Isa Beatriz Noll

Determination of ochratoxin A in wine by high-performance thin-layer chromatography using charged coupled device

A method was developed and validated in-house for determination of ochratoxin A (OTA) in wine using charge coupled device (CCD) to acquire the fluorescence images of mycotoxin from high-performance thin-layer chromatography (HPTLC) under UV lamp. The method showed a mean recovery of 90.4%. The quantification and detection limist were 0.1 μg L -1 and 0.016 μg L -1 per spot, respectively. The results of validation confirmed the efficiency of the method, which is sensitive enough to be used to quantify OTA in wine. The occurrence of OTA in Brazilian wines was evaluated. OTA was found in one sample at a level of 4.5 μg L -1 , which is higher than the limit of 2 μg L -1 considered acceptable by the Scientific Commission of the European Communities. This study demonstrated the applicability of HPTLC using CCD as a tool to determine OTA in wine.

Quantitative analysis of patulin in apple juice by thin-layer chromatography using a charge coupled device detector.

A method was developed and validated in-house for the detection and quantification of patulin in apple juice concentrate using a charge coupled device (CCD) on thin-layer chromatography (TLC) plates. Samples were extracted with ethyl acetate and then cleaned-up by extraction with a sodium carbonate solution. The method showed a mean recovery of 95%. The quantification and detection limit were 14 µg l−1 and 0.005 µg per spot, respectively. The CCD camera is sufficiently sensitive to detect changes in spot fluorescence intensity caused by small differences in mycotoxin concentration under homogeneous illumination from a UV light source. The results of validation confirmed the efficiency of the method, which is sensitive enough to be used to quantify patulin in apple juice by producers or for government monitoring/survey programs. The method was applied to the analysis of 16 apple juice concentrate samples and patulin levels ranged from 15 to 46 µg l−1. This study demonstrated the applicability of the TLC–CCD technique as a tool for monitoring patulin in apple juice.

Patulin accumulation in apples during storage by Penicillium expansum and Penicillium griseofulvum strains

A part of apples destined to juice production is generally of poor quality. Apples from cold storage or recently harvest (ground harvested or low quality apples) are stored under ambient conditions until they are processed. Since Penicillium expansum and P. griseofulvum are the principal fungal species isolated from stored apples in Brazil, the objective of this study was to investigate the ability of these strains to produce patulin in apples and report the consequences of this type of storage in loss of quality. The toxin was quantified using thin layer chromatography and charge-coupled device camera (TLC-CCD). The rate and quantities that P. expansum and P. griseofulvum can grow and produce patulin are highly dependent on the fungal strain and time. Lesion diameter resulted to be independent of the strain considered. The maximum period of time which apples were kept at cold storage (4 °C) without patulin accumulation was 27 days. When these apples were kept at 25 °C during 3 days, both factors lesion diameter and patulin production increased significantly. These results confirm that time in which apples are taken out from cold storage room before juice production is critical in order to prevent patulin accumulation.

Photometric procedure for quantitative analysis of Aflatoxin B1 in peanuts by thin-layer chromatography using charge coupled device detector

A photometric procedure was developed for determination of aflatoxin B1 in peanuts by TLC-CCD technique. The quantification and detection limit were 1.2 μg kg-1 and 0.4 ng per spot, respectively, with mean recovery of 98%. The CCD camera is sufficiently sensitive to detect small changes in spots fluorescence intensity and the results for performance confirmed the efficiency of the method. Another important property of CCD detector is its linearity for a wide range of luminous stimulus determined by analysis of five-point calibration curves using the intensity of AFB1 fluorescence versus AFB1 concentration (0.8 to 4.8 ng per spot). The method was applied to the analysis of thirty nine peanut samples and aflatoxin B1 levels ranged from 16 to 115 μg kg-1. The TLC-CCD and the photometric procedure developed in this study demonstrated to be a simple and efficient tool for quantitative analyses of AFB1 in peanut samples.

Determination of ochratoxin A in wine from the southern region of Brazil by thin layer chromatography with a charge-coupled detector.

The presence of ochratoxin A (OTA) is evaluated using thin layer chromatography (TLC) with a charge-coupled detector (CCD) in 88 red wine samples (2009 vintage) from Brazil. Samples included 75 wines from Rio Grande do Sul, nine from Santa Catarina and four from Paraná state; 56 wines were Cabernet Sauvignon and 32 were Merlot varieties. The method included the analysis of fluorescent images, acquired under UV light, using ImageJ software. Mean recovery of OTA was 82.3% using immunoaffinity columns (IAC). The limits of quantification (LOQ) and detection (LOD) were 0.8 and 0.2 µg l−1, respectively. Results showed a 5.7% contamination of OTA, with five positive samples – three Cabernet Sauvignon and two Merlot. Santa Catarina and Paraná showed one positive sample each, although the concentrations were below the limit of quantification. The highest concentration found was 0.84 µg l−1 in one sample from Rio Grande do Sul.

