Evaluation of an ozone–slurry ice combined refrigeration system for the storage of farmed turbot (Psetta maxima)

Abstract

The use of ozonised slurry ice was investigated as a new refrigeration system for the storage of farmed turbot (Psetta maxima), a non-fat fish species of high commercial value. With this purpose in mind, an ozone generator device was coupled to a slurry ice system working subzero at-1.5ºC. The ozone concentration was adjusted to a 700 mV of redox potential, and the slurry ice biphasic mixture was prepared at a 40% ice/60% water ratio and a 3.3% of salinity. Microbiological, chemical and sensory analyses were carried out throughout a storage period of 35 days. Although certain biochemical parameters indicative of fish freshness-such as the rate of nucleotide degradation or TMA-N formation-were not significantly affected by the presence of ozone in the slurry ice mixture, storage in ozonised slurry ice significantly slowed down of mechanisms responsible for lipid hydrolysis-as determined by the release of free fatty acids-and lipid oxidation-evaluated by the peroxide value, the thiobarbituric acidindex and by the rate of browning reactions determined at 450/400 nm-in farmed turbot. Storage in ozonised slurry ice also led to significant (p<0.05) lower counts of both total aerobes and psychrotrophic bacteria in both turbot muscle and skin, as compared with the control batch stored without ozone. Sensory analyses confirmed an extended shelf life of turbot specimens stored in ozonised slurry ice, these maintaining "A" sensory quality up to day 14, while counterpart batch stored in slurry ice kept this quality only up to day 7. The combination of ozone and slurry ice may be recommended for the chilling and storage of farmed turbot with a view to extend its shelf-life.

Ozone: an emerging technology for the seafood industry

“…During the reaction with other molecules, ozone is destroyed. The final products of organic molecule oxidation with ozone are carbon dioxide and the water (Seafish, 1997;King, 2001;Campos et al, 2005;Campos et al, 2006;Vaz-Velho et al, 2006;Chawla, Bell and Marlene, 2007;Zentox, 2007). Unlike other biocides agents such as chlorine, the time necessary to make the disinfection is lower.…”

“…On the other hand, its strong oxidizing capacity (Table 2) makes very appropriate for the water treatment with high organic content. About this form, an ozone treatment in organic wastes can be considered an effective and faster form, that other treatments with chlorine or hydrogen peroxide (Glaze;Kang and Chapin, 1987;King, 2001;Campos et al, 2006). In addition, the treatment with ozone is not exclusive and can be combined with the use of hydrogen peroxide or ultraviolet radiation, harnessing therefore the results by a synergic effect (King, 2001;Young and Setlow, 2004).…”

“…In fact, the water in which ozone is delivered can be filtered and even reused. Additionally, chlorinated wash systems require transport and storage of potentially hazardous, toxic chemicals (Brooks and Pierce, 1990;Campos et al, 2006). The ozone itself is not toxic in low concentrations.…”

“…The three major action pathways occur as follows (Brooks and Pierce, 1990;Seafish, 1997;Campos et al, 2006):…”

Valorization of Proteins from Co- and By-Products from the Fish and Meat Industry

“…Chilling by crushed ice addition is also possible but is difficult to apply in largescale operations. A promising option is the production of an ice-slurry by partial freezing of the seawater [20]. This technology gives a pumpable ice and a very high chilling rate due to the content of small ice crystals and high cooling capacity.…”