scholarly journals Significant Effect of Sample Pretreatment on Ara h1 Extraction and Improved Sensitive SWCNT-Based Detection through Optimization

Processes ◽  
2020 ◽  
Vol 8 (11) ◽  
pp. 1420
Author(s):  
Jinyoung Lee
Keyword(s):  
Peanut Butter ◽  
Extraction Procedure ◽  
Milk Powder ◽  
Sample Pretreatment ◽  
Linear Sweep Voltammetry ◽  
Peak Level ◽  
Extraction Time ◽  
Enzyme Linked Immunosorbent Assay ◽  
Food Matrix ◽  
Ara H1

Single-walled carbon nanotube (SWCNT)-based nanobiosensors have received increasing attention from food researchers as a future instrument of food safety due to their high sensitivity. However, the pretreatment process of the sample applying to SWCNT-based nanobiosensor is required to be more delicate compared to other analyses. In this study, the pretreatment process of Ara h1 protein from its retained complex food matrix was optimized using various buffer compounds and the pretreated allergenic Ara h1 obtained for the optimized process was detected by SWCNT-based nanobiosensor. In the pretreatment process, the buffer extraction method with tris buffer (Tris-HNO3, pH 8.4) was developed and used to extract native peanut allergens from foods. The extraction procedure for Ara h1 from peanut butter foods was performed by varying the temperature, extraction time, and additives (NaCl and skim milk powder). The results of these tests using our SWCNT-based biosensor were analyzed to evaluate the allergenic nature of the extracts. The peak level of Ara h1 extraction was achieved as 84.60 ± 7.50 ng/mL at 21 °C/60 min with the mixture of Tris-HNO3 and 1 M NaCl. In addition, other significant Ara h1 extractions were found to be 29.59 ± 2.57 at 21 °C/15 min and 27.74 ± 1.33 ng/mL at 60 °C/15 min. This study emphasizes the importance of adjusting the extraction time and temperature with respect to the target allergen and food matrix components. After the optimization of the sample pretreatment, the precision of SWCNT-based nanobiosensor by the resistance difference (ΔR) of the SWCNT-based biosensor via linear sweep voltammetry in a potentiostat was identified using the pretreated Ara h1 sample from the processed food compared with the indirect enzyme-linked immunosorbent assay (ELISA) results.

Determination of Aflatoxin B1 in Corn, Wheat, and Peanut Butter by Enzyme-linked Immunosorbent Assay and Solid Phase Radioimmunoassay

1981 ◽  
Vol 64 (5) ◽  
pp. 1077-1082 ◽  
Author(s):  
Ossama El-Nakib ◽  
James J Pestka ◽  
Fun S Chu
Keyword(s):  
Aflatoxin B1 ◽  
Solid Phase ◽  
Peanut Butter ◽  
Extraction Procedure ◽  
Tween 20 ◽  
Enzyme Linked Immunosorbent Assay ◽  
Coefficients Of Variation ◽  
Solid Phase Radioimmunoassay ◽  
Phosphate Buffered Saline

Abstract Determinations of aflatoxin B1 in corn, wheat, and peanut butter by an enzyme-linked immunoassay (ELISA) and a solid-phase radioimmunoassay (RIA) were compared. Samples spiked with 2.9-43.2 ppb B1 were subjected to AOAC extraction procedure 26.017 or 26.023. The extracts were concentrated, redissolved in methanol, diluted in phosphate-buffered saline with Tween 20, and directly analyzed for B1 by either ELISA or RIA. At 5.8 ppb or greater, recoveries for B1 in corn, wheat, and peanut butter samples were 80.0,86.6, and 94.8% by ELISA and 61.0, 93.3, and 110.0% by RIA, respectively. Recoveries greater than 120% were obtained for the wheat and peanut butter samples spiked with 2.9 ppb aflatoxin B1 by the RIA method but not by ELISA. Overall results indicated that ELISA gave more consistent data, relatively lower standard deviations, and lower coefficients of variation than did RIA. Analysis of 3 samples naturally contaminated with aflatoxins revealed that the ELISA data were comparable to those obtained by other established chemical methods.

scholarly journals A Case for Regular Aflatoxin Monitoring in Peanut Butter in Sub-Saharan Africa: Lessons from a 3-Year Survey in Zambia

