Antioxidants decrease an average of 32% after 6 months on the shelf, according to a 2009 study in the Journal of Food Science. These antioxidants, known as catechins, may decrease your risk of several types of cancer, but they are sensitive to both oxygen and light. Sadly, tea, unlike wine, does not improve with age.
Make it last: "Buy tea in airtight packages such as tins, rather than cellophane wraps, which air can penetrate," advises Rona Tison of ITO EN, the world's largest supplier of green tea. Store your tea bags in sealed, opaque canisters in a cool spot. "Green tea is more sensitive to heat than black tea, so place your sealed container in the refrigerator to keep the leaves fresh and healthy for as long as possible," she says.
Make it last: Skip the premade tomato sauce and make your own using boxed whole or diced tomatoes rather than pureed. Whole and diced tomatoes contain more solids, which provide added protection for the lycopene, says B. H. Chen, PhD, a food scientist at Fu Jen University in Taiwan who analyzes the stability of carotenoids. If ketchup sits in your fridge for months, buy smaller bottles, says Christine Gerbstadt, MD, RD. Fresh bottles tend to start off with higher levels of lycopene.
The potency of antioxidants declined 40% after 6 months, according to a 2009 Italian study of bottled olive oil in the Journal of Food Science. Yet in many households, bottles can sit on the shelf for much longer than that.
Make it last: Don't store oil near the stove or leave it uncapped for long, as it's sensitive to oxygen, heat and light, says Doug Balentine, PhD, director of nutrition sciences at Bertolli, an olive oil producer. If you don't cook with it often, buy smaller bottles.
Grains and dry goods
The riboflavin in enriched macaroni plummeted 50% after being exposed to light for only a day, according to a Journal of Food Science study. Even dim light can degrade riboflavin by 80% after 3 months, according to another study. The folic acid in enriched flour is also sensitive to both light and oxygen.
Make it last: Store grains in opaque ceramic containers, far from the stove's damaging heat. A dry cupboard is better than the fridge, except in the case of brown rice, which contains a small amount of oil and therefore spoils faster at room temperature.
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