MS Topic of the Week 11/23/2019 - Introductory & Certified

Aszú 101 last week from , and . As Inderpal pointed out, essencia is made from the free run which is gathered before taking the fruit and adding it to base wine. Guess how many kilograms of fruit it takes to produce three 750ml bottles worth of essencia? 800!!

This week: Malolactic fermentation

When is this employed and why? What causes it? What is the result from a flavor and texture standpoint?

  • MFL is technically not a fermentation but rather a decorboxylation of  the sharper (L) Malic acid (think green apples) to  (L) lactic acid (think milk). The results are a slight amount of alcohol, some diacetyl, reduction of pH polysaccharide formation (increased mouth-feel), and reduction of primary aromas. All these outcomes vary depending on when the MLF begins, what bacteria are used and temperature control. Diacetyl production can result in (toast, popcorn, hazelnuts) in white wines and (chocolate and roasted aromas) in red wines.

    It occurs more often than not for red wine production to add mouth feel and increase stability of the wine for bottling, by consuming bacterial nutrients. Due to more extraction in red wine production the diacety molecule rarely becomes perceptible. With reduction of primary aromas, one would use it sparingly in wines that the primary aromas are desired or in lighter red wines (Pinot Noir) as it can cause a slight reduction of color.

    For white wine production it becomes a stylistic decision. Again, there is a trade off where you gain stability but lose primary aromas. So varieties like Gewurtz, Riesling, Chenin Blanc would completely change the style of these wines. Also wines like Sauvignon Blanc, that have a signature acidic tang would reduce the acidity and result in a wine less 'bright'.

    The process can occur spontaneously but usually, for control, inoculation is performed by using certain strains of bacteria. Traditionally done after primary fermentation, producers have experimented inoculation at different times before end of primary fermentation. Also, Oenococcus oeni has been the bacteria used but experiments with Lactobacillus and Pediococcus due to different aromatics created and differing levels of diacetyl created. 

    We could talk about how to prevent and encourage based on sulfur addition, temperature range, etc but I think I have said enough.

    Some examples:

    Andy Howard MW remarks that trends have shifted from big bold wines to light crisp wines so the decisions of the winemakers change as well.

    Cote d' Or whites usually go through MLF

    Chablis wines usually avoid it

    Traditionally Swiss wines went through full MLF resulting in some flabby wines. This has changed to partial MLF and better balance.

    Most base wines for sparkling go through MLF for stability prior to second ferment

  • trivia:

    Which winery boasts the world’s first temperature-controlled malolactic steel tanks?

    Hanzell in Sonoma.

  • Awesome breakdown! My only comment is that most Chablis does go through ML due to high levels of TA. Every producer that I talked to when I was there in April utilizes it.

  • Christopher,

    Thank you for the information. I would not have guessed that for a number of reasons. I will make the corrections in my notes and do some further research. Always great to hear from the producer themselves. Thanks.

  • It overall reduces pH as well so is often used in cool climate regions where the ph/acidity maybe too aggressive so you desire reduction (think Chablis).

    One of the reds to NOT go through Malo is Red Vinho Verde for what that's worth.

  • So if you don't mind explaining, what is a normal level of TA and what is a high level of TA?