Acidos grasos esenciales en la producción actual de oleaginosas de la República Argentina: posibilidades futuras de diversificación / Essential fatty acids in the present vegetable oils production of the República Argentina: future possibiities in the diversification trends production

Se presenta un resumen de los logros alcanzados durante casi 50 años en un tema fundamental del conocimiento de las características de composición acídica de aceites vegetales de producción masiva en la república Argentina. Su desarrollo, en parte coincidente con la evolución del conocimiento analítico, ha sido de utilidad a la nutrición, normalización, legislación alimentaria, tecnología, uso y contralor de aceites vegetales y de pulpa de frutos. El progreso observado en los avances de modernas técnicas de la Biotecnología tiende a una apertura en la diversificación de la producción

Acidos grasos esenciales en la producción actual de oleaginosas de la República Argentina: posibilidades futuras de diversificación / Essential fatty acids in the present vegetable oils production of the República Argentina: future possibiities in the diversification trends production

Se presenta un resumen de los logros alcanzados durante casi 50 años en un tema fundamental del conocimiento de las características de composición acídica de aceites vegetales de producción masiva en la república Argentina. Su desarrollo, en parte coincidente con la evolución del conocimiento analítico, ha sido de utilidad a la nutrición, normalización, legislación alimentaria, tecnología, uso y contralor de aceites vegetales y de pulpa de frutos. El progreso observado en los avances de modernas técnicas de la Biotecnología tiende a una apertura en la diversificación de la producción

Automated aflatoxin analysis of foods and animal feeds using immunoaffinity column clean-up and high-performance liquid chromatographic determination.

A commercially available system is described for the fully automated clean-up and high-performance liquid chromatographic (HPLC) analysis of aflatoxins in foods and animal feeds. The system marketed primarily for handling solid-phase extraction columns has modified software to facilitate use with immunoaffinity columns. Sample extract clean-up followed by injection onto an HPLC column with post-column iodination and fluorescence detection is carried out completely unattended. A coefficient of variation of 5.1% for aflatoxin B1 analysis was obtained, and the accuracy of the system was demonstrated by the analysis of peanut butter certified reference material.

Immunoaffinity column coupled with solution fluorometry or liquid chromatography postcolumn derivatization for determination of aflatoxins in corn, peanuts, and peanut butter: collaborative study.

An AOAC/IUPAC (International Union of Pure and Applied Chemistry) collaborative study was conducted to evaluate the effectiveness of an immunoaffinity column for the determination of aflatoxin. The test portion is extracted with methanol-water (7 + 3), filtered, diluted to less than 30% methanol with water, and applied to the affinity column. The column is washed with water and the concentrated aflatoxins are eluted with methanol. Total aflatoxins are determined by solution fluorometry with bromine (SFB), and individual toxins are determined by reverse-phase liquid chromatography with postcolumn derivatization with iodine (PCD). Corn naturally contaminated with aflatoxins, and peanuts, peanut butter, and corn containing added aflatoxins (B1:B2:G1:G2 = 7:1:3:1) were sent to 24 collaborators in the United States, France, Canada, and the Republic of South Africa. Twelve collaborators used the SFB method, 9 used the PCD method, and 3 used both SFB and PCD methods. Twenty collaborators completed the study (10 used the SFB method, 7 used the PCD method, and 3 used both SFB and PCD methods). Test portions were spiked at 10, 20, and 30 ng/g. For SFB analyses, recoveries of total aflatoxins were 123, 105, and 107%, respectively; the relative standard deviation for repeatability (RSDr) ranged from 11.75 to 16.57%, and the relative standard deviation for reproducibility (RSDR) ranged from 10.97 to 33.09%. For PCD analyses, recoveries were 81, 81, and 83%, respectively; the RSDr ranged from 5.20 to 17.22%, and the RSDR ranged from 4.68 to 50.77%. The RSDr for aflatoxins B1 and G1 for spiked test portions ranged from 5.45 to 23.55%, and the RSDR ranged from 4.21 to 57.28%.(ABSTRACT TRUNCATED AT 250 WORDS)

Liquid chromatographic determination of aflatoxin levels in peanut butters using an immunoaffinity column cleanup method: international collaborative trial.

