Fatty acids and conjugated linoleic acid in organic milk produced in the southeast of Mexico

Objective. To determine the fatty acid (FA) profile, conjugated linoleic acid (CLA) and isomers in cow's milk produced under organic conditions in southeastern Mexico. Materials and methods. Forty-eight milk samples were collected during one year from three production units (PU 1, 2 and 3) and a collecting tank (CT) in the municipality of Tecpatán, Chiapas (12 months x 4 = 48), following the guidelines established in Mexican regulations. Fat was extracted with detergent solution; AG analysis was performed by gas chromatography with flame ionization detector and ALC and isomers were obtained by high performance liquid chromatography (HPLC) with UV-Vis detector. Results. Chromatographic analyses identified and quantified 23 FA in all milks, from C4 to C20:1. Statistical analysis (ANOVA, Tukey) showed significance (p<0.05) at C4-C10, C16, C18, C18:1n9t, C18:2n6 and C20; in all cases the CT was similar in at least two PU. The mean values over time exhibited homogeneous regularity behavior. CLA and 9 of its isomers were also determined; ANOVA did not show significance. The isomer C18:2 9c-11t had the highest percentage of total CLA with a mean value of 90.06%. Conclusions. Gas and liquid chromatographic analyses allowed characterization of FA, CLA and isomers profiles in organic milk produced in southeastern Mexico, which had not been studied so far.