Pure Science

Food safety is of paramount concern among consumers, as seen from the melamine contamination of milk products in China in 2008 and oil contaminated seafood in 2010. Product fraud or the adulteration of food is also a pressing issue evident in the industry today.

Product fraud involves the falsifying of a registered trademark in order to deceive consumers, which is also known as economically motivated adulteration (EMA), where a fi nished product has been intentionally modifi ed for economic gain, such as the substitution of a cheaper ingredient. In packaged or frozen seafood, it is apparently easy to replace expensive fi sh such as the red snapper with others of a lower value.

Analysts estimate that food product fraud may cost the food industry between $10-15 billion a year. In 2008, the melamine contamination of milk products due to adulteration reportedly cost the industry $10 billion and affected almost 300,000 consumers worldwide.

Such food substitution scams often result to financial damage and loss of consumer confi dence, which can seriously wreck the commercial market – consumer health is at risk when people purchase potentially harmful products. Marine conservation and management programs that are meant to preserve and protect habitats and endangered species would also be less effective to implement.

Safety measures
The industry therefore needs to improve the detection and prevention of food fraud in order to maintain consumer confi dence on food and beverages. Currently, regulatory bodies are conducting safety checks of food products offered by processors, distributors, importers, restaurants and supermarkets to eliminate all possible cases of fraud.

Regulatory organizations of the European Commission (EC) have on January 1, 2010 established product labeling laws that help to prevent and eliminate illegal and unregulated fi shing. All fi sh products imported into the EU after that date must be accompanied by catch certificates.

Combating fraud
More food companies are using technology to help ensure product traceability, as well as perform checks for safety and authenticity in the food distribution network. Deoxyribonuc leic acid (DNA) -based methods have recently become the preferred method to detect species of seafood because it is accurate, reliable and easy to use. They are also more efficient than the traditional methods of detecting seafood species that are often faulty due to the potential for inaccurate analysis and its ineffectiveness in differentiating closely related species.

Polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP) is popularly used to identify seafood using DNA analysis. This technique does not require expensive equipment. It is approved in many countries to determine seafood species. Researchers at Campden BRI in England have even developed a PCR-RFLP method that uses labon- a-chip technology.

The analysis and interpretation of results are generated automatically using the lab-on-a-chip technology. The resolution of the technology detects DNA fragments that may be small for visualization. An automated lab-on-a chip device generates the fragment patterns, compares them to a database of fi sh species, and generates a species match. The process typically takes less than six hours. It is fl exible and adaptable as the database can record thousands of species to accommodate new information and cater to future needs.

Ensuring safety
Checking for safe products involves the testing for possible harmful compounds ranging from small molecule compounds such as pesticides, mycotoxins, drugs and toxic trace elements to the presence of agents like bacterial and viral agents,which can cause food-borne illnesses (Salmonella). Chemical and biological tests are also commonly conducted. High performance liquid chromatography/mass spectrometry (LC/ MS) systems provide reliable and routine screening, identifi cation and quantifi cation of ultra-trace levels of various harmful components. Chemical testing using sensitive LC and LC/MS solutions provide rapid and reliable analyses.

Other techniques that can provide results in a matter of hours include richer media and stimulants that speed growth, as well as immunomagnetic methods concentrate cultures. The testing process can be shortened by using immunoassay to identify the microbes, rather than traditional selective culturing and staining techniques.

PCR can be used to amplify the genetic material of suspected microbes, a process that is similar to forensic DNA identifi cation. The positive identifi cation of the microbes present in a food sample can be done in hours. The USDA currently uses PCR-based tests to detect bacteria such as E. coli, Salmonella and Listeria in food and beverages.

Instrumentation
The globalization of food supply poses challenges for companies to test raw ingredients and fi nal products for contaminants or adulteration that may come from anywhere in the world. While the testing methods must be safe, fast and easy to use, they must also be contemporary and applied in various ways and generate reliable and accurate information. This is especially pertinent to biological testing to rapidly detect potential outbreaks during a food processing process.

Prevention, rather than damage control, of a potential outbreak is necessary. The seemingly massive human and economic impact of contaminated food warrants detection methods must be fast, easy and cost effective enough to be performed in the processing plant or in the fi eld.

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How lab-on-a-chip technology works

The lab-on-a-chip analysis of fish species in a sample involves a five-step process, which starts with the extraction of 40mg to 1g of DNA tissue. The second step is the amplification of the target DNA sequence by PCR, which involves 464 base pair (bp) segment of the gene that is found in all vertebrate fish with a sequence that is known in a large number of fish species.

The amplified DNA fragment is later digested with three restriction enzymes to generate fragment size patterns specific to the fish species. A kit that provides all the required reagents for the amplification and restriction digests usually comes with the lab-on-a-chip system.

The fourth step involves loading the digested sample onto the chip and performing the automated electrophoretic separation of the restriction fragment.

At the final stage, the automated analysis of the restriction fragment patterns is done by the onboard software that matches those in a database from known species and identifies the most likely species.

This results to rapid and reliable species identification, even in samples from a mixture of fish species. The technology is also able to detect as little as 5% of a second species in the same sample.