Differentiation between milk from low-input biodynamic, intermediate-input organic and high-input conventional farming systems using fluorescence excitation spectroscopy (FES) and fatty acids

ABSTRACT This study evaluated the ability of fluorescence excitation spectroscopy (FES) to differentiate milk samples from different origins. Three different farming systems were chosen: D-samples originating from low-input biodynamic farms (cows fed on hay or pasture); O-samples from intermediate-input organic farms (cows fed mainly on grass silage); and C-samples from high-input conventional farms (indoor housing, cows fed on maize and grass silage). Milk samples were collected every second month between July 2015 and June 2016 from 12 farms (four farms per system), and a total of 70 samples were obtained. Fat-, protein- and urea-concentrations, somatic-cell count and fatty acid levels (FA) were determined. FES-measurements were performed by exciting the sample with light of different wavelengths and detecting delayed luminescence. Differences between farming systems in each season were checked by ANOVA. Factors of season, system and breed were evaluated in a linear regression model. By linear-discriminant analysis, variables contributing to correct classification were analysed. Milk FAs, especially the concentration of omega-3 (n3) and omega-6 (n6) FAs, were different between farming systems, while conjugated linoleic acid (CLA) and C18:1t11 (tVA)-concentration was mainly influenced by season (pasture). FES-parameters showed slight seasonal variations, but strong farming-system impacts. Differentiation between the three farming systems was possible for 81% of the samples by using FAs as variables. FES-parameters discriminated up to 86% of the samples, and, in combination, 93% of the samples were classified correctly. These results indicated that FES-results contributed to correct discrimination and that FES-results may be linked with qualities different to the FA profile.