Cereal Grains Testing: Here Are Some of the New Methods Emerging for Rapid Detection

Andreia Bianchini, PhD, an associate professor in the department of food science and technology at the University of Nebraska in Lincoln, highlights how important it is for food processors to recognize the emerging hazard posed by pathogenic bacteria. “Until 10 or 15 years ago, microbiological concerns related to grains perhaps were more directed to molds and their potential to produce mycotoxins,” she says. Today, she adds, food scientists understand that pathogenic bacteria can also be associated with these products.

According to Dr. Bianchini, traditional methods continue to be the gold standard for reference testing for both mycotoxins and bacterial contaminants, but newer methods for rapid detection have emerged.

Dr. Morantes says that, unlike traditional culture-based methods that can take up to five days for preliminary results, rapid testing can significantly reduce the time needed to make an informed decision about the release of a product. This in turn, he says, can have significant implications for preventing foodborne outbreaks and reducing food losses.

Table 2 (below) lists a number of these newer rapid detection tests. Of these, Dr. Bianchini says that ELISA and PCR-based methods are the most commonly used. “No matter what testing platform is used, it is important that it be validated for the matrix (e.g., flour) in which it is to be used so [that] results obtained with the rapid methods are equivalent to those obtained using standard methods,” she says.

To ensure quality in cereal grains, Dr. Marshall underscores that the quality determines whether the grain is fit for use in a certain application. “The proximate composition of the grain determines its functional properties, such as amount of starch, protein, lipid, fiber, and moisture,” he says. “For example, the protein content of wheat dictates its performance as flour for pastas, breads, or cakes.”

Devin Rose, PhD, an associate professor of food science and technology and agronomy/horticulture at the University of Nebraska in Lincoln, says that the definition of quality in cereal grains means different things, depending on the industry. “Among others, wheat growers are concerned with disease resistance, drought tolerance, protein concentration, and yield; millers are concerned with wheat kernel size, shape, weight, hardness, and protein concentration; and bakers are concerned with such things as protein quality and sprout damage,” he adds.

Although many tests for cereal grains analysis are not new, Dr. Rose says that new applications are being discovered daily. He and Dr. Marshall highlight a number of new tests currently in use (see “Table 3: Newer Ways to Test Quality of Cereal Grains”).

Dr. Morantes highlights the new possibilities with near infra-red spectroscopy for measuring gluten, water absorption, and starch damage in wheat flour milling. “By using this type of analysis, it’s possible to assure constant product quality, which makes a consistent contribution to the profitability of mills,” he says.

Gaps and Vulnerabilities in Grains Testing

Dr. Bianchini notes that, although the potential for contamination of cereal grains from mycotoxins and bacterial pathogens always exists, ensuring food safety will require more than relying on sample testing alone because of the low incidence and low levels of toxins and bacterial pathogens that will be found.

Instead, testing needs to be a part of a preventive approach to food safety that may include screening methods, she says. For example, testing for indicator organisms can help reduce the amount of inferior or low-quality products from reaching the market. “We still have knowledge gaps that must be addressed, like a better understanding of routes and sources of these contaminations, natural frequency of occurrence and incidence levels, and the effect of emerging or innovative processing technologies on these contaminants,” she adds.