Rheological Behavior, Antimicrobial and Quorum Sensig Inhibition Study of an Argentinean Oregano Essential Oil Nanoemulsion.

In this study, Argentinean oregano essential oil (OEO) nanoemulsions (NEs) were developed. Four NEs were prepared: a control (CNE), EONE1 (10.6 mg EO/g NE), EONE2 (106 mg EO/ g NE), and EONE3 (160 mg EO/g NE) and tested for antimicrobial activity against Staphylococcus aureus ATCC 13565, Listeria monocytogenes Scott A, Pseudomonas aeruginosa ATCC 14213, and Escherichia coli O157:H7 using a broth microdilution assay and quorum sensing inhibition in a model using Chromobacterium violaceum ATCC 12472, where the production of violacein was quantified. The chemical composition of the EO was determined by gas chromatography-mass spectrometry. The average particle size (nm) and polydispersity index were monitored over 14 days at two different storage temperatures (4 and 23°C). A rheological behavior study was carried out using a dynamic shear rheometer, and flow curves, as well as viscoelastic properties, were determined. E. coli and L. monocytogenes were the most sensitive microorganisms to EONE (MIC of 2 and 5 mg/ml for EOEN3). Sub-MICs for NE were found at lower concentrations than those for pure EO. A significant reduction in violet pigment intensity and colorless coloration (p < 0.05) were observed at different NE concentrations concerning the control sample. The flow behavior index (n) decreased, and the consistency index (k) increased when the EO concentration was increased. CNE, EONE1, and EONE2 showed liquid-like behavior (G' < G″) in the low-frequency region, whereas a solid-like behavior (G' > G″) was observed in the high-frequency region, presenting a viscoelastic behavior, appearing as a wormlike micellar solution. For EONE3, a strong increase in both moduli was observed with increasing OEO concentration. The G' was about one order of magnitude higher than the G″ over the whole frequency range, indicating the presence of a gel-like structure. The incorporation of EOs into an NE increased their stability, lowering the particle size, leading to a wormlike micelle with higher viscosity. Moreover, this NE had good antimicrobial activity and novel quorum-sensing inhibition activity. The results of this study indicated that Argentinean OEO NE could be used in a food system as a natural and stable antimicrobial agent.

Detection of extraneous materials and histology identification of marjoram (Origanum majorana L.), oregano (Origanum vulgare L) and parsley (Petroselinum sativum Hoffm.) flakes commercialized in São Paulo state / Matérias estranhas e identificação histológica em manjerona (Origanum majorana L.), orégano (Origanum vulgare L.) e salsa (Petroselinum sativum Hoffim.), em flocos, comercializados no estado de São Paulo

The seasonings and spices are consisted of different parts of dried vegetables that present characteristic aromas, and they are used to add flavor and to improve the food taste. The objectives of this work were to investigate frauds by identifying characteristic histological elements, the adequacy of methods for extraneous materials identification by means of sieving and floating procedures and to evaluate the hygienic conditions of condiments (marjoram, oregano, and parsley flakes). The 41 samples of marjoram, 84 of oregano and 57 samples of parsley flakes were obtained during the period of August to November, 1998, in six cities of the state of São Paulo. The technique described by Rodrigues et al. was used for investigating the histological elements. The technical procedures described by AOAC-2000 were used for identifying the extraneous materials. No fraud was detected in the three chosen and analyzed condiments. Of 182 analyzed samples, 98.90% were not in accordance to the law determination of July 7, 2003. The identified insects belonged to orders Hemiptera (aphids), Coleoptera (beetles) and Psocoptera, and the mostly frequent extraneous materials were fragments of insects. The floating method was the most efficient to recover extraneous materials, especially in detecting the presence of mites.

Os condimentos ou especiarias são constituídos de diferentes partes de vegetais dessecados, apresentam aroma característico e são utilizados para realçar o sabor dos alimentos. Este trabalho teve como objetivos a pesquisa de fraudes pela identificação dos elementos histológicos característicos, a adequação e implantação de métodos para pesquisa de matérias estranhas, por peneiração e flutuação em manjerona, orégano e salsa em flocos e a avaliação das condições higiênicas desses condimentos. As 41 amostras de manjerona, 84 de orégano e 57 amostras de salsa em flocos foram adquiridas no período de agosto a novembro de 1998, em seis cidades do estado de São Paulo. Para identificação dos elementos histológicos utilizou-se a técnica descrita por Rodrigues et al. e para identificação das matérias estranhas foram utilizados os métodos descritos pela AOAC-2000. Não foi caracterizado qualquer tipo de fraude nos três condimentos analisados. Das 182 amostras analisadas, 98,90% estavam em desacordo com a legislação utilizada até 07/07/2003. As ordens de insetos identificadas foram Hemiptera (afídeos), Coleoptera (carunchos) e Psocoptera (psócides) e os fragmentos de insetos foram a matéria estranha mais freqüente. O método de flutuação foi mais eficiente para a recuperação de matérias estranhas do que a peneiração, inclusive para detectar a presença de ácaros.