A limited survey of fumonisins in corn and corn-based products in Asian countries

Natural occurrence of fumonisins B₁ (FB₁) and B₂ (FB₂), a promoter for hepato-carcinogenesis, was investigated in corn and corn — based products sampled in Japan, Nepal, and China by high — performance liquid chromatographic method. From the 9 imported corn kernel and 6 gluten feed samples, FB₁ was detected in 8 corn (0.6 ～ 4.1μg/g) and all gluten feed (0.3 ～ 2.4μg/g) samples, while FB₂ was found in the same corn (0.3 ～ 10μg/g) and 3 gluten feed (0.8 ～ 8.5μg/g) samples. ELISA analysis also revealed the contamination of aflatoxin B₁ in 2 corn and all gluten feed samples along with fumonisins. Of 17 corn grit samples, 14 and 5 samples were contaminated with fumonisin B₁ and B₂, with maximum levels of 2.6 and 2.8μg/g, respectively. As for corn-based foodstuffs marketed in Japan, no significant contamination of fumonisins was observed. Among 24 corn kernel samples in Nepal, 12 and 7 samples were positive for FB₁ and FB₂, and averaged to 0.6 and 1.6μg/g, respectively. One sample showed the highest fumonisin contents as 4.6 and 5.5μg/g, respectively. In corn samples harvested at Shanghai and Beijing, China, FB₁ and FB₂ were detected in various concentrations. Mycological survey has also revealed the presence of a fumonisin — producing fungus in a crop field of Japan. These findings have for the first time demonstrated high levels of contamination of fumonisins in corn and corn — based products in Asian countries. Natural co — occurrence of fumonisins and aflatoxin B₁ was also detected in raw materials for mixed feed.     

Determination of trichothecenes, zearalenone and zearalenols in commercially available corn-based foods in Spain

Among the main Spanish commercially available trademarks, we have selected a total of 25 samples of corn-based foods, which have the highest consume rate, to carry out the analysis of deoxynivalenol (DON), T-2 toxin, zearalenone (ZEA) and zearalenols (ZOL). The contents of mycotoxins were determined by gas chromatography with flame ionization detection, and those of ZEA were confirmed by HPLC with fluorescence detection. Of the 25 analyzed samples, the incidence of DON, ZEA and alfa-ZOL was 68, 44 and 24%, respectively; levels detected ranged from 29-195, 34-216, and 36-71 microg/kg, respectively. T-2 toxin was only detected in one sample (<50 microg/kg). Beta-ZOL was not present in excess of the detection limit in the investigated samples. The results suggest a risk for consumers of corn products and the need to monitor the final products before consumption. This is the first report in Spain on natural contamination with these mycotoxins in corn-based foods.     

Occurrence of fumonisins b(1) and b(2) in corn-based products from the spanish market

The natural occurrence of fumonisins B(1) and B(2), the incidence of Fusarium organisms, and the capacity of Fusarium isolates to produce fumonisins were investigated with 50 corn-based samples from Spain destined for human consumption. Eight samples (16%) were found to be contaminated with fumonisins. The levels of contamination were very low, with a mean of 80 ng/g.     

A survey of fumonisins (B1, B2, B3) in Indonesian corn-based food and feed samples

In this paper a survey is described for determination of contamination level of fumonisins (B¹, B², B³) in Indonesian cornbased feed and food samples. The survey was conducted from February to May 2001. Foodstuffs, which are consumed directly such as snacks and other products, were investigated for fumonisin contamination. Of 105 food and feed samples purchased from local retail stores and local poultry shops around Yogyakarta, Java, Indonesia were analyzed using ELISA. Results indicate that 74.3% of samples analyzed were contaminated in a large range of 10.0 – 3307 μg/kg, and the concentration of fumonisins depends on the type of samples. Detection limit of the method used was 9 μg/kg.From eight food samples of maize flour, and corn-based beverages and cereals, none was contaminated (below detection limit). For food samples of industrial products (19 samples), 13 were contaminated in the range of 22.8 – 105 μg/kg and 19 of 20 samples from home made products were contaminated between 12.9 – 234 μg/kg. The food samples contaminated in highest level occurred in corn. Of ten samples, 6 were contaminated from 68.0 – 2471 μg/kg. For feed samples, 17 corn samples were evaluated. Of those samples, 16 contained in a large range of 17.6 – 3306 μg/kg.     

