Modeling the effect of pre-treatment with nisin enriched osmotic solution on the shelf life of chilled vacuum packed tuna

- Temperature effect on quality and shelf life of osmotically pre-treated and refrigerated tuna slices was kinetically studied.
- Osmotic pre-treatment (30 min, 15°C, 50% maltodextrin (DE 47) plus 5% NaCl) resulted in aw = 0.96 in tuna slices.
- LAB growth, TVB-N and TBARs values showed high correlation with sensory scores.
- Nisin (2·104 IU/100 g) in the osmotic solution further delayed spoilage and increased shelf life of tuna slices.
- Based on LAB growth, shelf life of tuna slices at 5 °C was 10, 27 and 51 days for Control, OD and ODn samples, respectively.

The objective of this study was the kinetic modeling of the effect of storage temperature on the quality and shelf life of chilled tuna, vacuum packed and osmotically pre-treated with the addition of nisin as antimicrobial agent. Tuna fillets were treated at 15 °C in osmotic solution with 50% high dextrose equivalent maltodextrin (DE 47) plus 5% NaCl, for 0-360 min. Untreated and 30 min osmotically pre-treated fish slices with and without nisin (2·104 IU/100 g osmotic solution), vacuum packed and stored at controlled isothermal conditions (0-15 °C) were studied. Quality assessment and modeling was based on microbial growth, total volatile basic nitrogen (TVB-N), trimethylamine nitrogen (TMA-N), lipid oxidation (TBARS) and sensory scoring.The water activity decreased to 0.96 at 30 min of pre-treatment. Osmotic pre-treatment led to significant shelf life extension of fish, in terms of microbial growth and sensory quality. The addition of nisin in the osmotic solution further increased the shelf life of tuna. Based on LAB growth, the shelf life was 10 days for untreated and 27 days for osmotically treated vacuum packed fish at 5 °C. The addition of nisin increased shelf life to 51 days at 5 °C.