FAMEs In Monterey Jack Cheese by GC/FID Using Zebron™ ZB-FAME

Significance of the Topic

Fatty acid profiling in dairy products is critical for quality control, nutritional labeling and detecting adulteration. Converting fats to fatty acid methyl esters (FAMEs) and analyzing them by gas chromatography with flame ionization detection (GC/FID) provides precise quantitation of saturated and unsaturated fatty acids. Short analysis times and robust sample preparation increase laboratory throughput and data reliability in routine cheese testing.

Objectives and Study Overview

This work demonstrates an optimized protocol for extracting, derivatizing and analyzing FAMEs from Monterey Jack cheese. By employing a 30 m Zebron ZB-FAME column and a streamlined extraction/derivatization scheme, total run time is reduced below 22 minutes without sacrificing resolution of twelve key FAMEs ranging from C10:0 to C20:2.

Methodology and Instrumentation

• Sample Preparation and Derivatization
  – Weigh 100–200 mg cheese; add 100 mg pyrogallic acid as antioxidant.
  – Add 2 mL ethanol, 4 mL deionized water and 4 mL concentrated NH₄OH; incubate 70 °C for 20 min.
  – Acidify with 10 mL HCl and incubate further 25 min.
  – Extract lipids with 2 mL diethyl ether and 2 mL chloroform; evaporate solvent.
  – Derivatize residue with 1 mL toluene and 2 mL 8 % BF₃ in methanol at 100 °C for 45 min.
  – Quench with water, extract FAMEs into hexane for GC analysis.
  
• Instrumentation Details
  – Gas Chromatograph: GC/FID with Zebron ZB-FAME column (30 m × 0.25 mm × 0.20 µm).
  – Carrier Gas: Helium at 1.2 mL/min (constant flow).
  – Injection: Split 50:1, 1 µL at 240 °C; liner: Zebron PLUS single taper with wool.
  – Oven Program: 100 °C (2 min), to 140 °C at 10 °C/min, to 190 °C at 3 °C/min, to 260 °C at 30 °C/min (2 min hold).
  – Detector: FID at 260 °C.

Main Results and Discussion

• Twelve FAMEs (C10:0, C11:0, C12:0, C13:0, C14:0, C15:0, C16:0, C18:0, C18:1 trans-9, C18:1 cis-9, C18:2 cis-9,12, C20:2 cis-11,14) were baseline-resolved in under 22 minutes.
• The optimized temperature ramp delivered sharp peaks and minimal coelution, enhancing quantitation accuracy.
• Short column length reduced analysis time by more than 30 % compared to longer phases, with comparable or superior resolution.

Benefits and Practical Applications

• High sample throughput for dairy quality control and regulatory compliance.
• Reliable profiling of saturated and unsaturated fatty acids to assess nutritional composition and detect adulteration.
• Simplified workflow suitable for routine laboratories with minimal solvent consumption and robust reproducibility.

Future Trends and Possibilities

Advances may include coupling fast GC columns with mass spectrometry for structural confirmation, fully automated on-line derivatization systems, and greener derivatization reagents. Miniaturized capillary columns and higher-speed detectors could further reduce run times while expanding coverage to minor lipid classes.

Conclusion

The described method offers a rapid, reproducible and high-resolution approach for FAME analysis in cheese, leveraging a short Zebron ZB-FAME column and streamlined sample preparation. Laboratories can achieve reliable fatty acid profiles in under 22 minutes, enhancing throughput without compromising data quality.

Reference

• Trass M, Becerra A, Parnell K. FAMEs in Monterey Jack Cheese by GC/FID Using Zebron ZB-FAME. Phenomenex Application Note 23823; 2017.