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PubMedDate not supplied

Improved liquid chromatographic method for determination of aflatoxins in peanut butter and other commodities.

A combination of the extraction and cleanup procedures of Pons and Franz with the liquid chromatographic (LC) derivatization technique of Beebe is proposed as an accurate, precise, and sensitive method for determination of aflatoxins B1, B2, G1, and G2 in various foodstuffs. Mean recoveries of total aflatoxins added in the range 15-34 ng/g to peanut butter were 86-94% in 2 laboratories. Recovery of total aflatoxins (30 ng/g) from shelled peanuts, shelled Brazil nuts, pistachios, cashews, walnuts, and filberts exceeded 86% and from pumpkin seeds was 80%. Coefficients of variation for total aflatoxins were less than 7% for spiked samples and 15% for peanuts naturally contaminated with 16.7 ng/g of total aflatoxin (B1 + B2). Analyses of peanut meal, yellow corn meal, and peanut butter check samples (AOCS Smalley Series 1980/81 and 1981/82, IARC Series 1982/83) by this method compared favorably with reported averages. The detection limit is about 0.3 ng/g for each aflatoxin.

Aflatoxins↗
PubMed1976

Distribution of aflatoxins in some samples of peanuts.

Naturally occurring G aflatoxins were found at approximately 20 times the level of B aflatoxins in one lot of roasted, blanched peanuts. Official methods, as well as high-pressure liquid chromatography, were used to confirm this finding. Additional routine sample analysis data of raw and roasted peanuts revealed that this finding is not so unusual formerly thought. It was found that 9.8% of the raw peanut samples contained higher levels of G than B aflatoxin; 4.9% containing 2-8 times more G than B aflatoxins. In a smaller sampling of roasted peanuts, 28% of the contaminated peanuts contained more G than B aflatoxins.

Aflatoxins↗
PubMed1998

[The problem of hidden food allergens: two cases of anaphylaxis to peanut proteins concealed in a pizza sauce].

Peanut is one of the major food allergens inducing anaphylaxis. It is increasingly consumed and often used as a hidden ingredient, thus making avoidance especially difficult for allergic patients. In Switzerland legislation stipulates that all ingredients of a processed food exceeding 2% of the total mass of the finished food product should be labelled. However, in the case of a mixture of vegetables it can be labelled as "vegetable mix" if it does not exceed 10% of the total weight. Peanut, which is a member of the legume family, can thus form up to 10% of processed foods without being mentioned on the label, thus making avoidance impossible. We report on two patients who presented severe anaphylaxis from peanut hidden in a pizza from a fast food restaurant. We were able to provide evidence for the presence of major peanut antigens in the pizza sauce by immunochemical analysis. These two cases clearly demonstrate the danger of peanut hidden in foods and point up the necessity of a change in legislation.

Adolescent↗
PubMed2001

Sialomucin complex (rat Muc4) transmembrane subunit binds the differentiation marker peanut lectin in the normal rat mammary gland.

Sialomucin complex (SMC, rat Muc4) is a heterodimeric glycoprotein composed of two subunits, the mucin component ASGP-1 and the transmembrane subunit ASGP-2. SMC/Muc4 is highly expressed on the surface of 13762 rat mammary adenocarcinoma cells at approximately 100 times the level found in the lactating mammary gland. Immunocytochemical staining of SMC/Muc4 in the developing rat mammary gland is localized to the apical membrane of the ductal epithelium. This staining pattern is similar to that for peanut lectin, a differentiation marker, which binds to cells expressing the disaccharide Thomsen-Friedenreich or TF antigen. Blotting of glycoproteins expressing the TF antigen from mammary tissues with peanut lectin detects a protein matching the migration of ASGP-2. Analysis of immunoprecipitated SMC/Muc4 by peanut lectin blotting shows that the TF antigen is abundantly present on the ASGP-2 subunit, hence the similarity of staining pattern with SMC/Muc4 antisera and peroxidase-conjugated lectin in mammary tissues. The TF antigen is also present on ASGP-2 of SMC/Muc4 produced by confluent cultures of Rama 37 rat mammary epithelial stem cells after their induction to an alveolar-like phenotype with prolactin. These results indicate that the TF antigen is present on the ASGP-2 transmembrane subunit of SMC/Muc4 from phenotypically normal tissues and cells, in contrast to malignant cells whose peanut lectin-binding disaccharide is located on ASGP-1.

