baltic herring
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Foods ◽  
2022 ◽  
Vol 11 (2) ◽  
pp. 230
Author(s):  
Tanja Kakko ◽  
Annelie Damerau ◽  
Anni Nisov ◽  
Anna Puganen ◽  
Saska Tuomasjukka ◽  
...  

Fractionation is a potential way to valorize under-utilized fishes, but the quality of the resulting fractions is crucial in terms of their applicability. The aim of this work was to study the quality of protein isolates and hydrolysates extracted from roach (Rutilus rutilus) and Baltic herring (Clupea harengus membras) using either pH shift or enzymatic hydrolysis. The amino acid composition of protein isolates and hydrolysates mostly complied with the nutritional requirements for adults, but protein isolates produced using pH shift showed higher essential to non-essential amino acid ratios compared with enzymatically produced hydrolysates, 0.84–0.85 vs. 0.65–0.70, respectively. Enzymatically produced protein hydrolysates had a lower total lipid content, lower proportion of phospholipids, and exhibited lower degrees of protein and lipid oxidation compared with pH-shift-produced isolates. These findings suggest enzymatic hydrolysis to be more promising from a lipid oxidation perspective while the pH-shift method ranked higher from a nutrient perspective. However, due to the different applications of protein isolates and hydrolysates produced using pH shift or enzymatic hydrolysis, respectively, the further optimization of both studied methods is recommended.


2021 ◽  
Vol 8 ◽  
Author(s):  
Marjut Rajasilta ◽  
Katja Mäkinen ◽  
Suvi Ruuskanen ◽  
Jari Hänninen ◽  
Päivi Laine

In fish, the lipid resources of the female form a link between the environment and progeny, contributing to the contents of the egg yolk. Variation of the environmental conditions is therefore expected to affect the egg quality via maternal pathways, reflecting the female’s response to the environmental factors before spawning. We investigated the content of lipids and thyroid hormones in the ovary and eggs of the Baltic herring during 1988–2019, when salinity of the Baltic Sea first declined and then stabilized to a lower level, and winters varied between severe and mild. The total lipid resources of spawning females decreased by 40–50% during the study, and the ovarian lipid concentration followed this trend resulting in a decrease of the lipid content of eggs. The concentration of thyroid hormones in the ovary suggested a hormonal response in females to salinity and winter temperature and was observable also in the content of thyroid hormones in the eggs. A change in the egg lipid content took place approximately around 1998 (SE ± 3 years) suggesting that in declining salinity, egg quality was associated with salinity and intrinsic factors in the female, i.e., fecundity and amount of lipids deposited into the ovary. However, during the period of stable salinity, egg quality was mainly limited by the female’s lipid resources. As also the body size of the females decreased over the years, it is suggested that small body size can be a key phenotypic trait to reduce the environmental impact on egg quality in variable environmental conditions.


2021 ◽  
Vol 12 (1) ◽  
pp. 237-250
Author(s):  
Krzysztof Tomasz Witczak
Keyword(s):  

The paper discusses 9 Old Prussian words suspected of being borrowed from a Finno-Ugric source. The following words are verified as Finno-Ugricisms: OPrus. jūrī ‘sea’ (← FV. *järwä ‘lake, sea’); OPrus. kadegis ‘juniper’ (← BF. *kataŋa ‘id.’ ← Ur. *kača ‘resin’); OPrus. kaywe ‘mare’ (← BF. *keewe ‘female horse or reindeer’ < Ur. *kewe ‘female animal’); OPrus. kērdan ‘time’ (← FV. *kerta ‘succession, order, time’); OPrus. *palwe in toponymy (← FU. *palγɜ ‘village’); OPrus. *salavō ‘island’ (← FU. *sala-wɜ ‘island; dry place in the swamp’ < Ur. *sala); OPrus. sylecke ‘Baltic herring’ (← BF. *silakka ‘id.’ ← Ur. śilä ‘fat’); OPrus. wargien ‘copper’ (← FU. *würγɜnɜ ‘id.’).


