Samples of used frying oils and fats from 63 restaurants and fast‐food outlets, from the inner and outer suburbs of Athens, were randomly collected during a 1‐month period. Sampling was performed after deep‐frying or pan‐frying of several foods, of both vegetable and animal origin, in different frying oils or fats (sunflower oil, cottonseed oil, corn oil, palm oil, palm kernel oil, soybean oil, vegetable shortening oil, vegetable cooking oils and fats). Sunflower oil was the most widely used frying medium and deep‐fried potatoes (French fries) were the most common fried food. Sixteen samples (approximately 25%) were found with polymerized triglycerides (PTG) over the 12% limit of rejection, while 11 of them (approximately 17%) with total polar materials (TPM) over the 25% limit of rejection. From the above ‘over‐limit’ samples, only one was from the pan‐frying process. The higher TPM and PTG mean values were found in low‐unsaturated vegetable frying oils and cooking fats, with the highest values observed when food of animal origin was fried. Vitamin E content of the fried samples examined was lower than that of the respective fresh samples (28% mean loss), but in most cases in relatively high levels.

Individual triglyceride (TG) species of olive oil and several seed oils (corn, cottonseed, palm, peanut, soybean, and sunflower) are baseline separated on a WCOT TAP CB fused-silica capillary column by capillary gas chromatography (CGC) with a flame-ionization detector (FID) and either cold on-column or split injection. An adulteration of olive oil with a low content (< 5%) of these seed oils (except peanut oil) can be verified by the detection of the increasing levels of trilinolein or tripalmitin in olive oil in which these TG species are normally absent or present at very low levels (< 0.5%). An adulteration with over 20% peanut oil can be detected by the increasing levels of palmitodilinolein. TG species that can be coeluted with trilinolein in the reversed-phase high-performance liquid chromatographic (RP-HPLC) mode are baseline separated by the CGC technique, and their structures are identified by selective ion monitoring mass spectrometry. The following comparisons--the CGC-FID and RP-HPLC methods for detection of adulteration, cold on-column and split-injection modes for CGC-FID, and silylation or thin-layer chromatography pretreatment and simple dilution of one or more of the oil samples--are also presented. The normalized percentage area of the TG species is sufficient for the method limits used in this study. Mixtures of virgin olive oil with refined or residue olive oil could not be distinguished from the virgin type by the method used in this study.

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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.

A new sensitive and selective gas chromatography tandem mass spectrometry (GC-MS/MS) method was developed for the analysis of 26 polycyclic aromatic hydrocarbons (PAHs), including 16 Environmental Protection Agency (EPA) and 15 + 1 European Union (EU) PAHs, in mussel samples from aquaculture farms in Thermaikos and Strymonian Gulf, Central Macedonia Region, in three sampling periods. Concentrations were found at moderate to low values at all sampling sites, without exceeding maximum levels set by EU. Low molecular weight PAHs were predominant in all samples. Seasonal variation of the concentrations was observed; values were slightly higher in the winter period. Use of diagnostic ratios for potential sources of PAHs showed both petrogenic and pyrolitic origin. In comparison to other related studies of mussels from the Mediterranean Sea, Greek mussels cultivated in the studied gulfs are low in contaminants due to minimal environmental pollution effects. Low concentrations of PAHs are in compliance with the low values of other POPs which were found in the mussels.