Want to avoid brine/ umami off-flavors, especially in short meads? This article proposes taking the YAN contribution from Go-ferm into account and avoid excessive minerals by tailoring the nutrients to your water profile.
A common complaint for short meads is that they can have a briny/ umami flavor. I have lost many 1 gallon short mead batches to these off-flavors when using YAN nutrient calculators such as the Meadmakr nutrient calculators. This is also a common compliant for many who have tried to replicate public recipes of the short meads published by Groennfell or Havoc Meadery and didn’t have Wyeast Yeast Nutrient. But what makes these off-flavors more likely in short meads and in small batches?
From my experience, the umami flavor (think wet dog food/ aged cheese) is because the YAN contribution of Go-ferm rehydration nutrient is completely ignored in nutrient calculators. The Scott Labs 2016 Handbook suggests that when using a dose of 25 g/hL Go-ferm adds 7.5 mgN/L. This is three-quarters of the YAN contribution compared to Fermaid-O. However, no current calculator takes this into account! Also, the combination of Fermaid-K and Go-ferm can add quite a bit of minerals to your water profile, which combined with a hard water profile can potentially result in mineral flavors.
The extent of the biases induced by Go-ferm in nutrient calculators is a larger problem in short meads and smaller batch sizes, but still exists in larger volumes and higher gravity. This article discusses biases in nutrient calculators. It also provides a recommendation for a revised best practice for nutrient regimes when using Go-ferm. I call it Tailored Additions of Nutrients with Go-ferm (TANG).
YAN Overload Example: a 5 gallon 7% ABV sparkling dry traditional mead using the default Fermaid-O / Fermaid-K / DAP nutrient protocol for a yeast with a low nutrient need from the The MeadMakr BatchBuildr. The MeadMakr Advanced Nutrient Calculator recommends 99 YAN, 10 grams of dry yeast, and the following nutrients:
In this example, you can see the total YAN addition inclusive of Go-ferm is 178.4 YAN, 80 percent more than the recommended 99 YAN. Why would this matter? Well, if you took the nutrient calculator and try to have Fermaid-O provide the extra 99 YAN, any addition of Fermaid-O above 8.5g would give you a warning that it “risks adding yeasty flavors.” Go-ferm is mostly deactivated yeast cells so such a large addition of Go-ferm with this protocol would most likely add yeasty flavors.
This example could be further compounded if one tried to follow Groennfell’s recipes and pitched with 5 grams of yeast per gallon. In such a case you would rehydrate 25 grams of yeast using 31.5 grams of Go-ferm (using 1.25 g of Go-ferm per gram of dry yeast), which would contribute 198.5 YAN from the Go-ferm alone, 200 percent the recommended YAN. It is also a bigger problem in smaller batches, due to rounding up to a full packet of yeast, see examples below.
The Pitch Rate and ABV Biases:
The below figure graphs the recommended and actual YAN contributions which include the YAN contribution from Go-ferm. The recommended YAN and Go-ferm amounts are from the The MeadMakr BatchBuildr. The meads are a 6.5% ABV dry traditional mead, and a 14% ABV traditional semi-sweet mead finishing at 1.01, both with a low YAN requirement yeast. The nutrient regime is the Fermaid-O / Fermaid-K / DAP which is based on Travis Blount-Elliott’s white paper, but the values do not depend on the nutrient regimes using the protocols from The MeadMakr BatchBuilder.
You can see here that the problem of high YAN is larger in smaller batches, especially for one gallon batches. At one gallon batch sizes, for the lower ABV mead, the total YAN taking into account the contribution of Go-ferm is over three times the recommended amount, and has 100 more YAN than a two gallon batch. At one gallon batch size, total YAN is twice as high for the higher ABV mead and again has 100 more YAN than a two gallon batch. This reflects two things:
- Pitch Rate Bias: introduced by not pitching a constant amount of yeast/Go-ferm per gallon
- ABV Bias: introduced by using the same amount of yeast/Go-ferm per ABV level
The Pitch Rate Bias is driven by not pitching a consistent amount of yeast per gallon and is what drives the downward and fluctuating total YAN by volume. The ABV Bias is driven by pitching a consistent amount of yeast for each ABV level and is what drives a constant gap between the recommended and total YAN even at high volumes of must. The total YAN is 90% higher than recommended at 12 gallons for the 6.5% ABV must, but only 40% higher than recommended at 12 gallons for the 14% ABV must. Hence, the Pitch Rate Bias is more of a problem for small batch sizes, but the ABV Bias is more of a problem for smaller ABV meads compared to higher ABV meads.
