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pH and fermentation time


Les Trois Clocher

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We are having long fermentation times. Our pH starts around 4.5-4.8 and quickly drops to 3.5. We use a Dark brown sugar wash with yeast nutrients. We are thinking the low pH is causing our yeast to struggle . We are thinking of adding sodium bicarbonate or magnesium oxide, or some sort of food grade base. What do you guys think. Any experience with this? I can give cell counts if that helps.

Thank you for your time

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Sugar crashes a PH like no other. We regularly get Ph of 2.9 for our sugar washes (our starting PH is 5). You can use potassium carbonate and/or calcium carbonate to raise the PH, but it will crash right back down in a day or two. Sugar washes just like to be at a low PH, so make sure your yeast can go that low and still do it's thing. There are yeasts designed for sugar/rum washes and they do a pretty good job. You might also ration DAP across the run of your ferment.

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Rum needs a low ph to start. Say around 4. If not, acid producing bacteria take old and produce acid that stress yeast. And run needs a ton of nutrients. You can also use and ant microbial like isostab from betatec. This will keep bacteria at bay. But this is for light rum. Not heavy high ester rum, you want bacteria then.

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This is from Lallemand for a light rum using hightest molasses *

Recommend:

Yeast Distilamax SR

Nutrients: Distilavite GN (You may need a little DAP)

Target final alcohol Start at 10%

Fermentation Temperature 33°C

pH should not be a problem should start between 5.0 to 5.5 and decrease over fermentation to about 4.8. Buffering is a little lower in the High test so watch it and worry if it goes below 4.0

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Low pH and slow fermentation are common, but you should see that if you're patient it will eventually finish below 1.0 specific gravity. Suggested remedies would be reducing your sugar amount and target ABV, or just being patient and investing in more fermenters.

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Here is the deal. Low ph at start and fast fermentation are normal. A high ph of 5 or better and a big drop in ph in the first few hours will without a doubt cause a slow ferment. And this is not normal at all. Rum, a light one should ferment dry from 20 Brix in 48 hours. Starting at a high ph, with molasses, with less than say a pound of dap per 300 gallons at start will allow gram positive, acid producing bacteria to outrun your yeast. If you want a light rum do what I just said. If you want a heavy rum, high ester, that is a whole other process. Another way to keep a rum ferment going and keeping the acid producing bacteria at bay, is to use isostab from betatec, I can provide it. But you drop the ph yourself to start with, to make the yeast happy. I do not mean to speak ill of lallemand, but that way of using their yeast and nutrient will not work. If anybody doubts me that is making rum, get a hold of me, I will tell you what you need to do, and you can see for yourself that it works. Every plant is unique so a general post hear about how to do it other than what I have said, may not work for your plant. Rum is one of the hardest things for micros to get their head around, but once they do, it is money in the bank.

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I like the sound of Money in the bank! Distillery Resources, would you be willing to take a look at our SOP for our rum and give advice? we have done a bunch of small batches and have just up-sized. we are definitely not finishing that quickly.

thanks

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  • 6 years later...

Hi, i got the same problem, when i mash sugar with fermaid k plus DAP (2 grams per us gallon thats a lot more then 1 lb per 300 gallon) or i make the PoSW (a lot of yeast for nutrients plus DAP) recipe,  starting SG. about 5-5.6  the sg drops like a hot potato in 24 hours to about 3.5+ and it stops fermenting at about 2 -3 days remaining sg. is 1.035-40, when i add calcium sulfate it revives a bit but its basically its already stressed out so i'm making sugar washes only the twp recipe what works all the time (fizzes like a shaken bottle of seltzer ) just not so clean so i treat with carbon  .  I wish somebody can advise the proper practice. 

Thanks in advanced.

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I was making sugar washes for sanitizer many moons ago, and found a ph buffer was necessary. You can buy them, or make it by mixing equal quantity calcium carbonate and citric acid. I'd pitch 4 oz of buffer per 100 gallons then adjust the ph again the next day with just calcium carbonate, and it would hold pretty steady the rest of the ferment. If any brewers near you make a hard seltzer regularly you could also ask them what they do.

