Influence of pasteurization temperature on flesh firmness of table olives cv. Nocellara del Belice

The application of heat treatment is especially important in maintaining the organoleptic characteristics of fermented agro-food products, which potential consumers perceive as reflecting the quality of these foodstuffs. The aim of this study was to evaluate the influence of pasteurization time and temperature on the flesh firmness of table olives cv. Nocellara del Belice, packaged in glass jars, and to study their effect on the microbial community of table olives. Four different treatments were applied, one for each of the pasteurization temperatures adopted: 65 °C, 75 °C, 85 °C and 95 °C. A control test was also carried out (test Tc, not pasteurized). Each test was repeated with treatments lasting 4, 8 and 12 minutes. In order to determine the mechanical properties of the olives, all of the batches were subsequently subjected to a laboratory compression test using a dynamometer (Imada DPS 5R - USA) connected to a stand and a PC for data download. The compression force was recorded continuously along the entire pulp sample. Microbiological analyses were performed on olives and brines immediately after the heat treatment (t0) and after 2 months (t1). The results obtained here show that it is appropriate to employ pasteurization temperatures at least equal to 75 °C for a time not lower than 8 minutes from the microbiological point of view. Regarding the olive fruits mechanical properties, it is advisable to use a pasteurization temperature of 75 °C even for a time of 4 minutes in order to maintain a good flesh firmness thus satisfying the consumers' taste.