For today’s post, I am going to stray away from our usual discussion of all things V. vinifera, and discuss current research related to another type of wine. Part of the foray into something new is that well, for one, one can make wine out of more than just vinifera grapes, and two, I really don’t know too much about other types of wine and wanted to learn a little more myself!
That being said, today I’m going to present and discuss a current peer-reviewed article related to mead.
Mead, also known as honey wine, has been consumed for centuries. It is believed to be the oldest alcoholic beverage, and often conjures up images of ancient castles and heroic knights. Honey has been used to create not only meads, but also “sherry-esque” wines, sparkling wines, and wines with some combination of fruit and honey. Like grape wine, honey also displays several properties that are beneficial to one’s health, including antimicrobial and antioxidant properties.
The fermentation and maturation process for honey meads can be extremely variable in length, from a few months to many years. There can often be many problems during this time which ultimately prolong the fermentation process, or stop it all together. In grape wine, often these problems are related to the yeast strain involved in the fermentation process. In fact, the same yeast strain that is often used in wine production has been used to start fermentation in honey meads as well (Saccharomyces cerevisiae). When subject to similar stress conditions, S. cerevisiae behaves similarly in honey mead fermentation than in grape fermentation processes and runs the risk of failure.
As in grape fermentation, nutrients (particularly yeast-assimilable nitrogen; YAN) are critical in the growth and development of yeasts. In honey mead, the level of nitrogen actually changes the sensory characteristics of the finished wine, specifically as a result of the amino acid composition.
Another problem in honey mead fermentation comes as a result of the low pH and low mineral content of light honey (compared to dark honey), which results in poor yeast growth. Often, supplements are added to help aid in the growth of yeast and ultimately the success of the fermentation process, including fruit juices, salts, acids, ammonium phosphate, potassium sodium tartrate, magnesium sulfate, calcium sulfate, citric acid, tartaric acid, and vitamins. Other supplements that have been studied in improving the success of honey mead fermentation include thiamine chlorhydrate, yeast extract, pollen, and royal jelly (produced by bees). Many of the previous studies have shown that pollen may be a important supplement in improving the fermentation process of mead, which is the primary focus of the study presented today.
Pollen, which is actually the primary focus of my Masters thesis from the University of Virginia (permission to dork out for a minute: woohoo!), is the primary protein source for bees, and is also the male gamete of plants. It is often used as a dietary supplement for protein, and more specifically, amino acids. Pollen can contain up to 60% protein, which translate to a huge resource for the bees and other insects that feed upon it, as well as allowing it to be a great protein and amino acid supplement for other animals. I can go on and on about pollen, but alas, I digress…
Based on the studies performed on honey mead fermentation thus far, the goal of the study presented today was to examine the influence of pollen addition on the fermentation process of honey mead, specially examining the fermentation kinetics, physiochemical characteristics, aroma profiles, and sensory characteristics of the finished wine.
Since I’m not sure how many of my readers are familiar with the winemaking process for honey meads, I will go into a little more detail about the process than I would for more familiar V. vinifera wines.
Commercial honey (at 75o Brix) was diluted with water until a honey of 20-22o Brix was obtained. Acidity was corrected to 3.6. Potassium metabisulfite was added to prevent lactic acid bacterial growth. The diluted honey was divided into 5 L fermentation tanks and commercially produced pollen was added in concentrations of 10, 20, 30, 40 and 50g/L, for each treatment. A control with no pollen added was also included. After addition of pollen, turbidity and yeast-assimilable nitrogen (YAN) of the honey must was measured.
The honey musts were inoculated with a wine yeast strain of S. cerevisiae (ENSIS-LE5) at a dose of 15g/hL and incubated at 25oC. Density and biomass were measured throughout fermentation. At the completion of fermentation, the meads were cold stabilized at 6oC for one week, and then treated with gelatin (4g/hL) and bentonite (40g/hL). Lastly, meads were filtered and bottled. All treatments were performed in triplicate.
The following were measured for all mead treatments: nitrogen, amino acids, Beaumé degree, pH, total acidity, sulphurous anhydride, YAN, alcohol content, volatile acidity, residual sugars, and finally, major and minor aromatic compounds. To simplify the aromatic profile of meads, the authors calculated an odor activity value (OAV) for each mead, calculated as the ratio between the concentration of each compound and its perception threshold. An OAV greater than 1 were considered contributors to the aromatic profile of the mead.
Sensory evaluations of the different treatment meads were also performed. The panel consisted of 10 panelists, between the ages of 30 and 50 (4 women and 6 men), who all had wine tasting experience and were trained in the evaluation of honey meads. Each panelist evaluated visual characteristics (turbidity and color), aroma characteristics (quality and intensity), and taste characteristics (quality and intensity). General acceptability was also determined.
- The addition of pollen corresponded to a probable increase in alcohol content of the mead.
- Total acidity and tartaric acid were increased by pollen addition.
- pH remained constant.
o The increase of acidity was due to weak acids.
- The addition of pollen increased the total polyphenol index by 0.130 absorbance units per gram of pollen.
- Honey must color was altered by the addition of pollen.
o Brown and yellow colors were enhanced.
- The addition of pollen increased the turbidity and YAN levels.
o According to the authors, pollen is a major source of YAN and could be used to enrich nitrogen-poor media.
