Biospeckle Decorrelation Quantifies the Performance of Alginate-Encapsulated Probiotic Bacteria

In recent years, the use of probiotics in food and health has increased so much that usually market offers several functional fermented food or nutraceuticals containing probiotics, often also associated to prebiotics. Both in food industry and in pharmaceutics, it is very important the development and use of methodologies that quickly allow a precise overview about the microbial population present in a specific biological matrix, and to monitor over time any changes that it may undergo. In this paper, we propose biospeckle decorrelation as a tool for the fast evaluation of the effectiveness of microencapsulation as a preservation system. Although speckle grains are often treated as an impairment for imaging, they represent a precious source of information. Such information is rich enough to characterize bacterial dynamics in a fast and simple way suitable for applications in food science and industry. In fact, here we show that through biospeckle decorrelation it is possible to quantify the shelf-time of alginate-encapsulated probiotic bacteria and their survival rate under simulated gastrointestinal conditions.