Evaluation of Methods to Quantify Sialic Acid on Glycomacropeptide

Area of Science:

• Dairy Science
• Analytical Chemistry
• Food Science

Background:

• Glycomacropeptide (GMP), derived from whey, is crucial for phenylketonuria-safe foods due to its lack of phenylalanine.
• GMP is heavily glycosylated, featuring multiple sites for N-acetylneuraminic acid (NANA) attachment.
• Current NANA quantification in dairy proteins lacks a standardized industry method, utilizing colorimetric, fluorometric, enzymatic, and chromatographic techniques.

Purpose of the Study:

• To evaluate and compare various NANA quantification methods using GMP as the target analyte.
• To determine the most suitable method for NANA measurement in GMP for the dairy industry.
• To assess methods based on assay time, protein specificity, linearity, precision, and accuracy.

Main Methods:

• Evaluation of multiple NANA quantification techniques including colorimetric, fluorometric, enzymatic, and chromatographic procedures.
• Application of these methods to a commercial GMP product.
• Validation of the chosen method using spike and recovery experiments.

Main Results:

• Chromatography emerged as the most beneficial method for NANA quantification in GMP within the dairy industry context.
• The chromatographic method yielded an average NANA content of 6.18% ± 0.12% in GMP, with the lowest relative standard deviation (1.94%).
• Spike and recovery experiments validated the chromatographic approach, demonstrating an average recovery rate of 90.25%.

Conclusions:

• Chromatography is recommended as the industry-standard method for quantifying NANA in GMP.
• This method provides superior precision and accuracy compared to other evaluated techniques.
• The findings support the reliable measurement of NANA in GMP, essential for its application in specialized food products.