Thirteen laboratories in 7 different countries participated in a collaborative trial to evaluate the immunoaffinity column cleanup procedure with quantitation by fluorescence liquid chromatography (post-column derivatization) for the determination of aflatoxins in peanut butters. Participants were sent 10 randomly numbered samples of roasted peanut butter for analysis (5 pairs of undisclosed duplicates). Two of the pairs were "blank" peanut butters to which aflatoxin standards had been added; these "spiked" samples were used for recovery purposes. The other 3 pairs of samples were a nominal "blank" and 2 naturally contaminated peanut butters. A full statistical presentation of the results is given. Coefficients of variation (CVs) for the total aflatoxin determinations for mean levels of 4, 15, and 38 microns/kg were between 32 and 44% for the blank and 2 trial samples. Recovery levels for the 2 spiked samples were 51-67%, with aflatoxin B1 recovery of 60%. Relative standard deviations for method repeatability (RSDr) and reproductibility (RSDR) for the 3 trial samples were 15-26% and 33-45%, respectively.

Inhibition of chemically-induced skin carcinogenesis in mice by peanut oil preparations.

Epidermal hyperplasia and sebaceous gland destruction - good indicators of carcinogenic potential - were studied in short-term mouse skin experiments following application of BaP and TPA dissolved either in a peanut oil mixture or in acetone. Subsequently, the carcinogenicity of BaP and DMBA alone or in association with TPA was dissolved in the same vehicles, and determined in mouse long-term skin tests. In parallel, ODC activity and binding to DNA, RNA and proteins were examined in epidermal cells after exposure to TPA and BaP respectively. When the peanut oil excipient was used as a solvent, a complete inhibition of BaP and TPA activities was observed in short-term skin tests, as well as a complete inhibition of BaP, DMBA and TPA carcinogenicity in long-term tests. TPA-induced ODC activity was suppressed by the peanut oil mixture while BaP binding to nucleic acids and proteins of epidermal cells was only slightly inhibited. These results indicate that the excipient possesses anti-carcinogenic potentials for epidermal cells. The persistence of BaP binding to macromolecules in epidermal cells without tumor development suggests that the carcinogenic action of BaP may include both genotoxic and epigenetic mechanisms.

Reproducibility of a commercially available kit utilizing enzyme-linked immunosorbent assay for determination of aflatoxin in peanut butter.

The reproducibility of a commercially available kit utilising enzyme-linked immunosorbent assay (ELISA) for determination of total aflatoxins has been analysed. Peanut butter samples contaminated with aflatoxin at three concentrations (mean 5.8, 11.7 and 24.8 ng/g) were analysed on different occasions using four kits. Coefficients of variation at all concentrations ranged from 2.6% to 13.6% within replicate, 0.3% to 16.2% within plate and 6.7% to 10.2% between kits. Standard curve precision profiles showed a minimum coefficient variation (CV) of 2-4% and a working range (below 10% CV) covering almost the entire standard curve.

Analytical methodology for the determination of aflatoxins in peanut butter: comparison of high-performance thin-layer chromatographic, enzyme-linked immunosorbent assay and high-performance liquid chromatographic methods.

High-performance thin-layer chromatography (HPTLC) was applied to the separation and quantification of aflatoxin in 300 jars of "crunchy" peanut butter. A critical evaluation of the proposed HPTLC method has been carried out by statistical comparisons with a commercially available enzyme-linked immunosorbent assay (ELISA) kit and a high-performance liquid chromatographic (HPLC) method. The statistical tests indicated that whilst the distributions of the data sets obtained with each method were similar, the HPLC method was found to be biased. Over-all results indicated that the HPTLC method gave more consistent data, relatively lower standard deviations and lower coefficients of variation. The ELISA kit was found to be less precise than the HPTLC and HPLC methods and prone to some loss of sensitivity caused by matrix interference.

