Items you will need
Degrees Brix measures the sugar content in a solution such as fruit juice or syrup. In wine making calculating the amount of sugar present in the grape juice allows you to estimate the alcohol content of the finished product. One degree Brix equals one gram of sugar per 100 grams of solution, or 1 percent sugar. You can purchase a refractometer that gives readings in degrees Brix. The refractometer measures how much light refract as it passes through a substance. Light bends more in a substance with higher sugar content.
Pick up a little of the test liquid in the eyedropper. Squeeze two or three drops onto the lens of the refractometer.
Close the cover of the refractometer. Look through the refractometer eyepiece and read the scale where the color changes.
Record the scale reading to the nearest 10th of a degree. Use units of degrees Brix; you can abbreviate the unit with the degree symbol and "Bx."
To measure degrees Brix for fruit, mash a small piece of the fruit. Wrap the mashed fruit in cheesecloth and squeeze or wring it to obtain juice for the refractometer.
Multiply the degrees Brix in unfermented juice by 0.55 to estimate the alcohol content of the finished wine.