Studies on the extraction of nitrogenous and phosphorus-containing materials from the seeds of kidney beans (Phaseolus vulgaris)

1. The conditions of extracting nitrogenous, phosphorus-containing and glucosamine-containing components of the seeds of kidney bean have been studied. 2. The dispersing of proteins was incomplete below pH 7, and the exact amount of protein extracted depended on the pH and the ionic strength of the solvent. 3. The extraction of proteins was practically complete in the range pH 7–9, but the relative amounts of the individual proteins obtained still depended on the pH of the extracting media, indicating a pH-dependent association–dissociation reaction between the protein molecules present. 4. The extraction of phosphorus-containing material showed an optimum at pH 6–7, and only a part of this was removed on dialysis. The precipitates obtained with trichloroacetic acid, on the other hand, retained very little phosphorus-containing material. 5. The significance of these findings is discussed.     

黑米色素提取工艺的优化

黑米稻为中国著名的珍稀稻种。黑米不仅富含的蛋白质、氨基酸、维生素以及钙、铁、锌、硒等矿物营养元素,而且还含有具重要天然色素＂黑米色素＂。由于黑米营养价值高于普通稻米,且富含花色甘类抗氧化色素,是现代食品行业理想的天然抗氧化剂来源。以黑糙米作为研究材料,无水乙醇作为提取溶剂,采用萃取法对黑米色素的提取工艺做了较为全面的研究。试验结果表明：以无水乙醇作为黑米色素萃取剂时,按照料液比（w/v）1∶8,萃取时间60 min,萃取温度80℃,黑米色素提取效果最佳。     

Extracting fumonisins from maize: efficiency of different extraction solvents in multi-mycotoxin analytics

The complete extraction of analytes is of utmost importance when analyzing matrix samples for mycotoxins. Mycotoxins consist of substances with widely different physicochemical properties; therefore, the loss of toxins that occurs in multi-mycotoxin methods due to compromises in the extraction solvent is currently a topic under discussion. With regard to fumonisins, several extractants from recently published multi-mycotoxin methods were investigated when analyzing unprocessed and processed maize matrices. All extractants were tested in a validated on-site method and the extraction yields were compared to those of an HPLC-FLD reference method (EN 14352). Most of the compared multi-mycotoxin methods that have been published were only for analyzing fumonisins in maize or maize-meal; we have applied the extractants of these methods to processed, complex maize matrices for the first time. Our results show that, for extractions with aqueous acetonitrile mixtures with the addition of acid, e.g. MeCN/H₂O/acetic acid (79/20/1, v/v/v), higher extraction yields are obtained than with MeCN/H₂O (80/20, v/v), in both spiked and naturally contaminated maize matrices. But compared to the results of the reference method EN 14352, the two extractants did not show a similar extraction efficiency. Overall, the extractant MeCN/MeOH/H₂O (1/1/2, v/v/v) turned out to be the most appropriate extractant applied in all experiments, obtaining the best and most comparable extraction yields and recoveries. Furthermore, our investigations showed that, with some of the tested extraction solvents, e.g. MeCN/H₂O (75/25) containing 50 mmol/l formic acid, stark differences occur when analyzing spiked and naturally contaminated matrices. With spiked matrices, recoveries of approximately 80–110 % were obtained, but with naturally contaminated matrices no results comparable to the EN method have been achieved. In contrast, a double extraction with MeCN/H₂O/formic acid (80/19,9/0,1, v/v/v), followed by a second polar extraction step with MeCN/H₂O/formic acid (20/79,9/0,1, v/v/v), led, for most naturally contaminated samples, to comparable results with the EN method. However, for spiked samples, the same extractant led to raised recoveries of between 120 and 140 %. For some processed matrices, like taco-chips, all tested extractants showed a poor extraction efficiency for fumonisins. By extending the extraction time from 1 to 15 min, a result comparable to that of the reference method could also be obtained for the extractant using MeCN/MeOH/H₂O (1/1/2, v/v/v). As this extractant has been used in our recently published method (Trebstein et al. Mycotoxin Res 25:201, 2009), this work also presents an update on this method with respect to the extended extraction time.     