Reaction to a paper by Whitaker and Dickens on aflatoxin testing plans for shelled peanuts in the U.S. and the export market.

The present paper examines a technical paper of Whitaker and Dickens on aflatoxin testing plans that discusses (without a literature reference) a testing plan used in The Netherlands. However, this testing plan has never been in operation. We present the current situation in The Netherlands with respect to legislation and sampling plans on aflatoxin, which has fairly important consequences for the results of the simulation study of Whitaker and Dickens. It is shown that the percentage of rejected U.S.-exported lots in The Netherlands would increase from 16% to 27% based on the actual testing plan in The Netherlands. The need for international harmonization of testing, and the role of Codex Allmentarius is also emphasized.

Determination of aflatoxin B1 levels in peanut butter using an immunoaffinity column clean-up procedure: inter-laboratory study.

Ten United Kingdom laboratories participated in an evaluation of an immunoaffinity column sample preparation procedure used to prepare aflatoxin B1 containing extracts obtained from peanut butters contaminated by aflatoxins. Each laboratory was sent seven randomly numbered samples of roasted peanut butter which included two sets of undisclosed triplicates. These two peanut butters were naturally contaminated with aflatoxin B1 at levels of about 12 and 35 micrograms/kg. The other sample was a nominal blank peanut butter containing approximately 2 micrograms/kg of aflatoxin B1 which was also employed by participants for recovery experiments. Participating laboratories were instructed to follow a protocol regarding the use of the immunoaffinity columns for extract preparation, but were allowed a free choice of instrumental technique for quantification of aflatoxin levels. Mean recovery for spikes was 72%. Coefficients of variation for the results from the 10 participants for the two contaminated roasted peanut butters were, respectively, 45% (on a mean of 13.6 micrograms/kg) and 36% (on a mean of 37.2 micrograms/kg).

Effect of peanut tannin extracts on growth of Aspergillus parasiticus and aflatoxin production.

Twenty-three peanut (Arachis hypogaea L.) genotypes were evaluated for kernel resistance to Aspergillus parasiticus Spear. colonization and aflatoxin contamination when incubated under high relative humidity. Also, tannin-containing extracts from kernel coats (testae) and cotyledons of these genotypes were prepared and tested for their effect on A. parasiticus growth and aflatoxin production in vitro. The lowest degree of colonization, less than 30%, was noted in kernels from the genotypes, Toalson x UF 73-4022 (selections TX-798731 and TX-798736), A72118, SN 55-437, PI337409, and Florunner. Genotypes with low levels of colonization also had the lowest aflatoxin contamination. The coefficient of correlation between infection frequency and aflatoxin contamination was 0.66. Higher levels of tannins were detected in the testae (23.9-97.2 mg g tissue) compared to the cotyledons (0.17-0.82 mg g tissue). Some of the methanol-extracted and water-soluble tannin extracts from testae and cotyledons, when incorporated in yeast extract sucrose liquid medium (100 mg l), significantly inhibited A. parasiticus growth and reduced the levels of aflatoxin produced. There was no overall correlation between the peanut genotypes and the influence of tannin extracts on A parasiticus growth and aflatoxin production. However, correlations were higher for specific genotypes. For example, the coefficient of correlation between the ability of tannin extracts from testae of genotypes PI337409 and TX-798736 to inhibit aflatoxin production was 0.93 and 0.85 respectively.

Complete amino acid sequence of arachin subunit of molecular weight 21,000.

A subunit of molecular weight 21,000 from arachin, the major peanut protein, was isolated in pure form and primary structure was determined. The subunit was fragmented with CNBr, trypsin, and NBS; the fragments were separated and isolated by PAGE, gel filtration, Dowex treatment, and paper electrophoresis, and Edman degradation on each fragment, including the intact subunit, was performed. The PTH-amino acids thus obtained were identified by UV spectroscopy and TLC. The complete sequence of 176 residues was established by overlapping technique.

Comparison of two immunochemical methods with thin-layer chromatographic methods for determination of aflatoxins.

