The Effects of Three Traditional Smoking Methods on the Concentrations of Polycyclic Aromatic Hydrocarbons (PAHS) in Smoked Fishes

The effects of three traditional smoking methods on the concentrations of Polycyclic Aromatic Hydrocarbons (PAHs) in smoked fishes were studied to determine the concentration of PAHs in locally available and commonly consumed smoked fish species. Samples of two highly traded species of fish, Scomber scombrus and Horse markerel, among the low income people for immediate consumption were purchased from the market and processed using sawdust smoke, firewood smoke and charcoal smoke respectively. Some of the fresh fishes were also analyzed as control. The PAHs content were extracted with standard dichloromethane using solid-liquid extraction, and analyzed using Gas chromatography – Mass spectrophotometer (GC-MS) method. The results showed that fish samples processed with sawdust smoke recorded the highest concentrations of total PAHs, having 1.295 mg/kg in Horse markerel and 2.020 mg/kg in Scomber scombrus, followed by firewood smoked samples with total PAHs content of 0.910mg/kg in Horse markrel and 1.175 g/kg in Scomber scombrus while charcoal smoked samples recorded the least total PAHs levels of 0.590 mg/kg in Horse markerel and 0.960 mg/kg in Scomber scombrus. Benzo(a)pyrene concentrations which is usually used to estimate the carcinogenicity of other PAHs was below detection level in both species of fish. PAH4 was proposed by European food safety authority, recommendation level of 30 mg/kg was concluded by the EU regulation. Any PAHs have been associated with intense carcinogenicity in humans, and thus have implication for the quality and safety of these fish products. Therefore, it is imperative that regulatory bodies conduct awareness campaigns to educate the smoked fish processors, traders and consumers on the need to discourage the use of sawdust in smoking fish and adopt safer and improved methods of smoking fishes.

First thorough assessment of de novo oocyte recruitment in a teleost serial spawner, the Northeast Atlantic mackerel (Scomber scombrus) case

The understanding of teleost fecundity type (determinate or indeterminate) is essential when deciding which egg production method should be applied to ultimately estimate spawning stock biomass. The fecundity type is, however, unknown or controversial for several commercial stocks, including the Northeast Atlantic mackerel (Scomber scombrus). Aiming at solving this problem, we applied state-of-the-art laboratory methods to document the mackerel fecundity type, including any de novo oocyte recruitment during spawning. Initially, active mackerel spawning females were precisely classified according to their spawning status. The number and size of all phasei-specific oocytes (12 phases), with a special attention to previtellogenic oocytes phases (PVO [PVO2 to PVO4a–c]), were also thoroughly investigated. Examinations of relative fecundity (RFi) clarified that the latest phase of PVOs (PVO4c) are de novo recruited to the cortical alveoli–vitellogenic pool during the spawning period, resulting in a dome-shaped seasonal pattern in RFi. Hence, we unequivocally classify mackerel as a true indeterminate spawner. As PVO4c oocytes were currently identified around 230 µm, mackerel fecundity counts should rather use this diameter as the lower threshold instead of historically 185 µm. Any use of a too low threshold value in this context will inevitably lead to an overestimation of RFi and thereby underestimated spawning stock biomass.

MICROBIAL ASSESSMENT OF FROZEN FOODS SOLD IN AYOBO, LAGOS

This study seeks to investigate the microbial profile of frozen fish and meat. Forty samples consisting of Scomber scombrus (Titus), Clupea harengus (Shawa) and frozen meat (Chicken, Turkey) were purchased from different retail outlets in Ayobo-Ipaja markets for microbiological analysis. The samples were analysed for the total viable count using standard microbiological procedures. The mean bacterial and fungal counts for Scomber scombrus, Chicken, Clupea harengus and Turkey are 254.70±83.81 CFU/G and 5.50±4.45 CFU/G; 210.10±55.03 CFU/G and 6.80±3.39 CFU/G; 298.20±67.35 CFU/G and 6.10±3.87 CFU/G; 221.30±80.33 CFU/G and 4.30±2.00 CFU/G respectively. Clupea harengus has the highest bacterial count while Scomber scombrus has the lowest bacterial count. Chicken has the highest fungal count while Turkey had the lowest fungal count. The microbial isolates from the frozen food samples include species of S. aureus, E. coli, Salmonella, Micrococcus, Aspergillus, and Penicillium. Escherichia coli were susceptible to all the antibiotics while Salmonella sp., Staphylococcus aureus, and Micrococcus were resistance to Augmentin, Gentamycin, Tarivid, and susceptible to Sparfloxacin and Chloramphenicol. Although freezing retard pathogens multiplication, post-harvest contaminants can multiply during thawing to a level that can have a major impact on the quality of the final consumer product. It is advised that frozen foods must be properly cooked before consumption and effective hazard analysis and critical control point implemented.

