From an interview with Alissa Hamilton, author of the forthcoming book Squeezed: What You Don't Know About Orange Juice:
What isn't straightforward about orange juice?
It's a heavily processed product. It's heavily engineered as well. In the process of pasteurizing, juice is heated and stripped of oxygen, a process called deaeration, so it doesn't oxidize. Then it's put in huge storage tanks where it can be kept for upwards of a year. It gets stripped of flavor-providing chemicals, which are volatile. When it's ready for packaging, companies such as Tropicana hire flavor companies such as Firmenich to engineer flavor packs to make it taste fresh. People think not-from-concentrate is a fresher product, but it also sits in storage for quite a long time.
So parse the carton for us. For example, what is the phrase "not from concentrate" really about?
In the '80s, Tropicana had a hold on ready-to-serve orange juice with full-strength juice. Then this new product, reconstituted orange juice, started appearing in supermarkets. Tropicana had to make decisions. Storing concentrate is much cheaper than full-strength juice. The phrase "not from concentrate" was to try to make consumers pay more for the product because it's a more expensive product to manufacture. It didn't have to do with the product being fresher; the product didn't change, the name simply changed. Tropicana didn't want to have to switch to concentrate technology.
Q&A with Alissa Hamilton (Boston Globe)