Triacylglycerol Profile of Summer and Winter Bovine Milk Fat and the Feasibility of Triacylglycerol Fragmentation

Abstract

Bovine milk fat (MF) is considered to be one of the most complex fats, as it can consist of 400 FA which are non‐randomly esterified into the TAG molecule. This study aims to determine specific differences on MF TAG profile between summer and winter cow's milk, and to study the feasibility of TAG fragmentation on non‐chemically hydrogenated MF using MALDI‐TOF/TOF MS with post source decay. The most notable discrimination between summer and winter MF is seen in polyunsaturated TAG, which are more abundant in summer. The feasibility of MF TAG fragmentation in non‐chemically hydrogenated TAG is assessed using bulk MF and TAG previously separated according to degree of unsaturation. This last approach shows to be the most suitable. We show that sample concentration and abundance ratio with neighboring TAG affects TAG fragmentation. Non‐chemically hydrogenated MF TAG has not been previously fragmented. Furthermore, this is the first time that the conditions affecting TAG fragmentation in MF are reported. Practical Application: TAG constitute the fundamental unit of fat crystals. Hence, fat crystal network is affected by variations in TAG profile. Understanding the variability of MF TAG profile between seasons may help to explain differences on crystallization behavior seen through the year in industrial processes. Moreover, TAG fragmentation allows determination of FA composition of individual TAG. This information is needed when studying the mechanism of FA acylation into TAG. For instance, when studying the effect of genetic variation of diacylglycerol acyl transferase isomer one in cows. The reported technique increases the capacity of MALDI‐TOF MS in lipidomic analysis. This study aims to determine specific differences in milk‐fat triacylglycerol (TAG) profiles between summer and winter cow's milk, and to study the feasibility of TAG fragmentation on non‐chemically hydrogenated milk fat using MALDI‐TOF/TOF MS with post source decay.

The DGAT1 K232A polymorphism and feeding modify milk fat triacylglycerol composition

“…The most abundant TAG species present in both winter and summer were CN36, CN38, CN40, CN48, and CN50. These TAG composition profiles were similar to those in previous studies using MF DGAT1 POLYMORPHISM AND MILK FAT TRIACYLGLYCEROL 6845 from individual cows (Tzompa-Sosa et al, 2016;Liu et al, 2017) and bulk MF samples (Capuano et al, 2014;Larsen et al, 2014;Tzompa-Sosa et al, 2018). The relative concentrations of each identified TAG species (CN26 to CN54) were within the ranges reported in the review by Jensen (2002).…”

“…Feeding dairy cows with PUFA present in fresh grass reduces de novo synthesized FA and increases long-chain FA (LCFA) in MF (Chilliard et al, 2001), The DGAT1 K232A polymorphism and feeding modify milk fat triacylglycerol composition Sara Pacheco-Pappenheim, 1 Sine Yener, 1 Hein J. F. van Valenberg, 1 Daylan A. Tzompa-Sosa, 1,2 and Henk Bovenhuis 3 * 6843 probably inducing significant changes in TAG composition. Seasonal changes in TAG composition occur mainly due to alterations in the cow's diet, which goes from a silage-based diet (winter) to a fresh grass-based diet (summer) irrespective of the country (Capuano et al, 2014;Liu et al, 2017;Tzompa-Sosa et al, 2018). Capuano et al (2014) reported that MF of cows on a summer diet rich in unsaturated C18 FA (e.g., linolenic acid) shows relative decreases in concentrations of TAG CN34, CN36, CN42, CN44, and CN46; and relative increases in concentrations of TAG CN24, CN26, CN40, CN50, CN52, and CN54 compared with cows on a winter diet.…”

Varying Levels of Medium‐Chain Fatty Acids Affect Triacylglycerol Composition and Crystallization Behavior of African Elephant Milk Fat

“…TAG were detected as Na + ‐adducts according to the method described by Tzompa‐Sosa and coworkers. [ 12 ] The mass spectra were acquired within 400–1000 Da. Each sample was analyzed in duplicate and plated on seven times on MALDI target plate.…”

“…Recent studies have shown the value of matrix‐assisted laser desorption/ionization‐time of flight‐mass spectrometry (MALDI‐TOF‐MS) and further fragmentation in profiling MF composition. [ 11,12 ] To the extent of the authors’ knowledge, the study of EMF composition has been limited to FA composition and no published information is available on TAG composition. Thus, this work provides a study of both composition and crystallization of EMF with varying levels of MCFA to a deeper extent than has ever been reported.…”

Detection of Edible Plant Oil Adulteration by Triacylglycerol Profiles Using an Atmospheric Pressure Chemical Ionization Source and MS3 Ion Trap Mass Spectrometry

“…Non‐aqueous reversed‐phase HPLC (NARP‐HPLC) with an acetonitrile/isopropyl alcohol mobile phase system generally separates triacylglycerol according to equivalent carbon numbers (ECNs), which are calculated by deducting twice the number of double bonds from the total number of carbon atoms (CNs). Several types of MS detectors are usually coupled with HPLC for triacylglycerol analysis, such as time‐of‐flight mass spectrometry (TOF‐MS), matrix assisted laser desorption ionization‐time of flight Mass spectrometry (MALDI‐TOF/MS), ion trap mass spectrometry (IT‐MS), and triple quadrupole mass spectrometry (TQ‐MS) . However, complete analysis of overlapping triacylglycerol isomers has not yet been achieved with the same chromatographic retention behavior as one‐dimensional liquid chromatography .…”