PDA

View Full Version : Sluggish Fermentation...any suggestions?



Metal Fireworks
05-11-2010, 01:22 AM
So I started an Orange Blossom traditional mead last Sunday and things aren't progressing as quickly as I have hoped. I have been following a staggered nutrient addition program that I found in an old Ken Schramm article. Let me give you the details:

05/02/10 - 15lbs Orange Blossom Honey
1 lb Ollalie Berry Honey
5g Lalvin 71B-112 Yeast
6.2g GoFerm
Sanitized all equipment, added the GoFerm to 100ml of water at 108 degrees, added the yeast at 102 degrees and let sit for 8 minutes. I stirred up the yeast and gradually added my mixed must until temperature was around 70 degrees. Aerated the must for 10 minutes by hand with a large whisk and added the yeast. More aerating.

SG=1.113

After 6 hours I added 3g of Fermaid K and 4g of DAP

05/03/10 - Added .2g DAP and .1g Fermaid K (oops, read the instructions I was following incorrectly!!) Aerated twice

05/04/10 - 1g DAP, 1g Fermaid K. Aerated twice. Gravity = 1.110

05/05/10 - 1g DAP, 1g Fermaid K. Aerated twice. Gravity = 1.100

05/06/10 - 1g DAP, 1g Fermaid K. Aerated twice. Gravity = 1.092

05/07/10 - 1g DAP, 1g Fermaid K. Aerated twice. Gravity = 1.083

05/08/10 - 1g DAP, 1g Fermaid K. Aerated twice. Gravity = 1.078

05/10/10 - Today I thought things were moving a bit slowly so I added 2.5g DAP, and 2.5g Fermaid K and mixed things around a bit.(It was really happy to get this dose and gave me some good foam) Gravity = 1.069

I've been checking the ph level and it seems to be sticking around 3.4 which seems in the ballpark to me.

So why is this one not moving as quickly as it should? Is it a nutrient deficiency? I have added a total of 10.6g of Fermaid K and 11.7g of DAP and on the eighth day it isn't even at the 1/2 sugar break. Since Orange Blossom is a lighter honey does it need more nutrients? Potassium? (this is the one ingredient from the article that I did not add)

I have to admit that I don't ever rehydrate my nutrients when I add them. I have always just thrown them in and stirred immediately. Would this be a problem at all?

Thanks for reading this onslaught of questions and I hope some of you have some answers or suggestions!!

wayneb
05-11-2010, 07:35 AM
I don't believe that your sluggish fermentation is due to nutrient insufficiency. I guess I have some questions first: 1) What is the temperature of your must, and has it stayed constant over the entire primary fermentation interval? 2) What are you using to measure pH, and have you calibrated it recently?

Those questions will help us to pinpoint why things might be slow. Additionally I notice that you have rehydrated your yeast for less than the recommended time (Lallemand suggests 15 minutes for rehydration before you either pitch or start to attemperate). While that isn't always a problem, it might be in this case. Additionally, now that you are near the 1/2 sugar break, additions of DAP probably won't help since inorganic nitrogen will no longer be used by your yeast.

Metal Fireworks
05-11-2010, 03:49 PM
Thanks for the reply, Wayne. And to answer your questions:

1) The temperature has remained at a constant 68-69 in the room where my bucket sits so I assume the temperature of the must is a few degrees higher. Wouldn't a higher temperature create a faster (but harsher) fermentation?

2) Calibrate my ph reader?? Well, I made sure to get the ph strips with the least sun faded color chart!!!!! Yeah, I know that it's not the most sofisticated but it gets me in the basic ballpark and let's me know if I'm way off. Would you suggest an addition of Calcium Carbonate? Will it make a difference this far into primary fermentation??

