  Measuring microorganisms in food products is a critical issue for food safety
and human health. Although various approaches for detecting low-levels of
microorganisms in food have been developed, they require high-cost, complex
equipment, invasive procedures, and skilled technicians which limit their
widespread use in the food industry. Here, we present a simple,
non-destructive, non-contact, and rapid optical method for measuring living
microorganisms in meat products using laser speckle decorrelation. By simply
measuring dynamic speckle intensity patterns reflected from samples and
analyzing the temporal correlation time, the presence of living microorganisms
can be non-invasively detected with high sensitivity. We present
proof-of-principle demonstrations for detecting E. coli and B. cereus in
chicken breast tissues.
