Modeling Microbial Spoilage and Quality of Gilthead Seabream Fillets: Combined Effect of Osmotic Pretreatment, Modified Atmosphere Packaging, and Nisin on Shelf Life

Abstract

The objective of the study was the kinetic modeling of the effect of storage temperature on the quality and shelf life of chilled fish, modified atmosphere-packed (MAP), and osmotically pretreated with the addition of nisin as antimicrobial agent. Fresh gilthead seabream (Sparus aurata) fillets were osmotically treated with 50% high dextrose equivalent maltodextrin (DE 47) plus 5% NaCl. Water loss, solid gain, salt content, and water activity were monitored throughout treatment and treatment conditions were selected for the shelf life study. Untreated and osmotically pretreated slices with and without nisin (2 x 10(4) IU/100 g osmotic solution), packed in air or modified atmosphere (50% CO(2)-50% air), and stored at controlled isothermal conditions (0, 5, 10, and 15 degrees C) were studied. Quality assessment and modeling were based on growth of several microbial indices, total volatile nitrogen, trimethylamine nitrogen, lipid oxidation (TBARS), and sensory scoring. Temperature dependence of quality loss rates was modeled by the Arrhenius equation, validated under dynamic conditions. Pretreated samples showed improved quality stability during subsequent refrigerated storage, in terms of microbial growth, chemical changes, and organoleptic degradation. Osmotic pretreatment with the addition of nisin in combination with MAP was the most effective treatment resulting in significant shelf life extension of gilthead seabream fillets (48 days compared to 10 days for the control at 0 degrees C).

Influence of the process parameters on osmotic dehydration of mapara (Hypophthalmus edentatus) fillet

“…However, according to Connell (1995), only TBA values between 1 and 2 mg malondialdehyde/kg fresh fish are usually regarded as the limit of acceptability due to the formation of unacceptable odour and flavour. Additionally, Tsironi and Taoukis (2010) observed sensory rejection of gilthead seabream (Sparus aurata) fillets at an average TBA value of 0.9 mg malondialdehyde/kg fresh fish. Chaijan (2011) observed TBA values of 3 mg malondialdehyde/kg fresh tilapia (Oreochromis niloticus) muscle, which was about twice as much in the product subjected to wet salting in brine with 25 % NaCl at 25°C for 180 min.…”

Shelf-life extension of gilthead seabream fillets by osmotic treatment and antimicrobial agents

“…The addition of the antimicrobial agents did not have any effect on the mass transfer into fish slices. Processing time of 45 min was selected as the reference pretreatment used in the shelf-life study (Tsironi and Taoukis 2010). At the selected pretreatment conditions (1 : 5 ratio of product to solution of 50% HDM + 5% NaCl for 45 min at 15°C), the fish flesh has 69% moisture, 2AE5% SG and 0AE95 water activity.…”

“…Sliced samples were osmotically treated at 15°C for 0,20,40,60,90,120,180,240,300 and 360 min, as described by Tsironi and Taoukis (2010). The solution-to-sample ratio was 5 : 1 (w ⁄ w) to avoid significant dilution of the medium by water removal, which would lead to local reduction in the osmotic driving force during process (Medina-Vivanco et al 2002).…”

“…Gilthead seabream slices were cooked individually wrapped in aluminium foil, at 180°C for 20 min, in preheated oven, as described by Tsironi and Taoukis (2010).…”

“…The further development and validation of kinetic quality models in the whole temperature range of chilled products would allow the application of the results in the real cold chain. The combined effect of osmotic pretreatment with the addition of nisin and modified atmosphere packaging on quality deterioration of gilthead seabream during refrigerated storage was recently modelled (Tsironi and Taoukis 2010).…”