The Pitch Rate Bias does not exist for the TOSNA 2.0 regime in the MeadMakr TOSNA 2.0 Calculator, but does still exist if you use the TOSNA 2.0 regime in The MeadMakr BatchBuildr due to rounding up to full packets of yeast. Lets look at the TOSNA 2.0 regime using the MeadMakr TOSNA 2.0 Calculator to see if the two biases still exist.
Note that in the figure, the recommended YAN number comes from the MeadMakr BatchBuildr (since this article has been published the calculator changed the wording of “YAN recommended” has been changed to “YAN provided”). You can clearly see that the pitch rate bias is lost – the amounts of YAN are constant for each volume of must. However, since the pitch rate is the same for both the 6.5% and 14% ABV meads, the contribution of Go-ferm adds a constant amount of YAN to the total YAN for both meads. This can be seen by comparing the total and recommended YAN in TOSNA 2.0 by ABV level.
The contribution of the YAN from the Go-ferm is a constant amount of YAN added to the YAN contributed from Fermaid-O. How different the total and recommended is by ABV can be seen from the below figure.
For a 4% ABV short mead, the total YAN is 90% higher than recommended whereas for a 11.5% ABV standard mead, the total YAN is only 30% higher than recommended.
Lets stop and reflect for a second on the severity of the biases.
- The pitch rate bias is the largest for one gallon batches, and is clearly inconsistent with recommendations. Not rounding to full 5 gram packets and pitching the same amount of yeast per gallon (like TOSNA 2.0) can easily fix this.
- The ABV bias from not taking into account the contribution of Go-ferm by ABV is really an argument about how much YAN to add (the appropriate Recommended/Provided YAN level), and is more debatable. A slight overload on nutrients is not likely to be a big problem in larger meads (also smaller pitch rates, more oxygen additions, higher temperatures, or anything else that increases nutrient uptake), but for dry short meads, the nutrients may be detectable. Moreover, nutrients are expensive and an overload can encourage spoilage. Also, you want your yeast to clean up fermentation by-products (such as acetaldehyde) and too many nutrients may make your yeast lazy, and less prone to cleaning up.
Before we go into detail how to correct for the biases, lets review water profiles and minerals.
Water mineral profile: While water mineral profiles is an important topic in making beer, it is mostly overlooked in mead making. This must change. It is important to consider that your nutrients are building a water mineral profile and that the combined minerals from your water and nutrients should be taken into account.
Go-ferm and Fermaid-K have minerals in the nutrient, whereas DAP and Fermaid-O do not (although, they naturally exist in the yeast hulls in Fermaid-O). Thus, in excessive amounts Go-ferm and Fermaid-K risk adding mineral or brine character depending on the mineral profile of the water. I have used all nutrient protocols with either spring water, 50/50 spring water and distilled water, and filtered city water to make meads. I found that the spring water gave me a brine flavor (especially in short meads) and the filtered tap water did not. The table below shows the mineral profile for an example of a typical natural spring water from Kingston, Ontario, Canada:
In contrast, the Bicarbonate and Calcium levels of the Kingston, Ontario tap water are more than half of that of the spring water:
I also noticed that the spring water gave much better flocculation of the yeast compared to the filtered city water, something that I attribute to the higher calcium levels. The same nutrient additions to the above two water profiles will give very different mineral contents in the final product.
Just for fun, lets compare this to the Ozarka® Brand Natural Spring Water that Bray Denard prefers to use in his BOMM recipes.
Here I report the highest values in the 2016 water analysis. You can see that the water profile recommended for the BOMM is very light on minerals. In fact, the total dissolved minerals in the Ozarka® Brand Natural Spring Water is 20-120 ppm. This puts the water in the slight to moderate hardness range. In contrast, the water profile of the Kingston Ontario City water is 120-140 putting it in the moderate to hard water range and the natural spring water that is sold in Ontario is 300 ppm, which is really hard.
The softness of the Ozarka® Brand Natural Spring Water may be why Bray adds potassium bi-carbinate to his meads – as there is less minerals to buffer against the PH drop compared to a higher bi-carbonate water. An interesting question: do you need to add potassium bi-carbinate (or potassium carbonate ), depending on the original carbonate levels of your water? Probably not if you have harder water.
It is also notable that Sergio Moutela owner of Melovino Meadery and creator of TOSNA 2.0, uses reverse osmosis water in his mead making. While there has been little attention attached to water profiles/ building water profiles from nutrients, this is likely to be a topic explored in the future.
Tailored Additions of Nutrients with Go-ferm (TANG) :
- Use The MeadMakr BatchBuildr to calculate total YAN provided (recommended).