Toxigenic potential of Aspergillus flavus tested in different culture conditions

O objetivo do presente trabalho foi avaliar a capacidade produtora de aflatoxina de tres isolados de Aspergillus flavus sob diferentes condicoes de crescimento. O experimento foi baseado num delineamento experimental 23, tendo como variaveis independentes a temperatura (20-40 °C), tempo de incubacao (7-21 dias) e pH (2,0 e 6,0) em dois meios de cultura diferentes. As melhores condicoes encontradas foram empregadas com isolados nao toxigenicos testados previamente em Agar Coco. A aflatoxina B1 foi extraida com cloroformio, diretamente dos meios sinteticos. A identificacao e a quantificacao do composto foram efetuadas por Cromatografia em Camada Delgada e Fotometria Fotografica. Como resultados preliminares, o meio de cultura YES se mostrou como uma alternativa para detectar o potencial toxigenico de Aspergillus flavus, nas seguintes condicoes: pH 5,2, temperatura de 25 °C e tempo de incubacao de 11 dias, com uma producao de 206,05 ng.UFC-1 de aflatoxina B1. Dos 30 isolados nao toxigenicos, 12 apresentaram resultado positivo nas condicoes e meios de cultura testados.

Ocorrência, aspectos toxicológicos, métodos analíticos e controle da patulina em alimentos

Patulin is a mycotoxin produced by several Penicillium, Aspergillus and Byssochlamys species. Patulin is a highly toxic compound which has shown to be mutagenic, carcinogenic and teratogenic in experiments with animals. It has often been found in apples and apple products. Patulin is easily transfered into apple juice during processing due to its high solubility in water. This mycotoxin is very stable to heat in acidic medium as in apple juice. Thus, patulin content of apple juice is an indicator of the quality of the apples used to juice production. Many methods have been developed for the patulin determination mainly based on liquid-liquid extraction with ethyl acetate and use of HPLC for detection. It is important to show the need of legislation that imposes patulin limits in foods in Brazil. The objectives of this review are to describe the main patulin characteristics, occurrence, toxicological aspects, methods developed for patulin detection and control during the stages of apple and juice production.

Fungos e fumonisinas no período pré-colheita do milho

SUMMARY FUNGI AND FUMONISINS AT MAIZE’S PRE-HARVEST PERIOD. Fungal and mycotoxin contamination in maize can take place even before harvest time, with large economic losses in consequence. Fusarium spp. is a ubiquitous contaminant of corn in the field and several species of this genera are responsible for fumonisins production. Fumonisins are reported to be toxic to animals and humans, implicated in equine leukoencephalomacia disease and associated with pulmonary edema syndrome in swine and esophageal cancer in humans. The objective of this work was to identify critical points of fungal contamination and fumonisins production during pre-harvest growth stage. Results showed fungal growth since the dough stage, with no significant difference at both following stages: dent and physiological maturity. Non sporulated fungi were predominant at the silking stage (100%) and at the dough stage (95%). Saprophytes species were identified at the dent stage (23.25%). Fusarium spp. was evident since the dough stage (5%) increasing considerably through the dent stage (62.5%) to the physiological maturity (90%). All Fusarium spp. strains tested showed toxigenic potential. Fumonisins were evident at the latest development stages increasing considerably from the dent stage (0.2 ppm) to the physiological maturity (2.5 ppm). Authors suggest special attention and adopting preventive measures in

The occurrence of aflatoxin B1 contamination in peanuts and peanut products marketed in southern Brazil

This study investigated the occurrence of aflatoxin B1 in peanuts and peanut products marketed in the State of Rio Grande do Sul, Brazil. One hundred one samples of peanuts and peanut products were collected and analyzed by thin-layer chromatography with a charge-coupled device system. Aflatoxin B1 was present in 14% of the samples analyzed, in concentrations ranging from 24.0 to 87.5 µg/kg in the peanut samples and from 22.0 to 84.6 µg/kg in the peanut-product samples. These values exceeded the Brazilian regulatory limit (20.0 µg/Kg for aflatoxins B1+G1+B2+G2 ). These results suggest that although aflatoxin contamination in peanuts marketed in southern Brazil is lower than in other Brazilian regions, it is still a serious problem for human health and the economy.

Micobiota e micotoxinas em amostras de arroz coletadas durante o sistema estacionário de secagem e armazenamento

Considering the qualitative and quantitative losses in post-harvest of grain, in this research was evaluated fungi and mycotoxins contamination in whole rice (Oryza sativa L.) during the stationary drying and storage system. Samples were collected in a period of sixty days in two heights of the warehouse during storage. The initial sample presented 5.4x10 4 CFU g -1 ; the contamination increased significantly during drying and storage, up to 10 5 CFU g -1 . Fungi contamination was different inside the warehouse with higher contamination in the upper portion. The more abundant fungi genera were Aspergillus and Penicillium, A. flavus (26.3%) and P. commune (19.1%) which presented higher incidence. Aflatoxin B1 was produced by four A. flavus isolates, but mycotoxins were not detected in the samples.