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Development of a human milk protein standard
1Department of Nutrition, University of California, Davis.
Acta Paediatrica Scandinavica
|March 1, 1989
Summary
Accurate human milk protein (HMP) quantitation is crucial for infant nutrition. A novel HMP standard improved colorimetric assay accuracy, reducing overestimation compared to Kjeldahl protein (KP) methods.
Area of Science:
- Biochemistry
- Pediatric Nutrition
- Analytical Chemistry
Background:
- Accurate protein quantitation in human milk (HM) is vital for assessing infant nutrition.
- Colorimetric assays offer convenience but often overestimate protein content compared to Kjeldahl protein (KP).
Purpose of the Study:
- To develop and validate a human milk protein standard (HMPS) for improved colorimetric protein analysis.
- To compare the accuracy of different colorimetric assays using various protein standards against KP.
Main Methods:
- Isolation of HMPS using size exclusion chromatography.
- Purity and composition analysis of HMPS via gel electrophoresis, Kjeldahl, and amino acid analyses.
- Determination of protein in 20 mature HM samples using Lowry, BCA, and BioRad assays with different standards, compared to KP.
Main Results:
- All colorimetric assays, regardless of standard, overestimated protein content relative to KP.
- The Lowry assay, particularly with HMPS, provided the closest protein values to the KP reference.
- The developed HMPS demonstrated improved accuracy in colorimetric protein determination.
Conclusions:
- A human milk protein standard (HMPS) is essential for accurate colorimetric protein quantification in human milk.
- The Lowry assay, when calibrated with HMPS, offers a more reliable method for determining human milk protein content.
- This improved method supports better nutritional assessment for infants fed human milk.