Purpose: The aim of this work was to develop an active biobased chitosan film with incorporated pink pepper extract to extend the microbiological quality of salmon fillets stored under modified atmosphere (MA; 100% CO2) at 2°C.
Methods: Fillets, with and without skin, were packed in MA and stored at 2±1°C according to the following treatments: without chitosan film (TC), with chitosan film (TFQ), and with chitosan film incorporated with pink pepper extract (TFQPR). Every week, nine trays of each treatment were analyzed for aerobic mesophilic and psychrotrophic bacteria, lactic acid bacteria (LAB), thermotolerant bacteria and total coliform. Differences between means were compared using ANOVA.
Results: The aerobic microflora increased with storage time for all treatments. After 28 days of storage, aerobic counts of TFQ, TFQPR, and TC (fillets with skin) samples did not exceed six log CFU/g, considered the upper acceptability limit for fresh fish. The control treatment (TC), composed of fillets without skin, had higher mesophilic counts (near to seven log CFU/g) in comparison to the others treatments (P<0.05), which demonstrated the additional antimicrobial protection of active biobased chitosan films against deterioration of salmon fillet. The anoxic atmosphere favored the selection of LAB, but the counts (<six log CFU/g) were not enough to compromise the microbiological quality of TFQ and TFQPR fillets. Thermotolerant bacteria and total coliform microorganisms remained within the limits established by ICMSF (<103 MPN/g) in all treatments.
Significance: Results observed in this study provide a new insight for active biobased chitosan film/pink pepper as a potential antimicrobial agent for fresh fish. Such extended storage time would not be obtained with poor initial product quality.