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Alternative methods for infrared analysis of fat in milk: interlaboratory study
Journal - Association of Official Analytical Chemists
|September 1, 1989
Summary
Improving infrared analysis of fat in milk involves measuring IR absorption by CH2 and CH3 groups, enhancing accuracy over traditional carbonyl group measurements. This advancement offers more precise fat quantification in dairy products.
Area of Science:
- Analytical Chemistry
- Food Science
Background:
- Traditional infrared (IR) analysis for milk fat content relies on measuring carbonyl group absorption.
- Existing AOAC method 16.083-16.092 has limitations in accuracy for fat determination.
Purpose of the Study:
- To improve the accuracy of infrared milk fat analysis.
- To explore alternative IR absorption measurements beyond carbonyl groups.
Main Methods:
- Measuring IR absorption by CH2 and CH3 groups in fat molecules.
- Applying Beer-Lambert law principles for optical arrangements (dual wavelength, double beam, single beam).
- Utilizing multiple linear regression for calibration parameter estimation.
Main Results:
- Accuracy improved by measuring CH2 and CH3 group absorption compared to carbonyls.
- Mean bias for randomly selected check samples reduced to <0.01%.
- Standard deviation of difference for fat estimates ranged from 0.026% to 0.034%.
Conclusions:
- Measuring CH2 and CH3 group absorption significantly enhances infrared milk fat analysis accuracy.
- Optimized calibration and quality control procedures are crucial for precise fat quantification.
- Revised AOAC method 16.083-16.092 incorporates Fat B and Fat A/B filters for improved fat analysis.