Roice Eliana Rosim

Determination of Aflatoxins in Peanut Products in the Northeast Region of São Paulo, Brazil

The aim of the present study was to determine aflatoxin levels in peanut products traded in the Northeast region of São Paulo, Brazil. To this end, 240 samples of peanut products traded in the cities of Araras, Leme, Pirassununga and Porto Ferreira were collected from June 2006 to May 2007. The samples were analyzed for aflatoxins (AF) B1, B2, G1 and G2 by high performance liquid chromatography. Results showed 44.2% samples positive for AF at levels of 0.5 to 103.8 μg·kg−1. Nine of the positive samples (3.7% of the analysed samples) had total aflatoxin concentrations (B1+B2+G1+G2) higher than the limit established by Brazilian regulations (20 μg·kg−1). Based on the above data, the probable mean daily intake (PDIM) of aflatoxins from peanut products in the Northeast region of São Paulo was estimated to be 0.23 ng kg b.w. day−1. Although this PDIM value was relatively low, results indicate that aflatoxin contamination of peanut products may be a public health concern in Brazil, when considering the potential exposure of highly susceptible consumers. For example, it should be emphasized that children are potentially exposed to aflatoxins, since they consume large quantities of peanut candies, and these products had the highest number of samples positive for AFB1.

Viability of probiotic bacteria in fermented skim milk produced with different levels of milk powder and sugar

In this work, the effect of skim milk powder (0, 5%, 10%, 15% w/v) and sugar (0%, 10% w/v) on the viability of probiotic micro-organisms and on the quality of fermented milks was investigated. Fermented milks were submitted to physicochemical, microbiological and sensory analyses on the 1st, 10th and 21st days after production. Sugar inclusion did not affect the probiotic growth in fermented milks, but milk powder levels of 10–15% influenced positively the probiotic counts, which were above six log colony-forming units (cfu)/g. These findings can be useful for small dairy industries that are interested in producing flavoured fermented milks without decreasing the viability of probiotic micro-organisms during its shelf life.

Survey of aflatoxin M1 in cheese from the North-east region of Sao Paulo, Brazil

In the present study, 24 samples of Minas Frescal cheese and 24 samples of Minas Padrão cheese produced in the North-east region of the state of São Paulo, Brazil, were analysed for aflatoxin M1 (AFM1) by high-performance liquid chromatography (HPLC) between March and August 2008. AFM1 was detected in 13 (27.1%) samples at concentrations ranging from 0.037 to 0.313 ng g−1. The mean concentrations of AFM1 in positive samples of Minas Frescal and Minas Padrão cheese were 0.142 ± 0.118 and 0.118 ± 0.054 ng g−1, respectively. It is concluded that the incidence of AFM1 in Minas cheese may contribute to an increase in the overall ingestion of aflatoxins in the diet, hence indicating the need for the adoption of a tolerance limit for AFM1 in cheese in Brazil.

Aflatoxins and cyclopiazonic acid in feed and milk from dairy farms in São Paulo, Brazil

The occurrence of aflatoxins (AF) B1, B2, G1, G2 and cyclopiazonic acid (CPA) in feeds, and AFM1 and CPA in milk was determined in dairy farms located in the northeastern region of São Paulo state, Brazil, between October 2005 and February 2006. AF and CPA determinations were performed by HPLC. AFB1 was found in 42% of feed at levels of 1.0–26.4 µg kg−1 (mean: 7.1 ± 7.2 µg kg−1). The concentrations of AFM1 in raw milk varied between 0.010 and 0.645 µg l−1 (mean: 0.104 ± 0.138 µg l−1). Only one sample was above the tolerance limit adopted in Brazil (0.50 µg l−1) for AFM1 in milk. Regarding CPA in feed, six (12%) samples showed concentrations of 12.5–153.3 µg kg−1 (mean: 57.6 ± 48.7 µg kg−1). CPA was detected in only three milk samples (6%) at levels of 6.4, 8.8 and 9.1 µg l−1. Concentrations of aflatoxins and CPA in feed and milk were relatively low, although the high frequency of both mycotoxins indicates the necessity to continuously monitor dairy farms to prevent contamination of feed ingredients.

Biofilm-producing ability of Listeria monocytogenes isolates from Brazilian cheese processing plants

The persistence of Listeria monocytogenes in food industry environments has been associated to the ability of specific isolates to produce biofilms. This study aimed to evaluate the biofilm production of 85 L. monocytogenes strains previously isolated from samples of cheese, brine and the environment of two cheese processing plants located in São Paulo, Brazil. The L. monocytogenes isolates belonged to serotypes 4b, 1/2b and 1/2c, yielded 30 different pulsotypes by pulsed-field gel electrophoresis (PFGE), and were submitted to biofilm-formation assays on polystyrene microplates and stainless steel coupons incubated statically at 35±0.5°C for 48h. All isolates from different sources showed ability to produce biofilms on polystyrene microplates, from which 21 (24.7%) also produced biofilms on stainless steel. Four isolates (4.7%) belonging to four different pulsotypes were classified as strong biofilms-producers on polystyrene microplates, while isolates belonging to four pulsotypes previously evaluated as persistent had weak or moderate ability to produce biofilms on polystyrene microplates. No relationship between the serotypes or pulsotypes and their biofilm-forming ability was observed. This study highlights the high variability in the biofilm production among L. monocytogenes strains collected from cheese and cheese-production environment, also indicating that strong biofilm-formation ability is not a key factor for persistence of specific isolates in cheese processing plants.

