There are several methods to preserve homemade tomato sauce, which allows one to make healthy pasta sauces from fresh tomato products and use them throughout the year. This is a great way to have a better product – one that uses olive oil instead of canola, and minimal sugar, for example – than what's available in mass market production. Spaghetti sauce may be frozen or jarred (canned) for best results. With high-acid tomatoes, a water bath may work; typically, however, pressure canning is necessary.
A good way to get started is to make a double batch when preparing tomato sauce for pasta as part of the regular family menu. After dinner, freeze all the leftover sauce in a well-sealed freezer container. Be sure to leave enough headspace – room above the sauce under the lid – to allow for expansion while it undergoes the freezing process. This is a simple and painless way to get extra tomato sauce into the freezer, one batch at a time. Another idea is to make a quadruple batch of your regular sauce and freeze all of it in four separate containers so that just enough for one meal may be taken out at a time.
Having frozen sauces on hand, fully prepared with spices, meat and veggies as desired, is very convenient for weekday meal prep, even with busy schedules and lives. The sauce may be defrosted in the fridge for a couple days ahead of time, or taken out a few hours before dinner for last-minute menus.
When using frozen tomato sauce, allow it to defrost at room temperature or put the frozen sauce into a pot on low until it is fully liquid again; then raise the temperature to bring the sauce to desired hotness. The crockpot, set on low, is another way to gently bring the preserved sauce from its frozen state to an edible temperature. Turn it up to medium or high for the last 30 minutes if needed.
Canning tomato sauce is a great way to preserve your tomatoes while saving freezer space and allowing for long-term storage. Modern canning techniques and standards make this a safe endeavor. Highly acidic tomatoes are preservable with water bath canning methods, but prepared sauce with oil, spices, and other ingredients should be pressure canned as the acidity level changes with added ingredients. Spaghetti sauce with meat must always, without exception, be jarred using a pressure canner. Any product with meat or meat-based broth needs pressure canning to be a safe product.