Principal components analysis: an innovative approach to establish interferences in ochratoxin A detection.

This work aimed to establish an innovative approach to evaluate the effect of cereals composition on ochratoxin A extraction by multivariate analysis. Principal components analysis was applied to identify the effect of major matrix components on the recovery of ochratoxin A by QuEChERS method using HPTLC and HPLC, and to validate the method for ochratoxin A determination in wheat flour by HPLC. The matrices rice bran, wheat bran and wheat flour were characterized for their physical and chemical attributes. The ochratoxin A recovery in these matrices was highly influenced (R=0.99) by the sugar content of the matrix, while the lipids content showed a minor interference (R=0.29). From these data, the QuEChERS method was standardized for extracting ochratoxin A from flour using 1% ACN:water (2:1) as extraction solvent and dried magnesium sulfate and sodium chloride as salts. The recovery values ranged from 97.6% to 105%. The validated method was applied to evaluate natural occurrence of ochratoxin A in 20 wheat flour samples, which were contaminated with ochratoxin A levels in the range of 0.22-0.85 µg kg(-1).

Reduction of aflatoxins by Rhizopus oryzae and Trichoderma reesei.

This study evaluated the ability of the microorganisms Rhizopus oryzae (CCT7560) and Trichoderma reesei (QM9414), producers of generally recognized as safe (GRAS) enzymes, to reduce the level of aflatoxins B1, B2, G1, G2, and M1. The variables considered to the screening were the initial number of spores in the inoculum and the culture time. The culture was conducted in contaminated 4 % potato dextrose agar (PDA) medium, and the residual mycotoxins were determined every 24 h by HPLC-FL. The fungus R. oryzae has reduced aflatoxins B1, B2, and G1 in the 96 h and aflatoxins M1 and G2 in the range of 120 h of culture by approximately 100 %. The fungus T. reesei has reduced aflatoxins B1, B2, and M1 in the 96 h and aflatoxin G1 in the range of 120 h of culture by approximately 100 %. The highest reduction occurred in the middle of R. oryzae culture.

Aflatoxin B1 and M1 in milk.

The aflatoxin M1 (AFLAM1) is a mycotoxin that results from the hydroxylation of the aflatoxin B1 (AFLAB1). It contaminates the milk of animals fed with a diet containing its precursor. In this work, we determined the occurrence of AFLAB1 and AFLAM1 in milk, as well as the chromatographic conditions to quantify these mycotoxins. The extraction and quantification of AFLAB1 and AFLAM1 in naturally contaminated and artificially spiked milk samples which are produced and marketed in the state of RS were performed using the AOAC official method and UHPLC with fluorescence detection. We obtained a separation factor of 2.3 for AFLAB1 and AFLAM1 using a mobile phase consisting of 1% acetic acid:acetonitrile:methanol (55:10:35). The analytical curves had a wide linearity range and the limit of quantification (LOQm) concentrations of AFLAB1 and AFLAM1 were equal to 0.5 and 0.25 µg L(-1), respectively. Samples of pasteurized and ultra-high-temperature processed (UHT) milk showed natural contamination, and the levels for both aflatoxins ranged from 0.7 to 1.5 µg L(-1). Raw and concentrated milk samples only contained AFLAM1, with a maximum average concentration of 1.7 µg L(-1). These concentrations, higher than permitted by legislation, confirm the existence of a health risk, as well as highlight the relevance of searching for alternatives to reduce this contamination.

Fish Balistes capriscus skin extract-induced relaxation in mesenteric arterial bed of rat.

The vasorelaxing activity of the aqueous extract of fish Balistes capriscus skin (AEBc) on mesenteric arterial bed (MAB) of rats was studied. The bolus injections of AEBc (bolus of 5.1, 10.2, 20.5, and 41.1mg) significantly inhibited, in a concentration-dependent manner, the maximal contractile response induced by methoxamine (30 microM) in MAB. The vasodilatation action of AEBc is not mediated through beta-adrenoceptors or cyclo-oxigenase, since it was not affected by propranolol (20 microM) or diclofenac sodium (3 microM). The vasodilator response induced by subsequent addition of AEBc Balistes capriscus in bolus was significantly reduced in water infusion for endothelium removal. Treatment with an inhibitor of NO synthase (L-NAME, 10 microM) decreased AEBc effect. The guanylate cyclase inhibitor methylene blue (MB, 100 microM) had no significant effect on AEBc-induced vasodilatation. These results suggest that the vasorelaxing effect of AEBc is mediated by endothelium-dependent (NO/EDRF) and endothelium-independent neurally induced vasorelaxation from nonadrenergic and noncholinergic nerves (NO).

Enzymatic determination of soluble and insoluble dietary fiber in rice and wheat bran.

The information about dietary fiber presents controversies in many research areas such as in nomenclature, related illnesses, recommended quantities and terminology, mainly because of lack of analytical data. Different needs and interests for the dietary fiber composition of foods and forages have led to a proliferation of methods for its analysis. This research, a further adaptation of the enzymatic method of Asp et al. (1983) for its application is proposed for rice and wheat bran, byproducts of agroindustries in the southern region of Rio Grande do Sul (Brazil). The inclusion of Amyloglucosidase in the proposed methodology contributed to the decrease in the content of residual starch at the end of the experiment, like Prosky et al (1992). To increase the efficiency of the enzyme system in this type of samples, other changes were made with respect to incubation time and proteolytic enzyme concentration. In the final adaptation, a decrease of 51.33% of the starch content was observed in rice bran (RB) and of 52.93% in wheat bran (WB). This decrease was also verified in the model system (MS) (52.08%), which demonstrates the adequacy of the proposed adaptation. With respect to the residual protein, it was verified that the measures adopted provoked a reduction of 42.15% (RB), 52.19% (WB) and 42.11% (MS) as compared to the original method. Then the proposed conditions has been shown to be efficient in decreasing the level of interference (indigestible starch and protein) in the quantification of dietary fiber in rice and wheat bran.