PDA

View Full Version : Additive explanations



teejay58
08-28-2010, 07:39 PM
I am so confused. I tried searching on chemicals and got a bunch of posts on "natural" mead making. But none answered my question of today. If there is a post that will answer these things, please feel free to point me to it. I can read the forum happily for hours at a time, but I'd *really* like to make some mead this weekend instead of read!

1. Sulfates, sulphur dioxide, campden, metabisulfite. I read that you should not use dried fruit in your mead that has been treated with sulphur dioxide, for fear it will impair or kill the fermentation. Yet, campden tablets and metabisulfite are designed to produce sulphur dioxide to sterilize the must and kill any undesired yeasts. And... these ingredients are sometimes used before pitching the yeast???

2. Sorbates - used to stop the yeasts from reproducing and continuing to ferment. Isn't this kinda the same thing that metabisulfite does? Why do you need both?

3. Nutrient additions - this is where I'm really confused. DAP apparently is toxic to new yeast colonies. But it's supposed to feed yeast. So how do you use it?

Which nutrients are best? And when do you use each? There are a lot of variations between the different nutrients. I don't know the pros and cons between adding some of these things.

Fermaid K: ammonia salts, alpha amino nitrogen, sterols, unsaturated fatty acids, other key nutrients, and inactive yeast.

Fermax: Di-ammonium phosphate and yeast hulls.

Go-Ferm: a yeast nutrient used during the rehydration of dried yeast.

Yeast Energizer: DAP, yeast hulls, vitamins, and magnesium sulphate

Yeast Hulls

On a side note, I think I scored something cool today. Picked up a pound of dried mango with zero added ingredients in it. No sugar, no sulphur dioxide, etc. Now... what to do with it... Hmmm... ;) Ideas are solicited.

Medsen Fey
08-28-2010, 10:19 PM
I'll tackle at least a few of your questions.

1. Sulfites. In whichever form they are added, they serve multiple purposes. When added to crushed fruit they inhibit polyphenol oxidase which causes browning. Sulfites also suppress (not sterilize) wild yeast because wild yeast happen to be much more sensitive to SO2 than wine yeast which have be subject to SO2 for hundreds of years. It also inhibits bacteria that can interfere with fermentation. Usually when sulfites are added, the recommendation is to pitch your yeast 12-24 hours later (though if you ignore that rule, your yeast will probably still take off). I rarely use sulfites prior to fermentation.

2. Sorbate. Sorbate (Sorbic acid) interferes with yeast metabolism in a different way. It helps prevent cell growth and function and when used in addition to sulfites can help to prevent yeast from restarting fermentation when more honey (or other sugar) is added for sweetening after fermentation.

3. DAP toxicity. When dried yeast are rehydrated, their membranes are leaky and an influx of DAP can be damaging so you do not want to rehydrate yeast in a solution with DAP. After rehydration, DAP is an important source of nitrogen for the yeast, but yeast aren't able to assimilate it late in a fermentation (somewhere after the 1/2 fermentation point).

4) There are various nutrients. DAP and Fermaid K are popular here because we know the nitrogen content, and because we know they consistently work well. It is good to have both. Fermaid K contains DAP as well as autolyzed yeast and provides micronutrient that the yeast need other than nitrogen. If you are planning a recipe post up your plan and folks can help you tweak the nutrients.

I hope that helps.

Medsen

fatbloke
08-29-2010, 10:41 AM
I'll tackle at least a few of your questions.

1. Sulfites. In whichever form they are added, they serve multiple purposes. When added to crushed fruit they inhibit polyphenol oxidase which causes browning. Sulfites also suppress (not sterilize) wild yeast because wild yeast happen to be much more sensitive to SO2 than wine yeast which have be subject to SO2 for hundreds of years. It also inhibits bacteria that can interfere with fermentation. Usually when sulfites are added, the recommendation is to pitch your yeast 12-24 hours later (though if you ignore that rule, your yeast will probably still take off). I rarely use sulfites prior to fermentation.

2. Sorbate. Sorbate (Sorbic acid) interferes with yeast metabolism in a different way. It helps prevent cell growth and function and when used in addition to sulfites can help to prevent yeast from restarting fermentation when more honey (or other sugar) is added for sweetening after fermentation.

3. DAP toxicity. When dried yeast are rehydrated, their membranes are leaky and an influx of DAP can be damaging so you do not want to rehydrate yeast in a solution with DAP. After rehydration, DAP is an important source of nitrogen for the yeast, but yeast aren't able to assimilate it late in a fermentation (somewhere after the 1/2 fermentation point).

4) There are various nutrients. DAP and Fermaid K are popular here because we know the nitrogen content, and because we know they consistently work well. It is good to have both. Fermaid K contains DAP as well as autolyzed yeast and provides micronutrient that the yeast need other than nitrogen. If you are planning a recipe post up your plan and folks can help you tweak the nutrients.

I hope that helps.

Medsen
Further to Medsens excellent (as usual) explaination, Go-Ferm is designed to help with the rehydration of the yeast, I think it's right to say that it helps with all the needs of the rehydrating yeast, except nitrogen. The idea being that it helps the newly rehydrated yeast to be a stronger, more vigorous colony.

Then once some signs of fermentation are showing in the must, indicating the end of the "lag phase", it's time to add the Fermaid-K......

regards

fatbloke