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Lecture Hall A1 SPIE Optical Metrology > Optical Methods for Inspection, Characterization, and Imaging of Biomaterials IV > Advanced Diagnostics by Speckle Techniques
11:50-12:10 h | Hall A1 Room 8 "Gustav Hertz"
Subjects: Optical Measurement Systems / Optical Metrology
Chairman: Aydogan Ozcan (, Univ. of California, Los Angeles)
Bacteria are often associated with the insurgence of diseases and many efforts have been made to develop methods for accurate identification of bacteria in food for industry and new generation smart farms. Hence, the use of field portable sensors able to detect bacteria in meat, vegetables or fruits is highly demanded. On the other hand, there is a wide category of “good” bacteria that are used in food and pharmaceutic industry. In particular, probiotics are microbial species that have been demonstrated to confer benefits to health. A sufficient concentration of probiotics in the intestine acts against pathologies such as obesity, diabetes, etc. However, if probiotics are not able to maintain their viability during their transit through the gastro-intestinal apparatus, they cannot act to enhance the immune system. The use of alginate microcapsules is one of the most common methods of preservation, applicable to several biological matrices, including probiotics. Whenever food products or pharmaceutical formulations contain microencapsulated probiotics, it is important to quantify the effectiveness of micro-encapsulation as a microbial protection system over the time, e.g. during the shelf life of a functional product containing encapsulated probiotics, conserved in the supermarket, and during gastro-intestinal transit. Here we use bio-speckle decorrelation as a tool for the rapid assessment of microencapsulation effectiveness. Although speckles are often thought as a source of noise, these can be fruitfully used to increase the sensitivity of coherent imaging sensors. Thus, it is possible to characterize bacteria motion and to use it as a contrast agent for applications in food science and industry. Through bio-speckle decorrelation, we detect the presence of bacteria in food without any chemical analysis. Moreover, we quantify the shelf-time of alginate-encapsulated Lactobacillus rhamnosus and Lactobacillus plantarum probiotic bacteria and their survival rate under simulated gastro-intestinal conditions.