El presente estudio tuvo como objetivo identificar la composición de aceites de bellota de tres especies del grupo del roble blanco del Mediterráneo, Quercus Aegilops (QA), Quercus infectoria (QI) y Quercus calliprinus (QC). Las muestras fueron evaluadas por el contenido de aceite, pará-metros físico-químicos del aceite, perfil de ácidos grasos, tocoferoles, compuestos fenólicos y esteroles. El contenido de aceite, expresado en peso seco encontrado fue de 3,40 a 7,51%. Las constantes físico-químicas fueron: densidad 0,912-0,922, índice de refracción 1,4529 a 1,4645, extinción específica a 232 nm 2,497-2,536 y a 270 nm 1,495-2,037, índice de yodo 75,2-87,6, e índice de saponificación 192,6-219,4. Las composiciones de ácidos grasos se determinaron por GC como ésteres metilicos. Los ácidos grasos más abundantes fueron oleico 53,3-56,1%, linoleico 21,3-23,4%, palmítico 17,8-18,7%, linolénico 1.5-1.6% y esteárico 1,02-1,60%. El contenido de tocoferoles fue alto: 1440-1783 mg kg -1 , constituyendo el γ-tocoferol entre el 84-91% de los tocoferoles totales. Los compuestos fenólicos estaban presentes en cantidades notables en las tres especies 84-109 mg de ácido gálico kg -1 aceite. El contenido total de esteroles fue de 2040-2480 mg kg -1 de aceite, siendo el β-sitosterol el componente principal que comprende de 77,2-84,6%, seguido de la Δ5-avenasterol 5.8-11.4, campesterol 3.6-4.5%, y estigmasterol 2.6-3.8%.El contenido de colesterol fue relativamente alto (0,42-0,55%). PALABRAS CLAVE: Aceite de bellota -Compuestos fenólicos -Esteroles -Perfil de ácidos grasos -Quercus spp. -Tocoferoles. SUMMARY Characterization of Acorn Fruit Oils Extracted from Selected Mediterranean Quercus SpeciesThe present study is aimed to identifying the acorn fruit oil composition of three Mediterranean white oak group species, Quercus aegilops (QA), Quercus infectoria (QI), and Quercus calliprinus (QC). Samples were estimated for the oil contents of acorn fruits, oil chemical and physical constants, fatty acid profile, tocopherols, phenolic compounds, and sterols.The oil content, expressed as dry weight, was found to be 3.40-7.51%. The physical and chemical constants included specific gravity 0.912-0.922, refractive index 1.4529-1.4645, specific extinction at 232 nm 2.497-2.536 and at 270 nm 1.495-2.037, iodine value 75.2-87.6, and saponification value 192.6-219.4. The fatty acid compositions were determined by GC as methyl esters. The most abundant fatty acids were oleic (53.3-56.1%), linoleic 21.3-23.4%, palmitic 17.8-18.7%, linolenic 1.5-1.6% and stearic acid 1.02-1.60%. The Tocopherol content was high in the range of 1440-1783 mg kg -1 , γ-tocopherol constituted 84-91% of total tocopherols. Phenolic compounds were in remarkable amounts in all the three species 84-109 mg gallic acid kg -1 oil. Total sterol contents were between 2040-2480 mg kg -1 oil, with β-sitosterol being the main component comprising of 77.20-84.61%, followed by Δ 5 -avenasterol (5.8-11.4%), campesterol (3.6-4.5%), and stigmasterol (2.6-3.8). The cholesterol content wa...

Listeria monocytogenes is a serious foodborne pathogen that has been isolated from different dairy food products. Several foodborne outbreaks of listeriosis have been associated with consumption of cheese. The aims of this study were to determine the occurrence of L. monocytogenes and Listeria spp. in brined white cheese (BWC) sold in Jordan, and to determine the susceptibility of isolated L. monocytogenes to antimicrobials. Three hundred and fifty samples of 5 different types of BWC (akkawi, boiled, halloumi, pasteurized, and shellal) were collected from a local market in Jordan. The ISO (11290-1) procedure was followed for isolation and identification of Listeria spp. from cheese samples and a polymerase chain reaction (PCR) technique was used for confirmation of L. monocytogenes isolates. The VITEK2 automated system was used for testing antimicrobial susceptibility of L. monocytogenes isolates. The overall prevalence of Listeria spp. in cheese sample was 27.1%. L. monocytogenes was isolated from 39 (11.1%) samples. Other isolated species were L. grayi (6.9%), L. innocua (2%), L. ivanovii (4%), L. seeligeri (2%), and L. welshimeri (0.3%). The pH values and salt concentrations of L. monocytogenes positive cheese samples ranged from 5.10 to 6.32 and 5.64 to 13.16, respectively. L. monocytogenes isolates were sensitive or intermediate susceptible to imipenem, gentamicin, linezolid, teicoplanin, vancomycin, fusidic acid, trimethoprim/sulfamethoxazole, benzylpenicillin, ciprofloxacin, erythromycin, tetracycline, and rifampicin, but resistant to fosfomycin, oxacillin, and clindamycin.

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Tahini (sesame paste) is a traditional food. Numerous foodborne outbreaks have been associated with it. This study aimed to (i) explore the efficiency of 2450 MHz microwave heating at 220, 330, 440, 550, and 660 W on the inactivation of Salmonella spp, Escherichia coli O157:H7, and Listeria monocytogenes in tahini; (ii) determine the impact of desiccation and starvation stresses on pathogen survival; (iii) assess the impact of microwave heating on the physicochemical characteristics of tahini. The inoculated microorganisms in tahini were reduced with higher microwave power levels (p < 0.05) and longer exposure times. The D-values of unstressed Salmonella spp., Escherichia coli O157:H7, and L. monocytogenes ranged from 6.18 to 0.50 min, 6.08 to 0.50 min, and 4.69 to 0.48 min, respectively, at power levels of 220 to 660 W, with z-values of 410, 440, and 460 W, respectively. Generally, desiccation and starvation stress levels prior to heating increased microbial resistance to heat treatment. Microwave heating did not affect acid, peroxide, p-anisidine, or color values of tahini up to 90 °C. These findings reveal microwave heating as a potential method for lowering the risk of Salmonella spp., E. coli O157:H7 and L. monocytogenes in tahini with no compromise on quality.

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