Effect of chitosan, nisin and storage time on the growth of Listeria innocua and Shewanella putrefaciens in fish homogenates

SCHELEGUEDA; GLIEMMO; CAMPOS

Badajoz

Conferencia; I International Conference on Antimicrobial Research; 2011

The aim of this study was to evaluate the effect of chitosan, nisin and storage time on the growth of Listeria innocua and Shewanella putrefaciens in fish homogenates at pH 5.5. For such purpose a factorial design in three blocks and a central point was performed. Fish homogenate was prepared processing Argentine hake fillets (Merluccius hubbsi) and distilled water in a ratio of 1:1; pH was adjusted to 5.5 using citric acid 10%w/w. Then, homogenates were sterilized for 15 minutes at 100ºC. When antimicrobials were added, bacterial counts were significantly reduced. However, this effect depended on the microorganism being tested. After 48 hours of storage, both antimicrobials showed an additive effect reducing the development of both microorganisms between 4 and 5 log cycles. Furthermore, different trends with respect to storage time were noted. Nisin effect on counts was shown immediately after its application, while chitosan effect was noticed during storage.