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On 10/29/2020 at 10:00 AM, Bronfen said:

Hi, i got the same problem, when i mash sugar with fermaid k plus DAP (2 grams per us gallon thats a lot more then 1 lb per 300 gallon) or i make the PoSW (a lot of yeast for nutrients plus DAP) recipe,  starting SG. about 5-5.6  the sg drops like a hot potato in 24 hours to about 3.5+ and it stops fermenting at about 2 -3 days remaining sg. is 1.035-40, when i add calcium sulfate it revives a bit but its basically its already stressed out so i'm making sugar washes only the twp recipe what works all the time (fizzes like a shaken bottle of seltzer ) just not so clean so i treat with carbon  .  I wish somebody can advise the proper practice. 

Thanks in advanced.

I’ve been doing raw sugar washes for 7 years now. Different fermenters and nutrients and even sugars types. My best suggestions are this. 
 

-keep your start gravity around 1.070-1.075 until you have everything working reliably. 
 

-oxygenate your wash prior to yeast pitching   This is more important than you think in sugar washes  

- control your temps carefully within the listed operating ranges. Going above the max temp will effect either the flavor or the yeasts production or both.  Temperature is key to flavor. 
 

- start your wash between 5.5-6ph.  The more yeast you pitch the more tolerant it can be to starting ph. It will ALWAYS crash during the yeast growth phase  or the first 12-30 hours.    I’ve seen it crash in as little as 4 hours. 
 

- after the initial crash you will need to adjust back up. A second adjustment a day or two later may also be needed.  I’ve used sodium bicarbonate, sodium hydroxide, citric acid, EDTA, calcium carbonate,  of the “basic” adjustments calcium carbonate seemed the cleanest but sodium hydroxide caused the least amount of gas release and required less quantity to adjust  

-adjust working ph to around 4.25 on first adjustment. Then let it work between 3.85 and 4.2. The lower the gravity is the more you can leave it to drop.   A second adjustment would not want to go to 4.25 but would only be high enough to allow it to coast to a finish at 3.85ish. Typically keeping it around 4.0 is good enough. A good steady sugar wash will finish in 4-5 days  with one adjustment and finish at about 3.8-3.9 ph. 

 

- temperature fluctuations are a precursor to what the wash will do in a few hours  watch it like a hawk and measure it accurately and consistently with the same thermometer  if your temperature is dropping and your ph is low that means you are stopping fermentation  ITS WAY EASIER TO CORRECT A WASH BEFORE IT STOPS THAN AFTER  

 

-make sure to you are using mineralized chlorine/chloride FREE and sterile water for your ferment.  Rainwater and RO will cause issues with finishing or yeast health problems without remineralization. 


 

- nutrients are important to flavor as well as yeast health. DAP is required and suggested quantities are easily found. Adjust it based on other additions to balance total YAN.  If my nutrient load is balance between dap, commercial nutrients and a biological then I usually only need to add them at the beginning  I you use less Biologicals then you may wish to stage your nutrients   Do not add nutrients after the 48 hours or with less than 60% of fermentables remaining  I have not found much benefit to this on malnourished or stalled ferments  if they stall it seems like it’s best to distill it quickly or just dump it  

 

    I’ve not found any commercial yeast nutrients that would really work well in a sugar wash BY THEMSELVES (apart from turbos).  They can be “part” of the solution but I have found that a botanical/plant based source of nutrients can really provide those micro nutrients and flavor profile that send a sugar wash over the top in quality. 
 

 

 

sugar washes can be an incredibly specific thing to your local conditions and equipment.   THE MOST COMMON CAUSE OF FAILURES IVE SEEN are not following the basic requirements.  It’s rarely just one thing wrong. It’s usually 3-5 thing “just a hair off”. 

 

hope that can help you diagnose!  :)
 


p.s.  you will note I have not mentioned sugar. If you follow the above guidelines I haven’t found that the source or type of the sucrose makes much difference in the fermentation process (for flavor it totally can).   If you find that it does for you, that might be an indicator that you need to pick up the slack in other areas. 