- Pitch a constant amount of yeast (for example 4 grams/gallon) per volume of must.
- Include the YAN contribution of Go-ferm into the total YAN provided.
- If using a hard water profile, substitute up to half of the remaining YAN with DAP or use Fermaid-O (which does not add extra minerals).
To calculate the YAN contribution from Go-ferm, pretend it is Fermaid-O with an effectiveness of 3 using The MeadMakr Advanced Nutrient Calculator. If the equivalent amount of Go-ferm in Fermaid-O gives a warning of adding yeasty flavors in the calculator reduce the amount of Go-ferm. If you want to do the calculations for other types of nutrients see the YAN contribution of common nutrients.
“Fermaid O does not contain any DAP or supplemented micronutrients. For optimal results, Fermaid O should be used in conjunction with an appropriate yeast rehydration nutrient (GoFerm or Go-ferm Protect Evolution) to assure proper micronutrient nutrition of selected yeast from rehydration through completed fermentation.”
Another option, as mentioned by Jeff at The Mead House Podcast when TANG was discussed on Episode 67, is to not use Go-ferm at all for low gravity meads. Osmotic stress to yeast only really kicks in at 1.104 OG or higher, so Go-ferm may not be totally necessary at lower gravity. This may work as the rehydrated yeast should already have a store of minerals and amino acids, needed for the quick fermentation of a short mead. However, I still recommend the use of Go-ferm even at low gravity. First, because Scott Labs recommends it and it is prudent. Second, I prefer to make an activated starter to ensure a quick start to fermentation and reduce the contact of nutrients with spoilage organism. This is particularly true for yeasts that have a low competitiveness factor.
What should the pitch rate be for a mead? Groennfell meadery pitches at 5 g per gallon. Ken Schramm of Schramm’s Mead pitches at 3-4 g per gallon. Michael Fairbrother of Moonlight meadery pitches at 1 g per gallon. I usually pitch between 3-4 g per gallon. But beware: there is very little evidence of how pitch rate interacts with recommended YAN to affect the presence of off-flavors. Over pitching may increase the risk of off-flavors since the dry yeast are already relatively well fed with nutrients. At the very least, choosing a pitch rate and sticking with will make you a more consistent mead maker.
Staggered Nutrients, Oxygen, Temperature and TANG:
Finally, I generally recommend following a staggered nutrient regime. I suggest not using a hard and fast rule for timing and amounts, but rules of thumb:
- For short meads, with high pitch rates, the fermentation is done very quickly (2-5) days. In this case, add all or most (~60-75%) nutrients upfront at pitch and the remainder at 12, and 24 hours.
- For standard/ sack meads follow the gravity readings closely. Rehydrate using Go-ferm, then stagger the other nutrients for the first few days and get the last one in before 1/3 sugar break, but especially before the 1/2 sugar break and well below 8% ABV.
The reason you need to be flexible is given by the following example. I have pitched the same yeast on two 1.120 OG musts, where one had grape juice and the other had whole currents. The grape juice fermented out twice as fast as the other and passed the 1/3 sugar break by the day 2, showing signs of yeast stress (smells of rotten egg – which I fixed right away by adding Fermaid-O and degassing). You would want to pre-emptively avoid this yeast stress by adding nutrients sooner to the pyment in this case compared to the current mead.
Oxygen: The more additions of oxygen will delay/restart the lag phase and increase the yeast count, and result in more nutrient absorption. Make sure to stagger nutrients to insure that there is plenty of YAN/ micronutrients for the lag phases induced by the oxygen additions. From Scott Labs 2017 Handbook page 36: “When adding more oxygen to the must/juice, nitrogen is captured faster and more is needed when compared to fermentations taking place under anaerobic conditions.”
Temperature: The warmer the temperature, the faster the lag phase and fermentation so you may want to get your nutrients in sooner to ensure that there is plenty of YAN/ micronutrients. From Scott Labs 2017 Handbook page 36: “An increase in temperature stimulates the growth of yeast and fermentation rate, thereby requiring increased levels of nitrogen.”
