mead

Kieselsol and Chitosan in Fruit Meads

The haze craze is off to the races in juicy IPAs, but the opposite is still true for meads. A crystal clear mead can be the difference between a medal and a flop at competitions. A wide range of fining agents are in the arsenal of a mead maker. Most fining agents work by attracting positively or negatively charged particulates suspended within the mead. This causes suspended particles to precipitate to the bottom of the vessel. A common practice is to use a positively charged agent, such as gelatin or Chitosan, followed by a negatively charged agent, primarily Kieselsol. The treatment will bind with proteins, yeast, polyphenols and other negatively-charged particles, and is especially effective. Chitosan has the advantage that it does not require tannins to work properly, allowing its use in meads, white wines, ciders, etc. Most home brew and wine making stores sell Kieselsol and Chitosan together, sometimes under the brand name Super Kleer.

Kieselsol and Chitosan works really, really well at clarifying meads. It can even be added right at the end of primary when the mead is all hazy and full of gunk, and will drop the mead clear in little time, allowing for clear mead in secondary with very little lees. It is also been stated that fining agents “improve the color, odor, flavor, stability and mouthfeel of the finished product – along with many additional, subtle, benefits.” However, despite all the advantages, are we losing anything other than unwanted particulates when using Kieselsol and Chitosan?

It is common to find comments, for example from my local home brew store, that Kieselsol is not recommended for red wines as it can strip color. Moreover, within mead making circles, the use of some fining agents such as gelatin have been commented to strip tannin. However, it is unclear, at least to me, if Kieselsol and Chitosan does the same. See an excellent GotMead podcast with Tom Repas for information on use of fining agents in secondary and the ability of gelatin to strip tannin. However, there is little hard evidence on adding Kieselsol and Chitosan in meads.

Interestingly, the common advice on Kieselsol and Chitosan seems at odds with the current literature on wines. A recent article in the Critical Reviews in Food Science and Nutrition provides a literature review when pertaining to wine. In summary, researchers have found that red wine color loss is only found at dosing rates that are four or more times higher than the maximum dosing rates used by home brewers. Thus, the risk to color loss may be overblown. However, researchers have found that there are significant loss in flavanols, medium-chain fatty acid ethyl esters, and terpenes in both red and white wines at common dosage rates. Moreover, Kieselsol and Chitosan have been documented to reduce both tartaric and malic acids. Finally, there is emerging evidence that Kieselsol and Chitosan may result in perception of astringency, even at low levels. These findings all suggest potential effects on flavor. Maybe this fining agent is not as neutral as commonly assumed?

Are we losing anything else in our path to clarity? Clearly, this needs to be clarified. 

In this experiment, the use of a common two stage clarifying agents, Kieselol and Chitosan, is tested for its flavor and aroma contributions in a 4.5% ABV, carbonated, dry cream soda mead fermented using D-47. The mead was fermented in one batch, then split between two identical secondary vessels and one was given the clarifying treatment. Other than the clarifying treatment, all other variables were identical, and the batches were from the same ferment. Triangle tests are conducted to see if participants can correctly identify the difference between the two meads. Respondents also provided feedback on the differences perceived in the two meads.

My hypothesis was that the treatment may remove mouthfeel due to the reduction in particulates, but at the low dosage would not affect color. I had some suspicion that it would affect aroma/taste.

Recipe: 4.5%, Dry, Cream Soda Mead, Nov. 2020, 15 liters

  • OG = 1.034
  • 1 liter of 2020 golden wildflower Honey from Nith Valley apiaries
  • 0.5 kg of creamed, organic, raw, Peace River honey
  • 15 liter spring water
  • 7 gallon fermonster fermentor
  • 1.5 grams of calcium chloride
  • 0.5 grams of gypsum
  • 0.5 grams of Himalayan sea salt
  • 10 grams of D-47
  • 2 grams of ascorbic acid
  • 3 grams of citric acid

Treatment:

  • Chitosan 1% at 8.3ml per gallon (2.18 ml/grams per liter)
  • Kieselsol at 2.5ml per gallon (0.66 ml/grams per liter)

Nith Valley honey tasting notes:

