摘要:

Hemisuccinate (HS) and hemiglutarate (HG) of aflatoxin B2a(afla B2a) were prepared by refluxing afla B2awith the corresponding anhydride and 4‐N, N‐dimethylaminopyridine in tetrahydrofuran. Two epimers of the respective HS or HG which show different chromatographic behavior and physiochemical properties were isolated and characterized. Afla B2a‐HS hydrolyzes very rapidly in aqueous solution and was not used for further study. Afla B2a‐HG hydrolyzes at a much slower rate and was selected for the coupling to protein. Using the mixed anhydride method, as much as 12 moles of afla B2a‐HG were conjugated to each mole of bovine serum albumin (BSA). The antibody obtained from rabbits immunized with afla B2a‐HG BSA is most specific to afla B1and shows little cross reaction with afla G1and aflatoxicol. The lower limit for detection of afla B1by radioimmunoassay using this antibody is in the range of 30–50

ISSN:0149-6085    

DOI:10.1111/j.1745-4565.1980.tb00404.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

The comparative sensitivity of an enzyme linked immunosorbent assay (ELISA) using four different antistaphylococcal antisera and a spectrophotometric assay for thermonuclease were determined using cheese and ravioli samples seeded with strains of Staphylococcus aureus and S. epidermidis. The ELISA used antisera to enterotoxin A, enterotoxin B, S. aureus strains 14609 (human), and UNH‐570 (bovine). The 570 ELISA and spectrophotometric thermonuclease assay were of comparable sensitivity and detected seeded culture in concentrations as low as 2 × 107CFU/g of cheese. A simple two hour method for extracting thermonuclease from foods was 50% efficient when as little as 50 ng of purified enzyme was seeded per g of cheese. Analyses of 43 commercial cheeses for viable S. aureus found five (12%) positive with 3 × 104CFU/g of cheese being the highest counts detected. All samples were negative by ELISA and thermonuclease assay. A simple screening procedure for demonstration of S. aureus contamination of foods is discus

ISSN:0149-6085    

DOI:10.1111/j.1745-4565.1980.tb00405.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

The formation of lysinoalanine (LAL) in casein, zein, and wheat gluten was studied in relation to varied levels of alkali, added cysteine, and added lysine. Protein suspensions were heated in alkali, subjected to acid hydrolysis conditions, and then analyzed for LAL using high‐pressure liquid chromatography. Cysteine generally decreased LAL formations while lysine decreased formation in casein and increased the LAL level in zein and gluten. In a separate experiment, samples of normal and high lysine corn varieties were heated in a calcium hydroxide solution. Low levels of LAL were formed (200–217 ppm) but there was no significant difference between the two varieties in the amount of LAL found. Lysine fortification of the normal corn did not increase LAL formation. The addition of cysteine to high lysine corn caused increased levels of

ISSN:0149-6085    

DOI:10.1111/j.1745-4565.1980.tb00406.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

Five isolates of Alternaria alternata, five isolates of A. tenuis, one isolate of A. hemicota and three isolates of unidentified Alternaria spp. were examined for their production of alternariol methyl ether (AME) and alternariol (AOH) in complex liquid media. The data were compared with the production of these two toxins on solid substrate rice cultures. A new high‐performance liquid chromatography method with minimum detection levels for AME and AOH of 20 ng and 40 ng, respectively, was used to quantitate the toxins. All isolates produced AME and AOH, but the amount varied considerably with the isolates and media tested. Of the three different liquid media tested, the highest quantity of AME and AOH was produced in a modified Czapek‐Dox broth. The highest yield of toxins was obtained in the solid rice cultures. As much as 125 mg of AME and 16 mg of AOH were produced by one A. tenuis isolate on 300 g of rice after 14 days of incubation at 25°C in dark

ISSN:0149-6085    

DOI:10.1111/j.1745-4565.1980.tb00407.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

The feasibility of improving broiler neck shelf‐life by chlorinating chill water with sodium hypochlorite at 65 and 190 ppm residual chlorine was investigated. An initial reduction in bacterial counts was obtained with both concentrations, but a residual effect on counts was obtained only with 190 ppm chlorine during 20 days of storage at 2°C ± 1. This additional count reduction was somewhat off‐set by a residual chlorine odor in the product. Because of the high level of organic matter found in giblet and neck flume and chill water coupled with little or no improvement in shelf‐life of necks chilled in water containing 65 ppm residual chlorine, it was concluded the use of 50 ppm or less chlorine in chiller input water as recommended by FDA and FSQS, would not result in effective bactericidal action. Other means will have to be sought to extend shelf‐life o

ISSN:0149-6085    

DOI:10.1111/j.1745-4565.1980.tb00408.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY