Rapid detection of vegetable oils in milk fat by on-line LC-GC analysis of β-sitosterol as marker

Abstract

On-line liquid chromatography-gas chromatography (LC-GC) has been applied to the detection of vegetable oils in milk fat using β-sitosterol as marker. The method involves transesterification of the fat, pre-separation of the sterol fraction from other lipid constituents and on-line transfer to the capillary GC system. The on-line approach avoids time-consuming sample preparation steps prior to GC analysis. The suitability of this analytical approach was tested with model mixtures of milk fat with cotton and rapeseed oil. The method allows the detection of adulterations at low levels. Simultaneous quantification of cholesterol in milk fat is also possible. Considering the rapid sample preparation, the described method can be applied for screening of large sample numbers.

Analysis of phytosterols in foods

“…The method involves trans-esterification of the fat, pre-separation of the sterol fraction from other lipid constituents, and on-line transfer to the capillary GC system. This method avoids time-consuming sample preparation steps prior to GC analysis [99]. Supercritical fluid chromatography (SFC) employs inert supercritical carbon dioxide as mobile phase eluent.…”

Study on sterol fraction of commercial brands of milk, yoghurt and butter sold in Iranian market and chemometric data analysis

“…In addition, it is not efficient for the detection of low percentages (<10%) of extraneous fats (Kamm et al . ). In addition, analysis of TAGs is laborious (Fontecha et al .…”

“…Fatty acid analysis is a limited approach for fat authentication, as variations in animal feeding, as well as regional and seasonal conditions influence the composition of the milk fat (Palmquist et al 1993;Larsen et al 2014). In addition, it is not efficient for the detection of low percentages (<10%) of extraneous fats (Kamm et al 2002). In addition, analysis of TAGs is laborious (Fontecha et al 1998).…”

On-line reversed–phase liquid chromatography-gas chromatography coupled to mass spectrometry for enantiomeric analysis of chiral compounds in fruit beverages

“…In this respect, the use of multidimensional techniques for food analysis has been mostly focused on multidimensional gas chromatography [7][8][9] and, to a far lesser extent, on the on-line coupling of high-performance liquid-chromatography (LC) with gas chromatography (GC) using normal phase in the pre-separation step [10][11][12]. Nonetheless, it is necessary to take into account that a very high percentage of LC separations are performed by reversed phase LC (RPLC) as the employment of hydrophobic packing materials and aqueous mobile phases enlarges the range of compounds which can be analysed.…”