  • Moderate floral
  • High perceived sweetness,
  • Honey comb, honey like, bees wax
  • Citrus

Nutrients (calculated using The MeadMakr BatchBuildr):

  • Low nutrient profile recommends 65.2 ppm YAN
  • Actual: 82 ppm YAN (medium level, scaled up due to high pitch rate)
    • Fermaid-K: 2 grams (contributed 13 ppm YAN)
    • DAP: 5 grams (contributed 69 ppm YAN)

At pitch

  • Mixed honey, water, salts.
  • Shook jug for two minutes to aerate
  • Sprinkled yeast on top of must

Fermentation Notes

Regular temperature, pH, gravity and aroma tests were taken. The table below summarizes the observations.

  • +time 0, Mixed honey, water salts. Sprinkled yeast on must. Must is 62-63°F. Swirled after 1 minute.
  • +1 hour, fed with 1g of Fermaid-k and 2 g of DAP.
  • +1 day, fed with 1g of Fermaid-k and 2g of DAP. 64°F
  • +2 days, degassed. Fed with 1g of DAP. 64°F. 1.024
  • +3 days, degassed, 64°F , 1.012
  • +4 days, degassed, 64°F , 1.002, added ~2 kg of polish sour cherries in a mesh bag warmed to 65°F
  • +5 days, removed fruit, hardly any color left in fruit mush. 1.000
  • +7 days, racked into 2 x 8 liter jugs. Added half a vanilla bean split down the center, 1 gram of ascorbic acid, and 1.5 grams of citric acid to each vessel. Mead dropped relatively clear quickly.

Secondary

  • After two weeks, added 1st stage clarifier to one jug then swirled gently
  • 24 hours later added 2nd stage after 24 hours to one jug, swirled gently
  • Bottled after another week to 2.5 volumes (65 grams of honey).

The meads were both pretty clear before bottling. It was not possible to tell which was more clear in secondary.

Water profile 

The mineral profile of the spring water, contribution of the salt additions and the final water profile was as follows.

Initial Tasting Notes

At two months old, I tasted both meads, and they seemed different. The baseline mead was really nice. It had bright fresh cherry flavor and mild vanilla. I would have liked more vanilla intensity to make it taste like a cream soda and less of a cherry mead. The fermentation was clean and had little fermentation characteristics apart from some mild malt-like yeast character. However, the mead with the clarifying treatment was slightly bitter and less well carbonated. I figure the low carbonation was due to less residual yeast in suspension. I let them sit for a while so that they both fully carbonated.

Triangle Tests 

Due to Covid-19, and in consultation with statisticians, every participant was sent two bottles and completed up to five triangle tests. Participants were sent four or five experiments and knew that I was testing something around nutrient regimes, clarifying agents, and acidity levels. The bottles were labeled experiment A, B, C etc. as well as being labeled as treatment or baseline. Every participant was also sent enough identical red solo cups.

One scoresheet was filled out by each participant for each experiment. Participants were asked their experience level with meads, how blown their palate was, and their status as judges and home/professional brewers. Experience was given a value from one to five where one is first time having a mead to five being well-experienced. Palate was given a value from one to five where one is having had nothing to drink yet, and five was that they’ve already had too much (like just drank an IPA and sitting in a brewery). Participants were asked to say which mead they preferred, and just select one if they couldn’t tell the difference.

There were 6 participants, each completed five triangle tests, so there were 30 triangle tests completed overall. We had a good selection of mead experts and mead enthusiasts. There were two BJCP certified beer judges and two BJCP mead judges.

On average, people were experienced with meads and their palate was not tired. All had some experience with meads and off flavors. Basic summary statistics on the self reporting of participants experience and palate when taking the triangle tests:

All responses were collected within the same month. Tests were evaluated when the meads were 6-8 months old.

Results

There was a significant difference between the two meads. Out of the 30 triangle tests, 20 could identify the odd mead out! The null hypothesis that the results were from random guessing is rejected with near 100 percent confidence. Moreover, all participants preferred the mead that was not clarified. The null hypothesis of equal preference between the meads is rejected with 96.8 percent confidence. Here is a summary of the results:

I did five triangle tests and got the first two wrong. It wasn’t until I noticed the flavor intensity that I got the remaining correct. Another participant got the first few correct, and the remaining incorrect. Most other participants’ incorrect responses were seemingly random, and no time fixed effects were significant. Some participants commented that the meads could be distinguished from each other relatively easily.

