1,720,966 research outputs found
HPLC determination of taurine in energy drinks [Determinazione HPLC della taurina in bevande energetiche]
No full textContamination of vegetables oils with mineral oils [La contaminazione degli oli vegetali con oli minerali]
No full textMineral oils are complex mixtures of hydrocarbons (saturated and unsaturated) deriving from petroleum. Different products such as combustible oils, fuel oils, bases for lubricating oils, motor oils, hydraulic oils and purified mineral oils (food grade), are obtained from fractional distillation and further processing of petroleum. Toxicity of mineral oils depends on the molecular weight of the hydrocarbons and the refining degree. Raw mineral oils contain high amounts of aromatics and are classified as carcinogens to humans, meanwhile refined paraffins are responsible for adverse effects when administered to rats (F-344) at levels ranging from 0.01 to 20 mg/kg b.w. (Depending on the oil type and its viscosity). High contamination levels have been also found in human milk and adipose tissues.
There are many possible sources of contamination for vegetable oils and we can not exclude a contribution by the environment. Among other possible sources we can remember: the lubricating oils used in the extraction plant, storage and transport in jute bags, transport in ship previously used to transport mineral oils, handling and storage of the raw matter (it is the case of pomace) under inappropriate conditions.
Coupled LC-GC represents an optimal choice for determining the contamination: it allows to analyse a high number of samples per day, minimising sample preparation which is reduced to a simple sample dilution before injection. Except for extra virgin olive oils, which rarely result contaminated with levels above the detection limit, the different types of vegetable oils have a contamination level generally above 10 mg/kg. Among the different vegetable oils, pomace olive oils result to be the most contaminated (with amounts always higher than 100 mg/kg)
A survey on the presence of free glutamic acid in foodstuffs, with and without added monosodium glutamate
No full textA survey on free glutamic acid (Glu) content in a variety of foods (broths, soups, sauces and salad dressings), with and without added monosodium glutamate (MSG), was carried out. A simple procedure, involving a dilution step for liquid samples or homogenization with 0.1 N HCl for solid and slurry samples, followed by derivatization with o-phthaldialdehyde, HPLC separation on C18 column and spectrofluorometric detection, was employed to quantify Glu, as well as a number of other free amino acids and biogenic amines. Broths and soups with added MSG had Glu contents of 92.7–341 mg/100 g. The highest amounts of Glu in foods with no added MSG were found in products containing hydrolyzed proteins (up to 129 mg/100 g). None of the products ready for consumption exceeded the limit of 10 g/kg of food, established by the European Directive, 95/2/CE [European Parliament and Council Directive (1995). No. 95/2/ EC of 20 February 1995 on food additives other than colours and sweeteners. Official Journal, L061, 1–40].
Relatively high amounts of biogenic amines were found in marmite (77.3 mg/100 g of putrescine and 32.2 mg/100 g of tyramine) and soy sauce while broths and soups showed generally low amounts of biogenic amines, putrescine being the most represented.
Ó 2007 Elsevier Ltd. All rights reserved
Variety Differentiation of Virgin Olive Oil Based on n-Alkane profile
No full textAn on-line LC–GC method was used to assess the n-alkane composition of 40 olive oil samples obtained from three different
cultivars from a restricted grove zone in Croatia. Olive samples were handpicked at three different ripening stages during four
consecutive years. No significant differences were found in relation to the variable ‘‘period of harvesting’’, while the effects ‘‘variety’’ and ‘‘year’’ as well as their interaction caused significant differences for most of the n-alkane components (p60:05). Despite the influence of the production year, linear discriminant analysis based on the n-alkane components was able to correctly identify the variety of 97.5% of the samples
HPLC determination of free nitrogenous compounds of Centaurea solstitialis (Asteraceae), the cause of equine nigropallidal encephalomalacia
No full textRelative hopane content confirming the mineral origin of hydrocarbons contaminating foods and human milk
No full textHopanes, triterpenoid hydrocarbons formed under
geological conditions, were analysed to confirm the
mineral origin of the unresolved complex mixtures of
hydrocarbons observed in the gas chromatography with
flame ionization detection chromatograms of human
milk and certain foodstuffs. The ‘relative hopane content’
(RHC) is introduced, i.e. it is the area ratio of
the sum of the hopanes and the paraffins in the same
segment of the chromatogram. The RHC in various
mineral oil products (motor oils, hydraulic oils, lubricating
oils, Vaseline) was 3.4%, with a relative
standard deviation of 19%. The RHC determined in
samples of vegetable oils, mussels and clams as well
as of human milk containing an unresolved complex
mixture of hydrocarbons was in the same range,
confirming that these samples were contaminated by
mineral oil material
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