Analytical Trends in Measuring Food Quality

Early pesticide methods were targeted for specific pesticides. A welcome development was the development of methods which extract and quantify a broader scope of pesticides. One common example was the Luke extraction with rapid extraction followed by pesticide detection using a number of chromatographic systems with specific detectors. Confirmation of detected pesticides was performed by subsequent analysis using a mass spectrometer detector. This approach is being used less often, however, it is still available due to its versatility in testing for some matrix types.

The QuEChERS method is a streamlined version of extracting pesticides combined with GC-MS/MS and LC-MS/MS separation and quantification. This approach is very common today. The original method was developed in 2001/2002 by Michelango Anastassiades while at USDA in the laboratory of Steve Lehotay⁴ and has since been standardized as AOAC 2007.01. This method has been demonstrated to reliably test for more than 300 pesticides in fruits, vegetables, and most grains. The scope of pesticides covered by the method can be expanded as needed.

When analyzing foods and ingredients outside the original scope, an “on-the-fly” method validation is performed. For example, if a laboratory is testing eggplant for the first time, the sample is analyzed alongside a spiked eggplant sample (matrix-match standards). Acceptable recovery of the spiked amounts demonstrates and documents the method’s applicability for testing eggplant by the laboratory.

Improvements in Sensory Analysis

At one point in my career, I was a quality engineer for a yogurt company. On my first day at this new position, my boss told me to taste every type of product we make, including every product style, every flavor, and samples from all our production locations. I became quite the yogurt-tasting connoisseur, which was the intent of this exercise.

The more someone understands their products, the faster quality issues can be identified. More and more companies are asking production site personnel to taste finished products. Fully trained Sensory Panels are also becoming more common at production sites. Members of these panels receive training to calibrate their tasting of the foods with focus on identified key characteristics. For example, if a product’s creaminess is recognized as a critical attribute, a commercially available product (i.e., a baby food) can be used to “remind” panel members what the desired creaminess level is.

Additional Thought

Encapsulation of nutrients to improve stability can challenge analytical methods. Traditional extraction techniques may need to be improved for use on these new ingredient forms, both on the base ingredients and on finished products. Some encapsulating agent(s) require more dedicated dispersal to safely liberate the protected nutrient. Some approaches include enzymatic digestion of the encapsulating agents (i.e., proteins, fats, starches), use of alternate solvents to break the encapsulation, adjusted heat treatments, sonication of the sample in the extraction solution, and more aggressive agitation.

In Closing

The food industry has benefited greatly from the constant improvement of the tools and processes to monitor food quality. This does require keeping abreast of what is occurring in the supporting area of analytical testing, but in the long run will result in better quality and safer foods.

Dr. Szpylka is the director of chemistry NA, Silliker Laboratories, a Merieux NutriSciences Co. He can be reached at [email protected].

References

1. Schreiber, A., Sims, A., “Advances in LC/MS for Food Safety Testing: New Liquid Chromatography/Mass Spec Technologies Make a Difference in the Lab,” Food Quality, Feb/March 2011.
2. AOAC International Official Methods of Analysis.
3. Szpylka, J., DeVries, J., Cheney, A., House, S., Determination of Total Folates in Infant Formula and Adult Nutritionals by Trienzyme Extraction and UPLC-MS/MS Quantitation, J. AOAC Int, 95(6), 1547-1554, (2012).
4. Anastassiades, M., Lehotay, S. J., Stajnbaher, D., Schenck, F.J., Fast and Easy Multiresidue Method Employing Acetonitrile Extraction/Partitioning and “Dispersive Solid-Phase Extraction” for the Determination of Pesticide Residues in Produce, JAOAC Int, 86(2), 412-31, (2003).