Whey Protein Powder Analysis by Mid-Infrared Spectroscopy

Area of Science:

• Analytical Chemistry
• Food Science
• Spectroscopy

Background:

• High protein supplements are widely marketed across various consumer groups.
• Accurate protein content labeling is vital for consumer trust and product value.
• The Kjeldahl method (KM), the industry standard for dairy protein analysis, estimates protein content based on total nitrogen, which can be artificially inflated through product adulteration.

Purpose of the Study:

• To evaluate Mid-infrared (MIR) spectroscopy as a complementary method for dairy protein quantification.
• To assess MIR spectroscopy's potential in detecting adulteration in protein supplements.

Main Methods:

• Analysis of eight protein standards using MIR spectroscopy, focusing on amide I and amide II peak absorbance.
• Protein doping experiments to observe changes in spectral peak characteristics with increasing protein concentration.
• Amino acid doping experiments (lysine, glutamic acid, glycine) to determine MIR spectroscopy's limit of detection for adulterants.

Main Results:

• MIR spectroscopy successfully provided qualitative characterization of protein standards via amide I and II peaks.
• Protein doping altered spectral peak shapes, distinguishing between broad protein powder peaks and narrower individual protein peaks.
• MIR spectroscopy demonstrated a 25% limit of detection for added amino acids, indicating its sensitivity to adulteration.

Conclusions:

• MIR spectroscopy offers a nuanced approach to dairy protein analysis, complementing the traditional Kjeldahl method.
• This technique shows promise for ensuring product quality assurance and detecting fraudulent protein content inflation in supplements.