How To Know If Spaghetti Sauce Has Gone Bad

While unopened cans can be kept and used up to a yera past their expiration date, when it comes to opened jars of spaghetti sauce, the directions by the manufacturer might be a good place to start, Eat By Date. They can vary depending on the brand and kind of sauce. However, there are other determinants like if the sauce was homemade or store-bought and if it was left out at room temperature before going in the fridge, according to Food Champs. 

There are also some warning signs to look out for before you use that opened can of spaghetti sauce. A change in color and texture might be the first sign you see, per Lacademie, although you won't need to throw it in the garbage just yet. If your sauce has turned from red to a darker shade and if the texture has become denser, that means it's losing its quality, so you might want to use it soon. Definite signs of decay, however, will manifest as mold (green or white) on the surface or lid, white fluid sitting atop the sauce, and a putrid smell once you open the lid. 

Although tomato-based spaghetti sauces take longer to spoil because of the inherent acidity in the product (via Pasta Evangelists), the telling signs are a good indicator for when they've gone bad. Homemade sauces might spoil faster because they don't contain preservatives.