Chlorine-free extraction of cellulose from rice husk and whisker isolation

This work reports the isolation of cellulose whiskers from rice husk (RH) by means of an environmental friendly process for cellulose extraction and bleaching. The multistep process begins with the removal of pectin, cutin, waxes and other extractives from rice husk, then an alkaline treatment for the removal of hemicelluloses and lignin, and a two-step bleaching with hydrogen peroxide/tetra-acetylethylenediamine (TAED), followed by a mixture of acetic and nitric acids, for further delignification of the cellulose pulp. The techniques of infrared absorption spectroscopy (ATR-FTIR), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), modulated differential scanning calorimetry (MDSC) and X-ray diffraction (XRD) showed that the overall process is adequate to obtain cellulose with high purity and crystallinity. This cellulose was submitted to sulfuric acid hydrolysis with the aim to isolate the whiskers. They showed the typical elongated rod-like aspect as revealed by transmission electron microscopy (TEM) and atomic force microscopy (AFM).     

Studies on by-products from the industrial extraction of alginate

The chemical composition of fucans isolated from leach-water, an industrial alginate extraction by-product, was investigated. Several fractions were obtained by anion exchange and gel permeation chromatography. They all contained fucose, but differed in the uronic acid, sulfate, xylose and galactose contents. They distributed as a continuum between uronic acid rich and sulfate poor to sulfate rich and uronic acid poor molecules. Two highly sulfated fractions were studied in particularly by chemical means (methylation, carboxy reduction, desulfation, controlled acid hydrolysis) and by¹³C nuclear magnetic resonance spectroscopy. One fraction consisted of a highly branched fucan (43.8% fucose) composed mostly of 1,2,3,4- and 1,2,4-linked fucose with some 1,4-,1,3,4- and 1,3-linkages and sulfate (23.9%) occurring on O₂ and/or O₃ and/or O₄. The other was composed mainly of fucose (31.6%), galactose (24.7%) and sulfate (23.7%). It consisted primarily of 1,6-, 1,4,6-, 1,3- and 1,3,6-linked galactose 6-and/or 4- and/or 3-sulfate on which are linked essentially terminal fucose or 1,4-linked with sulfate on O₂ and/or O₃ and/or O₄. None of these highly branched fractions contained sufficiently regular segments to yield series of homologous oligosaccharides on partial acid hydrolysis or interpretable¹³C NMR spectra.author for correspondence     

Studies on by-products from the industrial extraction of alginate

The content, the chemical composition and some physical-chemical properties of soluble and insoluble dietary fibres from an industrial alginate extraction by-product, flotation cellulose, were measured by two enzymatic gravimetric methods: an adaptation of the AOAC method (standard method) and a physiological method which used conditions closer to those prevailing in the digestive tract (pH, temperature, ionic strength and ionic composition). Total dietary fibres content obtained with the two methods were close (48.4–52.7; 56.3–59.8%) and about 68–95% of them were insoluble. Soluble fibre were essentially composed of uronic acids and were extracted under the simulated gastric conditions.Swelling in water and water absorption in NaCl (154 mM) of insoluble fibres with particle size between 250–500 µm were 21.9 g g^-1 and 3.6 gg^-1, respectively. The content and physical-chemical characteristics of fibres from flotation cellulose are close to those obtained from other plant and algal industrial by-products. Soluble fibre presented low intrinsic viscosity (152 ml g^-1).     

Studies on Entomophthora in populations of Aphis fabae on field beans

The population of Aphis fabae on field beans at a site in Highfield, Rothamsted in 1973 reached its peak 1 wk earlier than that at an equivalent site in Mill Dam Close, Woburn, 29 km NW of Rothamsted. Epizootics of Entomophthora caused weekly maximum mortalities of adult apterae of 71% at Highfield and 67% at Mill Dam Close. These epizootics and the periodicity of Entomophthora conidia in the air closely paralleled the development of the aphid population. There was little evidence of a consistent relationship between Entomophthora infection and any of the weather factors considered. At both sites most mortality was caused by E. planchoniana though many aphids were killed by E. aphidis and E. obscura. E. fresenii and E. virulenta killed very few aphids. Most conidia in the air were of the E. aphidis-type. Up to 44% of alatae emigrating from bean crops were infected with Entomophthora, confirming that aphid migration is an important means of distributing the fungi. Aphid numbers rose to more than 1600/plant at both sites, in spite of the action of Entomophthora, and would probably have been less had the fungi been more abundant earlier in the season.     

