Near infrared aquaphotomics study on common dietary fatty acids in cow's liquid, thawed milk

Abstract

This study was aimed at two objectives: 1) explore the possibility of near infrared (NIR) spectroscopy to determine the content of common dietary fatty acids (FAs) and fat content in cow's liquid milk for better individual cow's feed management; 2) using aquaphotomics obtain better understanding of interaction between water molecular structure and FAs and gain more insight into their functionality.For these purposes, 252 milk samples were collected from 9 cows during 14 weeks and FAs content measured using gas chromatography as a reference method. Applying aquaphotomics NIR spectral analysis, quantification was attempted using 1300–1850 nm region where both water and FAs absorbance bands are located. The results showed possibility of quantification for 8 common dietary FAs which was more accurate when spectral region was narrowed to 1600–1800 nm. In the external validation, good predictions (R2> 0.75, RPD>1.5), were obtained for caproic and caprylic and acceptable for capric, lauric, myristic, myristoleic, palmitoleic and oleic acid (0.55<R2<0.75, RPD>1.5). Interpretation of influential variables in regression models revealed contribution of water absorbance bands related to protonated and hydration water, which originate from the water-FAs interaction and are important for their self-organization into assemblies with different morphologies.