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We characterized vacuum-packed whole saury (Cololabis saira) treated using radio-frequency (RF) heating and compared it with that treated using conventional retort heating. RF heating is electrical heating based on dielectric heating. In this study, the effect of RF heating on softening and collagen in backbone was analyzed. RF heating heated the center of fish faster than water. The backbone was softened to a chewable level, and the heating time was shortened to one-third. The amount of crude protein and collagen in backbone decreased with decreasing elasticity, although that heated using RF (131°C) still contained a higher amount than conventional heating. However, β and γ collagen, and then α1 and α2 collagen chain in backbone disappeared with heating; therefore, collagen was degraded to collagen peptide. Results confirmed that RF heating provided wholly eatable fish containing low-molecular collagen peptide in a short heating time. [ABSTRACT FROM AUTHOR]

A new model for estimation of daily probability for the Pacific saury (Cololabis saira) encounter was proposed. The model performance was tested for the period of 2004–2018 (August–November) using the data from the Russian vessel monitoring system. The following physical oceanographic variables were used for encounter probability prediction: the absolute values and gradients (∇) of speed (V) of passive particles, imitating water parcels, and Lagrangian indicators. The positive effects on the encounter probability of saury were found for V, ∇V, and for the gradient of the finite-time Lyapunov exponent (∇Λ), while the effect of particle path length was negative. That means that saury preferred places close to the boundaries of the oceanographic features, where Lagrangian fronts are situated, but not inside the features themselves, because Λ is small in regular flows and large at Lagrangiam fronts. The model did not include information about years and volume of saury catches, but its monthly mean of catch probability in September had the highest correlation with Russian annual catches outside the national waters between Russia and Japan (r = 0.76, p = 0.001) and total annual catches there (r = 0.73, p = 0.002). Timeseries analysis of principle components (PC) from daily predictions of saury catch probabilities has also shown that the third PC correlated highly with the annual biomass of saury (r ≥ 0.8, p < 0.05). The model seems to be useful to manage Russian fishery and may help to explain the reasons for the saury biomass decline. The latter is very important to take into account for development of the stock assessment models. [ABSTRACT FROM AUTHOR]

During the metabolism in human body, the purines from food, nucleic acid and adenosine triphosphate (ATP) would all turn into hypoxanthine, and then the hypoxanthine would change into uric acid treated by xanthine oxidase (XOD). Thus the XOD plays a key role during the whole process. In addition, it has been reported that the XOD can not only combine with hypoxanthine, but also do with pyrazolopyrimidines, purines, phenylprazole derivatives, flavones and so on. Therefore, uric acid can be decreased by combining heterocyclic compounds with XOD. Recently, the western medicines have been widely used in the treatment of the high uric acid and gout, but some side effects from these western medicines may appear on human body. Allopurinol is the only drug in the medicine market which reduces the production of uric acid through the inhibition of XOD, but it is also proved to have side effects on liver and kidney. With the development of the enzymatic hydrolysis technology, more and more bioactive peptides have been prepared and studied for drug use or health care. The small peptides have many advantages, for example, they are safe without any side effects and can be absorbed more quickly. The saury is mostly used to only produce can and dry foods due to the backward science and technology, which doesn't fully tap its potential economic and nutritional value. In fact, the saury is very rich in protein and it might have many special functions due to the hard environment in the sea. Therefore, the saury might be a perfect raw protein material for the preparation of the urate-lowering peptide. This can bring not only better nutrition but also higher economic value. In the present paper, the XOD inhibition peptide was prepared by hydrolyzing saury. By detecting the protein recovery and inhibition activity of XOD of different hydrolysates, the neutral protease and pancreatin were proved the best protease through the single factor experiment. Then the effects of protease concentration, hydrolysis time and ratio of neutral protease on protein recovery and inhibition activity of XOD were studied by using response surface method to improve the preparing technology. Results showed that protease concentration and ratio of neutral protease had a significant influence on the protein recovery (P<0.001), while protease concentration and hydrolysis time had a significant effect on inhibition activity of XOD (P<0.001). The best technology of preparing the XOD inhibition peptides from saury was optimized based on the research results above. The best process parameters were as follows: the ratio of liquor to material was set to 1:2, the total protease concentration was 0.3% (the pancreatin accounted for 40% and the neutral protease accounted for 60%), the pH value of the enzymatic hydrolysis system was 7.0, the temperature was 55°C, and the hydrolysis time was 6 h. The theoretical protein recovery rate could reach 72.69%, and the theoretical inhibition activity of the XOD was 30.32%. The established model was of high reliability, and it could be used to prepare the XOD inhibition peptide from saury hydrolysate. The test of molecular weight distribution indicated that saury hydrolysate mainly consisted of the peptide fragments smaller than 3 kDa (76.35%). The paper indicated that the saury hydrolysate with XOD inhibition peptide was a potential material for decreasing uric acid in food industry. [ABSTRACT FROM AUTHOR]

The Pacific saury is often preserved using salt, which helps to maintain the main taste component of the fish, inosinic acid (IMP). IMP is degraded by the IMP-degrading enzyme IMPase, the activity of which may be differentially affected by the type of salt used for preservation. Understanding the effects of these salts will help to maintain the desired amount of IMP to preserve the taste of saury. In saury, 40 % of all muscle is dark muscle, thereby; therefore, the effect of various salts on IMPase activity should be investigated in both the white and dark muscle. In this study, the IMPase activity in the white and dark muscle of saury was compared under different processing conditions, and the most suitable salts for processing were determined. There was almost no difference in IMPase activity between the white and dark muscle with respect to variations in pH, temperature, and salt type, indicating that the two muscle types could be processed under the same conditions. In addition, IMPase activity in the dark muscle of saury was promoted by MgCl and MgSO, indicating that salt manufactured using an ion-exchange membrane to remove SO and to decrease Mg is most suitable for use in saury preservation. [ABSTRACT FROM AUTHOR]

