scholarly journals Quality of Protein Isolates and Hydrolysates from Baltic Herring (Clupea harengus membras) and Roach (Rutilus rutilus) Produced by pH-Shift Processes and Enzymatic Hydrolysis

Foods ◽  
2022 ◽  
Vol 11 (2) ◽  
pp. 230
Author(s):  
Tanja Kakko ◽  
Annelie Damerau ◽  
Anni Nisov ◽  
Anna Puganen ◽  
Saska Tuomasjukka ◽  
...  
Keyword(s):  
Amino Acid ◽  
Enzymatic Hydrolysis ◽  
Lipid Oxidation ◽  
Rutilus Rutilus ◽  
Clupea Harengus ◽  
Roach Rutilus Rutilus ◽  
Protein Isolates ◽  
Ph Shift ◽  
Baltic Herring

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.

Foraging efficiency and prey selectivity in a visual predator: differential effects of turbid and humic water

2013 ◽  
Vol 70 (12) ◽  
pp. 1685-1690 ◽  
Author(s):  
Mikael Jönsson ◽  
Lynn Ranåker ◽  
P. Anders Nilsson ◽  
Christer Brönmark
Keyword(s):  
Visual Information ◽  
Prey Size ◽  
Rutilus Rutilus ◽  
Trophic Levels ◽  
Foraging Efficiency ◽  
Size Selectivity ◽  
Roach Rutilus Rutilus ◽  
Visual Predator ◽  
Visual Degradation

Predators exert strong regulating forces on lower trophic levels through predation. As most fish are visual foragers, visual conditions in the water may alter the strength of this regulation. We evaluated effects of turbidity and humic water on foraging efficiency and prey-size selectivity in Northern pike (Esox lucius) feeding on roach (Rutilus rutilus). Encounter rates decreased in both turbid and humic water but were not counteracted by increased searching activity. Capture success was unaffected by turbidity but was nonlinearly affected by humic water by being high in clear and highly humic water but low in less humic water. In highly humic water, the visual range approached pike’s strike distance and, together with its cryptic colours, pike may have initiated its attack before the prey detected it, limiting the possibility for prey evasive manoeuvres. Prey-size selectivity towards small prey in clear water disappeared in turbid water but was maintained in humic water. Owing to its optical properties, turbidity degrades the quality of the visual information more through scattering than humic water does through absorption. We show that the effect of visual degradation on foraging depends on the cause of visual degradation, which has not previously been acknowledged in the visual foraging literature.

scholarly journals On the suitability of roach, perch, vendace and whitefish for canning in small scale canning stations

1978 ◽  
Vol 50 (4) ◽  
pp. 361-371
Author(s):  
Mailis Kuuppo ◽  
Juha Koivurinta ◽  
Pekka Koivistoinen
Keyword(s):  
Perca Fluviatilis ◽  
Rutilus Rutilus ◽  
Raw Material ◽  
Small Scale ◽  
Detectable Effect ◽  
Roach Rutilus Rutilus ◽  
Organoleptic Evaluation ◽  
Canned Fish ◽  
Perch Perca Fluviatilis

The suitability of roach (Rutilus rutilus), perch (Perca fluviatilis), vendace (Coregonus albula L.), and whitefish (Coregonus sp.) for canning in small scale canning stations was tested. Various pretreatment methods and processing conditions were evaluated for different fish species. Processing equipment suitable for small scale canning stations was developed in the course of this study. The keepability of the canned products was followed by physical, organoleptic and microbiological determinations during a period of 18 months. The roach, vendace and whitefish preserves were of the types »canned fish in tomato sauce» and »canned fish in oil and its own juice» and the perch preserves of the type »canned fish in brine». Roach, vendace and whitefish were salted by immersing into 21 % brine for 4—25 minutes depending on the size of the fish and preheated by smoking at 90° C for 60 —120 minutes. Products of good quality were obtained from whitefish which was dried by cooking in oil at 120 °C for 3 minutes instead of smoking. The perch were cooked in 3 % and 4 % brine for 15—20 minutes depending on the size of the fish. The best time and temperature combination for the aimed F value 10 and for a product of good quality was 60 minutes at 115°C when using rotation. In organoleptic evaluation all the canned products were judged to be of good quality and there were no significant changes in appearance, texture, taste or aroma during 18 months' storage at room temperature. No microbial growth or swelling of the cans was detected during storage. Use of frozen raw material in canning whitefish had no detectable effect on the quality of the final product.

