Kieselsol and Chitosan in a Traditional Mead

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 traditional mead fermented using S-04. 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. 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.

This is a sister experiment to the Kieselol and Chitosan in fruit mead. In that experiment, the use of the fining agent resulted in a significant deterioration in the flavor and aroma. However, that mead contained fruit, whereas this experiment is done on a traditional mead. Moreover, while the fruit mead was also relatively clear before adding the clarifier, the treatment for this traditional mead experiment was added directly after racking into secondary and the mead was still very hazy.

I wanted to do this test because I had observed the effect of fining agent on my meads. I made the same strawberry rhubarb mead a couple of times in the last year. Each time I added the fining agent, I noticed a major reduction in flavor and subsequently stopped using it. I wanted to do the test to see if it really did make a difference.

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 these potential advantages, are we losing anything other than unwanted particulates when using Kieselsol and Chitosan?

In an article in the Critical Reviews in Food Science and Nutrition, Marín et al (2020) provides a literature review pertaining to the use of Kieselsol and Chitosan in wine. The studies surveyed analyzed the chemical composition of the wines after treatment. Regarding white wines, researchers have found significant loss in flavanols, medium-chain fatty acid ethyl esters, and terpenes (such as rose-oxide, linalool, citronellol, and geraniol) at common dosage rates. Moreover, Milheiro et al. (2017) find reduction of volatile phenols in headspace.

Chitosan has also been documented to reduce both tartaric and malic acids. Due to white wine’s lower phenolic levels, removal rates are higher than red wines, reaching as high as 30% and 20% for certain acids and flavanols. Treatment removes acids by acting as a polycation; binding anions from organic acids (Bornet and Teissedre, 2007). In at least three studies, decreases in titratable acidity or increases in pH were documented due to the significant removal of tartaric and malic acids (Castro-Marin et al., 2018; Quintela et al. 2012; Colangelo et al. 2018).

Finally, there is mixed evidence on showing that Kieselsol and Chitosan may result in perception of astringency, even at low levels (again, see Marín et al (2020) for a complete review). These findings all suggest potential effects on flavor – not as neutral as commonly assumed. Moreover, the conclusion of Marín et al (2020)’s literature review study was that despite notable effects in chemical composition, there has not yet been any sensory analysis studies to date on the effect of Chitosan treatment in wines. Hence, to the best of my knowledge, this is the first sensory evaluation study of the treatment effect on traditional meads (let alone wines).

My hypothesis was that treatment would reduce flavor and acid levels. This is based on evidence summarized in Marín et al (2020) and found in the experiment on the effects of Kieselol and Chitosan in fruit mead. However, I also expected the effect to be less noticeable compared to the fruit mead, since there may be fewer compounds to drop out in a traditional mead.

Recipe: 4.5%, Dry Traditional Short Mead, Nov. 2020, 16.5 liters

  • OG = 1.034
  • 1 liter of 2020 dark, last harvest, 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 Himalayan sea salt
  • 11.5 gram packet of S-04
  • 0.5 grams of ascorbic acid
  • 1 gram of malic 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 late season darker honey tasting notes:

  • Low floral
  • Low perceived sweetness, not overtly honey like
  • Muddled caramel, minerality
  • Low acid
  • Low mixed herbal/woody, some foamed milk (alfalfa)

Nutrients (calculated using The MeadMakr BatchBuildr):

  • Recommended nutrient level is 78 ppm YAN for medium level
  • Actual: 73 ppm YAN (medium level, scaled up due to high pitch rate)
    • Fermaid-K: 2.3 grams (contibuted 13 ppm YAN)
    • DAP: 4.3 grams (contibuted 60 ppm YAN)

At pitch

  • Mixed honey, water, salts.
  • 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 64.6°F, pH 7.0.
  • +2 hours, fed all nutrients upfront with 2.3g of Fermaid-k and 4.3 g of DAP.
  • +1 days, active fermentation, 66.6°F
  • +2 days, degassed. Smells like apples. 66.1°F
  • +3 days, degassed, 66.5°F , 1.012
  • +4 days, 66.2°F , 1.002, smells of pear, apple.
  • +5 days, 65.6°F, fermentation slowing, smells like honey, apple. 1.000
  • +7 days, 65.6°F, FG 1.000. Racked into secondary. Added ascorbic acid and malic acid.

Secondary

  • Added 1st stage clarifier to one jug immediately, then swirled gently
  • +2 hours later added 2nd stage to one jug, swirled gently
  • The next day, treated mead dropped clear.
  • Bottled after another week to 2.5 volumes (primed with honey).

The untreated meads was still slightly hazy when bottling. The treated mead was clear.

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 was a bit disappointed with the character of the mead. They had a mild lager-like aroma. There was some nice apples esters and fermented honey character, but they were slightly muddled by the slight sulfur. I attribute this to not using Go-ferm, and just replying on aerating with a wine whip instead of by shaking or using pure 02. That said, the mead was intentionally fermented this way in a side-by-side with an identical batch using EC1118 (forthcoming, but as a preview, the EC1118 batch was much worse). I debated whether to continue with the experiment, but thought that it might be interesting to see the effect in the presence of an off-flavor.

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 when the meads were 6-8 months old.

Results

There was a significant difference between the two meads. In 19 of the 30 triangle tests, participants could identify the odd mead out! The null that the results were from random guessing is rejected with 99.99 percent confidence. However, participants were split on the mead that they preferred. The null hypothesis of equal preference between the meads is unable to be rejected. Here is a summary of the results:

My wife and I did five triangle tests and each got three right, mine the last three once I noted the difference in acid levels and hers the first three. One person got all five triangle tests wrong, two got all five triangle test correct. While participant fixed effects were significant, no time fixed effects were significant. Most participants commented that the meads could be distinguished from each other relatively easily, where others said it was difficult. What people described as the difference between the two meads is summarized in the table below. Note, the participant who got all five wrong, did not provide tasting notes. The participants and the percent of correct answers is shown in the table.

