I often make salsa containing tomato, onion, garlic salt, green pepper, red pepper, lemon, and salt. I store it in a Glasslock container in the refrigerator. By the second day, the taste is still reasonable. By the third day, though it starts to get a strange smell and has a strange appearance, sometimes with white dots, perhaps from mold.
Is there anything I can do so that the salsa stays fresh for at least three days?