"fruit juice" vs "fruit juices" How can such liquid substance as "juice" be pluralized unless it is contained in a can, bottle etc.?

Question

While reading this article from Bangkok Post.com, I noticed the word "juice" and its plural form "juices" are both used.

Consumers have long regarded fruit juice as a healthy option, especially when compared to carbonated soft drinks. But many credible scientific studies have found that drinking fruit juice is not the same as consuming fruit, because some commercial fruit juice products contain as much sugar as soft drinks, sometimes even more.

Such findings have been bad news for producers of mass-market fruit juices, as consumers are now looking for healthier alternatives.

... Many of these writers have noted the misconceptions about the health benefits of fruit juices and warned about high sugar content in some brands.

It isn't difficult to guess from the context that the "fruit juices" probably refers to fruit juice products, but if that is the case, I thought the writer should have written so.

Collins Dictionary defines "juice" and "juices" as below.

Juice:
1. Juice is the liquid that can be obtained from a fruit.
2. The juices of a piece of meat are the liquid that comes out of it when you cook it.
Juices:
1. the liquid that comes out of a piece of meat when it is cooked
2. the liquid that occurs naturally in or is secreted by plant or animal tissue

I wonder which one of the four definitions above is applicable to the "juices" described in the article.

Answer 1

Juice, like water, is usually uncountable, but it can be countable if used as a collective noun where there is more than one collection.

For example, the water in a glass is "some water". But when ordering two glasses of water, some might idiomatically ask for "two waters".

If you had a small amount of juice in a glass, or gallons of it, you could use "juice" to refer to it all. But if you had some orange juice, some pineapple juice, and some mango juice - you have three different juices. "Juice" then becomes a collective noun for each type of juice. Similarly, like my example with water, some may idiomatically order two glasses of juice by asking for "two juices".