Lemon juice and vinegar are both acidic elements that balance and bind the other flavors in chili sauce recipes. You can substitute lemon juice for vinegar in chili sauce made in small batches meant for immediate consumption. There are some tricks, though, to substituting the two when cooking chili sauce in larger batches for canning.
Substitute equal amounts of lemon juice for vinegar when making chili sauce. The juice from one medium-sized lemon equals four tablespoons of vinegar. Lemon juice is more acidic than vinegar but less flavorful. Use lemon juice to add acidity without competing with the other flavors in the chili sauce. Use vinegar if you desire a tangier sauce.
Fresh Lemon Juice vs. Bottled
Fresh lemon juice has a vibrant flavor not found in bottled lemon juice but, since it has been commercially processed, the bottled lemon juice has a longer shelf life. Use fresh lemon juice for chili sauce that will be eaten the same day it is made. Store any leftovers in the refrigerator and use within a couple of days. Chili sauce made from bottled lemon juice will keep in the refrigerator for a week to 10 days.
Store chili sauce made with lemon juice in the refrigerator. Vinegar is a preservative. If vinegar is a main ingredient in a thin, liquid-based chili sauce, it is OK to store it at room temperature for a week or two but not indefinitely. Thicker chili sauces of a more paste-like consistency should be stored in the refrigerator, where they will keep for a month or more.
Canning Chili Sauce
The key to safe, successful canning of vegetable-based foods, including chili sauce, is acid content. Always use distilled vinegar of a 5 percent acidity level when canning. Use only bottled lemon juice, never fresh. Lemon is more acidic than vinegar so it is safe to use lemon juice when a canned chili sauce recipe calls for vinegar. Do not substitute vinegar when a recipe for canned chili sauce specifies lemon juice. Use only lemon juice to keep the sauce at a level of acidity safe for canning and long-term storage.