Aims: To relate sensory shelf-life of iced whole and gutted squid to bacterial growth and chemical changes. Methods and Results: Cooked mantles from whole and gutted individuals were rejected after 10 and 12 days of storage, respectively, due to ammoniacal off-odours. Rate of production of both ammonia and trimethylamine was highest in the whole lot. Agmatine, which was only present in trace amounts in freshly-caught squid, increased rapidly in both lots. The main microflora at the time of sensory rejection of iced whole squid included Gram-negative, motile and non-fermentative rods, which were psychrophilic and had a requirement for NaCl. 16S rDNA sequence analyses identified the strains as belonging to the genus Pseudoalteromonas. Shewanella putrefaciens, Pseudoalteromonas sp. and Pseudomonas sp. dominated in spoiled gutted squid. Identification of strains from the stomach and digestive gland of recently-captured squid showed that the main flora consisted of Photobacterium phosphoreum. Conclusions: Spoilage of iced squid is likely to result from a combination of autolytic and bacterial changes. Agmatine seems to be an excellent freshness indicator. Photobacterium phosphoreum may contribute to spoilage through activity in the digestive gland, followed by diffusion of volatile compounds and amines to the mantle. Significance and Impact of the Study: Due to the psychrophilic nature of P. phosphoreum and Pseudoalteromonas sp., spread-plating and low temperature incubation are recommended for bacteriological evaluation of iced squid.

Bacillus cereus un patógeno importante en el control microbiológico de los alimentos

<p>Bacillus cereus es un contaminante de alimentos<br />conocido por ser patogénico para los humanos,<br />causando síndromes de vómito y diarrea.<br />En este estudio se evaluó la presencia de B.<br />cereus toxigénicos utilizando PCR múltiple<br />directamente en complementos dietarios<br />para niños y en almidón de yuca colectados<br />en Medellín, Colombia. De 75 muestras de<br />complemento dietario para niños, 70,7%<br />estuvieron contaminadas con B. cereus<br />toxigénicos y se detectaron cuatro diferentes<br />consorcios toxigénicos: I: nheA, hblC, cytK<br />(9,8%), II: nheA, hblC (2%), III: hblC, cytK<br />(41.2%), IV: hblC (47%). De 75 muestras de<br />almidón de yuca, 44% estuvieron contaminadas<br />con B. cereus toxigénicos y se determinaron<br />cuatro diferentes consorcios toxigénicos: I:<br />nheA, hblC, cytK (48.5%), II: nheA, hblC, cytK,<br />cesB (3%), III: hblC, cytK (30,3%), IV: hblC<br />(18.2%). En general, en los complementos<br />dietarios para niños sólo se detectaron<br />consorcios enterotoxigénicos, mientras que en<br />el almidón los consorcios enterotoxigénicos<br />predominaron sobre el emético. La PCR<br />múltiple fue de utilidad para detectar<br />contaminación con B. cereus toxigénicos<br />permitiendo la detección directa y simultánea<br />de todos los genes tóxicos en los alimentos. Este<br />estudio es el primero en Colombia en evaluar B.<br />cereus toxigénicos y proporciona información<br />importante para la evaluación de riesgos<br />microbiológicos en los alimentos pulverizados</p>