Efeitos da temperatura e umidade relativa na sobrevivência de Salmonella enterica em pimentão (Capsicum annuum L.) minimamente processado durante o armazenamento

Abstract

Salmonella enterica causes a high number of human infections annually worldwide. Among the foods involved in outbreaks, minimally processed vegetables stand out. Minimally processed pepper a world market commodity and its involvement in salmonellosis outbreaks has increased. The present study aimed to evaluate the survival of Salmonella Typhimurium and Salmonella Enteritidis in minimally processed peppers as a function of temperature and relative humidity (RH). Combinations of 7, 14 and 21 ºC and 15, 50, 100% RH were evaluated for inoculum at 4.5 log CFU/g and 2.5 log CFU/g. After 0, 12, 24, 48, 72, 96, 120 and 144 h, viable Salmonella cells of each serovar were enumerated. S. Typhimurium and S. Enteritidis showed similar behavior in cut-peppers during storage at evaluated conditions and data were combined a single set (S. enterica) for extraction of kinetic parameters using using the Baranyi and Roberts equation for 4.5 log CFU/g inoculum and linear model for 2.5 log CFU/g inoculum. The kinetic parameters extracted from these models were adjusted in a polynomial equation for secondary models capable of predicting the growth of S. enterica in sweet pepper as a function of the tested parameters. S. enterica presented a maximum growth rate (µmax) ranging from - 0.0047 to 0.0681 1/h. The highest µmax was observed at 14 and 21 ºC and at the highest tested RH (100%), while the growth of S. enterica was not supported at the lowest temperatures and tested RH, regardless of the size of the inoculum. In the lowest temperature and highest RH tested, the pathogen showed a maximum growth rate of 0.0123 ± 0.0016 1/h when tested at 2.5 log CFU/g. In most of the conditions tested at 2.5 log CFU/g growth was observed however, in the inoculum of 4.5 log CFU/g only the conditions that comprise the highest temperatures and RH tested supported the growth of S. enterica over 144 h of storage. Linear regressions based on experimental data showed R2 close to 0.99 and a good prediction of µmax as a function of temperature (T) and relative humidity. The interaction of T and RH showed effects (p < 0.05) on the growth of S. enterica in cut-peppers inoculated at 4.5 log CFU/g. The quadratic term of RH showed effects (p < 0.05) when S. enterica was inoculated at 2.5 log CFU/g. The results describe the behavior of S. enterica in cut-peppers in a range of temperature and RH conditions and show the impact of the initial size. The generated models would be useful tools to manage the risk of this pathogen in cut-peppers.