Animals↗
PubMed2001

Microwave roasting of peanuts: Effects on oil characteristics and composition.

Roasting of peanuts by microwave heating (MWH) for different periods was studied in comparison with conventional heating method (CHM). The oils extracted from microwave roasted peanuts (MWRP) showed gradual darkening by time of heating. Colour indices of the oil samples were calculated to show the effect of heating on the oil colour. Chemical characteristics and fatty acid composition of the extracted oils were determined. In addition, peroxide value, conjugated dienes and trienes were determined. It was found that very low amounts of epoxy and conjugated fatty acids as well as fatty acid peroxides were formed as detected by GLC, UV spectrophotometry and peroxide value determinations. Freshly extracted peanut oils subjected directly to MWH showed increase of formation of conjugated trienes. In addition, the MW treatment causes oil darkening and higher colour indices were obtained. It was generally concluded that even short period MWH accelerates the formation of some undesirable and harmful compounds (e.g. oxidation products, transformed pigments ... etc.) during peanut roasting.

Arachis↗
PubMed1989

Carbohydrate components recognized by the cone-specific monoclonal antibody CSA-1 and by peanut agglutinin are associated with red and green-sensitive cone photoreceptors.

Previous investigations have demonstrated that the monoclonal antibody CSA-1 and peanut agglutinin label specifically cone photoreceptor cells. In the present study, we compared the binding of CSA-1 and peanut agglutinin to that of the monoclonal antibodies COS-1 and OS-2, which have been shown to recognize the red/green- and blue-sensitive cone visual pigments, respectively. Using lectin and immunocytochemistry on serial semithin sections of the pig retina, we have demonstrated in the present study that both CSA-1 and peanut agglutinin label specifically the red-, and green-sensitive, but not the blue-sensitive cone cell outer segments. Peanut agglutinin does bind, however, to the cone matrix sheaths associated with all three types of cones. These observations support the idea that red-, and green-sensitive cone cells share some common molecular epitopes and may represent a differentiation line of cones, considerably different from that of blue-sensitive cones.

Animals↗
PubMed1996

Conformation, protein-carbohydrate interactions and a novel subunit association in the refined structure of peanut lectin-lactose complex.

The structure of the complex of the tetrameric peanut lectin with lactose has been refined to an R-value of 16.4% using 2.25 angstroms resolution X-ray diffraction data. The subunit conformation in the structure is similar to that in other legume lectins except in the loops. It has been shown that in the tertiary structure of legume lectins, the short five-stranded sheet plays a major role in connecting the larger flat six-stranded and curved seven-stranded sheets. Furthermore, the loops that connect the strands at the two ends of the seven-stranded sheet curve toward and interact with each other to produce a second hydrophobic core in addition to the one between the two large sheets. The protein-lactose interactions involve the invariant features observed in other legume lectins in addition to those characteristic of peanut lectin. The "open" quaternary association in peanut lectin is stabilised by hydrophobic, hydrogen-bonded and water-mediated interactions. Contrary to the earlier belief, the structure of peanut lectin demonstrates that the variability in quaternary association in legume lectins, despite all of them having nearly the same tertiary structure, is not necessarily caused by covalently bound carbohydrate. An attempt has been made to provide a structural rationale for this variability, on the basis of buried surface areas during dimerisation. A total of 45 water molecules remain invariant when the hydration shells of the four subunits are compared. A majority of them appear to be involved in stabilising loops.

Carbohydrate Metabolism↗
PubMed1994

Cholinesterases and peanut agglutinin binding related to cell proliferation and axonal growth in embryonic chick limbs.

