The United States Department of Agriculture is responsible for establishing and maintaining standards for a variety of different agricultural products. This includes the grading of red tomatoes, which is based on a number of different parameters, including different levels of ripeness. These levels are classified as ripening stages and provide a means to visually grade red tomatoes.
In the first stage of ripeness, referred to as "green," the fruit surface is completely green. The shade of color can vary from light to dark green. There are no other colors present on the surface of the tomato.
With the next stage, there is a definite break in color of the tomato from green to tannish-yellow, pink or red. This color change occurs on 10 percent of the tomato's surface or less. Because of this break in color, tomatoes in this class are called "breakers."
Tomatoes classified as "turning" show a definite change in color from green to tannish-yellow, pink or red in more than 10 to 30 percent of the surface of the fruit. The percentage is an aggregate of any combination of colors other than green.
In this stage, the tomatoes will show from 30 to 60 percent as not green. The aggregate amount of colors shows true pink or red with no yellow at all. Tomatoes in this stage are referred to as "pinks."
Tomatoes that have an aggregate skin color of 60 to 90 percent pinkish-red or red are classified as "light red." Some green may still show.
When more than 90 percent of the surface of a tomato is not green and the aggregate color is primarily red, a tomato is said to be at the "red" stage. This is the final ripeness classification in the USDA Ripeness Stage Standard for red tomatoes.