Fungal mycoflora and mycotoxins in Korean polished rice destined for humans

Incidence of ochratoxin A in rice and dried fruits from Rabat and Salé area, Morocco

One hundred samples of dried fruits (20 dried raisins, 20 walnuts, 20 peanuts, 20 dried figs and 20 pistachios) and 20 samples of rice purchased from retail shops in the Rabat and Salé area in Morocco were analysed for ochratoxin A (OTA) by immunoaffinity clean-up (IAC) and liquid chromatography (LC) with fluorescence detection. The limit of quantification (LOQ) (S/N = 10:1) of OTA was 0.02 ng g(-1) in rice, 0.03 ng g(-1) in pistachio, peanut and walnut, and 0.03 ng g(-1) in dried raisins and dried figs. The incidences of occurrence of OTA in dried raisins, walnuts, peanuts, dried figs and rice were 30, 35, 25, 65 and 90%, respectively. Analytical results showed that pistachio samples contained no detectable OTA, but concentrations ranged from 0.02 +/- 0.01 to 32.4 +/- 2.10 ng g(-1) in rice, from 0.10 +/- 0.05 to 2.36 +/- 0.75 in peanut, from 0.03 +/- 0.01 to 1.42 +/- 0.45 in dried figs, from 0.05 +/- 0.02 to 4.95 +/- 0.02 in dried raisins, and from 0.04 +/- 0.01 to 0.23 +/- 0.05 in walnuts. The results also showed that 15% of the total number of rice samples analysed exceeded the 2002 regulatory limit set by European Union regulations for cereals. This is the first report on the occurrence of OTA in dried fruits and rice available in Morocco.

Occurrence of fumonisins B1 and B2 in broa, typical Portuguese maize bread

Fumonisin B(1) (FB(1)) and fumonisin B(2) (FB(2)) are mycotoxins mainly produced by Fusarium verticillioides, and Fusarium proliferatum, fungi species most commonly isolated from maize. The natural occurrence of FB(1) and FB(2) in broa, typical Portuguese maize bread, was evaluated in 30 samples. Twenty five were found positive with levels ranging from 142 to 550 microg kg(-1). The limit established by the European regulations was exceeded by 27% of the samples. The tolerable daily intake for fumonisin B(1), and B(2), alone or in combination, for all of the analysed samples, was lower than 2 microg kg(-1) body weight per day established by the European Commission.

Populations of fungi and bacteria associated with samples of stored rice in Korea

Stored rice was collected from rice processing complexes of National Agricultural Cooperative Federation of 11 regions in Korea to evaluate the occurrence of fungi and bacteria and to identify the predominant fungi and bacteria to the genus levels. Most rice samples generally produced the higher levels of fungi and bacteria than white rice. The occurrence of fungi and bacteria varied in various locations of Korea. Among fungi observed, Aspergillus spp. and Penicillium spp. were dominant in the samples and Aspergillus spp. were observed more frequently than Penicillium spp. Predominant bacteria from rice and white rice samples tentatively belonged to the Genus Bacillus, Pectobacterium, Pantoea, and Microbacterium according to BIOLOG and FAME analyses. The results of this study showed that rice in Korea was contaminated in a relatively high level by two dominant storage fungi such as Aspergillus spp. and Penicillium spp. In addition, occurrence of mycotoxins in rice by the fungi could be possible and thus it is necessary to control the storage fungi.

Review on the toxicity, occurrence, metabolism, detoxification, regulations and intake of zearalenone: An oestrogenic mycotoxin

Zearalenone (ZEA) is a mycotoxin produced mainly by fungi belonging to the genus Fusarium in foods and feeds. It is frequently implicated in reproductive disorders of farm animals and occasionally in hyperoestrogenic syndromes in humans. There is evidence that ZEA and its metabolites possess oestrogenic activity in pigs, cattle and sheep. However, ZEA is of a relatively low acute toxicity after oral or interperitoneal administration in mice, rat and pig. The biotransformation for ZEA in animals involves the formation of two metabolites alpha-zearalenol (alpha-ZEA) and beta-zearalenol (beta-ZEA) which are subsequently conjugated with glucuronic acid. Moreover, ZEA has also been shown to be hepatotoxic, haematotoxic, immunotoxic and genotoxic. The exact mechanism of ZEA toxicity is not completely established. This paper gives an overview about the acute, subacute and chronic toxicity, reproductive and developmental toxicity, carcinogenicity, genotoxicity and immunotoxicity of ZEA and its metabolites. ZEA is commonly found on several foods and feeds in the temperate regions of Europe, Africa, Asia, America and Oceania. Recent data about the worldwide contamination of foods and feeds by ZEA are considered in this review. Due to economic losses engendered by ZEA and its impact on human and animal health, several strategies for detoxifying contaminated foods and feeds have been described in the literature including physical, chemical and biological process. Dietary intakes of ZEA were reported from few countries from the world. The mean dietary intakes for ZEA have been estimated at 20 ng/kgb.w./day for Canada, Denmark and Norway and at 30 ng/kgb.w./day for the USA. The Joint FAO/WHO Expert Committee on Food Additives (JECFA) established a provisional maximum tolerable daily intake (PMTDI) for ZEA of 0.5 microg/kg of body weight.

Occurrence and daily intake of ochratoxin A of organic and non-organic rice and rice products

Ochratoxin A (OTA) was extracted from 84 rice samples and rice products by using accelerated solvent extraction (ASE) and analysed with liquid chromatography coupled with fluorescence detection. Samples were collected from rice cultivars, local markets and supermarkets; 64 were of non-organic and 20 of organic production. 7.8% of non-organic samples had OTA levels from 4.3 to 27.3 microg/kg and in 30% of organic samples was detected the presence of this mycotoxin varying from 1.0 to 7.1 microg/kg. OTA presence was confirmed by methyl-ester derivatization. Rice and rice products labelled with denomination of origin (DO) were not detected OTA due to the fact that its production has implemented food safety measures such as good agricultural practices (GAPs), good manufacturing practices (GMPs), and the hazard analysis and critical control point (HACCP) system. Estimated daily intake of OTA was 0.17 ng/kg b.w./day. This value reflects that the analysed samples have a minimal contribution to toxicological risk.

Fate of ochratoxin a during cooking of naturally contaminated polished rice

Ochratoxin A (OTA), a mycotoxin widespread in cereals, occurs in polished rice that is consumed as cooked rice after washing and steaming. Cooking decreases OTA levels in food to varying extents, but little is known about how cooking changes the biological activity of this mycotoxin. We therefore evaluated the fate of OTA during rice cooking to determine the OTA residues and cytotoxic potential in vitro. Water-washed rice, ordinary cooked rice, and pressure-cooked rice were prepared from three polished rice lots naturally contaminated with OTA. Residual OTA in each sample was analyzed by high-performance liquid chromatography (HPLC), whereas in vitro cytotoxicity of OTA to C6 glioma cells, susceptible to low levels (nanograms per milliliter) of OTA, was used to confirm the chemical analysis. OTA concentration, as determined by HPLC analysis, in the cooked rice by both types of cookers was significantly lower than (59 to 75%) in the raw polished rice and water-washed rice. The cytotoxicity of the OTA that remained in the pressure-cooked rice from three lots was markedly decreased (approximately 20%, P < 0.05) when compared with other samples in respective lots. This confirms that cooking lowers OTA residues. Although washing polished rice with water had little effect on OTA levels, pressure steaming appeared to be the critical cooking step not only to reduce OTA residues in polished rice before reaching the consumer as the dietary staple of cooked rice, but also to diminish cytotoxicity of OTA.