A study was carried out to investigate the antimicrobial effect of olive powder on Bacillus cereus. Microorganism spores were inoculated in nutrient broth containing different olive powder concentrations and incubated at 32 degrees , 20 degrees , and 7 degrees C. Results indicated that this food ingredient had a bacteriostatic effect. It was observed that B. cereus cells did not grow at 7 degrees C. In the cases where growth occurred, it was modelled and parameters were deduced. In general the higher the concentration of olive powder, the higher the lag phase at both 32 degrees and 20 degrees C. Regarding the maximum specific growth rate (mu(max)), an effect of the food ingredient concentration was observed only at 20 degrees C incubation temperature. This study shows the potential for using olive powder to control B. cereus and opens the door for its use in commodities other than bakery products, such as mixed vegetables or purées. Olive powder could be used as an additional control measure in the case of cold chain break due to its effects in the lag phase, as well as a contributor to the flavor and health properties of these foodstuffs.

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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.

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