If you like to drink your vegetables rather than eat them, you'll be happy to learn that vegetable juices are low in calories and sugar, and rich in nutrients such as vitamin C and beta carotene. To limit added salt and sugar, you may be fond of making your own fresh juice, especially from tasty veggies such as tomatoes. However, unlike bottled and canned tomato juice, fresh tomato juice doesn't go through any pasteurization and has a very short shelf life. Knowing how to tell if your fresh tomato juice has spoiled may help prevent an unfortunate swig.

For the best taste, fresh tomato juice should be consumed immediately. If you're making extra juice, store it in a tightly covered container in the refrigerator for up to 24 hours at 40 degrees Fahrenheit. Use a refrigerator thermometer to make sure the temperature is cold enough; this will keep all your food safe, not only your fresh tomato juice. If you've made enough juice to last a few days, put the extra in a freezer-safe container and freeze it. Fresh frozen tomato juice can be stored in the freezer for up to six months. Once thawed, however, drink your juice within 24 hours.

If it's been longer than 24 hours since you made your juice, or if you're fearful it has spoiled, there are a number of ways you can tell. First, look and see if you notice any discoloration. If so, it's possible your juice has spoiled. If you see mold, you'll want to toss the juice right away. A sour odor may also be an indicator that your juice has turned. If it smells like alcohol or vinegar, your juice has fermented and is no longer safe to drink. If you can't tell by sight or smell, a sip may be able to give you the answer. However, you risk illness, so it's best to err on the side of caution – if in doubt, throw the juice out.

While storage is certainly an important step in keeping your fresh tomato juice from spoiling, so is proper preparation before you juice. For safety, use fresh tomatoes free of bruising, cuts and mold within three days of purchase or picking. Wash the tomatoes in hot soapy water or a sanitizing solution of 1 teaspoon of chlorine bleach in 1 quart of water, or 1 cup of white vinegar mixed with 3 cups of water, and then scrub and rinse them thoroughly under running water.