2016 ◽  
Vol 79 (5) ◽  
pp. 795-800 ◽  
Author(s):  
SAMUEL M. C. NJOROGE ◽  
LIMBIKANI MATUMBA ◽  
KENNEDY KANENGA ◽  
MOSES SIAMBI ◽  
FARID WALIYAR ◽  
...  
Keyword(s):  
South Africa ◽  
Aflatoxin B1 ◽  
Peanut Butter ◽  
Aflatoxin Contamination ◽  
Comprehensive Analysis ◽  
Sub Saharan Africa ◽  
Enzyme Linked Immunosorbent Assay ◽  
Contamination Level ◽  
Batch Number ◽  
Sub Saharan

ABSTRACT A 3-year comprehensive analysis of aflatoxin contamination in peanut butter was conducted in Zambia, sub-Saharan Africa. The study analyzed 954 containers of 24 local and imported peanut butter brands collected from shops in Chipata, Mambwe, Petauke, Katete, and Nyimba districts and also in Lusaka from 2012 to 2014. For analysis, a sample included six containers of a single brand, from the same processing batch number and the same shop. Each container was quantitatively analyzed for aflatoxin B1 (AFB1) in six replicates by using competitive enzyme-linked immunosorbent assay; thus, aflatoxin contamination level of a given sample was derived from an average of 36 test values. Results showed that 73% of the brands tested in 2012 were contaminated with AFB1 levels >20 μg/kg and ranged up to 130 μg/kg. In 2013, 80% of the brands were contaminated with AFB1 levels >20 μg/kg and ranged up to 10,740 μg/kg. Compared with brand data from 2012 and 2013, fewer brands in 2014, i.e., 53%, had aflatoxin B1 levels >20 μg/kg and ranged up to 1,000 μg/kg. Of the eight brands tested repeatedly across the 3-year period, none consistently averaged ≤20 μg/kg. Our survey clearly demonstrates the regular occurrence of high levels of AF B1 in peanut butter in Zambia. Considering that some of the brands tested originated from neighboring countries such as Malawi, Zimbabwe, and South Africa, the current findings provide a sub-Saharan regional perspective regarding the safety of peanut butter.

Application of ELISA to Retail Survey of Aflatoxin B1 in Peanut Butter

1986 ◽  
Vol 49 (10) ◽  
pp. 792-795 ◽  
Author(s):  
BHANU P. RAM ◽  
L. PATRICK HART ◽  
RICHARD J. COLE ◽  
JAMES J. PESTKA
Keyword(s):  
Immunosorbent Assay ◽  
Aflatoxin B1 ◽  
Coefficient Of Variation ◽  
Simple Procedure ◽  
Peanut Butter ◽  
Competitive Elisa ◽  
Routine Screening ◽  
Enzyme Linked Immunosorbent Assay

A simple procedure was devised for the routine screening of aflatoxin B1 (AFB1) in peanut butter using enzyme-linked immunosorbent assay (ELISA). Peanut butter samples (5 g) were artificially contaminated with AFB1 and extracted by blending with 25 ml of 55% methanol and 10 ml of hexane. The extract was filtered and aqueous filtrate analyzed by a direct competitive ELISA. Recovery of AFB1 added to peanut butter samples ranged from 85 to 112%, with an average inter-well coefficient of variation of 18.4%. The inter-assay coefficient of variation was 22.7%. Using this procedure, only 3 of 63 commercial samples of peanut butter had detectable levels (>5.0 μg/kg) of AFB1.

Survival of Salmonella enterica Serotype Tennessee during Simulated Gastric Passage Is Improved by Low Water Activity and High Fat Content

2013 ◽  
Vol 76 (2) ◽  
pp. 333-337 ◽  
Author(s):  
BRYAN AVILES ◽  
COURTNEY KLOTZ ◽  
TWYLA SMITH ◽  
ROBERT WILLIAMS ◽  
MONICA PONDER
Keyword(s):  
Water Activity ◽  
Salmonella Enterica ◽  
Peanut Butter ◽  
Gastric Fluid ◽  
Fat Content ◽  
Simulated Gastric Fluid ◽  
Food Matrix ◽  
High Fat ◽  
Low Fat ◽  
Infectious Dose

