.....
Olive Oil Instead of Aeration Yeast cells need oxygen to synthesize sterols to keep cell walls flexible for reproductive budding. Homebrewers are constantly looking to generate the best yeast health for the least amount of fuss and expense and some saw the Holy Grail in olive oil.
In September 2005, Grady Hull came up with a completely new method when he published his Master’s thesis. He used a small dose of olive oil during yeast storage to remove the need to oxygenate the wort prior to pitching. Here’s a bit of the introduction of the paper:
“This paper reports the findings of a series of full-scale production tests that were conducted in an operating brewery to evaluate the effects of another type of yeast treatment. By mixing olive oil into the yeast, during storage, instead of aerating the wort, fermentations can be achieved with only a minor increase in fermentation time. The beers produced from these fermentations were comparable in flavor and foam retention to beers produced by traditional wort aeration. The ester profile of the beers produced using olive oil addition was significantly higher than the controls and the flavor stability of these beers was significantly improved .”
Homebrewers seized on adding olive oil as a way to get around other aeration methods. A liter of cheap olive oil is many times less expensive and lasts longer than the available cans of O2. What most overlook: the technique was used on yeast in storage. It had nothing to do with adding olive oil to the fermenter. Yet folks were adding it to the fermenter and reporting “Well, it didn’t hurt,” or “it seemed to work.” (Remember, there are plenty of homebrewers out there who do no aeration whatsoever and report that their beers are fantastic.)
There was little accounting for the infinitesimally small amount of olive oil needed for a five-gallon batch of homebrew. Reducing Grady’s numbers to our brew lengths brings the dose to less than 0.05 ml of oil per 5-gallon batch. The closest we can get without using lab equipment is to use a drop on the end of a pin or needle. Brewers attempting to use this technique usually also missed out on dissolving the oil in a solution of ethanol first to ensure that it would blend into the wort and not float in the watery wort.
We specifically asked Grady about how homebrewers were taking his research and using it in their own ways. Grady replied:
“We never tried using olive oil in propagations. Our tests were centered around using it as a nutrient in yeast storage vessels to eliminate the need for aeration at knockout. Also, we never tried adding the oil to the wort after pitching. The oil was always added to the yeast in the storage vessel and given plenty of time to mix and be absorbed into the cells prior to pitching. We found a slight increase in esters and a slight improvement in shelf life by using olive oil and not aerating. We do not currently use olive oil in our yeast storage vessels. The results did not bear out the shelf life improvements we were hoping for and did not justify installing an olive oil dosing and handling system.”
Topic: Shaking (Read 4649 times)
