Let's go back a few thousands of years. There were no refrigerators, and juice-production facilities were not very clean. Also, people were not aware of the exi

Let's go back a few thousands of years. There were no refrigerators, and juice-production facilities were not very clean. Also, people were not aware of the existence of bacteria and germs. And given these conditions, you want to drink juice, or the best available alternative, at any arbitrary moment during the year... The solution? fermentation. Just ferment the hell out of everything and store it for years. Now you can drink juice anytime you want, it just tastes weird but it's better than nothing.