Evaluation of medium polarity materials isolated from fried edible oils by RP-HPLC

Abstract

Some frying by-products of medium polarity called medium polarity materials (MPMs) were isolated by reversed-phase high-performance liquid chromatography (RP-HPLC) from three different cooking oils used for frying during the domestic successive deepfrying of potatoes. The cooking oils investigated were virgin olive oil, sunflower oil and a vegetable shortening oil. The relative RP-HPLC increments of the MPM fractions showed a significant correlation to the total polar material and to the polymerised triacylglycerol increment. They could be used as a new method for the assessment of fried oil deterioration. The capillary gas chromatography/mass spectrometry analysis revealed two main groups of peaks for the MPM fractions, which are almost identical in the three examined oils. This indicates that the MPM constituents rather result from the triglycerides than from minor constituents of the oils.

Monitoring of 2,4‐decadienal in oils and fats used for frying in restaurants in Athens, Greece

“…In the study of Andrikopoulos et al [6], MPM was detected in oils used for domestic frying, and its content was expressed as peak area (AU6s, absorbance units times seconds). The upper limit of MPM could be considered as 0.9 AU6s, since values of 0.6 AU6s and 0.7 AU6s have been reported for sunflower oil and vegetable shortening oil, respectively, after the 8 th successive deep-frying of potatoes.…”

“…For the isolation of sufficient MPM quantities, selected fried oil samples from the restaurants, rich in MPM, namely samples 1-3, 7, 8, 13-15, 17, and 25, were pooled together to form an oil pool of 10 mL total volume (1 mL from each sample) and diluted in hexane to a 50% solution. MPM were isolated from the oil pool according to the method proposed by Andrikopoulos et al [6]. In brief, the oil solution was extracted with methanol/water (6:4, vol/ vol), and the methanolic-aqueous extract was removed.…”

“…Peak areas were calculated utilizing an HP ChemStation data system. trans,trans-2,4-Decadienal was analyzed according to the method proposed by Andrikopoulos et al [6]. In brief, a quaternary solvent system consisting of water (acidified with phosphoric acid at pH 3), methanol, acetonitrile, and 2-propanol with gradient elution on a Nucleosil C18 120-5 (12064.6 mm) column (Macherey-Nagel) at a flow rate of 1 mL/min was used.…”

“…Oils and fats are used as means of heat transfer from the fryer to the food and are absorbed by the food [2][3][4]. The oil uptake of food ranges in percentages from 4% [5] to 14% [6] of total weight, depending on the type of food and the frying medium. Thus, the quality of oils and fats has a major influence on the quality of the final product.…”

“…The above substances have been blamed for cytotoxic effects on experimental animals [10]. oil, sunflower oil, and vegetable shortening oil [6]. The in vitro oxidation of LDL by different levels of MPM isolated from fried oils has also been reported [11].…”