It's not a discoloration. It a sign that the tomato was picked a bit too early.

Unripe tomato: All is green.

The green matter is made up of Chlorophyll, starches, sugars, acids, and all the rest of what make up a tomato. Chlorophyll is responsible for the green color, as it is in leaves. As a tomato ripens, the chlorophyll breaks up and Carotene and Lycopene are increased[1]. Carotene and lycopene are what creates the red-to-purple color of ripe tomatoes.

1. Caroteni e clorofilla nei pomodori in maturazione

Don’t throw away that gel surrounding tomato seeds! The color of the gel can vary, according to age of the fruit and the cultivar of the plant. It can be greenish, yellow, red, or brownish. The gel nourishes the maturing seeds, and helps prevent premature germination. It also protects the seeds while they remain dormant through the winter.

Although the gel and seeds (“pomace”) are usually discarded when manufacturing tomato products, plenty of health benefits are associated with consuming them. The gel has similar effects as aspirin in “anti platelet activation”, iow, reducing clotting. But, unlike aspirin, the gel doesn’t cause excessive bleeding. NutritionFacts.org | The Latest in Nutrition Related Research has a video— Inhibiting Platelet Activation with Tomato Seeds | NutritionFacts.org- che spiega i benefici cardiovascolari del gel di semi di pomodoro.

Ho sempre mangiato questa roba, semi e tutto, e avevo letto anni fa di qualcosa nel gel che fa bene. Così ora entrambi sappiamo perché.