- Pollen provided a good source of YAN, and the percentage of each individual amino acid remained constant as more pollen was added.
- Each 10g/L of pollen added provided an average of 70% of the amino acids that were already present in 1L of honey must.
- YAN levels in the 40g/L and 50g/L (pollen) meads were above 140mg/L, which is the minimum amount necessary for completing fermentation in grape musts.
- These results indicate that pollen provides a good supply of amino acids for completing honey must fermentation.
· In all treatments, when fermentation was complete, residuals sugars were less than 0.6g/L.
· In the control mead (no pollen added), fermentation lasted 6 weeks, indicating that honey alone is deficient in nutrients required for yeast fermentation.
· Fermentation rate increased with pollen supplementation.
· Compared to the control mead, fermentations supplemented with pollen showed a significantly increased fermentation rate, and a reduction in time to reach a maximum rate.
· Honeys with more than 30g/L of pollen added showed the highest fermentation rates and the shortest maximum time.
· Increases in the fermentation rate was correlated with an increase in YAN levels and turbidity values, which resulted in the overall improvement of fermentation kinetics.
o It is possible that the high polyunsaturated fats found in the pollen may have also contributed to the increased fermentation rate, since these compounds are metabolized by yeast cells during the fermentation process.
· The fermentation efficiency of the control mead was approximately 81%.
o The addition of pollen improved the fermentation yield and efficiency by more than 7% and 10%, respectively.
- The total acidity of the mead decreased with pollen addition.
- The final pH increased to more than 4.0 with pollen addition.
o The authors suggest this higher pH value might reduce the microbial stability of the meads, thereby justifying the need to adjust the final pH accordingly.
- Volatile acidity increased with pollen addition.
- The yellow hue of the mead increased with pollen addition.
- Total phenolic index increased with pollen addition.
- From these results, it seems that pollen not only increases fermentation kinetics, but also improves the overall physiochemical characteristics of the final mead.
- Isoamyl alcohols, acetaldehyde, and methanol increased with pollen addition.
- There was no correlation between the amount of pollen added and the total minor volatiles present.
o The main contributors to the minor volatile component of the meads were alcohols and acids.
- All other aromatic families of compounds increased with pollen addition.
- Pollen addition significantly increased the proportion of acids in the meads’ aroma, specifically octanoic and hexanoic acids.
- The addition of pollen increased the proportion of esters, particularly ethyl succinate and phenylethyl acetate, resulting in an increased fruity odor.
- The addition of pollen increased the proportion of aldehydes in the mead.
- To summarize, the addition of pollen was associated with increased values for all aromatic groups (particularly the fruity and oxidative groups), regardless of the amount of pollen added to the must.
- Meads with 20 and 30g/L pollen added showed the highest contribution to the fruity aroma, and lowest contribution to the oxidative aromas.
- The most acceptable meads were the 30 and 40g/L meads, which showed the highest flavor and aroma ratings.
- The most significant difference between all the meads was the color. With increasing pollen added, the more the mead changed from a pale yellow to an amber color.
- Aroma notes:
o The control wine had floral notes, as well as vinegar-like characteristics, which decreased acceptability.
o The 10g/L pollen mead had notes of “medicinal” and “floral”.
o The 20 and 30g/L pollen meads had notes of almond, dried fruit, apple, caramel and sweets, with a bit of pineapple on the nose.
o The 40g/L pollen mead had the strongest notes of honey.
o The 50g/L pollen mead had notes of toast, bitter almond, and honey.
- Mouthfeel increased as pollen addition increased.
- Flavor notes:
o The 40 and 50g/L meads were noted for sweetness, with honey and floral flavors.
o The 30g/L meads were noted for sourness.
o The 20g/L meads had hints of bitterness.
According to the authors of this study, these results show that pollen could be a good activator of alcoholic fermentation in honey meads, which results in an increase in fermentation kinetics and improved physiochemical and sensory characteristics of the finished wine. Based on their analysis, they came to the conclusion that the optimal dose of pollen to the honey must is 30g/L. This allows optimization of the fermentation process, while not using an overly excessive amount of the resource.
Knowing very little about the fermentation process of honey meads, I found this study fascinating. Since I also worked very closely with pollen during my Masters research, this study hit a little closer to home for me that it may for some others. Since my expertise and experience with honey meads is very limited, I cannot critique the methods of the results of this study too much, other than the fact that based on the results, the authors’ evaluations and interpretations sound legitimate to me.
I’d be curious to see them break down the polyphenol content of the mead. The results show that the total polyphenol index increased with pollen addition. Does this make the mead healthier for those that consume it? Is it better at protecting against oxidative or other stresses than a mead without pollen added? I’d be very interested in reading a study focused on the health implications of this type of pollen-supplemented mead.
I’d love to hear what you all think! Please feel free to leave your comments below!
Source: Roldán, A., van Muiswinkel, G.C.J., Lasanta, C., Palacios, V., and Caro, I. 2011. Influence of pollen addition on mead elaboration: Physiochemical and sensory characteristics. Food Chemistry 126: 574-582.
I am not a health professional, nor do I pretend to be. Please consult your doctor before altering your alcohol consumption habits. Do not consume alcohol if you are under the age of 21. Do not drink and drive. Enjoy responsibly!