Larger Batches Longer Fermentation?

[Hilltop Honey Farms Mead]

Hello Ladies and Gents!

First post here as I'm new to the site! I currently have:
-5 gallons of Blackberry melomel aging
-3 gallons of traditional mead in primary fermentation with D47
-1 gallon of blueberry in primary fermentation with 71B-1122
-1 gallon of peanut butter and jelly aging
-1 gallon of mixed berry (raspberry, blackberry, blueberry) aging
-1 gallon of cherry aging
-1 gallon of white grape cherry aging

Something I've noticed over the past year or so is that my larger batches typically take longer to reach the SG's I'm looking for when compared to smaller batches. Is that a "normal" thing? I understand if using the same amount of yeast in a smaller batch, more yeast will metabolize the sugar faster. However, I'm using the same amount of yeast proportionally to my batches and my 1 gallon batches reach the SG I'm looking for in around 2 weeks, and my 5 gallon batches usually take around 4 weeks. Am I missing something? Thanks and looking forward to learning more from all of you!

 

[Maylar]

You'd also have to consider the yeasts themselves, and the sugars in the different mixes. Fruits will generally be faster because they contain some of the nitrogen and minerals that yeast need. To really compare you'd have to use the exact same must and exact same yeast at the exact same temperature with the exact same ratio of nutrients (if you use them).

 

[bernardsmith]

Hi Hill Top Honey Farms - and welcome.
I suspect that you may be underpitching the yeast. Wineries and meaderies may ferment 500 gallons or 5000 gallons of wine or mead and my sense is that the fermentation time is the same as it takes to ferment a single gallon, but then they use enough viable yeast to ferment the quantity of sugar they have in their fermenters. Viable = living active cells and enough = enough to ferment the quantity in their batch without stressing the yeast. In my opinion it should take the same amount of time to ferment 5 gallons with a starting gravity of 1.100 (say) as it takes to ferment 1 gallon but it takes a great deal more yeast to do that and a pack of yeast is may not in fact be packaged to ferment as large a batch with as high a gravity as you may assume simply because the pack says that it is good for 1-6 gallons without any indication of the SG of the batch to which it refers.

 

[ShareBrewing]

Welcome HHFM!

Are you adding any nutrients for the yeast? Bernardsmith is right, batch size doesn’t matter. Given the exact same conditions, two different batches would ferment the same way.

 

[Hilltop Honey Farms Mead]

Thanks for the replies!

I use around 1/2 packet of dry yeast for 1 gallon batches, and usually use one packet of dry yeast for 5 gallon batches. Maybe I should use a packet and a half or two packets?

Also, I am adding nutrients for the yeast. I'm adding a yeast energizer when they are pitched and then I typically will add 1/2 of the diammonium phosphate on day 1 and the other half on day 7. I have had pretty good success with this overall. I also have been reading about people performing stepped nutrient additions every other day for the first 6 days or so and adding 25% of the yeast nutrient each day. Is that typically a better outcome comparatively? Not anything I have messed with! You know the old adage, "If it ain't broke don't fix it."

 

[bernardsmith]

Using a calendar to determine when to feed the yeast seems to me to be a little risky. Yeast cannot take up nutrients when there is about 9% alcohol in solution so feeding the yeast by the clock would seem to me to be a recipe for providing all kinds of bacteria and other organisms with a great source of food should the yeast be beyond capable of consuming the nutrients. I myself make small batches and am far too lazy to feed the yeast by any regimen. I pitch the yeast and then I feed 'em all the nutrients they are gonna get from me, but if this regimen is something that interests you I believe the approach that is advocated is to feed the yeast in light of the amount of sugar they have fermented - so after the lag phase has ended and they are starting to ferment; after they have consumed 1/3 of the sugar ; and after they have consumed 2/3 of the total sugar.

 

[Hilltop Honey Farms Mead]

Makes sense to me. I didn't know yeast stopped uptake of nutrients around 9% alcohol. Good to know, thank you!

 

[Maylar]

Yeast cannot use inorganic nitrogen, such as DAP, after about 9% alcohol. They can however use organic nutrient such as Fermaid-O, which is the preferred nutrient in the mead world nowadays.