Comparison of the observed distribution of aflatoxin in shelled peanuts to the negative binomial distribution

Whitaker, T. B.; Dickens, J. W.; Monroe, R. J.; Wiser, Edward H.

doi:10.1007/bf02609233

Cited by 69 publications

(25 citation statements)

References 6 publications

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“…While it cannot be shown in Table I, the skewness is greater for small sample sizes and the aflatoxin distribution among replicated samples taken from the same lot becomes more symmetrical as sample size increases (Whitaker et al 1972). The above characteristics described by Table I for aflatoxin in raw shelled peanuts are also generally found for other mycotoxins and other commodities (Whitaker et al 1993(Whitaker et al , 1998.…”

Section: Lotmentioning

confidence: 93%

“…Because of these uncertainties, the true mycotoxin concentration in the lot cannot be determined with 100% certainty by measuring the mycotoxin concentration in a test sample taken from the lot. For example, ten aflatoxin test results associated with taking ten replicated test samples from each of six contaminated shelled peanut lots are shown in Table I (Whitaker et al 1972). For each test result in Table I, the mycotoxin test procedure consisted of the following aspects:…”

Section: Uncertaintymentioning

confidence: 99%

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Sampling Foods for Mycotoxins

2006

Food Additives and Contaminants

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130

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It is difficult to obtain precise and accurate estimates of the true mycotoxin concentration of a bulk lot when using a mycotoxin-sampling plan that measures the concentration in only a small portion of the bulk lot. A mycotoxin-sampling plan is defined by a mycotoxin test procedure and a defined accept/reject limit. A mycotoxin test procedure is a complicated process and generally consists of several steps: (1) a sample of a given size is taken from the lot, (2) the sample is ground (comminuted) in a mill to reduce its particle size, (3) a subsample is removed from the comminuted sample, and (4) the mycotoxin is extracted from the comminuted subsample and quantified. Even when using accepted test procedures, there is uncertainty associated with each step of the mycotoxin test procedure. Because of this variability, the true mycotoxin concentration in the lot cannot be determined with 100% certainty by measuring the mycotoxin concentration in a sample taken from the lot. The variability for each step of the mycotoxin test procedure, as measured by the variance statistic, is shown to increase with mycotoxin concentration. Sampling is usually the largest source of variability associated with the mycotoxin test procedure. Sampling variability is large because a small percentage of kernels are contaminated and the level of contamination on a single seed can be very large. Methods to reduce sampling, sample preparation and analytical variability are discussed.

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Section: Lotmentioning

confidence: 93%

Section: Uncertaintymentioning

confidence: 99%

Sampling Foods for Mycotoxins

2006

Food Additives and Contaminants

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130

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“…Most of the published statistically designed plans have come from the efforts of the group from North Carolina State University and their colleagues (13,14,15,16). They choose to use the negative binomial distribution because it was found that the distribution of aflatoxin contaminated peanuts resembled the distribution of the incidence of contagious diseases (17) which have been described by this statistic.…”

Section: Associated Errorsmentioning

confidence: 99%

Sampling foodstuffs for mycotoxin analysis

Campbell¹

1980

Pure and Applied Chemistry

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-The obvious reason for sampling any given lot of material is to obtain a portion for determination or observation of attributes of the particular lot. It is also obvious that the sample must be representative of the lot to obtain meaningful results. Traditional means of sampling and sample preparation of agricultural crops and foodstuffs are usually not adequate for mycotoxin analyses . The main reason for this is that mycotoxin contamination is usually of a heterogenous nature and this presents problems in thepreparation of a homogenous sample for analysis. Sampling plans, sampling equipment, and sample preparation will be discussed. IWPROI1JCTION AND BACKGROU!The obvious reason for sampling any given lot of material is to obtain a portion for the determination or observation of attributes of the particular lot; in the discussion here it will be chemical analysis . It is also obvious that the sample must be representative of the lot if meaningful results are to be obtained. Traditional means of sampling and sample preparation of agricultural crops and foodstuffs are usually not adequate for mycotoxin analyses . The main reason for this is that mycotoxin contamination is usually of a heterogenous nature and this presents problems in obtaining a homogenous sample for analysis.For example, it has been shown that only a few kernels in a lot may be heavily contaminated but the rest of the kernels will not be contaminated. Therefore, in order to obtain a representative lot sample for analysis, it is necessary to take a relatively large amount from a number of sites in the lot and then properly prepare this lot sample in order to produce a representative sample for analysis.The exceptions are for foods which are readily flowable liquids, e . g., milk or beer, and foods which have been made into pastes by the processing, e.g., almond paste or smooth peanut butter or processed into powders, e.g., flour. The first class requires only a stirring whereas the latter classes require some mixing and blending to assure homogeneity.In analyzing foodstuffs for mycotoxins we are interested in finding out the true value (average or mean) of the contamination in any given lot. We will see later DE the true value of a lot is dependent upon at least three distinct but interdependent parts; namely, (1) sampling, (2) sample preparation, and (3) analysis. The analysis part of this problem will usually have the least error associated with it; the sampling part will have the largest and the sample preparation part will usually have an error lying somewhere between these two. I will not be discussing methods of analysis except as they inter-relate with sampling and sample preparation.Although we speak about plans for mycotoxin analysis, the plans developed to date have been devised for aflatoxin contaminations. There is little i.f any evidence to indicate that the nature of contaminations by other mycotoxins will be different from that of aflatoxin. So the information presented here for aflatoxin can be considered to apply to oth...

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“…The problem of sampling shelled peanuts for aflatoxin analysis has been intensely investigated and discussed by Whitaker et al (10,11,12,13,14 e 15). Whitaker et al (10) reported that the distribution of aflatoxin in a lot of shelled peanuts could be quantitatively represented by the negative binomial function.…”

Section: Introductionmentioning

confidence: 99%

Sampling plan for the analysis of aflatoxin in peanuts and corn: an update

Fonseca¹

2002

Braz. J. Microbiol.

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The aim of this paper was to update the sampling plan for analysis of mycotoxins in grains, formerly published by the author. The proposed alterations were based on the acquired experience on its application and on FAO recommendations. This update restricts the scope of the former plan and establishes a sampling plan for analysis of aflatoxin in peanuts and corn, by means of modified formulas, the minimum number of sacks or points (when in bulk) from which incremental samples should be drawn to make a bulk sample. Fractional exponents (square roots) of the formulas proportionally decrease the number of sacks/points to be sampled as the lot size increases. Operating Characteristic (OC) curves developed for in-shell and shelled peanuts and corn as well as trend curves of the coefficient variation for different sample sizes (weights) are presented.

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Comparison of the observed distribution of aflatoxin in shelled peanuts to the negative binomial distribution

Cited by 69 publications

References 6 publications

Sampling Foods for Mycotoxins

Sampling Foods for Mycotoxins

Sampling foodstuffs for mycotoxin analysis

Sampling plan for the analysis of aflatoxin in peanuts and corn: an update

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