scholarly journals Rapid Method Based on ATP Catabolites for Evaluating the Freshness of Baltic Herring: Interlaboratory Study

1996 ◽  
Vol 79 (3) ◽  
pp. 703-706 ◽  
Author(s):  
M Tapani Hattula ◽  
Harriet C Wallin
Keyword(s):  
Liquid Chromatography ◽  
Degradation Products ◽  
Screening Method ◽  
Clupea Harengus ◽  
Interlaboratory Study ◽  
Paper Strip ◽  
Strip Method ◽  
Baltic Herring ◽  
Fish Samples

Abstract An interlaboratory study was performed in 31 Finnish laboratories to determine the quality of Baltic herring (Clupea harengus membras). Three fish samples representing 3 levels of freshness were analyzed. To evaluate chemical freshness, a rapid paper strip method based on the degradation products of ATP was used by 22 participants. Eleven laboratories used liquid chromatography. Each laboratory also classified the samples by sensory evaluation. The rapid paper strip method proved to be a satisfactory screening method for assessing freshness of Baltic herring.

Population Characteristics and Feeding of Roach Rutilus rutilus in Small Regulated River of the Kyiv Polissya

2020 ◽  
Vol 56 (1) ◽  
pp. 42-48
Author(s):  
Ye. A. Gupalo ◽  
I. I. Abramyuk ◽  
S. A. Afanasyev ◽  
O. V. Manturova ◽  
Ye. V. Savchenko
Keyword(s):  
Rutilus Rutilus ◽  
Population Characteristics ◽  
Regulated River ◽  
Roach Rutilus Rutilus

EFFECT OF SODIUM LACTATE ON QUALITY OF LIGHTLY SALTED FISH IN OXYGEN FREE PACKAGING

2017 ◽  
pp. 128-137
Author(s):  
Elena Yuryevna Porotikova ◽  
Boris Lazarevich Nekhamkin ◽  
Mikhail Pavlovich Andreev
Keyword(s):  
Modified Atmosphere Packaging ◽  
Storage Period ◽  
Sodium Lactate ◽  
Vacuum Packaging ◽  
Storage Life ◽  
Clupea Harengus ◽  
Modified Atmosphere ◽  
Salted Fish ◽  
Baltic Herring ◽  
Organoleptic Characteristics

The present article investigates the effect of sodium lactate on microbiological, physico-chemical and sensory characteristics of lightly salted Pacific herring ( Clupea pallasii ) and Baltic herring ( Clupea harengus membras ) during refrigerated storage 5 ± 0.3°C. There have been analyzed different processing methods of lightly salted samples of Pacific and Baltic herring: control (without sodium lactate), and experiment (3% sodium lactate), both in vacuum packaging and modified atmosphere packaging (MAP - 40% CO2/60% N2). For vacuum and MAP there were used bags with low oxygen permeability (3 cm3/m2/day). It was found that 3% sodium lactate keeps firmness of the texture of salted fish muscle and reduces the release of water into the package during storage. Adding 3% sodium lactate reduces the value of the water activity in lightly salted Pacific and Baltic herring by 0.01-0,012 units. The lowest pH (0.02 units) was registered in samples without sodium lactate packed in MAP. Organoleptic signs of spoilage in fish without sodium lactate appeared much earlier, and using 3% sodium lactate both in vacuum and in MAP helped protect and improve organoleptic characteristics of the product during storage. Total biological semination of experimental samples packed in MAP kept at the very low level during the whole storage period, i.e. combined effect of using 3% sodium lactate and MAP inhibited microbial growth. This combination allows to reduce twice the rate of accumulation nitrogen in terminal amino-groups and to increase 1.5-2 times storage life of lightly salted Pacific and Baltic herring, compared to their storage life in vacuum packaging without sodium lactate. The results obtained allow us to recommend using sodium lactate in production of lightly salted fish in oxygen-free packaging, especially in modified atmosphere packaging (40% CO2/60% N2).

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