Tag Archives: rapid detection

Phil Coombs, Ph.D., Weber Scientific
In the Food Lab

Rapid Detection of Spoilage Organisms: The Forgotten Bad Guys?

By Phil Coombs, Ph.D.
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Phil Coombs, Ph.D., Weber Scientific

As rapid microbiology methods have been increasingly adopted by the food industry during the past 30 years, much emphasis has been placed on the detection of foodborne pathogens and  reducing test times as much as possible. Novel methods such as PCR, along with other molecular approaches, have done much to find these organisms more quickly and identify the source of an outbreak. Quite rightly so: We all have to eat, and we all prefer to eat safe food.

What is often forgotten, however, and what has been less fashionable in the development of novel methods, is the impact of spoilage organisms on the economics of food production and the lack of more sophisticated methods to detect them.  While media headlines may scream “Salmonella outbreak affects hundreds!”, the same outlets are less likely to report how much food is thrown away on any given day because of mold growth. “Penicillium spoils bread” is hardly an attention grabber on the 6 o’clock news.

A closely–related issue is that of food wastage, which together with spoilage accounts for billions of dollars of food that is thrown away. Estimates are in the region of $29–35 billion per year, and that doesn’t take into account the billions of dollars of wasted produce because of cosmetic imperfections—the so-called “ugly” fruit and vegetables that are still safe and nutritious to eat. In other estimates, it is suggested that in U.S. landfills, 21% of the contents are comprised of wasted food.

Another source of the problem is the confusion created by date labels–“best by”, “use by”, “sell by”.  What do they really mean? This has become such an issue that Walmart is leading an effort, spearheaded by Walmart’s VP of Food Safety, Frank Yiannas, to rationalize date labels so that consumers are far less likely to throw away perfectly wholesome food. In this aspect, he has worked closely with the Institute of Food Technologists, the Grocery Manufacturers Association and the Food Marketing Institute to address the problem.

The amount of waste and spoilage has reached almost scandalous proportions and the issue must be addressed, as the planet’s human population is estimated to grow to 9–10 billion by the year 2050. Improved agricultural practices and biotechnology will help to improve yields and increase the food supply, but greater efforts must be made to reduce wasting the food that is produced.

Weber Scientific
The PCR Yeast and Mold Qualitative test is distributed by Weber Scientific in North America.

In the overall context of facing these challenges, new technologies are being developed. One such technology is a four-hour PCR Yeast and Mold Qualitative test, manufactured by Germany-based Biotecon, for use in dairy products. Genetic methods are typically associated with identifying bacterial and viral pathogens. But the same approach may be taken with groups of microbes responsible for spoilage, if there is a unique gene sequence common to the target organisms.

Typical test times for yeast/molds are historically five days, although more recently incubation times have been reduced to three days with some new “rapid” plating media. Still, this is a relatively long time compared to four hours. And it is worth noting that the PCR Yeast and Mold test is a “true” four-hour test, as it does not require any pre-enrichment.

The protocol follows a standard PCR protocol for DNA extraction and amplification with an important inclusion—a treatment step that allows discrimination between viable and non-viable organisms. Another important aspect is the inclusion of UNG (Uracil-N-Glycosylase), which greatly reduces the chance of cross-contamination between one sample and the next.

The method is remarkably robust. 100% specificity has been demonstrated with more than 300 strains of yeasts and molds representing 260 species covering all the phylogenetic groups. Conversely, 100% exclusivity has been shown against 60 strains of non-targets—comprised of microbes typically found in similar ecological niches; plant DNA; and animal DNA from human, mouse and canine sources. Sensitivity of the method for yeasts/molds is 101 – 102 cfu/g.

The method is also quantitative, and PCR cycle threshold times can be very closely correlated with plate counts on agar media. Thus, once a standard curve is generated, subsequent samples need only be tested by this new PCR method. Equivalent counts are then determined from the standard curve.

The rapid detection of yeast and molds is a much-needed analytical technique for the dairy industry. For producers of yogurt and similar fermented milk product with a typical shelf-life of 60 days, having the ability to release product to market four days earlier will help with operational efficiency. More importantly, knowing early on of any possibility of product spoilage will help deliver superior product to consumers. The method won the Institute for Food Technologists’ Innovation Award, with one of the judges commenting, “a four-test versus five days for spoilage organisms is a major breakthrough.”

In view of the level of wastage and spoilage that currently occurs, this new PCR method is a step along the way to using more sophisticated methods for the detection of the organisms responsible. Guardians of the food supply should see this as an important development.

Mislabeled Salmon

Rapid Salmon ID Test the Latest in Fraud Prevention

By Food Safety Tech Staff
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Mislabeled Salmon

Two rapid test kits have been launched for the identification of salmon species: Chinook (Oncorhynchus tshawytscha) and Sockeye (Oncorhynchus nerka). The tool kits were developed in collaboration with the University of Guelph and allow distributors, food processors and government regulators to positively identify the salmon species in less than two hours. 

Recent studies have revealed that a significant amount of the salmon sold in the United States is mislabeled.

The test kits are used in conjunction with a portable, real-time PCR system that provides DNA detection. The tools are part of the Instant ID Species product line from InstantLabs, which include seafood identification tests for Atlantic (Salmo salar) and Coho Salmon (Oncorhynchus kisutch as well as Atlantic Blue Crab (Callinectes sapidus) and U.S. Catfish (Ictalurus species).

PerkinElmer Launches New Software for Rapid Detection of Food Adulterants

Adulterant Screen™ software pairs with PerkinElmer’s advanced FT-IR spectroscopy instruments for single-step screening and analysis of food authenticity and nutritional components.

PerkinElmerAdulterantScreenPerkinElmer Inc., a global leader focused on improving the health and safety of people and the environment, today announced the launch of its Adulterant Screen™ software. This automated solution can help food industry professionals evaluate the integrity of food ingredients to guard against existing and potential food adulteration threats.

Adulterant Screen software, when paired with PerkinElmer’s Fourier Transform Infrared (FT-IR) and Near Infrared (NIR) spectroscopy instruments, creates a unique, combined hardware and software system that can confirm authenticity and perform nutritional analysis in a single step.

“Food quality professionals face an increasing number of risks related to their ingredients which need to be continually screened for known contaminants as well as unknown contaminants that may be unsafe substitutions,” said Jon DiVincenzo, President, Environmental Health, PerkinElmer. “We are committed to delivering advanced detection solutions to help our global customers address increasingly complex industry regulations related to food quality control and safety in the supply chain.”

Adulterant Screen software performs rapid, targeted and non-targeted screening for several types of adulterants. Its customized set-up enables fast, effective implementation without lengthy calibrations. Its simple and intuitive green light/red light, “pass/fail” results system enables easy implementation, regardless of the knowledge level of its users. Click here for more information on the Adulterant Screen software.

PerkinElmer also offers the DairyGuard™ milk powder analyzer, a near infrared (NIR) spectrometer specifically developed for food suppliers and manufacturers. The DairyGuard analyzer is the only system available that tests for unknown adulterants as well as known compounds.