By Jeff Shouse
A series of popular alternatives for yeast nutrient additions were trialed in a tightly controlled manner in order to determine the most effective of five trials. Amongst these trials, results were evaluated in terms of both qualitative measures of attenuation and pH, as well as the subjective measure of quality at 3 months from yeast pitch as well as 6 months from mead pitch. In terms of qualitative measure, TOSNA achieved the most complete attenuation while effects on pH were negligible. Qualitatively the experimenter and his spouse felt at 3 months that Travis Blount-Elliot’s nutrient schedule was the most enjoyable at this point in time. However, at the 6 month mark, TOSNA was found to be subjectively more enjoyable.
Mead is thought to be one of the oldest alcoholic beverages consumed by humankind. Unlike other common beverages such as beer or wine, mead has largely fallen out of favor between its historical heyday and modern times. For a long period of its history, mead was thought to be slow and problematic to ferment. It was subsequently discovered that the major reason for this was the fact that honey, unlike malted grains or fruit, lacked a number of nutrients yeast required to successfully reproduce and metabolize sugars, chief among them a source of available nitrogen.
Modern mead makers have at their disposal a number of different formulations of yeast nutrient, most popular among them a series of products branded Fermaid, most popular among them Fermaid K, though another recent product, Fermaid O (using organic rather than chemically derived nitrogen sources) is quickly gaining in popularity as well. Further, another product, diammonium phosphate (DAP), is commonly combined with Fermaid K in many nutrient regiments.
Many home mead makers have a favorite ‘pet’ regiment that they will use consistently and believe to provide the best results for their own brewing needs. To this researcher’s knowledge, no attempt at directly comparing multiple regiments using controlled conditions has been undertaken in order to directly compare the fermentation process and subjective qualities which are derived from each with regards to flavor, mouthfeel and other qualities. The intent of this experiment was principally to identify which Staggered Nutrient Addition Protocol yielded the best results for this researcher’s personal brewing efforts. However, due to the paucity of research directly comparing nutrient additions, it is also likely that these results would be of interest to other home mead makers.
Recently, a nutrient regiment referred to as TOSNA or Tailored Organic Staggered Nutrient Addition created by Sergio Moutela has gained a popular following on various message boards and forums, in part because of its approach to a specific regiment tailored to the batch of mead and providing a specific nutrient requirement to that end. In addition to the amounts of Fermaid O, TOSNA also proscribes a method for rehydrating yeast, as well as regular degassing during the first week. These protocols were adapted across all trials for the purposes of this experiment. Other protocols selected for this experiment included a more established combination of Fermaid K and DAP, a combination of nutrients proposed by Travis Blount-Elliot which starts with Fermaid O for the first two feedings, and finishes with Fermaid K and DAP, and the reverse of this protocol, starting with Fermaid K and DAP and finishing with Fermaid O under the logic that the nitrogen in Fermaid O is bioavailable for a longer period of fermentation than its counterparts.
A single 5 gallon batch of mead made from commercially available blended clover honey was created and mixed to a starting gravity of 1.120. Using the proscribed rehydration method from TOSNA, 10g of D47 was rehydrated with 12.5g GoFerm in 250ml of water, pitched into the must and mixed well to combine. Subsequently the batch was divided into 5 one-gallon fermenters. This was intended to control as much as possible differences between the amount of honey, density, water quality, or disparity between batches of yeasts that could otherwise affect the outcome of the experiment.
From this separation, 5 trials were derived:
- Using Fermaid K and DAP for all 4 feedings
- TOSNA, using Fermaid O
- Travis Blount-Elliot’s method using Fermaid O for the first two feedings and finishing on Fermaid K and DAP
- The reversal of 3, starting with Fermaid K and DAP and finishing with Fermaid O
- Control – a volume based measure of Fermaid K and DAP added at pitch with no step feedings.
With the exception of trial 5, all batches received feedings 24, 48 and 72 hours after the start of fermentation, with a final feeding once SG reached 1.080. Fermentation occurred in a dark cabinet held at a stable 67 degrees Fahrenheit. All five trials were degassed twice daily using a sanitized glass rod, stirring gently until gas ceased to be released from solution, for the first 8 days of the experiment. After 21 days, all 5 trials were racked to a secondary vessel for aging and aged in their fermentation vessels for another two months before objective tasting sessions were held. No fining agents or stabilizing chemicals were applied to any of the trials. SG was recorded several times during the course of primary fermentation in order to ensure none of the trials encountered stalling, a final SG was recorded just prior to tasting. pH measurements were also recorded but differences between trials were ultimately negligible.
One dozen volunteers from amongst the researcher’s social circle were recruited for subjective taste testing. Each was given 2oz of each of the mead trials, though many declined to finish the entire sample. The volunteers were provided a BJCP sanctioned mead checklist in an attempt to help facilitate and prompt faults and characteristics present in each mead, and the participants were specifically asked to take characteristics rather than sweetness or dryness into account. In addition to specific feedback in the form of each sheet, an informal vote as to the preferences of the group was also taken and yielded fairly consistent results.
Results will be discussed in 3 separate regards: 1) Objective data relative to the completeness of fermentation. 2) Subjective opinions of study participants as well opinion of this researcher and his spouse 3 months after yeast pitch. 3) Subsequent subjective evaluation of the meads approximately 6 months after yeast pitch.
