Résumé :
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The production of toxin by a 10-strain mixture of proteolytic Clostridium botulinum in fresh produce packaged in polyethylene films having high (7,000 cc/m(2)/24 h; HOTR) and low (3,000 cc/m2/24 h; LOTR) relative oxygen permeability was determined. Shredded cabbage and lettuce inoculated with similar to 10(2) spores/g were placed in bags composed of the two films (1.4 kg/bag), and the bags were then vacuum sealed. Produce was stored at 4, 13, and 21°C for up to 21 (cabbage) or 28 (lettuce) days and analyzed periodically. At each sampling time, the gas composition within the bags, pH of the produce, and microbial populations (total aerobic and anaerobic microoganisms, lactic acid bacteria, psychrotrophic bacteria, and yeasts and molds) were determined. In addition, the presence of botulinal toxin was determined using the standard U.S. Food and Drug Administration mouse bioassay protocol. Bags made of HOTR film prolonged sensory quality of cabbage and lettuce, especially at 13 and 4 °C. Packaging material had an effect on the growth of various groups of microorganisms; however, there was not a general trend.
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