There are nine challenges to focus on when incorporating probiotics into food matrices. They are: 1. strain selection, 2. strain production, 3. how to inoculate food, 4. how to ensure survival during processing, 5. how to avoid loss of viability during storage, 6. how to calculate [Probiotics] Colony count, 7. Effects on food sensory properties, 8. [Preservation of product] stability in consumers' homes, 9. And play a role in the gastrointestinal tract.
Specifically, in juices, organic acids often bring the pH of the product below 4, which will inhibit the survival of probiotics. In selection, those probiotics that tolerate low pH should be considered, such as Lactobacillus over Bifidobacterium.