Embryonic cholinesterases are assigned important functions during morphogenesis. Here we describe the expression of butyrylcholinesterase and acetylcholinesterase, and the binding of peanut agglutinin, and relate the results to mitotic activity in chick wing and leg buds from embryonic day 4 to embryonic day 9. During early stages, butyrylcholinesterase is elevated in cells under the apical ectodermal ridge and around invading motoraxons, while acetylcholinesterase is found in the chondrogenic core, on motoraxons and along the ectoderm. Peanut agglutinin binds to the apical ectodermal ridge and most prominently to the chondrogenic core. Measurements of thymidine incorporation and enzyme activities were consistent with our histological findings. Butyrylcholinesterase is concentrated near proliferative zones and periods, while acetylcholinesterase is associated with low proliferative activity. At late stages of limb development, acetylcholinesterase is concentrated in muscles and nonexistent within bones, while butyrylcholinesterase shows an inverse pattern. Thus, as in other systems, in limb formation butyrylcholinesterase is a transmitotic marker preceding differentiation, acetylcholinesterase is found on navigating axons, while peanut agglutinin appears in non-invaded regions. These data suggest roles for cholinesterases as positive regulators and peanut-agglutinin-binding proteins as negative regulators of neural differentiation.

Acetylcholinesterase↗
PubMed1998

Regulated expression of keratan sulphate and peanut agglutinin binding sites during organogenesis in the developing chick.

Keratan sulphate proteoglycans are potentially important during development and are possible binding molecules for the lectin, peanut agglutinin, a marker for areas that are inhibitory for axonal growth in early embryos. The present study describes the spatiotemporal distributions of keratan sulphate epitopes and peanut agglutinin binding sites during organogenesis in the developing chick from E5 to hatching. The widespread distributions of these molecules did not often overlap but clearly delimited different carbohydrate compartments demonstrating that peanut agglutinin does not necessarily bind to keratan sulphate proteoglycans. These markers were mostly extracellular but keratan sulphate, in particular, was found within certain specific cells in cartilage, gonad, heart and pancreas, at certain ages. The presence of keratan sulphate in putative germ cells during their migrations and in the gonads may be of particular importance. Their distributions generally evoke modulation of adhesion allowing cell migrations or morphogenetic movements related to epitheliomesenchymal interactions, but may also suggest an involvement in axonal guidance in skin, cartilage, gut and possibly heart. Furthermore, in the kidney, peanut agglutinin binding sites seem to be related to the functional differentiation of the nephrons.

Animals↗
PubMed1983

A rapid and sensitive assay for neuraminidase using peanut lectin hemagglutination: application to Vibrio cholera and Trypanosoma cruzi.

A neuraminidase assay based on peanut lectin agglutination is described. Human red blood cells are used both as substrate for the enzyme and as probe for the lectin. The validity of the method is ascertained by measuring the enzyme and lectin activities on erythrocytes whose outer membrane sialic acid was labeled with tritium after oxidation with sodium periodate followed by reduction with sodium borotritiide. The neuraminidases of Trypanosoma cruzi and Vibrio cholera are used as examples; in both cases, a linear relationship is observed between the degree of erythrocyte desialylation and the peanut hemagglutination titer. For the hemagglutination assay, lectin in homogeneous form as well as in crude peanut extracts may be used, and free sialic acid need not be separated from substrate-bound sialic acid. The hemagglutinating activity of peanut lectin is not affected by pre-treatment of the erythrocytes with various proteases. The method is particularly useful in the neuraminidase analysis of multiple samples, such as in gel filtration chromatography and for screening of hybridoma antibodies against neuraminidase.

Chromatography, Gel↗
PubMed1983

Comparison of analysis of bovine surface immunoglobulin bearing and peanut agglutinin binding lymphocytes by flow cytometry and fluorescence microscopy.