What people described as the difference between the two meads is summarized below. The mead that did not have the clarifier was described as more vibrant, fruitier, and better balanced. In contrast, two participants described the clarified mead as being bitter and another described the perception as astringent. That is fascinating, as astringency was noted to occur in some previous wine studies. Moreover, three participants noted muted flavor, blander and being more watery. One participant commented that they thought the treatment was additional fruit added. Thus, there does seem to be perceived differences in the level of flavor and aroma, which is consistent with some previous studies. Surprisingly, the findings align with results in the abovementioned scientific studies, and there was quite a bit of consistency in feedback across participants.

Conclusion

I was really surprised by how different the two meads were. I often use Kieselol and Chitosan for a quick turn around time in short meads. Likewise, I also use it in relatively clear standard meads to make sure there is no dust of yeast in the bottom of bottles over time for competitions. It always does the job of clarifying.

Now, I have more clarity that mead clarity using Kieselol and Chitosan may not be worth the price. The loss of fruit character was significant. Astringent and bitterness was added. It’s also interesting, that the often cited reduction in color intensity was absent. However, this is all consistent with some recent studies for wine.

A couple of things to note. The meads where relatively clear when I added the clarifier. I would not usually add the clarifier for such a mead if it’s for my own personal use. However, I would use it for a standard strength mead to avoid yeast dust. It would be interesting to repeat the experiment for a standard strength mead. I also use the clarifier at the end of primary since it can knock the mead clear. I wonder if the impact would be similar for a treatment at the end of primary for a much hazier mead, as there maybe more positively charged particulates to help any residual Kieselol to drop out. More testing is still needed for this. Perhaps a bench trial to see what the threshold is.

The same treatment in a traditional mead was evaluated at the same time (forthcoming). Interestingly, participants were able to detect a significant difference; however, preference was split. This may suggest that the issues may pertain to fruit meads, although it could also be due to the fact the there were more particulates in the traditional mead. 

In the past, I recommended the two stage clarifier be used at the end of primary in a really hazy mead to speed the turn around time, for example for the Short Mead Recipes. Now, this comes with a caution for relatively clear fruit meads. 

Peer Reviews:

The comments on methods from the referees in the high versus low nutrient level experiment also pertain to the method used for this article. This includes: 1) Justin Angevaare, PhD, Statistician, author of p-value calculator and award winning homebrewer, https://onbrewing.com; and 2) Chris Kwietniowski, home brewer, participant. 

Additional peer reviews to follow.

Peer Review 1: Tom Repas, Master Beekeeper, owner of Canyon Rim Honey Bees, AMMA MeadCon speaker, award winning mead maker.

Excellent write up! Interesting results!

  • Responce: Thanks Tom. I have greatly benifited from your service to the mead community. Thanks for everything you have shared with other mead makers.

Oh and if I said a fining agent had potential for removing tannins that would’ve been gelatin (not Kieselsol or Chitosan). If I said something different on that podcast then I must have misspoken.

  • Responce: Oops. A previous version of this article had incorrectly stated “… in a recent GotMead podcast, Tom Repas commented that this clarifier should be used with caution as it can strip tannin but can also be used to strip excess tannin.” This has been corrected. I recommend anyone to check out this podcast as it is a wealth of information.

Peer Review 2: Ryan Dunlop, PhD, BJCP certified, award willing homebrewer, and statistics wizz.

…. shouldn’t the preference test be two sided?

For the “can we tell them apart?” question, one sided makes sense because you don’t care if you choose wrong more often than random chance. With a good design, you know that that is still random chance.

If either could be better than the other, I think two sided is better because you have two ways you can “have one more preferred than the other”. Otherwise you are kind of assuming that you know one is preferred and if the data show the opposite it’s just random chance. 

