Dec. 16, 2011— -- Natalya Murakhver, a New York food writer and mother of an 18-month year old daughter, loved her premium brand orange juice -- the "100 percent pure" and "not from concentrate" kind that comes in the colorful carton and tastes consistently delicious.
That is, until she said she learned from her first-time moms group that there's a "secret ingredient" in premium orange juices that companies are not required to put on their labeling.
"One of the moms said she had read about [how the juice is made] and they held it in tanks for up to a year and it pretty much lost all of its flavor and had to be reinvigorated with these flavor packs, which are essentially chemicals," said Murakhver, 40, and co-author of "They Eat What?: A Cultural Encyclopedia of Weird and Exotic Food from around the World."
In Murakhver's case, the juice her family drinks, Whole Foods' "365," apparently bucks common industry practice. Whole Foods told ABCNews.com that it does not include flavor packets in its juices, nor does it use long-term storage tanks before shipping juice to customers.
But the industry as a whole says that the methods generally are essential for keeping up with consumer demand for orange juice.
For the last 30 years, the citrus industry has used flavor packs to process what the Food and Drug Administration identifies as "pasteurized" orange juice. That includes top brands such as Tropicana, Minute Maid, Simply Orange and Florida Natural, among others.
Murakhver said the addition of the flavor packs long after orange juice is stored actually makes those premium juices more like a concentrate, and consumers need to know that.
Experts estimate two-thirds of all Americans drink Florida orange juice for breakfast, and companies spend millions on their marketing campaigns touting its health benefits.
The "not from concentrate" brands appeared on store shelves sometime in the 1980s to differentiate them from frozen juice and other bottled concentrates. Despite its high price tag -- now up to $4 a carton -- sales of the premium brands have soared.
But those juices don't just jump from the grove to the breakfast table.
After oranges are picked, they are shipped off to be processed. They are squeezed and pasteurized and, if they are not bound for frozen concentrate, are kept in aseptic storage, which involves stripping the juice of oxygen in a process called "deaeration," and kept in million-gallon tanks for up to a year.
Before packaging and shipping, the juice is then jazzed up with an added flavor pack, gleaned from orange byproducts such as the peel and pulp, to compensate for the loss of taste and aroma during the heating process.
Different brands use different flavor packs to give their product its unique and always consistent taste. Minute Maid, for example, has a distinctive candy-sweet flavor.
Kristen Gunter, executive director of the Florida Citrus Processors Association, confirmed that juices are blended and stored and that flavor packs are added to pasteurized juice before shipping to stores.
Flavor packs are created from the volatile compounds that escape from the orange during the pasteurization step.
But, she said, "It's not made in a lab or made in a chemical process, but comes through the physical process of boiling and capturing the [orange essence]."
The pasteurization process not only makes the food safe, but stabilizes the juice, which in its fresh state separates. Adding the flavor packs ensures a consistent flavor.
The United States Department of Agriculture (USDA) grades the quality of the juice based on color, flavor and defects.
"To get grade A, we have to blend it," she said. "Because oranges and their growing seasons vary, both the Valencia -- 'king of the oranges' -- and its lesser cousin, the Hamlin, are combined in the process.
"A processor is faced with harvesting the crop and giving the consumer some sense of what [he or she] might be getting," she said. "You buy branded orange juice, you kind of want it to taste, generally, the same. That expectation is met by blending different varieties and, in order to blend, storage is involved."