No abstract

For the first time, changes in lipid oxidation (peroxide value [PV], para‐anisidine value [p‐AnV], and total oxidation [Totox]) and related flesh qualities (titratable acidity [TA], water retention index [WRI] as well as volatile amines of total volatile basic nitrogen [TVB‐N], and trimethylamine nitrogen [TMA‐N]) of farm‐raised white shrimp (Litopenaeus vannamei) during iced storage of up to 11 days as affected by increasing ozone exposures were performed. Both fresh and ice‐stored sample situations were submitted to ozone exposures. Domestic facility commercially available that discharged ozone safely specifically was employed. Results indicated that PV, p‐AnV, Totox, and temporal PV/p‐AnV parameters at both ozone treatment situations would persist during the investigated storage. Increasing ozone exposures brought about some decreases in p‐AnV, Totox, and TVB‐N but less reliably in PV and TMA‐N. Most affected lipid oxidation and related flesh quality parameters would probably be p‐AnV and TVB‐N, respectively. Besides, the trends of TA and WRI over time seemed unclear. In this study, the domestic ozone facility appears promising to improve the quality of shrimp during iced storage. To help establish the ozone treatment approach that would improve the overall quality shelf of processed shrimp, further studies that involve other analyses such as browning development and sensorial acceptance are warranted and applicable to other economically important crustacea species. Practical applications: Domestic facilities that safely discharge ozone for home use are increasingly marketed in many parts of the globe. On the other hand, lipid oxidation although responsible for rancidification and a process that significantly deters the overall fish product quality, remains among the many cold/iced storage concerns. Herein via domestic facility, increasing ozone exposures safely discharged onto farm‐raised shrimp has allowed for the study of lipid oxidation and related flesh qualities of processed samples during iced storage. This is the first report to demonstrate that increasing ozone exposures applied either on fresh and or ice‐stored shrimp situation(s) would result in different changes in PV, p‐AnV, Totox, TA, WRI, TVB‐N as well as TMA‐N. The data provided herein reveals the use of domestic ozone facility as promising candidate towards food safety, and increases both knowledge and understanding concerning changes in lipid oxidation and related flesh attributes of ozone‐treated crustacea. During iced storage of up to 11 days, the evolution of tested parameters of ozone‐treated shrimp as it was affected by increasing ozone exposures showed that for lipid oxidation, the p‐anisidine value (p‐AnV) would appear the most affected probably because it would increase at a much faster rate to generate many secondary oxidation products fairly before the peroxide value (PV) attained the propagation reactions/periods. With respect to related flesh qualities, total volatile basic‐nitrogen (TVB‐N) would appear the most affected over the ...

Polyacrilamide gel electrophoresis (PAGE) of allozymes was used to investigate the intraspecies genetic variation and the genetic stock structure of Diplodus vulgaris and Lithognathus mormyrus captured from eight localities in the Mediterranean Sea. Twenty-two and 20 putative enzyme-coding loci were examined, respectively, in D. vulgaris and L. mormyrus. Polymorphic loci at the 95% level were used to assess the allozyme variability in D. vulgaris (AAT-2 * , EST-1 * , GLDH * , PEPB-2 * , PGI-2 * , PGM * , SDH * ) and L. mormyrus (AAT-2 * , EST-1 * , GLDH * , MDH-2 * , PGI-2 * , PGM * ). The proportion of polymorphic loci in both species ranged from 0.31 (D. vulgaris) to 0.30 (L. mormyrus), and the observed and expected mean heterozygosity varied between 0.082 and 0.093 (D. vulgaris) and between 0.069 and 0.072 (L. mormyrus). The mean value of observed heterozygosity in D. vulgaris showed a deficit of heterozygosites, thereby indicating a Wahlund effect in the samples examined. Significant genetic differentiation (mean value of θ = 0.013, p < 0.005) was found in D. vulgaris indicating an intraspecific genetic substructure among the samples examined, whereas the mean value of θ = 0.001, p > 0.05 found in L. mormyrus showed a high degree of genetic homogeneity. The results showed the presence of distinct subpopulations of D. vulgaris among the sampled sites, and suggested that analysis of allozymes may provide important information on the genetic stock structure of these two sparids to ensure sustainable management of these species.

Striped seabream Lithognathus mormyrus [n = 1269; total lengths (TLs) = 112-350 mm] were investigated in two coastal Sicilian fishing grounds (central Mediterranean Sea). Samples were collected from the two landing harbours, Licata and Selinunte, between October 1999 and September 2000. Seasonal and spatial variations in population structure, age, growth, reproduction and mortality were studied. It was found that seasonal differences in the main modes of lengthfrequency distributions corresponded well with the seasonal growth. The recruits in Licata grew faster and attained a larger size (by 10-20 mm) at ages up to 2 years than in Selinunte. Growth thereafter was relatively slow, with Selinunte specimens growing at a slightly faster rate. Spawning occurred between June and August. Length at the first maturity was different between females and males in the Selinunte (190-181 mm) and Licata (183-171 mm) fishing grounds. The species displayed protandrous hermaphroditism, and somatic growth practically ceased during the period of sex inversion. Total fishing mortality was considerably higher in Licata (F between 0.53 and 0.63 per year) than in Selinunte (F between 0.22 and 0.29 per year). Therefore it is suggested that the striped seabream population in Licata is more vulnerable to overfishing than that in Selinunte.