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View Full Version : will yeast eat supersolutions faster?



chris24
05-24-2010, 06:31 AM
hey everybody, great site. forgive my lack of an intro post, i was just thinking about all of the wonderful science behind brewing, and had an idea...

im sure there may be different opinions on this, but id like to hear them all anyways...ive read in some places that if all your honey is on the bottom of your jar, the yeast will find it and eat it...and other places i have read that you should shake up your must when you fist make it, and it should be stirred so often etc...


i would think that if it were spread throughout, the honey would have more surface area, and thus would get "eaten" faster...but i dont know.

and then in the midst of considering this, i thought about supersolutions.

if you arent familar with supersolutions, ill try to explain it. say you have an amount of cold or room tempreture water, we will say a gallon. you can only dissolve x amount of sugar in it before the water just wont disolve any more. (those of us in the south who drink ice tea know all about this problem). BUT if you were to heat up the water, i think to boiling, but im not sure...you can add more sugar! it will disolve, and even if you bring the temp back down, it will stay disolved. this is how you make REALLY sweet iced tea.

so okay, here are my questions, please feel free to answer/comment or discuss on as many as you can:

1) honey, keeping it stirred or all on bottom, does it make any difference, be it fermentation time or anything else? if so what?

2) can yeast eat disolved sugar? will it eat disolved sugar faster than non-disolved sugar?

3) can honey be made into a supersolution?

im wondering if anyone has done any kind of scientific test to see if there actually is any difference in fermentation time. maybe it would be a fun expiriment to try with two or three small 1 liter bottles and a quarter of a cup of honey or something. 1 normal, 1 stirred, 1 made into a supersolution (if possible).or maybe 6...3 as above with honey and 3 with sugar.

i suppose either way, it would not matter as far as the time spent ageing, but if you could knock off a significant time off of the fermentation part, it might be worth it. plus, id really like to understand as much of the science behind the whole process as i can. ive yet to make my first batch, so im totally clueless.

anyways. sorry for the rant, and any typos. its 5:30 am here, and i cant sleep! 8)

Medsen Fey
05-24-2010, 09:18 AM
Welcome to GotMead Chris!

Yeast will ferment the honey whether it is dissolved or not. DaleP often uses the approach where the honey is left on the bottom (BDC DYF for short). It works well and I have used it on a couple of batches with good results, and find that it is especially good for high-gravity, high-alcohol production. There are pros and cons to both methods and if you do a little searching (including the Patron's area) you will more info (try using the term "Bottom Dwelling" to narrow the search)

I have not done a side by side comparison of the rate of fermentation to see which is faster. I would guess in most cases, the dissolved would go a little faster, but that is purely speculation, and I would love to see you (or someone) do a comparison and test it.

Now there are some cases where the dissolved would be slower. That would be super-high-gravity musts (or a supersaturated solution). Honey is already a supersaturated solution and under some conditions it will crystallize. The degree of saturation of honey is so great that it prevents yeast from being able to grow and live in honey.

Sugar itself is toxic to yeast and starts to negatively impact yeast performance at a level above about 200 g/L (gravity 1.075), so as you increase the starting gravity of a must above that level, you start to hurt the yeast. By the time you are above 1.150, you are likely to see slower and possibly incomplete fermentation due to the osmotic stress. At 1.200 you are reaching gravity level that will prevent fermentation from starting. So going to extremely high gravity levels will not lead to a faster fermentation, but will instead give you slow, stuck fermentation.

akueck
05-24-2010, 06:04 PM
Medsen covered just about everything. I will add though that honey seems to be better at staying liquid than a plain sugar-water solution. If you make some simple syrup (which is a supersaturated sugar-water solution), it will crystallize pretty quickly at room temperature. Honey varies in its crystallization characteristics, but most will stay liquid for months if not years. Pretty amazing stuff!

As far as yeast "eating" sugar in solution vs. a solid lump, yeast take in nutrients through their cell walls & membranes from the environment. Sugar needs to be in solution for the yeast to access it. The "bottom dwelling" honey technique is successful because the honey will dissolve over time. The yeast doesn't consume the concentrated honey sitting on the bottom, but rather it eats what is in solution. As sugar leaves solution, more is dissolving from the honey sitting at the bottom.