Foods ◽  
2021 ◽  
Vol 10 (8) ◽  
pp. 1811
Author(s):  
Ella Aitta ◽  
Alexis Marsol-Vall ◽  
Annelie Damerau ◽  
Baoru Yang

Baltic herring (Clupea harengus membras) is one of the most abundant commercially caught fish species from the Baltic Sea. Despite the high content of fat and omega-3 fatty acids, the consumption of Baltic herring has decreased dramatically over the last four decades, mostly due to the small sizes and difficulty in processing. At the same time there is an increasing global demand for fish and fish oil rich in omega-3 fatty acids. This study aimed to investigate enzyme-assisted oil extraction as an environmentally friendly process for valorizing the underutilized fish species and by-products to high quality fish oil for human consumption. Three different commercially available proteolytic enzymes (Alcalase®, Neutrase® and Protamex®) and two treatment times (35 and 70 min) were investigated in the extraction of fish oil from whole fish and by-products from filleting of Baltic herring. The oil quality and stability were studied with peroxide- and p-anisidine value analyses, fatty acid analysis with GC-FID, and volatile compounds with HS-SPME-GC-MS. Overall, longer extraction times led to better oil yields but also increased oxidation of the oil. For whole fish, the highest oil yields were from the 70-min extractions with Neutrase and Protamex. Protamex extraction with 35 min resulted in the best fatty acid composition with the highest content of eicosapentaenoic acid (EPA; 20:5n-3) and docosahexaenoic acid (DHA; 22:6n-3) but also increased oxidation compared to treatment with other enzymes. For by-products, the highest oil yield was obtained from the 70-min extraction with Protamex without significant differences in EPA and DHA contents among the oils extracted with different enzymes. Oxidation was lowest in the oil produced with 35-min treatment using Neutrase and Protamex. This study showed the potential of using proteolytic enzymes in the extraction of crude oil from Baltic herring and its by-products. However, further research is needed to optimize enzymatic processing of Baltic herring and its by-products to improve yield and quality of crude oil.


2021 ◽  
pp. 110769
Author(s):  
Annelie Damerau ◽  
Dorota Ogrodowska ◽  
Paweł Banaszczyk ◽  
Fabian Dajnowiec ◽  
Małgorzata Tańska ◽  
...  

Foods ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 829
Author(s):  
Agnieszka Strzelczak ◽  
Jerzy Balejko ◽  
Mariusz Szymczak ◽  
Agata Witczak

The technological properties of raw fish are influenced by the changes in protein structure under heating, which determines the texture and quality of the product. The aim of the study was to examine the protein denaturation temperature and the rheological properties of Baltic herring muscle tissue. The thermal properties were determined by the differential scanning calorimetry (DSC) method and the rheological properties were determined using dynamic oscillatory tests. DSC showed four peaks associated with denaturing transformations of myosin (39.59 °C), sarcoplasm (51.67 °C), connective tissue (63.16 °C), and actin (74.40 °C). Analysis showed that not all transformations occurred according to the same kinetic model. The first two and the last peak are described by 1st order kinetics, while peak 3 is described by 2nd order kinetics. Correlating the changes in fish tissue structure during heating with the rheological characteristics provides more information. The obtained kinetics models correlated very strongly with the results of model testing. Rheological changes of the G’ and G” values had two inflexion points and demonstrate a high degree of convergence with the DSC changes of herring muscle tissue from 20 to 85 °C.


Biomolecules ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1631
Author(s):  
Robert Gustafsson ◽  
Ulrich Eckhard ◽  
Weihua Ye ◽  
Erik D. Enbody ◽  
Mats Pettersson ◽  
...  

Phosphoglucomutase 5 (PGM5) in humans is known as a structural muscle protein without enzymatic activity, but detailed understanding of its function is lacking. PGM5 belongs to the alpha-D-phosphohexomutase family and is closely related to the enzymatically active metabolic enzyme PGM1. In the Atlantic herring, Clupea harengus, PGM5 is one of the genes strongly associated with ecological adaptation to the brackish Baltic Sea. We here present the first crystal structures of PGM5, from the Atlantic and Baltic herring, differing by a single substitution Ala330Val. The structure of PGM5 is overall highly similar to structures of PGM1. The structure of the Baltic herring PGM5 in complex with the substrate glucose-1-phosphate shows conserved substrate binding and active site compared to human PGM1, but both PGM5 variants lack phosphoglucomutase activity under the tested conditions. Structure comparison and sequence analysis of PGM5 and PGM1 from fish and mammals suggest that the lacking enzymatic activity of PGM5 is related to differences in active-site loops that are important for flipping of the reaction intermediate. The Ala330Val substitution does not alter structure or biophysical properties of PGM5 but, due to its surface-exposed location, could affect interactions with protein-binding partners.


2020 ◽  
Vol 332 ◽  
pp. 127385
Author(s):  
Annelie Damerau ◽  
Tanja Kakko ◽  
Ye Tian ◽  
Saska Tuomasjukka ◽  
Mari Sandell ◽  
...  

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