O
- Oak
- The most commonly used wood source for fermentation vessel and barrel aging. Oak influence can also be imparted to a wine by the used of oak chips or staves.
- Oechsle
- a measure of must weight
- Oenology
- The science of wine and winemaking.
- Off-dry
- A wine that has the barest hint of sweetness; a slightly sweet wine in which the residual sugar is barely perceptible.
- Orange wine
- A white wine with extending skin contact, similar to red wine production. The opposite of a rosé
- Organic winemaking
- A style of winemaking using organically grown grapes and a minimum amount of chemical additives such as sulfur dioxide.
- Osmotic pressure
- The tendency of water of within two solutions separated by a semipermeable membrane to travel from a weaker solution to the more concentrated one to achieve equilibrium. In winemaking, osmotic pressure is observed in yeast cells added to grape must with a high sugar content. The water in the yeast cell escapes through the cell mebrane into the solution causing the cell to experience plasmolysis, caving in on itself and dying.
- Oxidation
- The degradation of wine through exposure to oxygen. In some aspects oxygen plays a vital role in fermentation and through the aging process of wine. But excessive amounts of oxygen can produce wine faults.
- OTR
- Oxygen transmission rate. A factor of cork closures which shows some variation in their oxygen transmission rate, which translates to a degree of bottle variation.
Read more about this topic: Glossary Of Winemaking Terms