Pesticides in rice-based products commercialised in Argentina.

People with coeliac disease have a limited diet. Therefore, rice-based products are an ideal alternative. Highlighting this import item, an analytical methodology was validated to determine pesticides in rice-based product samples. The precision was satisfactory for all pesticides since the RSD did not exceed 13% in any case. Regarding recovery, the method had values close to 100%. The limit of quantification was established at 10 µg/kg and the expanded uncertainty was less than 20%. After validation, 80 samples of toasts and rice crackers were analysed. All samples were compliant with the national regulations for dichlorvos and tebuconazole. The pesticide that was present in the highest number of samples was pirimiphos - methyl, but all below the maximum residue limit. From all samples analysed, 38 were positive for at least one pesticide and only one contained four pesticides simultaneously: deltamethrin, pirimiphos-methyl, kresoxim-methyl and epoxiconazole.

Citrus flavonoids against Fusarium verticillioides in post-harvest maize: Minimization of fumonisins and alteration of fungal ultrastructure.

AIMS: To minimize fumonisins (FBs) accumulation by Fusarium verticillioides in post-harvest maize, using flavonoids obtained from citrus residues: naringin (NAR), neohesperidin (NEO), quercetin (QUER), and its mixtures. METHODS AND RESULTS: Response surface methodology with Box-Behnken design was applied in maize at 0.98 and 0.95 aw . The optimal mixture found, composed of 0.40 mmol kg-1  NAR, 0.16 mmol kg-1  NEO and 0.37 mmol kg-1 QUER, reduced the accumulation of FBs B1, B2, and B3 by 88 ± 6%, 90 ± 6% and 85 ± 5%, respectively, when applied to maize at 0.98 aw . The mentioned mixture led to a 54 ± 9% reduction of fumonisin B1 accumulation in maize adjusted to 0.95 aw . These flavonoids applied individually and as a mixture, affected the structure of both the cell wall and the cytoplasm of F. verticillioides. The cell wall lost rigidity and the cells appeared highly deformed, with ruptured plasmalemma and disrupted endomembranes. CONCLUSIONS: It was possible to diminish the accumulation of FBs in maize by a highly toxigenic Fusarium strain, producing severe damage to its ultrastructure. SIGNIFICANCE AND IMPACT OF STUDY: The results indicate the possible use of flavonoids from citrus industry residues as natural and environmentally friendly antifungal agents to restrain the accumulation of FBs in stored maize.

Optimization of a rice cooking method using response surface methodology with desirability function approach to minimize pesticide concentration.

Rice is contaminated with pesticides applied in pre and post-harvest. These contaminations could be reduced through household operations like washing and cooking. Therefore, in the present research, a pre-soaking rice cooking method was used to reduce pesticides residues. Response Surface Methodology with Central Composite Design was applied to minimize pesticides concentration by choosing the best soaking time and water:rice grain relation before cooking. A quadratic polynomial equation was obtained. Desirability function approach gave the optimal cooking conditions as 14 h soaking time and water:rice grain relation of 3. This process allowed a pesticide elimination of 100.0%, 93.5%, 98.4%, 98.5%, 99.0%, and 95.0%, of azoxystrobin, cyproconazole, deltamethrin, epoxiconazole, kresoxim-methyl and penconazole, respectively.

Effect of household rice cooking on pesticide residues.

This investigation shows the pesticide distribution and reduction using three common household cooking methods. Extraction was performed using QuEChERS and solid phase microextraction methodologies for rice and water, respectively. Gas chromatography-mass spectrometry was used. Both methods showed good linearity (r2 > 0.9996 and 0.9945), adequate recoveries (between 98.9 and 107.8% and 90.5-104.2%) and relative standard deviations lower than 4.5% and 7.0%, for rice and water, respectively. The initial concentration of deltamethrin, penconazole, kresoxim-methyl, cyproconazole, epoxiconazole and azoxystrobin, were 84.9, 242.2, 298.5, 230.7, 253.4 and 293.5 µg/kg, respectively. Washing and soaking water reduce pesticides only 0.40 to 4.28%. The pesticide reduction during cooking were 20.73 to 57.72%, 32.74 to 70.39%, and 68.87 to 87.50% for traditional, excess water, and pre-soaking rice methods, respectively. Pre-soaking rice with extra water before cooking proved to be the method that generates the greatest reduction.

