Inactivation of Geobacillus stearothermophilus in canned food and coconut milk samples by addition of enterocin AS-48

The cyclic bacteriocin enterocin AS-48 was tested on a cocktail of two Geobacillus stearothermophilus strains in canned food samples (corn and peas), and in coconut milk. AS-48 (7 μg/g) reduced viable cell counts below detection levels in samples from canned corn and peas stored at 45 °C for 30 days. In coconut milk, bacterial inactivation by AS-48 (1.75 μg/ml) was even faster. In all canned food and drink samples inoculated with intact G. stearothermophilus endospores, bacteriocin addition (1.75 μg per g or ml of food sample) rapidly reduced viable cell counts below detection levels and avoided regrowth during storage. After a short-time bacteriocin treatment of endospores, trypsin addition markedly increased G. stearothermophilus survival, supporting the effect of residual bacteriocin on the observed loss of viability for endospores. Results from this study support the potential of enterocin AS-48 as a biopreservative against G. stearothermophilus.