Behavior of Salmonella Rubislaw on ground black pepper (Piper nigrum L.)

Among spices, black pepper is highly appreciated and Brazil is one of the largest producers of it in the world. However, spices may reach consumers presenting poor quality, due to the loss of volatile compounds, microbial contamination or even due to insect infestation. Salmonella spp. frequently contaminate ground black pepper and may be recovered from products with low levels of free water, even after they have been submitted to high temperatures. The objective of this trial was to evaluate the behavior of a Salmonella Rubislaw strain on ground black pepper (Piper Nigrum L.), as well as to study the effects of water activity (Aw) and storage temperature (5, 25 and 35 °C) for 2 and 15 days. The most probable number technique was used for the quantification of the S. Rubislaw. Data obtained in the present trial indicate that differences in the reduction in counts were observed in relation to Aw (P = 0.006) and storage temperature (P = 0.000). Nevertheless, there was no significance as to the interaction of the two factors (P’s > 0.05). Bonferroni multiple comparisons tests have shown significant differences only when related to the Aw: 0.663, 0.815 and 0.887 (P’s < 0.05). When the product is stored at 5 °C, the number of surviving cells is even greater (P = 0.000). Considering the data obtained, we may conclude that, after contamination, S. Rubislaw remains viable in pepper for up to 15 days.