Casein fractions of ultra high temperature milk with different somatic cell counts

The objective of this work was to evaluate the effect of somatic cell counts (SCC) in casein fractions of ultra high temperature (UHT) milk. Raw milks were categorized in SCC groups of low (200,000-320,000 cells mL-1), intermediate (380,000-560,000 cells mL-1) and high cells (600,000-800,000 cells mL-1). Five replicates of UHT milks within each SCC category were analyzed for casein fractions after 8, 30, 60, 90 and 120 days of storage through high performance liquid chromatography. SCC showed effect only on beta-casein reduction. SCC in raw milk increases the proteolysis of UHT milk, as a consequence of beta-casein degradation.

Determinação de aflatoxina B1 em rações e aflatoxina M1 no leite de propriedades do Estado de São Paulo

The occurrence of aflatoxin B 1 (AFB 1 ) in animal feed and aflatoxin M 1 (AFM 1 ) in raw milk was evaluated in dairy farms located in the Northeast region of Sao Paulo state, Brazil, from October 2005 to February 2006. The Aflatoxin analysis was performed using immunoaffinity clean-up with high performance liquid chromatography for quantification. AFB 1 was found in 40% of the animal feeds at the levels of 1.0 to 19.5 µg.kg –1 . The concentration of AFM1 in raw milk (36.7%) ranged from 0.010 to 0.645 µg.L –1 . Only one single sample of raw milk presented values above the tolerance limit adopted in Brazil (0.5 µg.L –1 ) for AFM 1 . In conclusion, the concentrations of aflatoxins in the animal feed and milk samples studied were relatively low although the high frequency of mycotoxins in the both analysed samples indicates the necessity of continuous monitoring in order to prevent mycotoxin contamination of animal feed ingredients for dairy cattle.

Synthesis and purification of the aflatoxin B1-lysine adduct

Abstract This work reports the chemical synthesis of aflatoxin B1 (AFB1)-lysine based on procedures available in the literature, but using lysine without a protection group in the α-amine group. AFB1-exo-8,9-epoxide was obtained by epoxidation of AFB1 with chloroperoxybenzoic acid in dichloromethane and phosphate buffer. Purification and identification of the AFB1-lysine were conducted by liquid chromatography (LC), and its structure was confirmed by LC with mass spectrometer and diode-array detection. The preparation of AFB1-lysine using lysine without a protection group in the α-amine group was completed in 24 h, being a practical modification of available methods that can be reproduced in analytical laboratories.

In vitro ability of beer fermentation residue and yeast-based products to bind aflatoxin B1.

This study aimed to verify the in vitro ability of beer fermentation residue (BFR) containing Saccharomyces cerevisiae cells and five commercial products that differed in the viability and integrity of S. cerevisiae cells to remove aflatoxin B1 (AFB1) from a citrate-phosphate buffer solution (CPBS). BFR was collected at a microbrewery and prepared by drying and milling. The commercial yeast-based products were as follows: inactive intact yeast cells from beer alcoholic fermentation, inactive intact yeast cells from sugarcane alcoholic fermentation, hydrolyzed yeast cells, yeast cell walls and active yeast cells. Adsorption assays were performed in CPBS spiked with 1.0 μg AFB1/mL at pH 3.0 and 6.0 for a contact time of 60 min at room temperature. Analysis of AFB1 in the samples was performed by high performance liquid chromatography. AFB1 adsorption by the products ranged from 45.5% to 69.4% at pH 3.0 and from 24.0% to 63.8% at pH 6.0. The higher percentages (p < 0.05) of AFB1 binding at both pH values were achieved with products containing hydrolyzed yeast cells or yeast cell walls rather than intact cells. The AFB1 binding percentages of BFR were 55.0 ± 5.0% at pH 3.0 and 49.2 ± 4.5% at pH 6.0, which was not significantly different (p > 0.05) from commercial products containing inactive intact yeast cells. The results of this trial indicate that the yeast-based products tested, especially the BFR, have potential applications in animal feeds as a suitable biological method for reducing the adverse effects of aflatoxins.

Fumonisin B1 in cereal mixtures marketed in Brazil.

The aim of this study was to detect and quantify fumonisin B1 (FB1) in cereal mixtures marketed in Brazil. Fifteen samples from different lots were acquired each month by internet from supermarkets during seven months, adding up to 105 analysed samples. The unit sample constituted of an original package with a minimum of 250 g. Extraction and clean-up of samples for FB1 determination were carried out using immunoaffinity columns. Identification and quantification of FB1 were performed by high performance liquid chromatography. Eighty-eight (83.8%) samples were contaminated with FB1 and four (3.8%) presented levels above 500 µg kg−1 (634, 703, 1269 and 1876 µg kg−1). Maximum FB1 + FB2 levels allowed by Brazilian regulations will reach 1500 µg kg−1 for corn flour in 2016 and 1000 µg kg−1 for others corn products. This study showed that even at levels below the legislative limits, human exposure to this toxin can occur constantly.