Incidence and levels of fumonisin contamination in Colombian corn and corn products.

A survey was conducted to determine the levels of fumonisins B1 and B2 in corn and corn-based products available in Colombia for human and animal consumption. A total of 120 samples were analyzed by acetonitrile-water extraction, cleanup with a strong-anion-exchange column, and liquid chromatography with o-phthaldialdehyde-2-mercaptoethanol derivatization and fluorescence detection. The samples of corn and corn-based products for animal intake were taken at different feed manufacturing plants, whereas the samples used for human foods where purchased from local retail stores. The number of positive samples for fumonisin B1 was 20.0% higher in corn and corn-based products for animal intake (75.0%) than in corn and corn-based products for human consumption (55.0%). The levels of fumonisin B1 were also higher in corn and corn-based products for animal intake (mean = 694 µg/kg; range = 32-2964 µg/kg), than in corn and corn-based products for human intake (mean = 218 µg/kg; range = 24-2170 µg/ kg). The incidence and levels of fumonisin B2 were lower than those for fumonisin B1. Corn and corn-based products for animal consumption had an incidence of fumonisin B2 of 58.3%, with a mean value of 283 µg/kg, and a range of 44-987 µg/kg. The incidence of fumonisin B2 in corn-based products for human intake was 35.0%, with a mean value of 118 µg/kg and a range of 21-833 µg/kg. The highest incidence and levels of fumonisins were found in samples of hominy feed, with concentrations ranging from 86 to 2964 µg/kg fumonisin B1 and 57 to 987 µg/kg fumonisin B2.

Occurrence of aflatoxins in selected colombian foods.

A survey of aflatoxin contamination in selected Colombian foods was conducted over a 12-month period on a total of 248 samples. Samples were collected in supermarkets, retail stores and stock centres and were grouped into five categories: (1) corn and corn products, (2) cereal grains, (3) rice and rice products, (4) legume seeds; and (5) snacks and breakfast cereals. Aflatoxins were identified and quantitated using a liquid chromatographic technique with a limit of detection of 1 ng/g for each aflatoxin. Aflatoxins were detected in 14 of 109 samples of corn and corn products, 4 of 40 samples of rice and rice products, 2 of 30 samples of legume seeds, and 2 of 11 samples of snacks and breakfast cereals. None of the cereal grains samples analysed contained detectable levels of aflatoxins. Twelve of the total of 22 positive samples exceeded the maximum tolerable level of aflatoxin B1 adopted in most countries (5 ng/g); 10 of these 12 samples corresponded to corn and corn products. The results of the present study indicate that aflatoxin B1 contamination in certain foods in Colombia is a major public health concern. Continuous monitoring of aflatoxin B1 levels in Colombian foods is advised.

First colombian interlaboratory study for the determination of aflatoxin B1 in yellow corn.

An interlaboratory study for the determination of aflatoxin B1 in yellow corn was conducted with 16 laboratories that analyze for aflatoxins in Colombia. Naturally contaminated ground yellow corn (Monsanto DK 4004) with an assigned reference value of 26.3 µg/kg aflatoxin B1 was distributed as double blind duplicates in sachets of 55 g. z-Scores were computed for each of the results; repeatability of the two replicate analysis was also calculated. Four of the participating laboratories used HPLC, seven used TLC, one used fluorometry, one ELISA and three a semi quantitative analytical technique (Aflacard®). Only 10 of the 26 quantitative results (39%) had satisfactory z-scores, two scores were questionable (8%) and 14 of the 26 results had unsatisfactory z-scores (54%). A total of 8 laboratories had satisfactory repeatability (62%), and 5 had unsatisfactory repeatability (39%). The present study indicates that only about one third of the results for aflatoxin reported by Colombian laboratories have good accuracy (as measured by the z-score of the result), although satisfactory precision (measured as repeatability) is achieved by about two thirds of the laboratories. These results indicate that an improvement in quality assurance is needed in Colombian laboratories. The routine use of reference standards and reference materials is highly recommended.

Method validation for the determination of ochratoxin A in green and soluble coffee by immunoaffinity column cleanup and liquid chromatography.

A method was validated for the determination of ochratoxin A (OTA) in soluble and green coffee. Performance parameters evaluated included selectivity, accuracy, intermediate precision, linearity, limit of detection, limit of quantitation, and ruggedness. The method was found to be selective for OTA in both matrices tested. Recovery rates from soluble coffee samples ranged from 73.5 to 91.2%, and from green coffee samples from 68.7 to 84.5%. The intermediate precision (RSDr) was between 9.1 and 9.4% for soluble coffee and between 14.3 and 15.5% for green coffee analysis. The linearity of the standard calibration curve (r(2)) was <0.999 for OTA levels of 1.0-20.0 µg/kg in coffee samples. The limit of detection was determined to be 0.01 ng of OTA on column, while the limit of quantitation was found to be 0.03 ng on column. The limit of quantitation is equivalent to 0.6 µg/kg in soluble coffee samples and 0.3 µg/kg in green coffee samples. The results of the ruggedness trial showed two factors are critical for soluble coffee analysis: the extraction method, and the flow rate of the mobile phase. For green coffee analysis two critical factors detected were the extraction method and the storage temperature of the immunoaffinity column.Five samples of soluble coffee and 42 of green coffee were analysed using the validated method. All soluble coffee samples contained OTA at levels that ranged from 8.4 to 13.9 µg/kg. Six of the 42 green coffee samples analysed (14.3%) contained OTA at levels ranging from 0.9 to 19.4 µg/kg. The validated method can be used to monitor OTA levels in Colombian coffee for export or for local consumption.

Effect of temperature of wet extrusion on the nutritional value of full-fat soyabeans for broiler chickens.

1. An experiment was conducted to determine the temperature for wet extrusion of full-fat soyabeans (FFS) needed to produce maximum chicken performance. 2. FFS were either unprocessed or extruded at 5 different temperatures (118 degrees, 120 degrees, 122 degrees, 126 degrees and 140 degrees C) in a wet extruder. Diets were prepared with the different FFS, and a diet prepared with soyabean meal (SBM) was included as a control. The 7 experimental diets were fed to individual groups of 40 chickens each, for a period of 35 d. Trypsin inhibitor activity (TIA), urease activity (UA), and protein solubility in potassium hydroxide (PS) were measured in all FFS and in the SBM. 3. Diets prepared with raw FFS and FFS extruded at 118 degrees and 120 degrees C resulted in significantly lower body weights and in pancreatic hypertrophy; maximum growth rate was obtained with FFS extruded at 122 degrees and 126 degrees C, while minimum pancreas weight was seen in chickens fed FFS extruded at 140 degrees C. 4. Although TIA, UA, and PS all decreased with increasing temperature of extrusion, TIA provided the best prediction of the feeding value of soyabeans for chickens.