TANG example 1: Nutrients for a 5 gallon batch of my 8 % ABV lemon basil mead with scored 40/50 and 45/50 in the Winnipeg 2017 Pro/ Am Brew Challenge. Recommended profile by The MeadMakr BatchBuildr is 112.5 YAN based on the following:
- 10 g yeast
- Go-ferm: 12.5g (80 YAN)
- Fermaid-O: 8.5g (72 YAN)
- Fermaid-K: 7.7g (40.5 YAN)
- Total actual YAN: 192.5
TANG (here I use DAP because of the use of hard spring water)
- 10 g yeast
- Go-ferm: 8.5 g (Contributed 58 YAN)
- Fermaid-K: 3 g (Contributed 16 YAN)
- DAP: 3.8 g (Contributed 41 YAN)
- Total actual YAN: 112.5
In this case you can see how the rehydration in Go-ferm would have resulted in excessive YAN additions using the The MeadMakr BatchBuildr. Taking this into account and tailoring nutrients to the water profile by using DAP to not add more minerals earned me silver and a 45/50 score for a bottle conditioned bone-dry short mead.
- Go-ferm: 6.25g (200 YAN)
- Fermaid-O: 1.7g (72 YAN)
- Fermaid-K: 0.76g (20.2 YAN)
- Total actual YAN: 292.2
In this case you can see how the problem of YAN provided by Go-ferm is exaggerated in lower batch sizes. Taking this into account and tailoring my nutrients reduces the risk of off-flavors.
TANG example 3: nutrients for a 5 gallon batch of 6.9 % ABV mead from Groennfell Meadery. I have made several of the recipes following the guidelines put forth in “How we brew everything we brew.” This includes fermenting at high temps, pitching 25 grams of D-47, and putting all nutrients in at pitch. All the meads turned out great using TANG. I always use a softer water profile from either filtered tap water or 50/50 hard spring and distilled water with only Go-ferm and Fermaid-K. I often lower the Fermaid-K down to six grams due to the high pitch rate, and my aversion to mineral flavors, and havent noticed any adverse effects. Recommended profile by The MeadMakr BatchBuildr is 99 YAN based on the following:
- Go-ferm: 31.25g (198 YAN) – assuming you use Scott Labs Guidelines of 1.25g/g yeast
- Fermaid-O: 8.5g (72 YAN)
- Fermaid-K: 5.1g (27 YAN)
- Total actual YAN: 297
TANG (here I have softer water so use Fermaid-K)
In this case you can see how high pitch rates and the use of Go-ferm can triple the actual YAN additions. Taking this into account and tailoring nutrients reduces the risk of off-flavors.
TANG example 4 (TOSANA 2.0): nutrients for a 3 gallon batch of 12 % ABV traditional semi-sweet mead. Note, in this case if you select the TOSANA regime in the MeadMakr BatchBuildr you get a different recommendation than the MeadMakr TOSNA 2.0 Calculator. Lets review both.
The MeadMakr BatchBuildr for low nutrient yeast, TOSANA 2.0, is 186 YAN with 10 grams of yeast and the following nutrients:
MeadMakr TOSNA 2.0 Calculator is 6 grams of yeast and the following nutrients:
TANG (TOSANA 2.0 ish)
In this case you can see that the overall YAN is highest for The MeadMakr BatchBuildr but still too high for the MeadMakr TOSNA 2.0 Calculator. Taking the YAN contribution from Go-ferm into account using TANG results in lower overall nutrient additions.
It seems that the calculators use the 1.25 grams of Go-ferm per gram of yeast pitched as a hard and fast rule. You either use Go-ferm or you don’t. However, why would calculators ignore the YAN and mineral contribution from Go-ferm? If you want to avoid brine/mineral off flavors and help the yeast clean up any extra off-flavors (like acetaldehyde) you may want to give TANG a try. Keep the following tips in mind:
- Pitch constant amount of yeast per gallon to avoid the pitch rate bias.
- Take the YAN contribution of Go-ferm into account (especially in short meads).
- Use softer water or watch the combined mineral content of the water and nutrients.
If you think the extra YAN is necessary from the Go-ferm increase the overall nitrogen requirement to avoid any YAN biases. There is undoubtedly a range of YAN that is a safe zone around the recommended YAN, conditional on your process, that ensures yeast health and reduces the risk of off-flavors. Keep in mind that even though you may not be noticing mineral and yeast off flavors, other off-flavors may not be as readily cleaned up.
This article shows some biases in calculators, but undoubtedly more research is needed. More research is needed to answer the following questions.
- What are the nutrient taste thresholds for the different regimes by ABV levels?
- What are the taste thresholds of water mineral profiles for different ABV levels?
- How the pitch rate and oxygen additions effect the recommended YAN?
This deserves full-blown experiments. Experimeads are currently in progress so stay tuned. I have used different variations of nutrient types in the TANG formula and found it to be quite flexible. I currently use a combination of Go-ferm, Fermaid-K, and Fermaid-O using the TANG guidelines in my meads. I havent lost a batch to off-flavors since using TANG.