Three different methods were compared for the determination of total flatoxins in corn and peanuts naturally contaminated with aflatoxins and in corn, peanuts, cottonseed, peanut butter, and poultry feed spiked with aflatoxins B1, B2, and G1. The 3 methods were an enzyme-linked immunosorbent assay (ELISA) screening test; a monoclonal antibody-affinity column-solid-phase separation method; and the AOAC official thin-layer chromatography (TLC) methods for all except poultry feed, for which Shannon's TLC method for mixed feed was used. The ELISA test is designed to provide only positive results for total aflatoxins at greater than or equal to 20 ng/g or negative results at less than 20 ng/g. The affinity column separation is coupled with either bromination solution fluorometry to estimate total aflatoxins or liquid chromatography (LC) to quantitate individual aflatoxins. Fluorodensitometry was used to determine aflatoxins in commodities analyzed by the TLC methods. The LC and TLC results were in good agreement for all the analyses. The results for the affinity column using bromination solution fluorometry were similar except those for cottonseed, which were about 60% higher. The ELISA screening method correctly identified naturally contaminated corn and peanut positive samples. No false positives were found for controls. The correct response for spiked corn, raw peanuts, peanut butter, and cottonseed at greater than or equal to 20 ng aflatoxins/g was about 90%. The correct response for spiked poultry feed at greater than or equal to 20 ng aflatoxins/g was about 50%.

Effects of roasting and storage on proteins and oil in peanut kernels.

Peanut kernels, untreated or soaked in salt solution, were roasted at 160 degrees C for 30 min in a hot air oven or oil roasted at 147 degrees C for 2 min and, stored at 27 degrees C and 5 degrees C up to 150 days. The heat treatments significantly decreased methionine, tryptophan and in vitro protein digestibility (IVPD) and, increased the soluble proteins and acid value of kernel oil. Storage of heated peanuts caused an increase in water-soluble proteins, IVPD, acid value and saponification value and a decrease in methionine, tryptophan and iodine value. The oil roasting was found to be more detrimental to nutritional quality and storage stability of peanuts as compared to dry roasting. The storage of heated peanuts at 5 degrees C was found to be beneficial in lowering the undesirable nutritional changes in the peanut kernels.

Liquid chromatographic method for determination of aflatoxins B1, B2, G1, and G2 in corn and peanut products: collaborative study.

A collaborative study of a liquid chromatographic method for the determination of aflatoxins B1, B2, G1, and G2 was conducted in laboratories located in the United States, Canada, South Africa, and Switzerland. Twenty-one artificially contaminated raw peanuts, peanut butter, and corn samples containing varying amounts of aflatoxins B1, B2, G1, and G2 were distributed to participating laboratories. The test portion was extracted with methanol-0.1N HCl (4 + 1), filtered, defatted with hexane, and then partitioned with methylene chloride. The concentrated extract was passed through a silica gel column. Aflatoxins B1 and G1 were derivatized with trifluoroacetic acid, and the individual aflatoxins were determined by reverse-phase liquid chromatography with fluorescence detection. Statistical analysis of the data was performed to determine or confirm outliers, and to compute repeatability and reproducibility of the method. For corn, relative standard deviations for repeatability (RSDr) for aflatoxin B1 ranged from 27.2 to 8.3% for contamination levels from 5 through 50 ng/g. For raw peanuts and peanut butter, RSDr values for aflatoxin B1 were 35.0 to 41.2% and 11.2 to 19.1%, respectively, for contamination levels from 5 through 25 ng/g. RSDr values for aflatoxins B2, G1, and G2 were similar. Relative standard deviations for reproducibility (RSDr) for aflatoxin B1 ranged from 15.8 to 38.4%, 24.4 to 33.4%, and 43.9 to 54.0% for corn, peanut butter, and raw peanuts, respectively. The method has been adopted official first action for the determination of aflatoxins B1, B2, G1, and G2 in peanut butter and corn at concentrations greater than or equal to 13 ng total aflatoxins/g.

Effect of addition of bovine milk and vegetable milks on the in vitro availability of iron from cereal meals.