  • Responce: I agree. Previously, a one-sided test was used to test the preference of one mead over the other. However, since the direction of the preference cannot be known a priori, this has been changed to a two-sided test. Also, thanks to Justin Angevaare for confirming the test should be two-sided.

Ale Yeast: High vs Low Inorganic Nutrients

Much more information is available on wine yeast than ale yeasts. While a mead maker can consult the Winemaking Handbook from Scott Labs to look up the nutrient requirement of most used wine yeasts, no similar bible exists for ale yeasts. I have personally contacted three ale yeast manufacturers, and they said that nutrient requirement information was not available for their ale yeasts. One example of the lack of data is the little-noticed but big change between TOSNA 2.0 and TOSNA 3.0, that reduced the recommended level of nutrients for ale yeast from high to low. Moreover, with the range of levels for wine yeasts its unfortunate that all ale yeasts get clumped together, an English ale yeast may have different nutrient requirements than a Kviek yeast in nutrient calculators. As nutrients are a major determinate of proper mead fermentation, mead makers really need more data for ale yeasts.

In this experiment, a high versus low nutrient rate is tested for its flavor and aroma contributions in a 4.5% ABV, carbonated, dry traditional mead fermented using an English ale yeast, Safale S-04. The ale yeast strain, S-04 is noted to have a clean flavor, contributing apple esters, and has a fast fermentation with good flocculation. Other than the nutrient level, all other variables were identical, and the batches were fermented side by side. Triangle tests are conducted to see if participants can correctly identify the difference between the two meads. Respondents also provided feedback on the differences perceived in the two meads.

My hypothesis was that it may affect the ester levels, but given my prior success using medium and high levels of nutrients, I thought that a low level of nutrients could cause a sluggish fermentation and could also have potential off flavors.

Recipe: 4.5%, Dry Traditional Short Mead, January 2021, 1 gallon

  • OG = 1.034
  • 0.33 liters of 2020 golden wildflower Honey from Nith Valley apiaries
  • 4 liter water spring water in 8 liter jug
  • 0.35 grams of calcium chloride
  • 0.2 grams of potassium bicarbonate
  • 0.12 grams of Himalayan sea salt
  • 1.5 grams of Safale S-04

Honey tasting notes:

  • Moderate floral
  • High perceived sweetness,
  • honey comb, honey like, bees wax
  • Citrus

Nutrients (calculated using The MeadMakr BatchBuildr):

  • Low nutrient requirement: 65.2 ppm YAN
    • Fermaid-K: 0.5 grams
    • DAP: 1 grams
  • High nutrient requirement: 108.7 ppm YAN
    • Fermaid-K: 0.9 grams
    • DAP: 1.7 grams

At pitch

  • Mixed honey, water, salts.
  • Shook jug for two minutes to aerate
  • Sprinkled yeast on top of must

Fermentation

  • Degassed by swirling the jug every 12 hours for the first two weeks.
  • +2 hours, first 1/3 nutrient addition. 64.3°F
  • +24 hours, second 1/3 nutrient addition. 65°F
  • +48 hours, third 1/3 nutrient addition. 65°F

Fermentation Notes

Regular temperature, pH, gravity and aroma tests were taken. The table below summarizes the observations.

Time/ Temp.HighLow
+0 hours  63°FpH 7,
SG 1.035		pH 7
SG 1.035
+20 hours 67.6°FHoney/ fermentaion/ yeast  Raw honey / light fermentation
+36 hours 66.9°FSome ferm stress/ light rubber, 1.026Raw honey / clean, 1.028
+3 days 66.6°FClean/ light esters, 1.012 Clean, honey, 1.014
+4 days 64°Ffruity esters, 1.006Raw honey, 1.014
+5 days 66.6°Ffruity esters/ clean, 1.004Clean/ honey, 1.012
+6 days 66.6°FClean/ floral/ light pomme esters. No heat/ smooth, 1.000
Transferred to secondary		Light esters/ honey, 1.008
+7 days 66.6°F Great/ honey/ some esters, 1.006
+9 days 66.6°F Hight raw honey clean, low pomme esters, 1.004
+13 days 66.6°F clean, light honey, low/no esters, 1.000
Transferred to secondary

Basically, the fermentation with the low nutrients took twice as long to ferment. Throughout the fermentation, the low nutrient regime smelled more like honey, whereas the high levels of nutrients has more pear and apple esters.

