When detection of dairy food fraud fails: An alternative approach through proton nuclear magnetic resonance spectroscopy

摘要

This paper investigated the limits of the current approachfor the determination of the fatty acids profileof milk fats from proton nuclear magnetic resonancedata based on the hypothesis that the signal at 0.96ppm, currently assigned in the literature as a markerfor the “short chain fatty acids,” is generated only bythe butyric moiety (not by all of the short-chain fattyacids, which also include C6:0-caproic acid). Thehypothesis was tested and experimentally confirmed.Moreover, the triplet at 0.96 ppm can also be due ton-3 fatty acids such as linolenic acid (C18:3); therefore,a previously reported methodology for the fatty acidsprofiling of dairy products-considered as general inthe literature-cannot be used in fraud-detection approachesbecause it allows linolenic acid to be mistakenfor butyric acid, consequently leading to misclassificationof adulterated samples as nonadulterated. To supportour opinion, we have applied the current literatureapproach for the determination of the fatty acids compositionof 3 synthetic nondairy fat blends and haveobtained fatty acid compositions similar to milk fats,allowing for their misclassification as genuine milk fats.However, in reality, the blends had very different compositions,as confirmed by gas chromatography. Consequently,we have highlighted the weaknesses of theexisting methodology for the detection of dairy foodadulteration. In return, new proton nuclear magneticresonance descriptors based on various integral ratiosof signals associated with CH_2 moiety versus signals associatedwith butyric and n-3 fatty acids were proposedto detect adulterations.