Home Brewing & Wine Making Glossary Terms
2 terms related to home brewing & wine making, explained in plain English.
What Does Original Gravity (OG) Mean in Home Brewing?
Original Gravity is a measurement, taken before fermentation starts, of how much fermentable sugar is dissolved in the wort or must — the higher the OG, the more sugar is available for yeast to convert into alcohol. Comparing OG against the Final Gravity (FG) reading taken after fermentation lets a home brewer calculate the approximate finished ABV of a beer or wine.
What Is an Airlock and Why Does Home Brewing Need One?
An airlock is a small valve fitted to a fermentation vessel that lets carbon dioxide produced during fermentation escape while stopping outside air (and the airborne bacteria or wild yeast it carries) from getting in and spoiling the brew. Watching bubbles pass through the airlock is also a simple, low-cost way to visually track whether fermentation is still active or has finished.