5 Keys to great Fermentations (By Shea A.J. Comfort)
1) Test and Adjust the Must: We are looking for Balance BeforeWe Start Fermenting! This is Very Important! • Sugar (water back (circa 24˚ Brix is more than enough alcohol)/ add sugar (min 23˚ for Reds)) • pH/TA (pH trumps all, but TA tells by how much we can/should adjust if needed) • Structure: • SIY (O2protection, colour stabilization, immediate coating/integration of acidity and tannins) • Tannin (O2 protection, adding/correction of tannin profile: often adding «good» tannins can help bad tannin profile in a must/wine)
2) Understand What Is Needed To Take Care Of Your Yeast! (& ML Bacteria if Co-Inoculating…) • Hydration: everything gets set here… • 2 elements needed: • Nutrition: • Organic Nitrogen (N) is critical for increasing cell mass/growth and reproduction, and for creating the higher alcohols and esters (ester acetates and ethyl esters) that boost aromatic complexity in our wines. • Vitamins & mineralsare needed for maintaining the glycolytic enzymatic pathways which increase tolerance to higher ethanol and temps, as well as help stabilize cell membrane structure. Ester production, cellular health, avoidance of H2S an VA production, along with increasing the speed of fermentation are also benefits of a proper vitamin and mineral nutritional supplement! • Temperature: 104˚ F • Best for converting crystalline dry state to supple fluid membrane. Avoids inter-digitation of the yeast cell membrane.
3) Choose The Strain(s) That Will Actually Make The Flavours & Aromas You Want! (True For Both Yeast & ML Bacteria…) • Individual strains can give focus to the following qualities: • Red Wines: • Fruit qualities can vary: cherry, plum, berry, cassis, blueberry. All of these can be «fresh», of concentrated and «jammy» • Spice: pepper, baking spice, cocoa/chocolate, caramel, leather, licorice, mineral, clove, nutmeg • Floral: violets, rose petals • Mouthfeel, tannin intensity, & colour stability • White Wines: • Fruit qualities can vary: apple/pear, tropical/pineapple, passion fruit, guava, melon, banana, peach/abricot, citrus, strawberry (rosé) • Nuts: hazelnut, almond, (butterscotch) • Floral: honey, jasmine (if precursors there in varietal) • Mouthfeel, acidity & tannin intensity
Strain selection continued… • Choose strains that are best tailored to your particular situation: • Cool-climate/Hybrid fruit musts are often high in malic acid. These high acid/low pH musts can be helped by certain strains that can metabolize up to 30% of the malic acid in a must. • Co-inoculation is also a great tool for these situations! • If you don’t have good temperature control, choose strains that have a low-moderate fermentation speed that don’t run hot. • If you are not open to using fermentation nutrients or can’t monitor nutrient timings well, best not to choose yeast that have high N needs to avoid H2S problems • (However, many high N yeast are the most interesting…)
4) Temperature: A Powerful and Critical Tool To Shape Your Wines! The fermentation temp has a very strong impact on the finished wine: • Lower fermentation temperatures • maintain more of the original fruit profile, but take longer to finish. • Higher fermentation temperatures • Result in faster sugar depletion and a higher rate of suphur compounds being produced (not ideal!). • Create more higher alcohols, which contribute to an edgy harshness in the finished wine. In addition, alcohol toxicity increases with higher fermentation temps. • However, ester production and mouthfeel increases with higher temperatures! Ultimately it up to us to control the temperature to get the qualities we are looking for.
5) Be Sensorally Engaged! • Try to avoid a «set & forget» mentality during fermentation. You should be monitoring for tannin/structure qualities, and any negative Volatile Sulphur Compound (VSC) production during the entire fermentation. This means tasting and smelling the must on a daily basis.
What We Are Looking For: • Tannins: we are looking to avoid/limit bitterness and astringency. This usually will be more problematic from the middle to latter 1/3 of the fermentation when seed tannins start to be released from the presence of alcohol in the must. Careful, limited, gentle punch downs can help with this (along with SIYs). • Note: green, unripe seeds will be the most problematic. Brown seeds will be less so, and their nuttiness may even be desired in a higher ratio in the final wine. It is important to taste the seeds at the crusher to decide the level of the potential «tannic threat» for that particular fruit!
Negative Volatile SulphurCompounds (-VSCs): While sulphur is a natural by-product of all fermentation, we can take steps to minimize its’ unwanted impact on our wines. • The first line of defense against negative VSCs is nutrition. As mentioned earlier, a hydration nutrient complex with vitamins and minerals, and organic forms of N are critical to a healthy fermentation. • Another benefit to an all organic form of N is that it can be added at later stages of a fermentation and completely utilized by the yeast, if needed (unlike DAP).
The second line of defense is Oxygen: • Oxygen exposure at the early stages of fermentation is an incredibly useful tool for two primary reasons: • Oxygen is an important nutrient for yeast health. Yeast need it to help create sterols, which they use to maintain healthy, selectively permeable cell walls. This helps them take in nutrients, excrete waste products and better function as the alcohol level climbs during the fermentation. • Oxygen also reacts with the sulphur compounds naturally created in the fermenting wine. This helps to remove the masking effect of negative VSCs. • Oxygen can be introduced into the fermenting wine by délestage, using an aeration stone, pump-overs with a venturi, or blowing a fan on the surface of the wine during punch- down/roll-over.
The third line of defense is to rouse the entire lees on every punch down for reds and daily for whites. Negative Volatile Sulphur Compounds are just that: volatile! By definition this means that are not yet fixed and can be blown-off from the must. Therefore, each time we rouse the lees, we are allowing the (-)VSC’s (which are coming from the lees) to be unburied and liberated from the vessel bottom and get carried to the surface of the wine to be removed.
OK, we have done all that but still have a problem... • If, however, we have carried-out all of the above «lines of defense», and we still are getting (–)VSC problems, then the addition of an all organic source of high quality yeast nutrient, such as Fermaid-O is highly recommended. • In addition to the Fermaid-O, adding yeast hulls, or, even better an SIY high in yeast cell wall fractions, such as Noblesse, is also beneficial due to their ability to help detoxify the must. • In the end, there is always Reduless…
To Sum Up: • If we follow these 5 keys, we will be greatly rewarded in our winemaking! • Balance the must: get your ˚Brix, pH/TA, & structure in order before you start fermentation! • Hydrate & feed the yeast correctly! • Choose the strain(s) that will help you make the wine you want (and fits your situation). • Temperature control is critical to making nice wines. Don’t underestimate this! • Be engaged throughout the entire fermentation: as soon as you smell or taste a –VSC problem, take action. Do not wait until the end of the fermentation to see what happened, you will most likely only allow the problem to get more entrenched in the wine if you do.
Thank you! Any Questions? Shea A.J. Comfort email@example.com www.yeastwhisperer.com