Objective Data Regarding Completeness of Fermentation
|Trial||Final Gravity||pH||Final Alcohol by Volume|
|Fermaid K + DAP||1.002||3.55||15.49|
|Reverse of TBE||1.006||3.52||14.96|
Subjective Results of Tasting After 3 Months
The majority of those surveyed for the purposes of this experiment had little contact with mead outside of commonly available sweet commercial offerings and this researcher’s previous efforts. Two participants have attempted to brew beer, cider or mead previously, and one participant demonstrated considerable knowledge in the field of wine tasting. Most subjects were naïve to the process of fermentation, especially to specific rigors of fermenting mead and none successfully deduced beforehand that the nutrient content was the only point of differentiation between these trials.
Despite requests to the contrary however, subjects displayed a strong preference for sweeter meads in general and tended to find favor or fault with meads that lined up with those qualities. The meads that finished with a higher specific gravity and therefor greater residual sweetness were most consistently rated the best – trial 4 which started with Fermaid K and DAP for the first two feedings and concluded with Fermaid O, and the control.
While the fourth condition did indeed leave a fair degree of residual sugar, it also showed to this researcher’s opinion the greatest degree of faults in flavor and mouthfeel, to the point where he could not in good conscience adopt this protocol as ‘preferred’ for his own personal use. In the words of this researcher’s spouse, the mead in question tasted distinctly of ‘charcoal lighter fluid’.
This researcher and his spouse both concluded that the 3rd trial, Travis Blount-Elliot’s nutrient regiment, produced the best tasting end result, despite being the 2nd driest, it produced the most pleasantly complex flavor profile and mouthfeel of the five trials with no apparent signs of stressed or flawed fermentation. This researcher felt that the 2nd trial, TOSNA, was a reasonable second option, being drier and therefore a more complete fermentation, though it lacked the depth and complexity of the 3rd trial. The researcher’s spouse felt that the control was her second favorite option.
Subjective Results of Tasting After 6 Months
An additional opportunity to allow for sample tasting arose while the researcher was given an opportunity to present his findings at an event at Bacchus and Barleycorn, a homebrew supply store in located in the Kansas City metropolitan area connected with the American Homebrewers Association’s Mead Day event. The participants at this event were more informed as to the process of fermentation being in general avid homebrewers, though not all had specifically brewed mead. Sampling in this case was voluntary and many of the participants in this event declined to sample all five trials. However, this researcher as well as the owners of the establishment did sample all five varieties and concluded that the impressions of all five trials had largely remained unchanged with the exception of the top two trials. In this instance, TOSNA produced a mead with the cleanest and best tasting profile as opposed to Travis Blount-Elliot’s.
It is clear that, on the basis that each of these trials started at the same original gravity and concluded at different gravities, using the same strain of yeast, that nutrient additions were the primary cause of some fermentations completing more thoroughly than others. Judging from final gravity and taste profiles, TOSNA and Travis Blount-Elliot’s regiments provided the least stressful conditions to allow the yeast to complete their metabolism, and are therefore good choices of nutrient regiments to follow for the purposes of ensuring a quality finished product. The finite differentiation in preference between these two trials after 3 and 6 month increments does not necessarily indicate that TOSNA produces better meads after aging, as these results are subjective and will vary from person to person.
The fact that the control condition, which featured all nutrients added up front, demonstrated a higher final gravity and thus less sugars converted to alcohol demonstrates the viability of the approach to staggering nutrient additions. The fact that none of the conditions demonstrated low enough pH to cause stalling action previously seen frequently while brewing under conditions similar to the control may also point to the role degassing plays in controlling acidity in solution, as dissolved CO2 is known to form carbonic acid in an aqueous solution.
This researcher believes that a strong possibility as to why my subjects preferred a flawed but sweeter sample to a dryer sample is simply an ingrained expectation for the drink in question to be sweet, and thus a dryer product will create cognitive dissonance in the mind of a consumer and may bear further examination in itself.
Both the experimental subjects and this researcher’s spouse preferred the control in second place, and this may in fact speak to the degree of subtly in differences between these trials. As one of the subjects at the 3 month trial commented, all 5 trials did in fact produce good meads, some simply preferred one to another.
This experiment was a success in that the researcher identified the nutrient protocols which produced to his mind the best meads and could use as the basis for future Staggered Nutrient Addition Protocols in the future. However, these results demonstrate a number of avenues where further research is warranted.
Firstly, it may be advisable to attempt to redo the trials using only Fermaid K and Fermaid O, without the inclusion of DAP as DAP is known to cause fermentations to run hot. Subsequent to the start of this experiment, Sergio Moutela released a second protocol referred to as TiOSNA or Tailored inOrganic Staggered Nutrient Additions which replaces Fermaid O with Fermaid K. As such, a repeat of this experiment using trials of 1) TOSNA, 2) TiOSNA and 3) Travis Blount-Elliot’s could provide a further finite degree of comparison.
Further, in order to foil the problem of subjects preference toward sweet meads, it may be advisable to start at a lower original gravity and allow each mead to ferment to complete dryness. However, this may in turn demonstrate that lower gravity meads are also less stress inducing than those of higher gravity, thus reducing the necessity of a well-managed staggered nutrient addition protocol in those instances.
Finally, the researcher possesses an additional 750ml bottle of each trial. After approximately 18 months prior to yeast pitch, the researcher intends to do a final subjective sampling to determine if any of the off flavors observed in less favored trials have been mitigated by a generous aging period, results of which will be forthcoming.