Frozen concentrated orange juice used to dominate the orange juice market in the United States. In 1989, frozen juice accounted for about 42 percent of all orange juice sold in U.S. retail markets, according to the University of Florida’s Cooperative Extension. By 1998, however, frozen concentrate represented only 21.5 percent of the market. Ready-to-drink orange juice has come to rule the O.J. market, and supermarkets today boast a variety of pasteurized ready-to-drink orange juice.
Ready-to-drink juice is heavily advertised and attractively packaged. With images of fresh-cut oranges on brightly colored cartons, who would doubt that the juice they contain is superior to the concentrate packaged in frosty little cans?
Scientists who have measured the vitamin C content in America’s favorite juice, that’s who.
Researchers at Arizona State University recently compared orange juice from frozen concentrate with ready-to-drink juice packaged three different ways. The team found that at four weeks before the expiration date, the level of vitamin C in orange juice varied greatly with its packaging. They also found the level decreased each week for juice in all forms of packaging, as light and oxygen attacked the vitamin.
According to this study, just after the frozen concentrate was mixed with water, it had the highest levels of the most biologically useful form of vitamin C, known as reduced ascorbic acid. Ready-to-drink juice in screw-top waxed cartons ranked second, followed by screw-top plastic containers and then non-resealable waxed cartons.
The researchers offered the following explanation. Unlike frozen concentrate, ready-to-drink juice is pasteurized, a process that partly accounts for the juices starting off at different levels of vitamin C. Frozen juice’s low temperature also lessens the chemical activity of oxygen that degrades vitamin C.
Over time, levels of reduced ascorbic acid fell for all the juices tested. Over four weeks in the refrigerator, reconstituted juice stored in screw-top plastic containers had lost reduced ascorbic acid at the same rate as ready-to-drink juices did, but it ended up with more because the reconstituted juice started at a higher level. As time passed, the ready-to-drink juice in plastic screw-top containers maintained higher levels than screw-top or non-resealable waxed paper cartons.
‘The key point is for consumers to try to consume orange juice as soon as possible after purchase,’ whatever they purchase, said Lola O’Rourke, spokesperson for the American Dietetic Association. She suggested that consumers purchase orange juice in containers small enough to be quickly finished.
Fortunately, few Americans will suffer acutely even if vitamin C consumption falls short of recommended levels, explained Jeffrey Blumberg, a specialist in dietary antioxidants and chronic disease prevention at Tufts University.
‘You’re not going to drop dead,’ Blumberg said, yet consuming enough to prevent scurvy but less than the recommended daily allowance can ‘have this consequence of developing a sub-clinical deficiency which is associated with poor health outcomes later in life.’ Such outcomes can include hypertension, progressive damage to the cardiovascular system, and increased risk for complications during pregnancy.