As a sommelier and brewer, I have had the pleasure of exploring the many nuances and complexities of wine. One aspect that often intrigues wine enthusiasts is the texture of a wine, particularly when it has an oily or creamy sensation on the palate. So, what exactly makes a wine oily?
The key factor that contributes to the oily texture in wine is the presence of certain bacteria, specifically Oenococcus oeni and various Lactobacillus strains. These bacteria play a crucial role in the winemaking process, particularly during malolactic fermentation.
During malolactic fermentation, the malic acid present in the wine is converted into lactic acid. This process is carried out by the aforementioned bacteria, which consume the malic acid and excrete lactic acid as a byproduct. It is this conversion that gives rise to the characteristic creamy texture in some wines.
To better understand this process, let's delve into the science behind it. Malic acid is a naturally occurring compound found in grapes, contributing to their tartness. However, it can also impart a sharpness or harshness to the wine. By converting malic acid into lactic acid, the bacteria help to soften the overall acidity of the wine, resulting in a smoother and more rounded mouthfeel.
The lactic acid produced by the bacteria has a different chemical structure compared to malic acid. It possesses a higher molecular weight and a slightly oily consistency, which contributes to the perceived “oily” texture in the wine. This velvety sensation can be particularly noticeable on the middle of the tongue, adding depth and complexity to the overall tasting experience.
It's important to note that not all wines undergo malolactic fermentation, and therefore, not all wines will exhibit an oily texture. Winemakers have control over whether or not to encourage malolactic fermentation, depending on the desired style and characteristics of the wine they wish to produce. Some wines, such as crisp and acidic whites, are intentionally prevented from undergoing this fermentation process to maintain their fresh and vibrant profile.
On the other hand, many red wines, particularly those with a fuller body and higher tannin levels, often undergo malolactic fermentation naturally. This can be attributed to the presence of lactic acid bacteria, which are more prevalent in red wine production. The result is a wine with a luxurious, almost buttery mouthfeel that enhances the overall richness and complexity of the wine.
In addition to malolactic fermentation, other factors can contribute to an oily texture in wine. For instance, extended aging in oak barrels can impart a creamy mouthfeel due to the presence of compounds such as lactones. These compounds are extracted from the wood and can contribute to the overall texture and flavor profile of the wine.
The oily texture in wine is primarily a result of malolactic fermentation, where bacteria convert malic acid into lactic acid. The lactic acid produced has a slightly oily consistency, adding a velvety texture to the wine. This process can be desired or controlled by winemakers, resulting in wines with varying levels of creaminess. So, next time you come across a wine with an oily sensation, you can appreciate the fascinating microbial processes that contribute to its unique character.