Secondary

  • Cold crashed at 58°F for 2 weeks.
  • Bottled after one month to 2.5 volumes.

Water profile 

The mineral profile of the spring water, contribution of the salt additions and the final water profile was as follows.

Initial Tasting Notes

At bottling, I tasted both meads and they both seemed different but were both excellent. The mead with the low nutrient levels had mild diacytal/butterscotch and some sulfur. However, it was sweeter, and had more raw honey, and minerality. In contrast, the high nutrient level was all apple and pear ester character. The high level nutrient mead also had more noticeable alcohol, was dryer, and tasted like fermented honey rather than raw honey.

Triangle Tests 

Due to Covid-19, and in consultation with statisticians, every participant was sent two bottles and completed up to five triangle tests. Participants were sent four or five experiments and knew that I was testing something around nutrient regimes, clarifying agents, and acidity levels. The bottles were labeled experiment A, B, C etc as well as being labeled as treatment or baseline. Every participant was also sent enough identical red solo cups.

One scoresheet was filled out by each participant for each experiment. Participants were asked their experience level with meads, how blown their palate was, and their status as judges and home/professional brewers. Experience was given a value from one to five where one is first time having a mead to five being well-experienced. Palate was given a value from one to five where one is having had nothing to drink yet, and five was that they’ve already had too much (like just drank an IPA and sitting in a brewery). Participants were asked to say which mead they preferred and just select one if they couldn’t tell the difference.

There were 6 participants and 26 triangle tests were completed overall. We had a good selection of mead experts and mead enthusiasts. There were two BJCP certified beer judges and two BJCP mead judges.

On average, people were experienced with meads and their palate was not tired. All had some experience with meads and off flavors. Basic summary statistics on the self reporting of participants experience and palate when taking the triangle tests:

All responses were collected within the same month. Tests were evaluated when the meads were 4-5 months.

Results

There was a significant difference between the two meads. Out of the 26 triangle tests 24 could identify the odd mead out! A test that the results were from random guessing is rejected with near 100 percent confidence. Moreover, all participants preferred the low nutrient rates. The null hypothesis of equal preference between the meads is rejected with 96.8 percent confidence. Here is a summary of the results.

I did three triangle tests and found them effortless. Participants commented that it could be done by aroma alone.

What people described as the difference between the two meads is summarized below. The high nutrient level mead was described less pleasantly, with alcohol and off flavors described. In contrast, the low nutrient as being more honey like and was smoother. I was surprised at the results, as my tasting at bottling was quite different.

Conclusion

I was really surprised by how different the two meads were. When I began making mead, I often used high level of nutrients with ale yeasts because that was what was recommended. Now, there is clear evidence that for me that when staggering with inorganic nutrients it’s better to go low. It’s also interesting that despite all the focus on quickly turning around meads, it is clear that you can lose out from too aggressive of a fermentation. Is it worth taking half the time in fermentation if the product is half as good?

I focused this test on inorganic nutrient because I want people who do not have access to Go-ferm and Fermaid-O to still be able to make great mead. That said, the use of Go-ferm and some organic nutrient may have further benefited the meads, especially for the first nutrient addition. More testing is still needed for this.

Moreover, I have done bench trials on the timing of the nutrient additions for short meads since this experiment. The timing of the nutrient additions was quick and could have benefited from staggered out more. As summarized in the metadata of Short Mead Recipes, S-04 is particularly susceptible to nutrient burn from staggering with inorganic nutrients when done within the first 24 hours. The yeast is one of the few I know that can handle all the nutrients up front. I plan to replicate this experiment but with a better staggering regime and compare a low and medium level of nutrients. It would also be interesting to compare all nutrients upfront versus stagger when using S-04.

I still use a medium to medium-low nutrient level when staggering inorganic nutrients in short meads with S-04 as I do like the extra apple esters that results. Of course, it is also needed to test nutrient levels for different ale yeast, including Kveik and US-05. What is clear is that when it comes to ale yeasts, there is still much to learn.

