氢氧化钾生产过程中三氯化氮的控制与去除

介绍了三氯化氮的性质，危险性及去除的方法，并就生产过程控制及去除三氯化氮的工艺作了进一步叙述。     

Variability of aflatoxin test results

Using 12 lb samples, 280 g subsamples, the Waltking method of analysis, and densitometric procedures, the sampling, subsampling, and analytical variances associated with aflatoxin test procedures were estimated. Regression analysis indicated that each of the above variance components is a function of the concentration of aflatoxin in the population being tested. Results, for the test procedures given above, showed that sampling constitutes the greatest single source of error, followed by subsampling and analysis. Functional relationships are presented to determine the sampling, subsampling, and analytical variance for any size sample, subsample, and number of analyses.     

The correlation of aflatoxin and norsolorinic acid production

Production of aflatoxins and norsolorinic acid by a mutant strain ofAspergillus parasiticus follows a similar course. Both substances are completely or partially inhibited when the mutant is grown in a chemically defined medium while illuminated continuously, at 37 C, in medium lacking zinc, and in the presence of para-aminobenzoic acid. Higher yields of both compounds are obtained when the mold is grown in an enriched medium. So. Utiliz. Res. Dev. Div., ARS, USDA.     

Evaluation of cottonseed aflatoxin testing programs

A computer model was developed to simulate cottonseed aflatoxin testing programs. By use of the model, probabilities of obtaining certain aflatoxin test results for various lot concentrations and sample sizes were determined. Also, the effects of sample size and the definition of good and bad sample quality on the probability of lot acceptance were demonstrated. Paper number 5247 of the Journal Series of the North Carolina Agricultural Experiment Station, Raleigh, NC 27607.     

Sampling diced almonds for aflatoxin

To ensure that diced almonds meet the current FDA guideline limit for total aflatoxin, it is necessary to have a sampling plant that will allow representative sampling with defined precision-i.e., with confidence limits on the average aflatoxin found. A sequential sampling plan using 4.54-kg samples of diced almonds or 150-g samples of meal by-product (fines screened from diced nuts during production) was constructed with data from a study of aflatoxin distribution among samples of 2 selected lots of almonds. These 2 lots of whole nuts, estimated to have 400 and 25 ppb aflatoxin, were diced and boxed with normal processing equipment and procedures to approximate the distribution of aflatoxin in the product during commercial production. With a square root trans-formation of the data from 4.54-kg samples of diced nuts, the aflatoxin in samples of both lots approximated a normal distribu-tion and the within-lot variances were not significantly different, which allowed the statistical plan described. A supplemental study was made of aflatoxin distribution in the meal by-product. The lack of a significant difference between the results for diced nuts and those for the corresponding meal suggests that diced almonds can be monitored for aflatoxin indirectly by sampling the meal, which will allow the use of fewer analyses of 150-g samples of less expen-sive product to reach a decision.     

Unavoidable low level aflatoxin contamination of peanuts

A major portion of aflatoxin contamination of peanuts probably occurs when decayed or discolored peanuts are incompletely removed by sorting. Quality control measures have been instituted in the United States to insure that unavoidable aflatoxins in consumer peanuts and peanut products do not exceed 20 μg/kg. However, low level aflatoxin contamination, from trace amounts to about 50 μg/kg in sound mature unblemished peanuts, can occur before peanuts are dug. This low level contamination is not related to high levels of Aspergillus flavus infection or to current production practices. Low level aflatoxin contamination of peanuts may be endemic, and current sorting procedures may not be effective in removing unblemished contaminated peanuts.     

黄曲霉毒素G族人工抗原的合成与免疫效果研究

以黄曲霉毒素(Aflatoxin G1,AFG1)的半缩醛(Aflatoxin G2a,AFG2a)为中间物,通过还原烷基法,使黄曲霉毒素G1在8、9羟基上与牛血清白蛋白(BSA)实现偶联,得到偶联物。对偶联物进行紫外全波长扫描显示,其特征吸收峰与BSA和AFG1的特征吸收峰有明显差异。经完全透析后检测偶联物与BSA荧光强度差异,均表明BSA与黄曲霉毒素G1偶联,AFG1-BSA物质的量结合比为3.2∶1。以合成人工抗原免疫小鼠,用间接非竞争ELISA测得抗血清中抗体的效价可达1∶128 000,间接竞争ELISA测定抗体IC50为14.7 ng/mL。为下一步研制黄曲霉毒素G族单克隆抗体提供了关键试剂,为研究建立黄曲霉毒素G族免疫速测技术奠定了基础。     

Absence of aflatoxin from refined vegetable oils

The present investigation is the first definitive study of the fate of the aflatoxins in vegetable oils undergoing processing. Crude oils, obtained by solvent extraction or by hydraulic pressing of ground moldy peanuts (not suitable for human consumption), contained only small fractions of the aflatoxin originally present in the peanuts; the meals retained the bulk of the aflatoxin. Conventional alkali refining and washing of the oils reduced aflatoxin content to a range of 10 to 14 ppb. The subsequent bleaching operation essentially eliminated aflatoxin from the oils; the concentrations were now less than 1 ppb. The above results were confirmed using corn oils obtained from corn germ deliberately contaminated in the laboratory withAspergillus flavus. The nonfluorescing forms of aflatoxins, capable of being produced during the alkali refining operations, are also absent from the refined vegetable oils; these aflatoxin derivatives are readily converted to their original form on acidification and thereby measurable by fluorescence, if present. Presented in part at the AOCS Meeting, Los Angeles, April 1966.     

Ethanol extraction of oil,gossypol and aflatoxin from cottonseed

Commercial processing of cottonseed requires hexane to extract and recover edible oil. Gossypol and aflatoxin are not removed from extracted meals. A bench-top extraction process with 95% (vol/vol) aqueous ethanol (EtOH) solvent has been developed that extracts all three of the above materials with a much less volatile solvent. In this process, cottonseed is pretreated and extracted with ambient 95% EtOH to remove gossypol and then extracted with hot 95% EtOH to extract oil and aflatoxin. Membranes and adsorption columns are used to purify the various extract streams, so that they can be recycled directly. A representative extracted meal contained a total gossypol content of 0.47% (a 70% reduction) and 3 ppb aflatoxin (a 95% reduction). Residual oil content was approximately 2%. Although the process is technically feasible, it is presently not economical unless a mill has a continual, serious aflatoxin contamination problem. However, if a plant cannot meet the hexane emission standards under the Clean Air Act of 1990, this process could provide a safer solvent that may expand the use and increase the value of cottonseed meal as a feed for nonruminants. Presented in part at the AOCS annual meeting, Toronto, Canada, May 1992.     

Sampling cottonseed lots for aflatoxin contamination

Large samples called “sublots” were drawn from 41 commercial lots of contaminated cottonseed. Each sublot was subdivided into twenty 5 lb samples which were analyzed for aflatoxin. The mean, median, variance, coefficient of variation, and the estimated range among the sample concentrations were computed. The results indicated that: (A) the variance among sample concentrations was large and was found to be a function of sample concentration and (B) the distribution of sample concentrations was skewed; the density of sample values was greater below the sublot concentration.