Steps #14-17: Extended Maceration to Press
Here is the detailed process chart; the thick lines indicate the path taken in 2020:
Step #16: Extended Maceration
On completion of Primary Fermentation, we can consider extending the maceration to extract more Tannins and increase the level of Bound Anthocyanins. Because the alcohol level is now high, Extended Maceration will extract relatively more seed tannins which can be beneficial if seeds were very ripe and if the addition of nutty/almondy taste is desired. We keep the temperature at 70 °F and continue with one punch-down per day for up to ten days (depending on taste).
The Extended Maceration punch-down process is:
Take the tank cover off.
Punch down the must while making sure not to crush seeds at the bottom of the tank.
Take two 2mL samples for chemical analysis.
Taste sample and decide whether to continue or end extended maceration.
Wipe down the walls of the tank with disinfectant (KMBS solution), cover the must with a new blanket of Argon or CO2, and put the tank cover back on
Step #17: Inoculating for Malolactic Fermentation\
In Malolactic Fermentation, bacteria transform malic acids into lactic acids. This reduces the young red wine's acidity and harsh fruitiness and helps create a rounder mouthfeel. These bacteria occur naturally in the vineyard on the grape skins and find their way into the must during crush. If an earlier SO2 addition killed the bacteria, they may be purchased from specialized laboratories/providers and added back. If the Primary Fermentation was done naturally (i.e., no SO2 was added at crush), then the Malolactic Fermentation is often also left to occur on its own.
Malolactic Fermentation, particularly when induced by naturally occurring bacteria, can take months to complete and is often only successful if the temperature of the wine remains around 70 dF for an extended period. It helps to add specialized nutrition to support the malolactic bacteria and accelerate the conversion. Thus we have three choices:
Leave it to chance: rely on the naturally occurring bacteria, assuming they were not killed off at crush
Middle road: Support the naturally occurring bacteria with specialized nutrition to accelerate the conversion
A safer bet for rapid conversion: Inoculate the young wine with commercial bacteria and matching nutrition.
We regularly measure malic and lactic acids (as part of the OenoFoss protocol) and monitor progress. Here is a more detailed discussion of the process and potential pitfalls from MoreWine.com: https://morewinemaking.com/articles/5_steps_to_mlf
Up to 2018, we used to inoculate with malolactic bacteria only after pressing, when the young wine was already racked into barrels and we kept the barrels above 60 dF. Given our mixed success, we changed the timing in 2018 and started malolactic fermentation when the fermentation finished, and before extended maceration, if any, and before pressing.
Steps #14,15 & 18: Pressing Decisions
We initiate pressing when
Primary Fermentation (step #13) was incomplete when Tannin levels reached 2000 or 110% on previous Anthocyanin peak, or
Primary Fermentation (step #13) completed in the fermentation tank, and tannin levels were high enough to skip Extended Maceration, or
Extended Maceration finished.
If we press before Primary Fermentation is complete, we press the cap only. We scoop the cap out of the fermentation tank into the press, press and return the pressed juice to the fermentation tank, and complete the primary fermentation.
Suppose the fermentation was not completed before pressing due to high tannin extraction during Phase 2 of the Primary Fermentation. In that case, the fermentation now needs to be completed in the fermentation tank. The process for this Step #15 is:
Take test samples, stir, and then recover with Argon blanket
Taste and measure (OenoFoss & WineXray)
Keep the temperature at 70 °F and continue the daily process until Brix reaches -1.5.
The side-by-side pictures show the two alternatives of pressing. On the left: When we press all the must (after the primary fermentation is completed), we first drain the juice into the press and then move the must over a steel channel into the press. On the right: When we press the cap only, we scoop out the cap in 5-gallon buckets, empty the buckets into the press, press and return the pressed juice to the fermentation tank by buckets.
We use a 1.5-ton bladder press: Bucher Vaslin XPro 5 (http://www.buchervaslin.com/en-bucher-France-bucher-pneumatic-presses-16-22-26.html) which, we now realise, is overkill for our requirements. We extract the additionally required juice at very low pressure (0.2 to 0.3 bar only) from the must in multiple rounds. This is called the Press-Run. The remaining pressed must (now called pomace) is scooped out and distributed in the vineyard as fertiliser for the next season.
For small fermentation batches, we don’t use the big bladder press. Instead, we use a small manual press which saves in setup and cleaning efforts. There are two types. In modern manual bladder presses, water pressure fills a bladder which presses the must outside against a stainless steel sieve. In old-fashioned screw presses, a wood lid is pressed down by a big screw, and the juice escapes laterally through a vertical wood lattice. We have used both types for the small lots from the upper vineyard. The picture on the right shows the two types.
Step #19: Mixing, Racking & SO2 Protection
We usually mix the free-run and press-run juice from different Fermentation Batches into what will become Cellar Batches in separate Settling Tanks. Because the fermentations are staggered time-wise, the mixing and holding of the young wine in the Settling Tanks can extend from a few days to a few weeks. During this time, dead yeast cells and other solid material sink to the bottom as sediment. To keep the malolactic fermentation progressing, we maintain a temperature of around 70 dF. We protect the young wine in the settlement tanks with an Argon gas cover to prevent oxidation and growth of microbes on the surface.
When all the fermentation batches are mixed as desired, and the dead yeast and other materials have settled at the bottom of the Settlement Tanks, we decide how much SO2 to add for protection and then siphon the young wine into Cellar Batch containers (barrels and top-up tanks). Until 2019, we regularly added the standard requirement of 30ppm free SO2 equivalent (see Step #8) at this juncture. Since then, we limited SO2 additions, if any, partly because the elevated pH of the 2019 and 2020 vintages made SO2 ineffective and we managed to keep infections at bay with more aggressive sanitation protocols (e.e. regular steaming of barrels)
Data Management
Data Management for Steps 14 to 16 is identical to Step 13.
Tracking Results 2018
In 2018 we made the following decisions:
We did not press any of the fermentations early, nor did we extend the maceration periods after the fermentations were complete. The tannin and anthocyanin levels were adequate without.
We pressed the two Merlot - Cabernet Franc ferments in the old-fashioned manual screw press and combined the juice for settlement into a single stainless steel barrel.
We pressed the Cabernet Sauvignon ferment in the large bladder press and settled the juice in the large Settling Tank
We free-flowed the Petit Verdot ferment into two glass carboys for settlement.
Finally, we mixed, at varying ratios, the different settlement tanks into 3 French barrels (one new, two neutral) and five topup tanks. The goal was to get one barrel of 100% Cabernet Sauvignon, two barrels of different Bordeaux-style mixes and separate topup tanks which reflect these mixes.
The following spreadsheet shows the allocations to barrels (green) and topup tanks (white):
:
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Last updated: November 27, 2021