A procedure is proposed for the supercritical fluid extraction of all-trans-lycopene from tomato using carbon dioxide at 40 degrees C without modifier. The present method minimizes the risk of degradation via isomerization and oxidation of health-promoting ingredients, such as lycopene. The effect of different experimental variables on the solvating power of the supercritical fluid was evaluated in terms of both the selectivity achievable in the process and the yield of the extraction of all-trans-lycopene. Satisfactory separations of the all-trans-lycopene isomers from the cis counterparts were achieved using a C(30) column. The obtained extract contained 88% all-trans-lycopene and 12% cis-lycopene.

β-Carbolines (βCs) are naturally occurring bioactive alkaloids, whereas α-dicarbonyl compounds are reactive substances generated in foods and in vivo. In this work, L-tryptophan reacted with α-dicarbonyl compounds affording new βcarbolines. Glyoxal afforded 1-hydroxymethyl-β-carboline (HME-βC) and its 3-carboxylic acid, and methylglyoxal afforded 1-(1hydroxyethyl)-β-carboline (HET-βC) and its 3-carboxylic acid. 2), and 1-(1,5-dihydroxypent-3-en-1-yl)-β-carboline (3). The formation of these βCs increased under acidic conditions and with increasing temperature. A mechanism is proposed explaining the conversion of a carbonyl into a hydroxy group based on tautomerism and cyclization to the dihydro-βC-3-COOH intermediates, which were isolated and gave the βCs. These α-dicarbonyl-derived βCs occurred in model reactions of L-tryptophan with fructose or glucose incubated under heating and can be considered as advanced glycation end products (AGEs). They were also present in foods and formed during heating processes. HET-βC appeared in processed foods, reaching up to 309 ng/g, with the highest amount found in dried tomato, fried onion, toasted bread, and Manuka honey. HME-βC was only detected in some foods with lower amounts than HET-βC. HET-βC appeared in foods as a racemic mixture of enantiomers suggesting the same mechanism of formation as the synthetized product. α-Dicarbonyl-derived βCs (HET-βC, HME-βC, and 1a/b-3) occur in foods and food processing and, therefore, they are ingested during diet.

ABSTRACT

Different methods for the analysis of hazelnut oil and olive oil are compared in terms of the potential of each procedure in detecting compositional differences for evaluation of authenticity. These methods involve the use of different sample preparation techniques, namely simultaneous distillation−extraction (SDE) and supercritical fluid extraction (SFE), and the subsequent analysis by capillary gas chromatography using a programmable temperature vaporizer (PTV). On-line coupling of reversed-phase liquid chromatography to gas chromatography (RPLC−GC) was also considered for the analysis of the samples investigated. Working under the experimental conditions proposed, identification of olive oil, hazelnut oil, and mixtures of both oils (85:15) may be possible on the basis of the determination of the presence or absence of (E)-5-methylhept-2-en-4-one (filbertone). Keywords: Olive oil; hazelnut oil; filbertone; adulteration