Bovine peripheral blood lymphocytes were examined for their binding to anti-immunoglobulin serum, peanut agglutinin, and mu, alpha, and epsilon heavy chain specific antisera by immunofluorescence. The percentage of total lymphocytes with positive staining was determined independently by flow cytometry and fluorescence microscopy. The correlation of data from both methods was best for analysis of total surface immunoglobulin and IgM bearing cells. The percentage of lymphocytes bearing surface immunoglobulin (B cells) was determined using both whole antiserum and a F(ab')2 reagent. Quantitation by flow cytometry did not show a significant difference when the two reagents were used, whereas fluorescence microscopy revealed a significant difference (p less than .05). The mean percent of total surface immunoglobulin bearing cells was 30 +/- 3% by either method. Flow cytometry gave significantly larger values than fluorescence microscopy for samples stained with fluorescein conjugated peanut agglutinin. Peanut agglutinin binding cells comprised 70 +/- 3% by flow cytometry and 51 +/- 3% by fluorescence microscopy. Similarly, there was a significant difference between both methods when IgA bearing lymphocytes were examined. Percentages of immunoglobulin E, A, and M bearing lymphocytes as well as total B and T cells in spleen and bronchial lymph node were determined by immunofluorescence using the cytofluorograph. Peanut agglutinin binding cells were less numerous in spleen and lymph node than in peripheral blood. Immunoglobulin E bearing lymphocytes increased from 0.07% in peripheral blood to 4% in spleen and 1.9% in lymph node. In this paper we demonstrate how flow cytometry can be used to examine a large number of samples in a rapid and reproducible manner. This is the first report in which bovine lymphocytes bearing surface IgE are quantitated.

Animals↗
PubMed2005

Diagnosing peanut allergy with skin prick and specific IgE testing.

BACKGROUND: Food allergy is common in childhood. It has been suggested that the magnitude of a skin prick test or specific IgE result can improve diagnostic usefulness, but this has been addressed in only a few tertiary challenge-based studies. OBJECTIVE: To determine the predictive value of a wheal > or = 8 mm or serum specific IgE > or = 15 kU A /L for clinical allergy and investigate whether results are generalizable. METHODS: All subjects, up to 16 years of age, who had been investigated with a peanut or tree nut food challenge were eligible for the study. Subjects were referred from either a tertiary allergy clinic or a community birth cohort. All subjects with a history suggestive of food allergy were offered a challenge unless there were features of anaphylaxis. Details of challenges were prospectively recorded. Results were modeled by using logistic regression. RESULTS: There was a total of 161 peanut challenges. Recent skin prick (longest wheal diameter) and specific IgE data were available for 135 and 136 challenges, respectively. The results suggest that a skin prick result > or = 8 mm and a specific IgE > or = 15 kU A /L have predictive values of 95% (95% CI, 76.2% to 99.9%) and 92.0% (74.0% to 99.0%), respectively, for a positive challenge. Age, the type of nut, and referral pattern of the subject did not appear to alter this relationship. CONCLUSION: These data suggest that a skin prick result > or = 8 mm or a specific IgE > or = 15 kU A /L have a high predictive value for clinical allergy to peanut and that these cutoff figures appear generalizable to different populations of children undergoing an assessment for peanut allergy.

Adolescent↗
PubMed1986

Qualitative and quantitative analysis of peanut oil triacylglycerols by reversed-phase liquid chromatography.

Triacylglycerols (TGs) from an african peanut oil were analysed and fractionated by reversed-phase liquid chromatography (RPLC) using a differential refractometer as a detector. The fatty acids of the 33 collected fractions were analysed by gas chromatography after pentadecanoic acid (15:0) was added as an internal standard to quantitate the TG fractions. The three major fatty acids in the oil were octadecenoic acid (oleic acid, 44.5%), octadecadienoic acid (linoleic acid, 32.3%) and hexadecanoic acid (palmitic acid, 13.9%) together amounting to ca. 90% of the total fatty acids. Very long-chain saturated fatty acids (20:0-26:0) were also found. Thirty TGs could be easily identified from the fatty acid composition of the fractions alone. Dioleoyllinoleoylglycerol (18:1, 18:1, 18:2) was the main TG, amounting to nearly 17% of the oil, followed by palmitoyloleoyllinoleoylglycerol (16:0, 18:1, 18:2) (13%), oleoyldilinoleoylglycerol (18:2, 18:2, 18:1) (12%) trioleoylglycerol (18:1, 18:1, 18:1) (10%) and palmitoyldioleoylglycerol (16:0, 18:1, 18:1) (8%). These five TGs, which were virtually the only TGs in their respective fractions, together represented ca. 60% of the peanut oil TGs. Straight parallel lines were found for different series of TGs on plotting the logarithm of the relative retention time of the identified TGs (and those further identified) versus the number of double bonds. Other straight parallel lines were also observed on plotting the carbon numbers versus the equivalent carbon numbers of the oil TGs. These linear relationships were used to predict the different TGs present in the complex fractions. Their proportions in most instances were easily determined from the fatty acid composition of the fractions. In a very few instances a mathematical method had to be applied to solve the problem. Using the above-mentioned methods, 84 TGs could be identified and their percentages determined in the studied peanut oil. The very long-chain saturated fatty acids were always found associated with unsaturated fatty acids, preferentially with two molecules of linoleic acid. On the other hand, correction factors, determined from commercial simple TGs, were applied to peak areas before calculating the percentages of the 33 eluted TG fractions. For the major fractions of the oil, the series of values thus obtained was comparable to the series determined by the internal standardization procedure. Data reported here for peanut oil TGs are likely to be useful in identifying and quantifying the component TGs of other oils analysed by RPLC under the reported conditions.

