Surimi industry produces a large quantity of byproducts that are currently being utilized to produce low-value commodities. This study aims to extract gelatin from pink perch skin and bone obtained from the surimi industry using a green single-step extraction method. In addition to using a green solvent, that is, acetic acid, the new method combines the multiple steps of pre-treatment and hydrolysis into one single-step extraction process. Response surface methodology was used to optimize extraction parameters (pH, temperature, and time) to maximize yield and l-hydroxyproline (l-hyp) content. The optimum condition for gelatin extraction was obtained at pH 3, 75°C, and 30 min. At optimum conditions, gelatin yield and l-hyp content were observed to be 16.07% and 41.26 mg g-1 , respectively. The gelatin obtained at optimized condition was further compared with commercial bovine gelatin (BG) in terms of chemical composition and textural, functional, and rheological properties. The results suggested that the optimized pink perch gelatin had higher protein content (92.06%), better gel strength (251.08 g), higher imino acid (18.01%), and improved textural and functional properties than the commercially available BG. The optimized single-step gelatin extraction method from pink perch skin and bones is a promising, rapid, and efficient method for the production of good-quality gelatin, which can be further used for the development of high-value products such as food formulations. PRACTICAL APPLICATION: Fish gelatin is widely used in food product development. Most of the existing methods of the development of high-value product such as gelatin, use multi-step process and harsh mineral acid, therefore, are time-consuming and harmful to the environment. This study provides a green single-step gelatin extraction method that provides an efficient, rapid, and convenient method of gelatin extraction and a sustainable solution for fish industry byproduct utilization. The data obtained with this laboratory-scale study provides a strong basis for scale-up studies.

The Japanese threadfin bream N. japonicus (Bloch) (Perciformes: Nemipteridae) is an important marine food fish in Asia. However, our present knowledge of the occurrence of its nematode parasites is still limited. In the present study, the species composition and infection rate of ascaridoid nematodes in N. japonicus from the South China Sea, were studied for the first time. Five ascaridoid species, namely Anisakis typica (L3), Hysterothylacium amoyense (L3), Hysterothylacium sp. IV-A (L3), adult of H. thalassini and Raphidascaris lophii (L3), were identified using integrative taxonomy. Hysterothylacium amoyense was the most prevalent species (prevalence 47.2%, mean intensity 14.9 ± 17.1). Hysterothylacium thalassini and R. lophii were reported in the Japanese threadfin bream for the first time. Two different genotypes of A. typica (overall prevalence of 3.4%; mean intensity 1.7 ± 0.9) were found in the South China Sea for the first time. The unique restriction polymorphism patterns of three species of Hysterothylacium are provided for rapid diagnosis. Our present results indicate that RFLP analysis of ITS region, using the restriction enzymes HhaI and RsaI, represents a simple and practical method for large-scale surveys of Hysterothylacium for seafood industry.

The third stage larvae (L3) of Anisakis typica were detected in 2 species of threadfin bream, Nemipterus hexodon and N. japonicus, from the Gulf of Thailand, and were morphologically and molecularly characterized. Total 100 threadfin breams, 50 Nemipterus hexodon and 50 N. japonicus, were examined with naked eyes after the opening of abdominal cavity with scissors. Almost all infected larvae remained alive and active even the fish were transported for 1-2 days. Anisakid larvae were exclusively distributed in the body cavity and rarely in the liver. The prevalence of A. typica L3 were 68.0% and 60.0% in N. hexodon and N. japonicus and their infection intensities were 3.5 and 4.2 per fish infected each. Morphological and morphometric analysis were performed by viewing specimens under both a light microscope and a scanning electron microscope. Interestingly, the protruded mucron of Anisakis typica under SEM showed a distinct cylindrical shape that differed from the cone shape of A. simplex. The protruded mucron could be used to identify A. typica L3 larvae in the future. A comparison of the ITS1-5.8S-ITS2 rDNA nucleotide sequences of these species revealed high blast scores with A. typica. Conclusively, it was confirmed that A. typica L3 are prevalent in threadfin breams from the Gulf of Thailand, and their morphological and molecular characters are something different from those of other anisakid larvae, including A. simplex and A. pegreffii.

In this study, chitosan coatings incorporated with propolis extract (PE) were utilized to extend the shelf-life of refrigerated Nemipterus japonicus fillets. Microbiological (total mesophilic bacteria (TMB) and total psychrotrophic count (TPC)), physicochemical (pH, total volatile bases nitrogen (TVB-N), 2-thiobarbituric acid reactive substances (TBARS), free fatty acid (FFA)) and sensory (color, odor and preference) characteristics of coated fillets were evaluated during 12days. The results showed that incorporating PE into chitosan solution could significantly (P<0.05) improve the quality of fish fillets. The results showed that the chitosan+PE samples reduced the extent of lipid oxidation, as judged by TBARS and FFA, suggesting that there is a synergistic effect between chitosan coating and propolis. Moreover, the application of chitosan coatings with PE improved the TVB-N and pH values of the Nemipterus japonicus samples significantly compared to untreated sample, thus extending the shelf life of Nemipterus japonicus fillet approximately >10days. All wrapped fillets in treatment samples incorporated with PE had lower bacterial counts compared to control (P<0.05). However, the bacterial counts of chitosan coating combined with PE were lower than those treated by chitosan or PE alone during the storage. The fillets treated with chitosan and PE had the best sensory properties. The increase (>10days) in the shelf-life was attributed to the antioxidant and antimicrobial characteristics of chitosan and PE. These results confirmed that chitosan coating enriched with PE can be an improving method to reducing deterioration of refrigerated Nemipterus japonicus fillets.

