Conjugated linoleic acid in ewe milk fat

Area of Science:

• Dairy Science
• Analytical Chemistry
• Food Chemistry

Background:

• Conjugated linoleic acid (CLA) is a group of fatty acids with potential health benefits.
• Understanding the isomer composition of CLA in ewe milk is important for nutritional studies.
• Previous analyses have not fully detailed the specific CLA isomers present in ewe milk fat.

Purpose of the Study:

• To determine the content and profile of conjugated linoleic acid (CLA) isomers in ewe milk fat.
• To identify and quantify major and minor CLA isomers in milk from different ewe herds.
• To investigate variations in CLA isomer composition among herds.

Main Methods:

• Combined gas chromatography-mass spectrometry (GC-MS) of fatty acid methyl esters (FAME) and 4,4-dimethyloxazolyne (DMOX) derivatives.
• Utilized silver ion-high performance liquid chromatography (Ag+-HPLC) for isomer quantification.
• Employed reconstructed mass spectral profiles of DMOX derivatives for positional isomer identification.

Main Results:

• Total CLA content ranged from 0.57 to 0.97 g/100 g of total fatty acids.
• Rumenic acid (9-cis 11-trans C18:2) was the most abundant isomer, comprising over 75% of total CLA.
• Other identified isomers included 11-trans 13-trans, 11-13 cis/trans, 7-9 cis/trans, 8-10, and 10-12 C18:2, with varying amounts across herds.

Conclusions:

• Ewe milk fat contains a diverse profile of CLA isomers, dominated by rumenic acid.
• Significant variations in the content of specific CLA isomers were observed among different ewe herds.
• The applied analytical methods provide a comprehensive approach for CLA isomer analysis in complex lipid matrices.