Evaluation of citrus flavonoids against Aspergillus parasiticus in maize: Aflatoxins reduction and ultrastructure alterations.

In this study, the effects of citrus flavonoids naringin (NAR), neohesperidin (NEO) and quercetin (QUER) on aflatoxins accumulation by a selected Aspergillus parasiticus strain in maize at 0.95 aw were studied by response surface methodology using a Box-Behnken design. Multiple response optimization was applied to simultaneously minimize the contamination with aflatoxins (AFs) B1, G1, B2 and G2. The application of the optimal mixture in maize at 0.95 aw (0.39 mM NAR, 0.24 mM NEO and 0.40 mM QUER) reduced from 85% to 100% AFs accumulation. The same mixture at 0.98 aw, led to a reduction in AFs accumulation that ranged from 93% to 98%. Ultrastructure alterations of cellular membranes and walls in A. parasiticus, evidenced by transmission electron microscopy images, were severe and depended on the type of flavonoid and their combination. Flavonoid mixtures may provide an environmentally friendly alternative for decreasing AFs accumulation in stored maize, replacing synthetic compounds.

Pesticides in randomly collected rice commercialised in Entre Ríos, Argentina.

An analytical method for determination of azoxystrobin, cyproconazole, deltamethrin, epoxiconazole, kresoxim-methyl, and penconazole in rice, using QuEChERS extraction and a gas chromatography, was validated. Recoveries ranged within the 98.9-107.8 % range for all pesticides. Limits of detection and of quantification were 0.27 and 0.90 µg/kg for azoxystrobin, 0.26 and 0.88 µg/kg for cyproconazole, 0.25 and 0.84 µg/kg for deltametrhin, 0.22 and 0.72 µg/kg for epoxiconazole, 0.22 and 0.73 µg/kg for kresoxim-methyl and 0.23 and 0.77 µg/kg for penconazole, respectively. The expanded measurement uncertainty was lower than 20% for all pesticides. The occurrence of these pesticides was evaluated in 100 rice samples commercialised in different supermarkets. Residues of at least two pesticides simultaneously were found in 94 samples. The concentrations were lower than European and Argentinean legislative limits, with exception of epoxiconazole that in 36 rice samples was found in concentrations above the limit established in Argentina.

Alternaria toxins in Argentinean wheat, bran, and flour.

Alternaria species have been reported to infect a wide variety of vegetables, fruits, and cereal crops. Wheat is one of the most consumed cereal worldwide. A sensitive HPLC-DAD methodology was applied to quantify alternariol (AOH), alternariol methyl ether (AME) and tenuazonic acid (TeA) in 65 samples of whole wheat, bran, and flour. The extraction methodology allowed extracting the three toxins simultaneously. Limits of detection in wheat were 3.4, 4.5, and 0.5 µg kg-1 for AOH, AME and TeA, respectively. For bran, these data were 3.1, 4.5, and 12 µg kg-1 and for flour 50, 70, and 14 µg kg-1, respectively. The studied recoveries were higher than 70% and RSD was below 10%. Wheat and bran samples showed low AOH and AME contamination compared to TeA. The averages levels found for TeA in wheat, bran and flour were 19,190, 16,760, and 7360 µg kg-1, respectively.

Alternaria alternata prevalence in cereal grains and soybean seeds from Entre Ríos, Argentina.

A mycological survey was carried out at Entre Ríos province, Argentina, on sorghum grain, maize, rice, soybean seeds and on freshly harvested and stored wheat. The isolation frequencies and relative densities of species belonging to genera Alternaria, Aspergillus, Fusarium, Penicillium and other fungi were calculated. Alternaria alternata was the major fungal species isolated from sorghum, rice, soybean seeds and on freshly harvested wheat, and a low incidence of Fusarium species was observed on the same substrates. In maize the major fungal species isolated was Fusarium verticillioides. The high incidence levels of A. alternata observed,suggest that it may be necessary to determine, among other mycotoxins, if Alternaria toxins occur in these commodities.