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FijiSpirits, Interesting, i resemble very much according your post and wondering, the starting SG. 1.070, ph is about 5.0-5.5. After the drop i adjust the ph with Calcium Sulfate (lime) usually after 3-4 days it stalls to ferment. the only recipe i succeeded was the TPW. Wineos plain ol sugar wash, i never succeeded for the above reason, as well any other, excluding the TPW.

what i'm thinking now is that when i adjusted the ph upward i tried to bring it back to 5.0-5.5, is it possible that this is the problem?

What recipe are you using? 

How do you oxygenate?

you mentioned nutrients, i used Fermaid K plus DAD 4 grams per Gallon in 1 shot, a pinch of epsom salt.

Thanks in advanced 

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8 hours ago, Bronfen said:

FijiSpirits, Interesting, i resemble very much according your post and wondering, the starting SG. 1.070, ph is about 5.0-5.5. After the drop i adjust the ph with Calcium Sulfate (lime) usually after 3-4 days it stalls to ferment. the only recipe i succeeded was the TPW. Wineos plain ol sugar wash, i never succeeded for the above reason, as well any other, excluding the TPW.

what i'm thinking now is that when i adjusted the ph upward i tried to bring it back to 5.0-5.5, is it possible that this is the problem?

What recipe are you using? 

How do you oxygenate?

you mentioned nutrients, i used Fermaid K plus DAD 4 grams per Gallon in 1 shot, a pinch of epsom salt.

Thanks in advanced 

If you are mixing sugar and nutrients and have to adjust UPWARD before pitching yeast, then something is weird.  Plain water will usually be around 7.5 and adding plain raw sugar shouldn’t change it much. Dap and fermaid won’t effect it much either. 
 

maybe you need a second or third way to measure PH. your instrument may be off.

 

what gravity is it stalling at?  What is the ph at stall?  How many liters are your ferments?

 

i don’t use a typical recipe. The guidelines I mention above will shape your recipe for your circumstances.  You will have the best results when you work within those guidelines (Read them carefully, they are quite specific) and have a very good understanding of yeast health ( start reading).  As to your biological element if you choose, things like Kale, spinach, legumes, a bit of molasses, fruits, tomato paste can all provide elements of a healthy sugar wash.  Each will also throw its own flavor elements.  
 

oxygenation:  this is just a fancy way to say “make a lot of bubbles in your wash when you mix the sugar in”. Splash mixing with a pump is fine usually. 

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On 10/30/2020 at 5:36 AM, FijiSpirits said:

If you are mixing sugar and nutrients and have to adjust UPWARD before pitching yeast, then something is weird.  Plain water will usually be around 7.5 and adding plain raw sugar shouldn’t change it much. Dap and fermaid won’t effect it much either. 

no, downward, as my water is 7.0. i'm adjusting upward after the drop.

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Sorry i apologize, for all what i wrote calcium sulfate its rather calcium hydroxide (lime). NOT SULFATE. my mistake. calcium sulfate is Gypsum which downs the ph a bit.

i tried to edit all above comments so not to confuse any reader who will see it later on, again my apology

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11 hours ago, Bronfen said:

will give it a shot now on a new batch.

Thanks to all

I forgot to mention that having a clean fermenter is also key. Clean everything that touches the wash. EVERYTHING. Rinse off any cleaning chemicals with sterile water. 
 

airlocked fermenters are easier to use than open or semi open types. Open or semi open seem a lot less tolerant to delays in distillation after finishing, thus timing of the ferment with distillation is important. 
 

im even hesitant to let a ferment sit in a vapor locked fermenter very long. Those flavors seem to change the longer it sits. 

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  • 1 year later...

 

 

 

On 10/30/2020 at 5:36 AM, FijiSpirits said:

things like..... a bit of molasses, fruits, tomato paste can all provide elements of a healthy sugar wash

Hi FijiSpirits, thanks for your posts, all of them.

question, How much molasses would you suggest? and type,  Blackstrap or Fancy Grade (golden or whatever its called)

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