Survival of Salmonella in Red Pepper under Different Environmental Conditions
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Abstract:
The survival of Salmonella at different temperatures and water activity (aw) levels was assessed in red pepper. The agar plate dilution method was used to detect the growth of Salmonella at different aw levels in red pepper over 48 hours to determine the minimum aw for growth. Scanning electron microscopy and adhesion strength tests were used to observe the adhesion ability of Salmonella to the inner and outer skins of red pepper at high and low aw values. The results showed that the growth of Salmonella differed significantly at different aw values in red pepper over 48 hours (p<0.05). In the test on pepper powder, the aw threshold for growth was determined as 0.92±0.01. In the long-term survival experiment, the rate of Salmonella population decline at 37 ℃ was higher than that at 25 ℃, the decline rate at high aw values was higher than that at low aw values, and the maximum survival time of Salmonella at 25 ℃ and low aw value was 70 d. In addition, at high aw value, the adhesion of Salmonella to the inner skin of pepper was more severe than that to the outer skin. Therefore, once pepper powder is contaminated with Salmonella, attention should be paid to the long-term survival capability of the bacteria. In addition, in contrast to conventional thinking, low-temperature storage can actually extend the life of Salmonella, thus increasing food safety risk. The fact that the adhesion of Salmonella on the outer skin was not as severe as that on the inner skin suggested that the preservation of complete peppers is beneficial to ensure food safety.