Arachis↗
PubMedDate not supplied

Self-diffusion of water and oil in peanuts investigated by PFG NMR.

Pulsed field gradient (PFG) nuclear magnetic resonance (NMR) has been used to study self-diffusion characteristics of water and oil in natural peanuts and in peanuts saturated with water. From the dependence on diffusion time of the echo decay due to diffusion, regions of completely restricted diffusion for the oil molecules were identified. The mean size and size distribution function of these regions were obtained. Combined analysis of diffusion data for peanuts with natural moisture content and for water saturated peanuts shows the cellular nature of these regions. The cell structure, consisting of a cell cavity surrounded by a double membrane was identified.

Arachis↗
PubMed2006

Compositional and sensory comparisons between normal- and high-oleic peanuts.

The high-oleic-acid trait improves the oxidative stability of peanuts (Arachis hypogaea L.) and their products. The explicit effect of the trait on sensory quality, particularly on off-flavors associated with oil rancidity, has not been well documented. To assess the effect of the trait on off-flavors, data from two independent databases were analyzed to compare sensory quality and composition in normal- versus high-oleic peanut genotypes. In data collected using a sensory panel in the Department of Food Science at North Carolina State University, there were small differences between near-isogenic lines for intensities of the roasted peanut, astringent, over-roast, and nutty attributes, with the high-oleic lines exhibiting slightly greater intensities of those attributes. There were no differences for off-flavors such as fruity, painty, stale, moldy, or petroleum. In data collected from the multistate Uniform Peanut Performance Test and evaluated by a panel in the USDA-ARS Market Quality and Handling Research Unit (MQHRU) at Raleigh, NC, there were differences in chemical composition associated with the high-oleic trait, including differences in oil content, tocopherols, and carbohydrates in addition to the expected differences in fatty acid contents. There were small decreases in the intensities of the sensory attributes cardboard and painty associated with the high-oleic trait in the MQHRU data when all high-oleic lines were compared with all normal-oleic lines. Comparison of the near-isogenic pair NC 7 and N00090ol showed differences in oil and glucose contents, but not in sensory attributes. The high-oleic trait does not appear to have a major impact on sensory quality on average, although there were individual instances in which the trait was associated with shifts in sensory attribute intensities that may be perceptible to consumers.

Arachis↗
PubMed1991

Lipid metabolism responses in rats fed beef tallow, native or randomized fish oil and native or randomized peanut oil.

In experiments with male Wistar rats, we measured the effects of nonpurified diets containing 9.1% added fat (beef tallow, native or randomized fish oil, native or randomized peanut oil) on apparent digestibility of total fat and individual fatty acids. We also investigated the effects of the diets on plasma contents of triglyceride, cholesterolesters and free and total cholesterol as well as on the fatty acid profiles of plasma and liver phospholipids. Randomization of fish oil or peanut oil had no significant effect on any of the lipid measurements. Fat digestibility was significantly lower in the rats fed beef tallow. Apparent absorption of 18:1(n-9) and polyunsaturated fatty acids was not dependent on the fatty acid profile of the dietary fat. Apparent absorption of 16:1(n-7) and saturated fatty acids was generally highest in the rats fed fish oil. Intake of fish oil or peanut oil significantly decreased plasma triglyceride content. Intake of fish oil resulted in substantially decreased contents of total cholesterol and cholesterolesters in plasma, but intake of peanut oil did not. Efficiency of conversion of 18:2(n-6) into 20:4(n-6) was inhibited by long-chain (n-3) fatty acids.

