Citrus oils analysis

Follow the same GC/FID conditions for citrus oil analysis (see Basic Protocol 1). 

Aroma compounds, see also Citrus Oils Flavor analysis GC analysis mouth simulators Ascorbic acid, 397... 

Basic Protocol 1 Qualitative Analysis of Citrus Oils by Gas Chromatography Basic Protocol 2 Quantitative Analysis of Citrus Compounds by Gas Gl.5.2... 

Basic Protocol 4 Analysis of Citrus Oils by Pycnometry Gl.5.5... 

Basic Protocol 6 Analysis of Citrus Oils by Polarimetry Gl.5.6... 

Basic Protocols 3 through 9 are primarily useful as quality control measures. They are rapid, usually within 30 min, given reagent preparation. The results are used to monitor the quality of a process. These results support established values for high quality citrus oil. Basic Protocols 1 and 2 are more involved and are better suited for research purposes. The equipment is more sensitive and also more expensive. Furthermore, the strength of the GC analysis can be enhanced by the addition of a mass spectrometer to identify either contaminates or unknown compounds present in a sample. 

Gas chromatography provides a rapid analysis of citrus oil quality. This technique can be further enhanced to determine quantitative levels of individual compounds. Compounds can be measured based on the FID response. A standard curve with known concentrations is used to extrapolate an unknown concentration. 

During the concentration of the press liquor to molasses, d-limonene is distilled and recovered. The recovery of c/-limonene is a function of evaporator capacity. Most citrus processors add the molasses back onto the wet peel. The difference between the press liquor and the molasses is the amount of distilled limonene. This is determined by Scott oil analysis. 

Depending on the choice of column, flow rates and temperature program are important parameters for the qualitative analysis of citrus oils. It is also important to have the same temperature program for quantifying compounds. Replication of injections for generating a standard curve is vital. Injections should be done on the same day by the same technician. A standard curve with an R2 value >0.9 is sufficient. 

Braddock, R.J. and Kesterson, J.W. 1976. Quantitative analysis of aldehydes, esters, alcohols, and acids from citrus oils. J. Food Sci. 41 1007-1010. 

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