BACKGROUND: Anisakid nematodes are common parasites of fish, mammals, fish-eating birds, and reptiles with a worldwide distribution, causing diseases in human, fish and important economic losses.
METHODS: A preliminary epidemiological study was carried out on Anisakid nematodes larvae in some commercially important fish species to evaluate the anisakid nematode larvae from greater lizardfish, (Saurida tumbil), Japanese thread fin bream (Nemipterus japonicus), crocodile longtom (Tylosurus crocodilus crocodiles) and longfin trevally (Carangoides armatus) from the Persian Gulf of Iran.
RESULTS: The collected larvae were identified mainly as the third larval stage (L3) of Hysterothylacium larval type A, B and C, Anisakis sp., Raphidascaris sp., Pseudoterranova sp. and Philometra sp. (Nematoda: Philometridae). The prevalence of Anisakid larvae infection of examined fishes was 97.2% in N. japonicus, 90.3% in S. tumbil, 20.5% in crocodile longtom and 5.5% in longfin trevally. Anisakis type III for the first time was different from Anisakis type I and Anisakis type II.
CONCLUSIONS: Zoonotic anisakids by high prevalence in edible fish could be a health hazard for people. So health practices should be considered in these areas.

A study was undertaken with the aim of reducing the concentration of cryoprotectants in surimi without adversely affecting frozen storage stability. Minced meat from a tropical fish, Nemipterus japonicus, was strained, water leached and mixed with different levels of sucrose-sorbitol (1:1) mixture (henceforth called sugar mixture), quick frozen at -35 °C and frozen stored at -20 °C. The surimi samples were subjected to storage stability studies for a period of 5 months. Water leaching resulted in slight absorption of water by meat and reduction in protein, fat and mineral contents. Surimi was found to have moderately white colour. Sensory evaluation studies were conducted on three products, viz., sausage, patty and cake, prepared using surimi containing different concentrations of sugar mixture. Sugar mixture content varying from 0% (control) to 4% in surimi resulted in products that were more acceptable to the taste panelists compared those with 6% and 8% sugar mixture. During frozen storage of surimi pH and total plate count remained nearly steady for all sugar mixture concentrations and throughout the storage period. Moisture content appeared to remain constant during storage, but decreased with increase in sugar concentration. The salt soluble nitrogen content of surimi and gel strength of sausage prepared from it decreased with storage period in all surimi samples, and increased with sugar mixture concentration. Expressible water content of surimi sausage showed an increasing trend with storage period of surimi and a decreasing trend with sugar mixture concentration. Sensory evaluation parameters-elasticity, sweetness and preference-remained more or less steady during storage. However elasticity and sweetness increased and preference decreased with sugar mixture concentration beyond 4%. Elasticity and gel strength of surimi sausage seemed to be much lower for control compared to even the lowest concentration of sugar (2%) used. A concentration of 2 to 4% sucrose-sorbitol mixture is well-accepted by the consumers in products-surimi sausage, patty and cake and at this range of concentration surimi could be well-preserved at -20 °C for at least 5 months.

We evaluated genetic differentiation among ten presumed Japanese threadfin bream, Nemipterus japonicus populations along the coast of Peninsular Malaysia based on the partial sequence of the mitochondrial cytochrome b gene (982 bp). Genetic divergences (Kimura-2 parameter) ranged from 0.5% to 0.8% among nine of the ten populations while these nine populations were 4.4% to 4.6% diverged from the Kuala Besar population located at the Northeast coast. The constructed Neighbour Joining (NJ) phylogenetic trees based on haplotypes showed the Kuala Besar population forming an isolated cluster. The Analysis of Molecular Variance (AMOVA) of the ten populations a priori assigned into four regions, revealed that most of the variation occurred within population with a fairly low but significant level of regional differentiation (FST = 0.07, p < 0.05, FSC = 0.00, p > 0.05 and FCT = 0.07, p < 0.05) attributed to the Kuala Besar population. p Value after Bonferroni correction revealed that only pairwise FST values involving the Kuala Besar population with the other nine populations were significant. Thus, this study revealed that the N. japonicus populations off Peninsular Malaysia were panmictic. However, the Kuala Besar population, although morphologically identical was composed of a genetically discrete taxon from the rest. These findings are important contributions in formulating sustainable fishery management policies for this important fishery in Peninsular Malaysia.

The complete mitochondrial sequence of the Japanese threadfin bream, Nemipterus japonicus has been determined. The circle genome is 16,995 bp in size, and consists of 13 protein-coding genes, 2 rRNA genes, 22 tRNA genes and a control region. The gene order and composition of N. japonicus was similar to that of most other teleosts. The base composition of H-strand is 28.11% (A), 28.02% (T), 16.64 % (G) and 27.24 % (C), with an AT content of 56.12%. All genes are encoded on the heavy strand with the exception of ND6 and eight tRNA genes. The mitochondrial genome of N. japonicus presented will be in favor of resolving phylogenetic relationships within the family Nemipteridae and the Perciformes.

Functional properties and antioxidant activity of pink perch (Nemipterus japonicus) muscle hydrolysed by three different enzymes papain, pepsin and trypsin were studied. The protein hydrolysates produced by trypsin had an excellent solubility (98%) compared to pepsin (77%) and papain hydrolysate (74%). Conversely, the emulsifying activity index (ESI) and foaming abilities were affected by pH. DPPH radical scavenging ability, reducing power and metal chelating activity of protein hydrolysates increased with increase in concentration. Lipid peroxidation was strongly inhibited by 64% by protein hydrolysates produced by trypsin. The results revealed that the functional properties and antioxidant activities of pink perch were greatly affected by the enzymes used.