The paper is concerned with two aspects only of microbial control: development of a rapid method for detection of contaminant bacteria, and assessment of the chick embryo bioassay of mycotoxins of barley and malt. The NBB medium of Back and Dachs gave satisfactory growth of beer samples contaminated with various bacteria [which did not include either Lactobacillus or Pediococcus] over 16 h at 30 degrees C, when the cultures were membrane filtered and stained with acridine orange for microscopical examination. The AOAC chick embryo assay for fungal toxins was used to study the degradation of mycotoxins in brewing. Although distilled water solutions of aflatoxin B, nivalenol, fusarenon X, T-2 toxin and diacetoxyscirpenol were unaffected by 30 min at 100 degrees C, most of the toxin was destroyed by 30 min boiling in pH 4.5 phosphate buffer or in wort, pH 5.7. It was concluded that any chance contamination of malt by fungal toxins would be rendered safe by wort boiling.
Keywords: analysis bacteria beer brewing culture medium contamination