Years ago, I remember using little strips that alerted us to whether the temperature of various objects had changed in transit. I was running a kosher food provider and we were shipping foods across the Northeast corridor, to Southern Florida, Chicago, Los Angeles and a few other clusters where there were plenty of folks who only ate kosher food.
The strips were ok- and probably beyond the state of the art – but we wanted more.

Especially when we know the government has changed the rules on expiration dates since I was young. (What? You really thought something happened to the way we process milk that it went from a routine 5 to 7 days expiration date to almost 15?)

But, now, a group of technologists at the Technion (that’s the Israeli version of MIT or Caltech) have found a way to identify if bacterial contamination abounds in food and water. Under the direction of Dr. Ester Segal (Biotechnology and Food Engineering), the research group has developed a nanoscale device, based upon a silicon chip, that captures bacteria and determines if the product is at risk. Instead of taking 24 to 168 hours to determine if there is bacterial contamination, the results are available in minutes.

Dr. Segal has been working in this area for some years, having started her work at UC San Diego about 8 years ago. Now, with her group of grad students, she has been using a porous silicon dioxide wafer (thin-film) as an optical transducer, in conjunction with a polyacrylamide hydrogel which comprises the active biosensor component. Monoclonal antibodies (IgG) are immobiized on the gel to yield predicable changes in the optical characteristics of the hybrid. Her most recent research was published in Advanced Functional Materials.

The work to date has centered upon using e. coli  (standard bacteria) as the model, which is both a ubiquitous and potentially dangerous (at least certain hybrids are) microbial culture. Given the hydrogel works as a receptor and the silicon wafer as transducer, cell densities of 1000 to 100,000 per milliter are detected within minutes.

Right now, testing is being effected in the Netherlands, because this country does not employ chlorine as a water disinfectant. (They use a more transient chemical- ozone- that is dissipated in seconds to minutes.) As such, potential contamination is of greater concern- and the residual chlorine won’t interfere with the test results.

Let’s hope it works. I’d like to know what IS growing in my fridge.

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