Peer Review 1: Justin Angevaare, PhD, Statistician, author of p-value calculator and award winning homebrewer, https://onbrewing.com

Is each triangle test considered an independent observation here, or is some kind of trial-dependence built in to your analysis?

  • Response: Yes, every observation was considered independent.

Would it be helpful for consistency if the mead was decanted into a serving vessel first, and exact measured quantities added to the cups (cups on a scale while being filled perhaps?) I’m wondering if a bias in fill level could be picked up by participant due to having 7 of one to fill and 8 of the other (FWIW seems unlikely to me). Maybe they should fill 8 from both, and randomly select one to discard after having done so?

  • Response: Each participant was given a 12 oz bottle and told to pour 1 to 1 1/2 of an oz in each cup, with the expectation that they would pour the same amount in each cup. I doubt the participants poured less for the sample with 7 vs 8 cups, but it’s an excellent idea to just say 1 oz for each cup from now on and do 8 to avoid the potential for this.

Was the identification rate equal on the early trials vs. later trials? I can imagine some learning rate by the taster based on them learning results after each trial. I can also imagine certain volatile compounds that may help in identification may have flashed off by trial #5.

  • Response: The incorrect responses were given on trial 2 and 5. Yes, there could be a time fixed effect from learning or volatilization. I also suspect there could be palate fatigue. I suspect there are forces in each direction but given the low failure rate, I suspect controlling for it would not matter for this experiment. It would be interesting to test for this in an experiment that exhibited more trial time variation.

Are the temperatures listed fermentation chamber temps or mead temperatures? Can it be assumed the faster fermentation resulted in a higher temperature for that mead?

  • Response: Mead temperatures. I did not detect temperature variations across meads possibly due to the small volume.

Is phenol production characteristics of yeast generally a matter of gene promotion rather than gene presence/absence? Asking as I can’t remember having had a non-phenolic yeast produce perceptible phenol.

  • Response: No idea. S04 is phenolic prone and in experience more sensitive to phenolic production relative to say US-05.

Are any components of your nutrient regime phenol precursors/directly used by yeast in phenol production? (ferulic acid on my mind)

  • Response: The exact formula of Fermaid-k is not published, so I do not know. It would be interesting to replicate the experiment, but with different nutrient sources. I suspect the use of DAP, particularly when combined with staggering in the first 48 hours, was a major reason for the phenolics. It’s an interesting question though, maybe S04 does have higher nutrient requirements, but it’s just that S04 is sensitive to DAP levels or a certain range. This could explain the sluggish fermentation and off-flavors noted at bottling. Replication with other yeast and nutrient regimes could give us a better idea of this.

Side comment: Reading this reminds me of something I’ve run into repeatedly with sourdough cultures – feeding mine with high nutrient flours like rye or fresh whole wheat seems to result in increased vigour, but also more sulfur, solvent aroma, and less depth.

  • Response: Interesting. When people advocate for certain nutrients by showing better fer mention speeds, like in the case for Go-ferm in the Scott labs Handbook, I always wonder to myself: “yea but what does the difference taste like?”

Peer Review 2 Chris Kwietniowski, award winning home brewer, triangle test participant.

Being one of the tasters having done the 7 of this and 8 of that pouring myself, I think for certain people there may be an element of “counting cards” when you reach the last trio of samples. I certainly didn’t, but maybe someone reaches the end knowing which sample must be the one with 2? But in red solo cups with 1/8th of a bottle, the filling level is like 1/2″ to 1″ with sort of random inconsistencies.

  • Response: It was good to hear your experience and that this did not affect your triangle tests. It will be a good idea from now on to just ensure the instructions insist the pour is identical across cups and not give the 1 to 1 1/2 of an oz range. I will also ask for the order of the tests to be randomized or make sure that 8th cup gets added randomly.

And about the side comment on speed… I think the assumption is right that “faster is better” when comparing to a miserable, sluggish, or incomplete ferment. But at some point you can probably make gains in speed without improving the product.

  • Response: Agree, and the focus on fermention optimization needs to continue to find that sweet spot.