At Ten Minutes by Tractor we're talking small-batch vinification for terroir and cool-climate expression and thus restrained alcohol (12 to 13% abv), wild ferments (i.e. the use of indigenous yeasts, for spontaneous rather than winemaker-induced fermentation, that are naturally present in the vineyard and winery rather than shop-bought 'cultured' yeasts), gentle handling, and the use of oak only to support/frame the wine not to flavour it. Style-wise what many look for in a wine and right on-the-money in terms of style and global winemaking trends.

As an aside, spontaneous fermentation by wild aka indigenous yeasts carries much more risk and requires much more focused and attentive winemaking, and increases the winemaker's stress levels no-end as bad things can happen (the fermentation stage tends to be much longer), but it is worth it for the enhanced complexity and terroir expression it brings to the wine. Most of my favourite wines are made this way.

Ten Minutes by Tractor is now highly revered for wines of purity, tension, and very fine rather than muscular structure.

The winemaking breakdown for the McCutcheon Pinot Noir:

20% whole bunches • 30 days on skins in concrete • following pressing, the wine was transferred to 25% new 228 litre French oak barrels for 8 months • natural malolactic fermentation before bottling unfined and with minimal filtration.

NB malolactic fermentation (MLF) is the conversion of sharp malic acid (the acid dominant in green apples) to softer lactic acid (the acid dominant in milk) by lactic acid bacteria (LAB) such as Oenococcus oeni and Lactiplantibacillus plantarum. MLF therefore softens a wine.

MLF can be induced by the winemaker through adding LAB cultures (that come in a packet!) or it takes place naturally (but often more slowly and less predictably). Some winemakers who like to stay safe add the LAB at the same time as alcoholic fermentation so that MLF takes place around the same time.

Some LAB that can be naturally present in wine are spoilage organisms so it helps to know what you've got in the wine by doing frequent analysis; the risk of these causing spoilage can then be minimised by adding the right amount of sulphur dioxide (SO₂) to which these spoilage LAB have low resistance and therefore can't reproduce.

High pH wines are always at more risk of spoilage as bacteria thrive much more at higher pH (3.4 and above) than at low pH - which is why higher pH wines have more SO₂ added as protectant (SO₂ being antimicrobial and antioxidant). Winemakers tend to use Lactiplantibacillus plantarum to complete MLF in high pH wines as this LAB is particularly effective at higher pH.

Temperature is important for MLF to take place - LAB are active above 16°C and optimal up to about 20°C. Winemakers can therefore delay MLF by holding the wine below 16°C to inhibit bacterial activity.

Some winemakers will avoid MLF entirely (e.g. for high acid styles and sparkling wines) by adding SO₂ early on - SO₂ being the primary tool for suppressing the bacteria. In any case, the bacteria struggle at a pH of less than 3.1 and under a pH of 3 is strongly inhibitory. Total SO₂ of around 40 mg/L becomes unfavourable for MLF while 50–60 mg/L can completely inhibit MLF.

Though an important caveat is that SO₂ effectiveness depends on pH, which is why winemakers always want to know what the pH of the grape juice and then the wine is. Another option and perhaps the most reliable way is to sterile filter (although this requires expensive equipment and can strip character), or you can use antimicrobial additives that suppress LAB such as Chitosan (in the form of commercially available professional winemaking products).

Ultimately, what a winemaker really looks to avoid is MLF taking place after the wine is bottled - as a by-product of MLF is carbon dioxide and this will make the wine fizzy when it's not meant to be, not to mention likely making it taste awful as well if the wrong LAB have been responsible!