Fractionation of menhaden oil and partially hydrogenated menhaden oil: Characterization of triacylglycerol fractions

Menhaden oil (MO) and partially hydrogenated menhaden oil (PHMO) were dry-f ractionated and solvent-fractionated from acetone. After conversion to fatt y acid methyl esters, the compositional distribution of saturated, monounsa turated, trans, and n-3 polyunsaturated fatty acids (PU FA) in the isolated fractions was determined by gas chromatography. Acetone fractionation of M O at -38 degreesC significantly increased the n-3 PUFA content in the liqui d fractions over that of starting MO (P < 0.05). For PHMO, liquid fractions obtained by low-temperature crystallization (-38, -18, and 0<degrees>C) fr om acetone showed significant increases (P < 0.05) in monounsaturated fatty acid (MUFA) content over that of the starting PHMO. For selected MUFA-enri ched fractions, reversed-phase high-performance liquid chromatography (HPLC ) was used to separate, isolate, and characterize the major triacylglycerol (TAG) molecular species present. Thermal crystallization patterns for thes e fractions also were determined by differential scanning calorimetry (DSC) . The results demonstrated that under the appropriate conditions it is poss ible to dry-fractionate or solvent-fractionate MO and PHMO into various sol id and liquid fractions that are enriched in either saturated, monounsatura ted, polyunsaturated, or the n-3 classes of fatty acids. Moreover, characte rization of these TAG fractions by reversed-phase HPLC gives insight into t he compositional nature of the TAG that are concentrated into the various f ractions produced by these fractionation processes. Finally, the DSC crysta llization patterns for the fractions in conjunction with their fatty acid c ompositional data allow for the optimization of the fractionation schemes d eveloped in this study. This information allows for the production of speci fic TAG fractions from MO and PHMO that are potentially useful as functiona l lipid products.