The low water activity (aw 0.3) of peanut butter prohibits the growth of Salmonella in a product; however, illnesses are reported from peanut butter contaminated with very small doses, suggesting the food matrix itself influences the infectious dose of Salmonella, potentially by improving Salmonella's survival in the gastrointestinal tract. The purpose of our study was to quantify the survival of a peanut butter outbreak–associated strain of Salmonella enterica serotype Tennessee when inoculated into peanut butters with different fat contents and aw (high fat, high aw; high fat, low aw; low fat, high aw; low fat, low aw) and then challenged with a simulated gastrointestinal system. Exposures to increased fat content and decreased aw both were associated with a protective effect on the survival of Salmonella Tennessee in the simulated gastric fluid compared with control cells. After a simulated intestinal phase, the populations of Salmonella Tennessee in the control and low-fat formulations were not significantly different; however, a 2-log CFU/g increase occurred in high-fat formulations. This study demonstrates that cross-protection from low-aw stress and the presence of high fat results in improved survival in the low pH of the stomach. The potential for interaction of food matrix and stress adaptations could influence the virulence of Salmonella and should be considered for risk analysis.

Determination of Total Aflatoxin Levels in Peanut Butter by Enzyme-Linked Immunosorbent Assay: Collaborative Study

1992 ◽  
Vol 75 (4) ◽  
pp. 693-697 ◽  
Author(s):  
Alan L Patey ◽  
Matthew Sharman ◽  
John Gilbert
Keyword(s):  
Immunosorbent Assay ◽  
Aflatoxin B1 ◽  
Peanut Butter ◽  
Collaborative Study ◽  
The United States ◽  
Enzyme Linked Immunosorbent Assay ◽  
Total Aflatoxin ◽  
Aflatoxin Level ◽  
Relative Standard

Abstract Laboratories in Australia, Japan, Spain, the United Kingdom, and the United States participated in a collaborative study to evaluate a commercial enzyme- linked immunosorbent assay for the determination of total aflatoxin. Collaborators were sent 10 randomly numbered samples (5 blind duplicates) of roasted peanut butter. Two pairs were "blank" peanut butters to which aflatoxin B1, B2, G1, and G2 standards had been added. The other 3 pairs of peanut butters were 1 low aflatoxin level sample and 2 naturally contaminated samples. The assay is based on indirect competition. Test samples containing (free) aflatoxin, added to aflatoxin-coated microwells, compete for specific monoclonal rat anti-aflatoxin. As the concentration of aflatoxin in the test samples increases, the amount of rat antiaflatoxin binding to the aflatoxin attached to the well decreases. After a wash step to remove unbound material, the amount of rat anti-aflatoxin bound to the well is determined by its reaction with peroxidase conjugated rabbit anti-rat globulin. Bound peroxidase activity is then determined by the addition of a substrate, whose color development is inversely proportional to the aflatoxin concentration and is measured by absorbance. Coefficients of variation (CV) for total aflatoxin concentrations, for mean levels of 9,30, and 89µg/kg, were between 28 and 37% for the low level and 2 naturally contaminated samples, which contained mainly aflatoxin B1. CVs for the spiked samples were lower (24-25%) for mean levels of 11 and 20 µg/kg; recoveries were 84 and 89%, respectively. Ranges for relative standard deviations for repeatabilty and reproducibility were 9-30% and 25-37%, respectively. The method has been adopted first action by AOAC International.

Comparison of Two Immunochemical Methods with Thin-Layer Chromatographic Methods for Determination of Aflatoxins

1990 ◽  
Vol 73 (3) ◽  
pp. 425-428
Author(s):  
Mary W Trucksess ◽  
Kathryn Young ◽  
Kevin F Donahue1 ◽  
Deborah K Morris ◽  
Ernie Lewis
Keyword(s):  
Thin Layer ◽  
Correct Response ◽  
Peanut Butter ◽  
Screening Method ◽  
Elisa Test ◽  
Poultry Feed ◽  
Enzyme Linked Immunosorbent Assay ◽  
Affinity Column ◽  
Negative Results

Abstract 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 Bi, B2, and d . The 3 methods were an enzyme-linked Immunosorbent assay (ELISA) screening test; a monoclonal antibody-affinity column-solld-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 >20 ng/g or negative results at <20 ng/g. The affinity column separation Is coupled with either brominatlon solution fluorometry to estimate total aflatoxins or liquid chromatography (LC) to quantltate 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 brominatlon 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 >20 ng aflatoxlns/g was about 90%. The correct response for spiked poultry feed at >20 ng aflatoxlns/ g was about 50%.