Animals↗
PubMed2004

In vitro allergenicity of peanut after hydrolysis in the presence of polysaccharides.

BACKGROUND: Peanut is a major allergenic product. Manufacturing processes used in food industries to improve the physicochemical properties of food-based peanut (stabilization, texturization), could cause a modification of the digestibility of peanut proteins and, consequently, their allergenicity. OBJECTIVE: This study aimed at examining the influence of polysaccharides, i.e., gum arabic, low methylated pectin (LMP) and xylan, on the in vitro hydrolysis of peanut protein isolate (PPI) and the in vitro allergenicity of the digestion products. METHODS: PPI was hydrolysed during a two-step in vitro hydrolysis by pepsin, followed by a trypsin/chymotrypsin (T/C) mixture performed in dialysis bags with molecular weight cut-offs (MWCO) of 1000 or 8000 Da. SDS-PAGE electrophoresis and immunoblotting were assessed on the peptic and T/C digestion products in (retentates) and out of the dialysis bags (dialysates). RESULTS: Hydrolysis by all of the digestive enzymes showed retention of some proteins in the dialysis bags in the presence of gum arabic and xylan. The retentates were recognized by IgG and IgE, particularly peptides <20 kDa. The IgE binding with peptides of retentate containing xylan from the dialysis bag with an MWCO of 1000 Da was reduced. The immunoreactivity of hydrolysis products in dialysates was considerably reduced by polysaccharides, regardless of the dialysis bag. CONCLUSION: Reduction of PPI hydrolysis was probably due to non-specific interactions between polysaccharides and peptides. In retentates, IgE-binding epitopes were reduced by digestion and the presence of xylan. In dialysates, they were reduced by all of the polysaccharides. This work highlights the possibility of modulating this food allergy through optimized formulation.

Allergens↗
PubMed2005

Does severity of low-dose, double-blind, placebo-controlled food challenges reflect severity of allergic reactions to peanut in the community?

BACKGROUND: The severity of allergic reactions to food appears to be affected by many interacting factors. It is uncertain whether challenge-based reactions reflect the severity of past reactions or can predict future risk. OBJECTIVE: To explore the relationship of a subject's clinical history of past reactions to the severity of reaction elicited by a low-dose, double-blind, placebo-controlled food challenge (DBPCFC) with peanut. METHOD: Cross-sectional questionnaire assessment of community-based allergic reactions and low-dose DBPCFC in self-selected peanut-allergic subjects. Reaction severity was assessed using a novel scoring system, taking account of the dose of allergen ingested. RESULTS: Forty subjects (15 males, 23 children, 23 asthmatics by history) were studied. Only the most recent community reaction predicted the severity of reaction in the DBPCFC, but even this association was weak (r=0.37, P=0.03). Peanut-specific IgE (PsIgE) and skin prick test (SPT) weal size were not associated with community score but PsIgE level correlated well with the challenge score (r=0.6, P=0.001). Asthma did not affect the eliciting dose or challenge score directly but the association of PsIgE and challenge score was stronger in those without asthma (r=0.72, P=0.001) than in those with asthma (r=0.48, P=0.02). CONCLUSIONS: The scoring system developed appears to improve the sensitivity of assessment of reactions induced by DBPCFC. This is the first prospective study showing an association between PsIgE levels and clinical reactivity in DBPCFC, an effect that is more pronounced in non-asthmatics. This finding has important implications for the clinical care of subjects with food allergy. There is a poor correlation between the severity of reported reactions in the community and the severity of reaction elicited during low-dose DBPCFC with peanut.

Administration, Oral↗