An investigation of green tea’s effect on mackerel (Scomber Scombrus)’s protein structure during frozen storage by FT-Raman spectroscopy

FT-Raman spectroscopy (FT-RS) was used to investigate green tea’s potential protective effect as an antioxidant during frozen storage of Atlantic mackerel (Scomber scombrus). Atlantic mackerel was stored for more than 26 weeks at −10°C or –80°C (control), with or without green tea (GT). Raman analysis showed substantial changes in protein structure due to frozen storage, especially at the higher storage temperature (−10°C), compared with the findings at −80°C or −10°C with instant GT, indicated by a decrease in the tyrosine doublet ratio, a-helix content. O-H stretching band intensity, along with an increase in tryptophan band intensity and β-sheet structure. GT as an antioxidant at a concentration of ~250 ppm can protect the structure of fish proteins for a limited storage period. However, for optimal freshness, fish should be stored at very low temperatures.

Quality characteristics of extracted oil from the head and gills of Catfish and Titus fish

Background The research was carried out to assess the lipid characteristics of oil extracted from the head and gills of Claris macrocephalus and Scomber scombrus. Results The results confirmed the presence of C16:0, C18:0, C18:1, C18:2, C18:3, C22:6 as the major fatty acids. Titus fish head (TFHD) oil had a total saturated fatty acid (TSFA) of 40.804 ± 0.002% of which C16:0 and C18:0 were the most dominant fatty acids present while the total monounsaturated fatty (TMUFA) acids present in the oil was 33.853 ± 0.001%. The total polyunsaturated fatty acid (TPUFA) content of the TFHD oil sample was found to be 25.368 ± 0.002%. The results revealed that the total unsaturated fatty acid (TUFA) present in the TFHD was higher than the TSFA. The results obtained for Titus fish gills (TFGL) oil sample followed the same trend as observed in the head sample. The results showed that the four (4) oil samples contain high level of palmitic acid (C16:0) and stearic acid (C18:0) both of which are saturated fatty acids (SFA). The main MUFA identified was C18:1 (cis-6) and ranged from 14.120 ± 0.004 to 20.418 ± 0.002% for TFHD, TFGL, CFHD, CFGL and oleic acid (C18:1) ranged from 10.297 ± 0.001 to 11.570 ± 0.003% for TFHD, TFGL, CFHD and CFGL. Conclusions Oils of CFHD and TFHD showed higher peroxide values indicating suitability for human consumption.

Revisión taxonómica de la ictiología marina de Galicia: Clase Actinopteri (Orden Trachiniformes al Orden Tetraodontiformes)

En este trabajo se realiza una revisión taxonómica de los peces óseos de Galicia (Clase Actinopteri) del Orden Trachiniformes al Orden Tetraodontiformes, a través de los distintos tratados y publicaciones ictiológicas publicadas a lo largo de la historia. Se listan un total de 188 especies, de las cuales 5 se consideran dudosas, al no estar su presencia suficientemente demostrada. Una revisión de la bibliografía y nomenclatura científica nos ha permitido citar nuevas especies para Galicia y reasignar antiguas denominaciones a nuevas especies, subsanando errores de identificación de otros autores. El orden Perciformes, con 145 especies, es el más numeroso de los peces de Galicia. A este orden pertenecen especies de alto interés comercial como el jurel Trachurus trachurus y la caballa Scomber scombrus. El listado también incluye también los primeros registros para Galicia de especies de carácter tropical desplazadas hacia el norte debido al cambio climático a lo largo de estas últimas décadas. Algunas de estas especies son el jurelo azul Caranx crysos, el pez globo Lagocephalus laevigatus y el mero tropical Epinephelus aeneus.