These days, there is increased awareness among consumers for the safety of food products they consume. Consumers' growing demand for fresh and appropriate forms of products has led to the advancement of food safety practices in the food industry. Moreover, the relatively high occurrence of outbreaks of foodborne diseases in many countries, including developed ones, has resulted in increasing concern and intensive investigation of foodborne pathogens. As a result, there is currently an increased demand for the microbiological testing of food products.
Microbiological testing can outline important information about a manufacturing process, processing environment, as well as a specific product batch. It also informs whether a sampling/testing procedure is correctly designed and finished following regulatory guidelines or not.
However, one must understand that microbiological testing cannot determine 100% safety from pathogens, as tests are done using samples, which are only a portion of the food products.
Although a wide range of technologies is used for the identification and verification of microorganisms, among these technologies, three types of methods are commercially popular.
A special medium that is used in microbiological laboratories to identify and detect different types of microorganisms by culturing or growing. Usually, a culture medium is composed of different nutrients to enhance microbial growth.
Traditionally, cultural techniques have been the tests of choice for both ready-to-eat foods and fresh produce. However, today immunoassay and PCR methods are more accepted than cultural methods, because recent developments of newer testing methods and validation studies have demonstrated that cultural methods aren't suitable for all food groups.
Immunoassay can be illustrated as a microbiological test that is used to measure the concentration of a macromolecule in a solution via using an antibody or immunoglobulin. The detected macromolecule from an immunoassay method is in many cases a protein and is widely termed as an "analyte". These analytes in biological liquids -- e.g. urine or serum -- are often measured following immunoassay test methods for various purposes.
PCR is a very recent and revolutionary method developed by Dr. Kary Mullis in 1983. Today, it is used in medical and biological research labs as a common and often indispensable technique for a variety of applications.
A PCR test can recognize pieces of DNA or RNA, which are expected to be unique to the target microorganism. PCR is based on using the ability of DNA polymerase and can generate billions of copies of a specific DNA sequence.