Studies were carried out on the in vitro availability of iron from a standard cereal meal with and without the addition of bovine milk (BM), groundnut milk (GM) and soybean milk (SM). Further, availability of iron from these milks per se was also investigated. Estimation of the total iron content from BM, GM, and SM revealed that it was highest in case of SM followed by GM and BM. This trend was reversed for percent available iron which was highest for BM followed by GM and SM. The in vitro availability of iron from the cereal meal was low (3.7%). Addition of BM and GM enhanced the availability of iron from the standard meal whereas SM had no particular enhancing quality. The practical implications of the findings for iron nutrition in humans are discussed.

Aflatoxin levels in foodstuffs in Fiji and Tonga islands.

Fungal growth is a major problem of food storage in humid environments, as occur in South Pacific countries for parts of the year. Major crops, including edible nuts, copra and root crops, are susceptible to Aspergillus growth and therefore potential contamination with aflatoxin. Liver cancer occurs in Fiji and Tonga, with the occurrence in Fijians being significantly higher than in the Indian population. Thirty-three peanut samples from farmers were analysed for aflatoxin and 50% of the samples from Fiji were positive but only 9% from Tonga, reflecting different storage practices. Local copra, cassava, and maize samples were found contaminated, with only the maize at a serious level. Twenty-five plate food samples from Fiji showed low contamination. When starch foods from the Fijian diet left after cooking were analysed to follow potential aflatoxin development only sweet potatoes showed some contamination.

Enzyme-linked immunosorbent assay of aflatoxins B1, B2, and G1 in corn, cottonseed, peanuts, peanut butter, and poultry feed: collaborative study.

A direct competitive enzyme-linked immunosorbent assay (ELISA) screening method for aflatoxins at 20 ng/g was studied by 12 collaborators. Test samples of peanut butter were extracted by blending with methanol-water-hexane (55 + 45 + 100) and heating the test extracts on a steam bath; test samples of the other commodities were extracted by blending with methanol-water (80 + 20). All test extracts were filtered and the filtrates were diluted with buffer to a final methanol concentration of less than 30%. Each diluted filtrate was applied to a cup containing a filter with immobilized polyclonal antibodies specific to aflatoxins B1, B2, and G1. Aflatoxin B1-peroxidase conjugate was added, the cup was washed with water, and a mixture of hydrogen peroxide and tetramethylbenzidine was added. The test sample was judged to contain greater than or equal to 20 ng aflatoxins/g when, after exactly 1 min, no color was observed on the filter; when a blue or gray color developed, the test sample was judged to contain less than 20 ng aflatoxins/g. All collaborators correctly identified naturally contaminated corn and raw peanut positive test samples. No false positives were found for controls containing less than 2 ng aflatoxins/g. The correct responses for positive test samples spiked at levels of 10, 20, and greater than or equal to 30 ng aflatoxins/g (the ratio of B1:B2:G1 was 10:1:3) were 52, 86, and 96%, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparison of two ELISA screening tests with liquid chromatography for determination of aflatoxins in raw peanuts.

A study was conducted to evaluate the performance of 2 enzyme-linked immunosorbent assays (ELISA) for rapidly screening samples of peanuts for the presence of aflatoxin. The EZ-Screen Quick Card Test and the Afla-10 Cup Test were compared with liquid chromatography in duplicate analyses of common extracts of peanuts contaminated in the range of 0-70 ppb (ng/g). Each assay properly identified 95% of samples containing no detectable aflatoxin as negative and greater than 97% of samples containing greater than 10 ppb aflatoxin as positive. The card test, which had a 20 ppb detection threshold, identified as positive 32 of 34 samples in the 11-20 ppb range. This indicates that the card test might actually have a detection threshold closer to 10 ppb. Most of the errors associated with the assays occurred on samples containing less than 10 ppb aflatoxin. The cup and card tests identified 76 and 67% of the samples, respectively, as negative, in the range of 4-10 ppb. For samples either negative or contaminated above their detection thresholds for the assays, the methods are well suited for use as rapid screening tests.