In general, the tasting notes are more varied than the experiment on the effects of Kieselol and Chitosan in fruit mead. The baseline mead was described by three participants as being more acidic, whereas the mead with the treatment was only described as being more acidic by one participant. In contrast, one participant described the treatment mead as being bitter, whereas another described baseline as dryer. The treated mead was described as having better balance by three participants, all of whom preferred the treated mead.

Regarding aroma and flavor intensity, two participants noted that the mead without treatment had more aroma and flavor, and another participant said it had more honey aroma. This contrasts with only one participant that said the treatment had more honey flavor.

Note that the one participant who got all five triangle tests wrong did not provide a preference at the time of submitting feedback and when asked to pick, randomly picked baseline. Moreover, the first participant was relatively split on the preference, but did settle on the baseline because they preferred the higher acid and intensity of the aroma and flavor. Even in the most generous case, three preferred the treatment, one only mildly preferred the baseline, and the other preferred the baseline.

It’s hard to make head and tails from the tasting notes. My interpretation, based on my triangle tests, was that the acidity of the baseline mead was perceived to be too high by some participants due to the added malic acid (0.25 grams per gallon). This is consistent with the three comments on better balance for the treated mead. In contrast, the two participants who liked the baseline mead commented that they liked the higher acidity level. Moreover, the treated mead had notable lower aroma and flavor. As the aroma was a combination of the lager-like character and the floral/honey intensity, those who didn’t like the lager-like character might have preferred the mead with suppression of both characteristics.

Conclusion

One of the most interesting outcomes of the experiment is that the meads were significantly different. Thus, treatment with Kieselsol and Chitosan is again shown in sensory analysis to not be neutral. This aligns with the scientific evidence on the reduction of acidity and flavor compounds when treating with Chitosan.

Relative to the experiment on Kieselol and Chitosan in fruit mead, the traditional mead had more particulates when the fining agent was added. For the fruit mead, a perception of bitterness was noted in the treated mead, that was not as commonly mentioned in this experiment. I do wonder if these are related. Perhaps, a hazy mead is needed for all the Chitosan to drop out and not leave any bitterness? More testing is needed.

Finally, I have successfully used the fact that Kieselsol and Chitosan can drop acid out of a mead. After this experiment was completed, I made a mojito mead. However, either the limes were much more acidic or had much more juice than the previous times I made the mead because the acidity ended up being too high. I was able to fix this by treating with Kieselsol and Chitosan and racking off the original keg. Then I added more mint to bring back the aroma, and voilà, it fixed the high acidity.

In the past, I recommended the two stage clarifier be used at the end of primary to speed the turn around time, for example for the Short Mead Recipes. Now, this comes with a caution of lower flavor, aroma, and acidity.

References

Bornet, A., & Teissedre, P. L. (2008). Chitosan, chitin-glucan and chitin effects on minerals (iron, lead, cadmium) and organic (ochratoxin A) contaminants in wines. European Food Research and Technology226(4), 681-689.

Castro-Marín, A., Buglia, A. G., Riponi, C., & Chinnici, F. (2018). Volatile and fixed composition of sulphite-free white wines obtained after fermentation in the presence of chitosan. LWT93, 174-180.

Castro Marín, A., Colangelo, D., Lambri, M., Riponi, C., & Chinnici, F. (2020). Relevance and perspectives of the use of chitosan in winemaking: a review. Critical Reviews in Food Science and Nutrition, 1-15.

Colangelo, D., Torchio, F., De Faveri, D. M., & Lambri, M. (2018). The use of chitosan as alternative to bentonite for wine fining: Effects on heat-stability, proteins, organic acids, colour, and volatile compounds in an aromatic white wine. Food chemistry264, 301-309.

Milheiro, J., Filipe-Ribeiro, L., Cosme, F., & Nunes, F. M. (2017). A simple, cheap and reliable method for control of 4-ethylphenol and 4-ethylguaiacol in red wines. Screening of fining agents for reducing volatile phenols levels in red wines. Journal of Chromatography B1041, 183-190.

Quintela, S., Villarán, M. C., De Armentia, I. L., & Elejalde, E. (2012). Ochratoxin A removal from red wine by several oenological fining agents: bentonite, egg albumin, allergen-free adsorbents, chitin and chitosan. Food Additives & Contaminants: Part A29(7), 1168-1174.

Peer Reviews:

The methodology comments 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 homebrewerhttps://onbrewing.comand 2) Chris Kwietniowski, award-winning home brewer, participant. 

Additional peer reviews to follow.

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

Not so much at the crux of this experiment, but did the participants pick up on the lager-like character you mentioned at all? I see you felt aroma – including this lager-like character – was lower in intensity in the treated mead.

  • Response: Thank you for making me go and double check. Yes, one participant mentioned it was more like a beer in balance. I lengthened the tasting notes to copy over everything that was written.

Can you be anymore specific on the sulfur you mention? Like low H2S?

  • No really. There was no rotten egg or matches, just tasted like a bud-light.

How do I read the tasting notes table? At first I thought it was 1 participant per line, but you had 6 participants listed and 7 tasting notes.

  • Response: The table has been updated to show the participant and the number of times each participant got it correct. This is much easier to read, and thank you for prompting this.