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Article

Whey Protein Powder Analysis by Mid-Infrared Spectroscopy

1
Biomolecular Sciences Graduate Program, Boise State University, Boise, ID 83725, USA
2
Department of Chemistry and Biochemistry, Boise State University, Boise, ID 83725, USA
*
Author to whom correspondence should be addressed.
Academic Editors: Ben Aernouts, Clement Grelet and Ines Adriaens
Foods 2021, 10(5), 1033; https://doi.org/10.3390/foods10051033
Received: 4 April 2021 / Revised: 5 May 2021 / Accepted: 6 May 2021 / Published: 10 May 2021
(This article belongs to the Special Issue Advances in Application of Spectral Analysis in Dairy Products)
There is an ever-expanding number of high protein dietary supplements marketed as beneficial to athletes, body builders, infant formulas, elder care, and animal feed. Consumers will pay more for products with high protein per serving data on their nutritional labels, making the accurate reporting of protein content critical to customer confidence. The Kjeldahl method (KM) is the industry standard to quantitate dairy proteins, but the result is based on nitrogen content, which is an approximation of nitrogen attributable to protein in milk. Product tampering by third-party manufacturers is an issue, due to the lack of United States Food and Drug Administration regulation of nutraceutical products, permitting formulators to add low-cost nitrogen-containing components to artificially inflate the KM approximated protein content in products. Optical spectroscopy is commonly used for quality control measurements and has been identified as having the potential to complement the KM as a more nuanced testing measure of dairy protein. Mid-infrared (MIR) spectroscopy spectra of eight protein standards provided qualitative characterization of each protein by amide I and amide II peak absorbance wavenumber. Protein doping experiments revealed that as protein amounts were increased, the amide I/II peak shape changed from the broad protein powder peaks to the narrower peaks characteristic of the individual protein. Amino acid doping experiments with lysine, glutamic acid, and glycine, determined the limit of detection by MIR spectroscopy as 25%, suggesting that MIR spectroscopy can provide product quality assurance complementary to dairy protein measurement by the KM. View Full-Text
Keywords: milk and dairy products; whey protein; spectroscopic analysis; mid-infrared spectroscopy; adulteration; Kjeldahl milk and dairy products; whey protein; spectroscopic analysis; mid-infrared spectroscopy; adulteration; Kjeldahl
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MDPI and ACS Style

Saxton, R.; McDougal, O.M. Whey Protein Powder Analysis by Mid-Infrared Spectroscopy. Foods 2021, 10, 1033. https://doi.org/10.3390/foods10051033

AMA Style

Saxton R, McDougal OM. Whey Protein Powder Analysis by Mid-Infrared Spectroscopy. Foods. 2021; 10(5):1033. https://doi.org/10.3390/foods10051033

Chicago/Turabian Style

Saxton, Rose, and Owen M. McDougal. 2021. "Whey Protein Powder Analysis by Mid-Infrared Spectroscopy" Foods 10, no. 5: 1033. https://doi.org/10.3390/foods10051033

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