It’s that time of year: The fruit is in, the rains have started and the wines are starting to ferment.
It all started, for me, in late September, when my son and I picked and crushed the Aglianico from the potted back-up vines in my back yard. Then, I lost my first Aglianico vineyard crop to birds. Disappointed, but undeterred, I prepared for making my first white wine.
The previous weekend, I brought down some Montepulciano fruit from my friend Jeff Miller‘s vineyard and my brother and I crushed it. I’ve had it in a cold soak (between 10°C and 15°C) for the past week. This past weekend, I stopped the cold soak.
My son and I checked the chemistry on his Aglianico and racked it. As I expected, we have exactly 1.5 liters – enough for four half-bottles. It smells of plums and blueberries and oak and still tastes hard, but not harsh, and angular with prominent plum and blueberry.
We re-calibrated the pH meter and got a reading of 3.35 from the Aglianico. Clinitest showed the wine to be just above trace RS.
We checked the malic acid level and got about 300 mg/L (fairly high reading). In a week or so, we will re-check the malic acid and residual sugars and pitch malolactic bacteria.
When it’s done with the malolactic conversion, I will probably chill stabilize the Aglianico to drop the acidity before bottling. But, that is months away.
Of note, the last half-gallon of last year’s mead (Orange Blossom honey with Chamomile infusion) is still going, slowly – as is not uncommon for meads – while the other three are already in bottle.
Luckily, these two jugs do not take up much space in the fermentation area. I plan to move the Fiano down to the cellar, now that it’s getting cooler outside and it will be easier to keep the ferment cool.
The Fiano has been going for three weeks now. To cool the ferment, I submerged a 5-gallon carboy full of fermenting Fiano in an ice bath in a 20 gallon plastic fermenter. With the water level to midway up the neck of the carboy, the ice bath is at 8°C and the wine is at 12°C.
I achieved these temperatures by, first, dumping half a dozen seven-pound bags of ice around the carboy in the fermenter and adding water until just before the carboy gained buoyancy. Afterwards, I placed reusable ice packs in the water (a fresh set, roughly, every 12 hours). This kept the ice bath in a range of 8°C to 14°C.
This temperature range needs to be narrowed to allow for a more constant wine temperature. I have the white wine fermenting in a room where the temperature ranges from 59°F (15°C) to 63°F (17°C). Because of the size of the ice packs and the capacity (both, spatial and energy) of the freezer I am using to freeze them, I can only change out the packs every 12 hours. A more frequent schedule may help keep the ice bath (and wine) at a more constant temperature. Another option I am investigating is an immersion chiller. More on that at a later date.
In the meantime, I need to get my Montepulciano going. Its pH was 3.45 before inoculation. Sugars were at 25°Bx.
An important things to know about one’s must is the YAN (yeast assimilable nitrogen) level. This is the sum of ammonia and amino acid levels in the must. More correctly, YAN (which ranges from 50 to 560 mg/L) is the sum of Ammonia Nitrogen and Primary Amino Nitrogen. This is why adding the ammonia (68 mg/L in my Montepulciano, considered a low value) and amino acid values (133.4 mg/L in my must) does not exactly equal the YAN (mine is around 186.4 mg/L, which is quite low and indicates a need for nutrients, particularly with the yeast I am using).
The point of all this measuring is to not add unnecessary chemicals while avoiding sulfide formation or stuck fermentations. All living organisms need nutrients (particularly, the building blocks of proteins) in order to function, grow, thrive and propagate. Sometimes, the must is able to provide these nutrients. Other times, it cannot. When yeasts have too little or too much nitrogen-rich nutrients, they five off sulfides.
It is not clear what the optimal ranges (as well as proportions) of ammonia nitrogen and amino acid nitrogen are. I did a quick check of the online literature and found out that California wine grapes range from 24 to 309 mg/L (average 123 mg/L). This article gives a good summary of YAN measurement. It seems, after talking to a few winemakers, the YAN value is the number to watch and act upon.
It stands to reason that a better choice of yeast nutrient would be products such as Fermaid K, or Superfood, rather than DAP (diammonium phosphate). The first two provide broad spectrum of nutrients, cofactors and substances necessary for biochemical processes. DAP is just a source of ammonia (from which nitorgen is derived by the yeasts).
What remains unclear is how one is to adjust nutrient additions based on a particular set of results and the nutrient demands of a given yeast selection. The Superfood directions say to give half a teaspoon for every gallon of juice or 10 pounds of fruit. Since I did not weigh my fruit, but can estimate that my 10 gallons of must will give seven gallons of finished wine, I added 1.5 teaspoon of Superfood before inoculation and will add another 1.5 to 2 teaspoons as the wine is around 18°Bx.
Incidentally, not intending to take up another debate with the proponents of “natural” winemaking I have to say the following: It seems to me that if you know your fruit is deficient in nutrients, but you have no idea of the nutrient demands of your “native” yeasts, what do you do to prevent sulfide formation or stuck fermentations? Knowing both the YAN value of one’s fruit as well as the biochemical demands of the fermentative species being used allows one to better shepherd the wine to completion without mishaps while avoiding adding unnecessary things to the wine.
Since I’m on the subject of yeast culture traits: let me touch on one final thing: temperature. Besides keeping the must from getting too hot (and “cooking off” aromatics), one has to aware of the optimal temperature range of a particular selection. One can stress yeasts at the fringes of the temperature comfort zone. This can, apparently most commonly, be manifested by sulfide formation. Aside of just killing off the culture when the ferment temperature goes outside this range, a ferment can have trouble getting started when the goes outside a strain’s optimal temperature range.
That is the current concern occupying the winemaking nooks and crannies of my brain.
I pulled the icepack from the fermenter some 48 hours ago. The temperature has gone from 10°C – 12°C to about 17°C. The must is till below the optimal temperature range for RC 212. The yeas activated well and I pitched it after bringing its temperature close to that of the must.
As of Monday morning, there are no signs of fermentation.
In my next post, I will recount my efforts and success or failure with starting this ferment.