Lipoprotein(a) quantified by an enzyme-linked immunosorbent assay with monoclonal antibodies.

1989 ◽  
Vol 35 (7) ◽  
pp. 1380-1384 ◽  
Author(s):  
C Labeur ◽  
G Michiels ◽  
J Bury ◽  
D C Usher ◽  
M Rosseneu
Keyword(s):  
Monoclonal Antibody ◽  
Immunosorbent Assay ◽  
Plasma Cholesterol ◽  
Sample Pretreatment ◽  
Hdl Cholesterol ◽  
Normal Subjects ◽  
Enzyme Linked Immunosorbent Assay ◽  
Apo B ◽  
Lipoprotein A ◽  
Screening Programs

Abstract This new, sensitive, specific "sandwich"-type enzyme-linked immunosorbent assay (ELISA) for quantifying lipoprotein(a) [Lp(a)] in human serum and in ultracentrifugal lipoprotein fractions is based on use of a monoclonal antibody raised against apolipoprotein(a) as coating protein and a polyclonal antibody, raised against either apo B or against Lp(a) and conjugated with peroxidase, for detection of bound Lp(a). Mean intra- and interassay CVs for assay of 16 samples were 3.0% and 5.6%, respectively. Sample pretreatment with urea did not enhance Lp(a) immunoreactivity, and treatment with nonionic detergents decreased binding to the monoclonal antibody. Results correlated well (r = 0.99, n = 38) with those by radial immunodiffusion (RID). The ELISA assay, however, detects amounts corresponding to Lp(a) contents of 10 to 1000 mg/L in plasma samples diluted 1000-fold, compared with 100-500 mg/L for RID. For 92 normolipidemic subjects, the mean Lp(a) concentration was 120 (SD 130) mg/L. In patients undergoing coronary angiography, Lp(a) concentrations increased with the severity of the disease but were not correlated with either HDL cholesterol, triglycerides, apo A-I, or apo B, and only weakly with plasma cholesterol and apo A-II. These two correlations were even weaker in normal subjects, and only the correlation with total cholesterol was valid. Lp(a), measured at birth and at seven days and six months, steadily increased with age. This assay is well suited for measuring Lp(a) in plasma and in lipoprotein fractions and also for screening programs evaluating this significant genetic risk factor for the development of atherosclerosis.

scholarly journals Application of Direct Solvent Extraction to the LC Quantification of Vitamin E in Peanuts, Peanut Butter, and Selected Nuts

1998 ◽  
Vol 25 (2) ◽  
pp. 123-128 ◽  
Author(s):  
J. Lee ◽  
W. O. Landen ◽  
R. D. Phillips ◽  
R. R. Eitenmiller
Keyword(s):  
Vitamin E ◽  
Solvent Extraction ◽  
Peanut Butter ◽  
Extraction Procedure ◽  
Soxhlet Extraction ◽  
Extraction Methods ◽  
Normal Phase ◽  
The Other ◽  
Direct Solvent Extraction ◽  
Peak Purity

Abstract Direct solvent extraction with hexane:ethyl acetate (90:10, v/v), saponification, and Soxhlet extraction with hexane were evaluated for their usefulness as extraction methods to determine vitamin E in peanuts and peanut butters. The direct solvent extraction procedure yielded higher values for each tocopherol homolog in peanut and peanut butter compared to the other methods. Coupling of the rapid, direct solvent extraction with normal phase chromatography on Si 60 provides a highly reproducible procedure to quantitate vitamin E in peanuts and peanut products. The overall % recoveries (means ± S.D.) of this study for α-, β-, γ-, and δ-tocopherol were 99.9 ± 3.29, 100.4 ± 11.7, 98.9 ± 5.94, and 100.3 ± 4.87, respectively. Limits of detection and limits of quantitation were 0.21, 0.06, 0.11, and 0.08 ng and 0.39, 0.14, 0.23, and 0.13 ng, respectively, for α-, β-, γ-, and δ-tocopherol. Repeatability, reproducibility, and accuracy of the methods were excellent with % CVs for accuracy of 1.19 (α-T), 1.55 (γ-T), and 2.69 (δ-T). Accuracy was not acceptable for β-T due to its extremely low concentration in the peanut and because peak purity was not obtained for β-T. The method was applied to other seeds with good success. Major homologs were γ-T in peanuts, pecans, cashews, walnuts, and pistachio; α-T in almonds; and α-T3 in macadamia.

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