Effect of olive powder and high hydrostatic pressure on the inactivation of Bacillus cereus spores in a reference medium.

The aim of this work was to study the effect of olive powder combined with high hydrostatic pressure (HHP) on the inactivation of Bacillus cereus spores, to use it as an additional control hurdle in beverages pasteurised by this technology. With this purpose, reference medium prepared at different concentrations of olive powder was inoculated with B. cereus spores and subjected to different pressure treatments. The outgrowth capacity of the treated spores was then determined at 20°C and 32°C. The addition of olive powder was found to slightly reduce the effectiveness of HHP, although in post-treatment storage there was an increased bacteriostatic effect in the samples with 2.5% of olive powder at both temperatures in the samples pressurised at 400 and 500 MPa, and only at 20°C in the samples pressurised at 200 MPa. The addition of olive powder therefore had an additive effect with storage temperature and HHP processing and could act as an additional control hurdle during the shelf-life of products pasteurised by HHP technologies or in the case of cold-chain breakage.