RESUMEN
As especiarias são utilizadas na alimentação, conferindo sabor e conservação prolongada aos alimentos, pois apresentam propriedades antimicrobianas provenientes dos óleos essenciais de sua constituição. O objetivo deste estudo foi avaliar a atividade antimicrobiana dos óleos essenciais de cravo, louro, manjericão, noz moscada e orégano frente a seis bactérias patogênicas e deteriorantes por meio da técnica de difusão em poços e determinação das Concentrações Inibitória Mínima (CIM) e Bactericida Mínima (CBM). O óleo essencial de orégano evidenciou forte atividade antibacteriana (CIM 50 - 800 μg.mL-1), seguido do cravo (CIM 800 - 3200 μg.mL-1), com atividade moderada para todos os microrganismos. Os outros óleos apresentaram baixa ação (CIM 400 - 3200 μg.mL-1), não apresentando atividade sobre todos as bactérias. Desta forma os óleos essenciais de cravo e orégano apresentaram melhor atividade antibacteriana e se apresentam como promissores para a aplicação e uso em alimentos.
Asunto(s)
Antiinfecciosos/análisis , Especias/microbiología , Laurus/microbiología , Myristica/microbiología , Ocimum basilicum/microbiología , Origanum/microbiología , Syzygium/microbiología , Técnicas Bacteriológicas/métodos , Aceites Volátiles/análisisRESUMEN
A simple and sensitive analytical method based on ultrasound-assisted solid-liquid extraction and immunoaffinity column clean-up coupled with high performance liquid chromatography and on-line post-column photochemical derivatization-fluorescence detection (USLE-IAC-HPLC-PCD-FLD) has been developed for simultaneous multi-mycotoxin determination of aflatoxins B1, B2, G1, G2 (AFB1, AFB2, AFG1, AFG2) and ochratoxin A (OTA) in 13 edible and medicinal nutmeg samples marketed in China. AFs and OTA were extracted from nutmeg samples by ultrasonication using a methanol : water (80 : 20, v/v) solution, followed by an IAC clean-up step. Different USL extraction conditions, pre-processing ways for nutmeg sample and clean-up columns for mycotoxins, as well as HPLC-PCD-FLD parameters (mobile phase, column temperature, elution procedure, excitation and emission wavelengths) were optimized. This method, which was appraised for analyzing nutmeg samples, showed satisfactory results with reference to limits of detection (LODs) (from 0.02 to 0.25 µg kg(-1)), limits of quantification (LOQs) (from 0.06 to 0.8 µg kg(-1)), linear ranges (up to 30 ng mL(-1) for AFB1, AFG1 and OTA and 9 ng mL(-1) for AFB2 and AFG2), intra- and inter-day variability (all <2%) and average recoveries (from 79.6 to 90.8% for AFs and from 93.6 to 97.3% for OTA, respectively). The results of the application of developed method in nutmeg samples have elucidated that four samples were detected with contamination of AFs and one with OTA. AFB1 was the most frequently found mycotoxin in 30.8% of nutmeg samples at contamination levels of 0.73-16.31 µg kg(-1). At least two different mycotoxins were co-occurred in three samples, and three AFs were simultaneously detected in one sample.
Asunto(s)
Aflatoxinas/análisis , Cromatografía Líquida de Alta Presión/métodos , Myristica/microbiología , Ocratoxinas/análisis , Extracción en Fase Sólida/métodos , Fluorescencia , Microbiología de Alimentos , Límite de Detección , Ultrasonido/métodosRESUMEN
This study examined the distribution of aflatoxigenic fungi in 25 imported Indonesian nutmeg samples contaminated with aflatoxins Bs or Bs and Gs. The incidence of aflatoxigenic fungi in the samples contaminated with high levels of aflatoxin was significantly higher than that in the samples with low levels of the toxins(r=0.752). The aflatoxin production of isolates from the samples in cultures of YES broth was examined by means of TLC and HPLC analyses. The ability of isolates to produce aflatoxins did not necessarily correlate with the contamination levels of aflatoxin in the samples. We isolated aflatoxins B and G-producing fungi from 3 samples contaminated with the high levels of aflatoxins B and G. The aflatoxigenic isolates were identified as Aspergillus nomius and A. bombycis based on morphological characters, growth rates at 37°C and 42°C and also molecular-genetic methods. Our results indicate that these two species are mainly responsible for aflatoxin G contamination in nutmeg products.