The consumer is very inadequately informed on seafood composition because of variable fat levels in some species, confusion in species nomenclature, failure to recognize the increasing proportion of imports, influence of aquaculture practices, and the actual fish contents of convenience foods. Concerns about safety considerations are primed by the controversy between advocates of fish as food and marketers of fish oil concentrates in capsules. There are in fact very few problems with fish and shellfish, when these are carefully inspected, or with fish oil concentrates, which are prepared from highly purified natural materials. The bioavailability of different forms of omega‐3 fatty acids attached to glycerol, or sold as ethyl esters or free fatty acids, must be addressed. Therefore, the absorption and distribution in the body of various forms of omega‐3 fatty acids is outlined.

Seafood lipids and fatty acids

Seventeen edible vegetable oils were analyzed spectrometrically for their metal (Cu, Fe, Mn, Co, Cr, Pb, Cd, Ni, and Zn) contents. Toxic metals in edible vegetable oils were determined by Inductively Coupled Plasma Atomic Emission Spectrometry (ICP-AES). The highest metal concentrations were measured as 0.0850, 0.0352, 0.0220, 0.0040, 0.0010, 0.0074, 0.0045, 0.0254 and 0.2870 mg/kg for copper in almond oil, for iron in corn oil-(c), for manganese in soybean oil, for cobalt in sunflower oil-(b) and almond oil, for chromium in almond oil, for lead in virgin olive oil, for cadmium in sunflower oil-(e), for nickel almond oil and for zinc in almond oil respectively. The method for determining toxic metals in edible vegetable oils by using ICP-AES is discussed. The metals were extracted from low quantities of oil (2-3 g) with a 10% nitric acid solution. The extracted metal in acid solution can be injected into the ICPAES. The proposed method is simple and allows the metals to be determined in edible vegetable oils with a precision estimated below 10% relative standard deviation (RSD) for Cu, 5% for Fe, 15% for Mn, 8% for Co, 10% for Cr, 20% for Pb, 5% for Cd, 16% for Ni and 11% for Zn.

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Determination of some inorganic metals in edible vegetable oils by inductively coupled plasma atomic emission spectroscopy (ICP-AES)

Determination of cadmium(II) and zinc(II) in olive oils by derivative potentiometric stripping analysis

A procedure, based on the standard additions method, has been developed for the direct determination of copper and iron in edible oils by flow injection flame atomic absorption spectrometry. An organic standard is added to the sample using a reverse single line manifold. The flow injection standard additions method allows the accurate determination of copper and iron in unrefined oil samples without any pre-treatment or dilution of the samples.

Direct determination of copper and iron in edible oils using flow injection flame atomic absorption spectrometry

Olive oil represents an important ingredient in the Mediterranean diet and is appreciated both for nutritional and sensory properties, often related to geographical origin and cultivar of olive fruits employed. Fraudsters trying to seek financial gain can adulterate the product causing economic repercussions and, sometimes sanitary risks. The “protected designation of origin” (PDO) label insures a relative protection of both consumers and honest producers, since it prescribes production techniques and specific geographical origin, but one of the main problems is to set down objective tools to control these specifications. We reviewed numerous studies using various analytical tools to discriminate PDO olive oils’ geographical origin depending on (1) volatiles compounds, (2) fatty acid and triacylglycerol composition, (3) trace elements, and/or (4) stable isotope ratios, but we highlighted that, despite their efficiency, none of them could provide an irrefutable identification. However, 87Sr/86Sr signature revealed to be an optimal geographical fingerprint in the same purpose for other food products like cereals, orange juice, coffee or alcoholic beverages. Such 87Sr/86Sr studies do not exist on olive oils, probably because of analytical issues, but we propose that developing complementary 87Sr/86Sr studies could be a promising tool to re-enforce the characterization of PDO olive oils.

https://hal.archives-ouvertes.fr/hal-01539820/document

Gholamreza Ghazi-Moghaddam

Papers

Variations of trace metal content of edible oils and fats during refining processes