Variation in virulence to dry beans, soybeans and maize among isolates of Rhizoctonia solani from beans

The relative susceptibility of dry beans ( Phaseolus vulgaris ), soybeans and maize to anastomosis group 4 isolates of Rhizoctonia solani was determined in greenhouse experiments. Large variations in virulence were found among 30 field isolates. This variation was not due to differential reductions in isolate virulence during axenic culture. There was considerable variation among isolates from within the same field but variability within isolates was small. Twelve of 30 isolates of R. solani were highly virulent to dry beans and soybeans, while the others were of low virulence. Soybeans were more susceptible than dry beans to both pre-emergence mortality and hypocotyl disease. No isolates were highly virulent to maize. The importance of using isolates with a high level of virulence for testing soybean cultivars for resistance to Rhizoctonia disease is stressed.     

A protocol for high-throughput extraction of DNA from rice leaves

Current DNA isolation methods have limitations between speed and purity in high-throughput molecular genetic analysis such as gene mapping and marker-assisted selection programs. We have optimized a simple and rapid method for isolating high-quality genomic DNA from rice that significantly minimizes time and the use of laboratory materials. One person can process as many as 384 samples in 2 h. The isolated DNA is suitable for polymerase chain reaction-based techniques and is stable for no less than 6 mo of storage at 4°C.     

Isolation,purification and characterization of phytase from germinating mung beans

Phytase isolated from mung bean cotyledons was purified about 80-fold with a recovery of 28%. The enzyme is stable at 0°, has a pH optimum at 7·5 and optimal temperature of 57°. The energy of activation is approximately 8500 cal/mole between 37° and 57°. Inhibition by P_i has been found to be competitive, the K_i value being 0·40–0·43 × 10⁻³ M; the K_m value with phytate is 0·65 × 10⁻³ M. Divalent cations are not required for activity. Lower members of inositol phosphates are better substrates, as shown by their V_max and K_m values. When subjected to polyacrylamide gel electrophoresis two bands have been resolved; one (major) corresponds to phytase and the other (minor) to phosphatase and pyrophosphatase activity. Filtration through Biogel P-200 partially resolves phytase from phosphatase and pyrophosphatase. The molecular weight of phytase is approximately 160,000.     

Mycoflora,and mycotoxins production in Nigerian corn and corn-based snacks

Thirty-one fungal species, mostly toxigenic and belonging to 11 genera were isolated from corn, corn cake and corn roll snack samples.Aspergillus, Penicillum andFusarium accounted for 10, 6 and 3 of the species and altogether, they constituted 90, 94 and 88 percent of the total fungi in corn, corn cake and corn roll snack respectively. Mycotoxins (aflatoxins and ochratoxin A) were detected in 45, 80 and 12 percent while the means and ranges of the total aflatoxins recorded were: 200(25–770 ppb); 233(15–1070 ppb) and 55(10–160 ppb) for corn, corn cake and corn roll snack samples respectively. Ochratoxin A was detected at toxicologically significant levels in only 15 percent of the corn cake samples analyzed. All the strains ofAspergillus flavus andA. ochraceus tested produced aflatoxin B and ochratoxin A, respectively, when they were cultured on each of the three substrates. In each case, substantial quantities of the toxins were produced from 25 to 35°C with the peak level recorded at 30°C. Toxin production was detected only in substrates with 15 percent moisture content and above; reaching the maximum at 25 or 30 percent moisture level. No substantial differences in the amount of toxins were elaborated with further increase in substrates' moisture content. Of the three substrates, corn cake was the most suitable for aflatoxin B production while they were all equally suitable for the elaboration of ochratoxin A.