Influence of high hydrostatic pressures on the storage of sliced vacuum-packed meat products (dry cured ham, mortadella, porchettaJ and stored at different temperatures

An HHP [High Hydrostatic Pressure) treatment was evaluated to extend the shelf-life or eliminate the post-slicing microbial population of some delicatessen products vacuum or Modified Atmosphere packed and stored at different temperatures (4°, 4° and 8°C and 25°C until the end of storage) for up to 180 days. Samples of cured meats, consisting of slices of mortadella, porchetta and dry cured ham, and subjected to HHP treatment, underwent the growth of LAB (lactic acid bacteria) and CBT (total bacterial count) within a short time from packaging. The HHP treatment, performed at 600 MPa for 3 min, did not allow the complete decontamination of the microbial population constituted of non-pathogenic Staphylococci and LAB. In fact, their presence at time 0 after treatment was 2-3 log CFU/g. Due to the high water activity (Aw 0.96) of mortadella and porchetta stored at 4° and 4°-8°C, the LAB grew rapidly, reaching 7-8 log CFU/g, verified by lowering the pH. However, despite their development, no patina and/or loss of vacuum were observed or in any case visible alteration typical of LABs was noted. Only in samples stored at 25°C, the packages swelled due to the development of autochthonous heterofermentative LAB. Conversely, in the dry cured ham samples, regardless of the type of film and storage temperature, no microbial increase was observed over time due to their low Aw, evaluated at a level below 0.89. In any case all the samples, except those stored at 25°C, were acceptable by a panel made with not trained tasters.