Abstract: The Atlantic saury Scomberesox saurus saurus (Walbaum) is a widely distributed epipelagic nekton species in the north Atlantic. It is considered one of the most abundant small pelagic species in the north Atlantic and is of increasing interest to commercial fisheries in American and European countries. Ageing of Atlantic saury is difficult, annual marks in otoliths, scales and other structures are often not present or are difficult to interpret, resulting in non-robust estimations. Growth of the Atlantic saury, from the northeastern Atlantic Ocean was studied by examining otoliths and scales for the presence of putative annual and daily growth marks. A description of Atlantic saury saggital otolith microstructure is given. No annual structures were observed on scales or otoliths. Counts of otolith micro-increments suggest that Atlantic saury exhibit a much faster growth rate than previously reported. Micro-increment counts ranged from 113 to 258 in fish from 110mm to 288mm of body size, suggesting that Atlantic saury is a short lived species. Assuming that otolith growth increments are deposited at a rate of one per day, average growth rates from hatching up to eight months old exceeded 1mm/day. The saury population available for exploitation in the northeast Atlantic is dominated by fish that are most likely less than one year old. Management of short-lived, forage species require special considerations and represents a challenge to fishery science. [Copyright &y& Elsevier]

Background: Saury oil contains considerable amounts of n-3 polyunsaturated fatty acids (PUFA) and monounsaturated fatty acids (MUFA) with long aliphatic tails (>18C atoms). Ingestion of saury oil reduces the risk of developing metabolic syndrome concomitant with increases in n-3 PUFA and long-chain MUFA in plasma and organs of mice. We therefore evaluated changes in postprandial plasma fatty acid levels and plasma parameters in healthy human subjects after ingestion of a single meal of saury. Findings: Five healthy human adults ingested 150 g of grilled saury. Blood was collected before the meal and at 2, 6, and 24 hr after the meal, and plasma was prepared. Plasma levels of eicosapentaenoic acid, docosahexaenoic acid, and long-chain MUFA (C20:1 and C22:1 isomers combined) increased significantly throughout the postprandial period compared with the pre-meal baseline. Postprandial plasma insulin concentration increased notably, and plasma levels of glucose and free fatty acids decreased significantly and subsequently returned to the pre-meal levels. Conclusions: Our study suggests that a single saury meal may alter the postprandial plasma levels of n-3 PUFA and long-chain MUFA in healthy human subjects. [ABSTRACT FROM AUTHOR]

Three canned fish species—Pacific saury (Cololabis saira), Pacific herring (Clupea harengus) and Baltic sprat (Sprattus sprattus)—most common and popular in Russia, were analyzed for fatty acids. Special attention was paid to long-chain essential polyunsaturated fatty acids: eicosapentaenoic acid (20:5ω3) and docosahexaenoic acid (22:6ω3). Sums of eicosapentaenoic acid and docosahexaenoic acid in saury, herring and sprat were, on average, 2.42, 1.80 and 1.43 g/100 g product, respectively. Contents of these essential acids in all the canned fish species were found to be very high compared with many other fish reported in the available literature. All the canned fish appeared to be highly valuable products for human nutrition concerning the content of eicosapentaenoic and docosahexaenoic acids. [ABSTRACT FROM AUTHOR]

A model is proposed that expresses the spatial and temporal migration pattern for stock of Pacific saury Cololabis saira (Brevoort), in order to investigate the effect of sea surface temperature (SST) on migration rates. Two factors are considered: (i) Saury emigrate to waters of an optimal SST zone; and (ii) saury immigrate from water zone that is extremely cold for saury. Parameters of migration and initial levels of stock are estimated with a maximum likelihood method based on catch per unit effort (CPUE) data for 1995–2001. The best model was selected using Akaike’s information criteria. The results suggested that the emigration rate to southern adjacent regions is dependent on the coverage proportion of their waters under some threshold temperatures; 20°C to Doutou and Sanriku, 23°C to Joban and Izu. [ABSTRACT FROM AUTHOR]

To establish a quantitative sampling method using mid-water trawls for estimating the stock abundance of Pacific saury (Cololabis saira), we carried out experimental fishing surveys using two types of mid-water trawl (SM-trawl: 4 panels, trawler 397 GRT and KM-trawl: 6 panels, trawler 2630 GRT). To confirm the occurrence of saury in the survey areas, we simultaneously conducted experimental fishing of M-driftnets (driftnets with multiple mesh-sized panels), which have been the traditional sampling gear for saury stock assessment research. The results of the experimental fishing revealed that the SM-trawl was effective for sampling saury when the length of the towing cable was shortened to 200 m. The KM-trawl was not effective in quantitatively sampling saury. Comparisons of the structure between the KM-trawl and the SM-trawl showed that the essential conditions on the design of the mid-water trawl for sampling saury are the following: (1) the whole head rope including both the wing tips should be floated up to the surface, (2) the width of the upper panel of the trawl at the mouth should be much longer than the maximum width of the trawler. It is required about 30 m, when the maximum width of the trawler is 9 m. The conclusion is that the SM-trawl is suitable for sampling saury quantitatively. Moreover, we made some suggestions for precisely determining the catch rate of the SM-trawl for estimating saury stock abundance. [Copyright &y& Elsevier]