3) As for my rehydration times, I didn't write it down correctly and missed a step. I actually follow the rehydration instructions per traditionalmead.com fairly closely:

[I]"In a sanitized jar or Erlenmeyer -type flask, add 100 milliliters (I recommend 20ml water per gram of yeast used; for example, 5 grams of yeast requires 100 ml water) of non-enhanced bottled drinking/spring water (no distilled water, and no municipal water) at 108 degrees Fahrenheit.

Add 5 grams (approximately 1 2/3rd teaspoons), of Go-Ferm (1 gram Go-Ferm to 1 gram yeast) to the flask, mix well, and adjust or wait for temperature to drop between 104 102 degrees Fahrenheit.


Add your "5-gram package of dried yeast" to the flask and let sit for 7 - 10 minutes. Stir and or shake to break up clumps (sanitized chopsticks work well). Wait 10 - 20 minutes.


Add 50 milliliters of your prepared (pH-adjusted if needed) must to the flask, let sit for 15 - 20 minutes. Add additional must to the flask until the temperature is within 15 degrees Fahrenheit of the total must (your 5 gallons of soon-to-be Mead) and let sit for 5 more minutes."

So that's my technique. I only added 5 grams of yeast to a five gallon batch. I know that mead makers with more experience use this amount but I may start off with more until I figure things out a bit more.

Another question, would adding yeast hulls at this point be beneficial?

Thanks again for the response and I hope to learn more!!

wayneb
05-11-2010, 05:17 PM
OK, your temp is perfect (and yes, you don't want the contents of the fermenter to be any warmer than that). Also, your rehydration process is OK, given all these additional details. That leaves calibration of your pH measuring process....

It is important to know that pH strips lose sensitivity with age, especially when exposed to the air (specifically the water and CO2 in the air). So, it is a good idea to periodically test them to see if they are still sensitive across their entire range of measurement. Here's one way: Mix up a solution of 50% vinegar, 50% tap water and place that in a non-reactive container (a small bowl or drinking glass will work). Next mix up a solution of one tsp of baking soda in 1/3 cup of water (or you can use one tablespoon in one full cup), and keep that handy in another non-reactive container. Next, take one strip of pH paper and dip it into the vinegar/water solution. It should almost instantly change color to the lowest pH shade in the range. If it takes longer than a second to change, your paper is kaput and should be thrown out. Now take the same paper (still damp from the vinegar test) and dip it into the baking soda solution. It should almost immediately shift color to the opposite end of the scale. If it takes longer than a second or two to do that, then the paper is still kaput and, well, you know what to do.

In any event, there is a strong possibility that your pH may be too low for your yeast to sustain a healthy fermentation rate. You can add a pH modifier, even this late in fermentation, and see some significant benefits. I personally prefer to use potassium carbonate or potassium bicarbonate rather than calcium carbonate since the potassium compounds are more easily dissolved in water and so they'll react quicker. But if the calcium carbonate is all you've got, it is better than nothing.

You should try adding 1g of any of the above per gallon of liquid, to your must. So for a 5 gallon batch try 5 grams of K or Ca carbonate. Stir it in and wait 12 hours, then check pH again. Also see if fermentation activity has increased any within that 12 hour interval. If low pH is your issue, then it should.

If a pH treatment doesn't help, then yeast hulls might, and are worth a shot. The yeast hulls will bind with many organic yeast toxins in your must and cause them to precipitate out of solution.

Metal Fireworks
05-13-2010, 12:26 AM
Thanks Wayne for the great advice.

I did the ph test you recommended and things seem fine with my strips. I actually get a better idea of the relationship between the colors on the label and the actual color the strip displays. The ph must have been lower than I thought because this morning I added 5g of calcium carbonate (all I had in the drawer) and this evening things seem to be moving along much better. I tested the ph and it is in a much more alkaline territory. For my next batch, I will plan to get potassium bicarbonate and do a preliminary dose (again, 1g per gallon?) just to tackle the problem in the beginning so as not to stress the yeast. Good thing it's Orange Blossom season and my honey guy is overflowing with the sweet goodness!

Thanks again, and I will keep you posted on the progress