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The use of angiotensin-I converting enzyme (ACE) inhibitors is a common strategy for treating kidney disease. Several amino acid sequences with ACE inhibiting activity are identified in filet and rest raw material from various species of fish, and fish protein hydrolysates could be of interest for possible treatment or prevention of kidney disease. Therefore, we hypothesized that protein hydrolysates from rest raw material from herring and salmon contained ACE inhibiting motifs, and could beneficially affect typical markers for kidney function in an obesity rat model prone to developing renal failure. We identified 81 and 49 peptide sequences with known ACE inhibiting activity in herring and salmon protein hydrolysates from rest raw material, respectively. To investigate the effects of fish protein hydrolysates on markers of kidney function, obese Zucker fa/fa rats consumed diets with 25% of protein from herring (HER) or salmon (SAL) protein hydrolysate from rest raw material and 75% of protein from casein/whey, or 100% protein from casein/whey (CAS) for 4 weeks. Rats fed HER or SAL diets had lower urine concentrations (relative to creatinine) of protein, cystatin C and glucose when compared to rats fed CAS diets, with no differences between groups for serum concentrations of protein, creatinine and cystatin C. To conclude, protein hydrolysates from herring and salmon rest raw material contained several peptide sequences with known ACE inhibiting activities, and resulted in lower urine concentrations of proteins, cystatin C and glucose when fed to obese Zucker rats., (Copyright © 2018 Elsevier Inc. All rights reserved.)

The world's fisheries and aquaculture industries produce vast amounts of protein-containing by-products that can be enzymatically hydrolysed to smaller peptides and possibly be used as additives to functional foods and nutraceuticals targeted for patients with obesity-related metabolic disorders. To investigate the effects of fish protein hydrolysates on markers of metabolic disorders, obese Zucker fa/fa rats consumed diets with 75 % of protein from casein/whey (CAS) and 25 % from herring (HER) or salmon (SAL) protein hydrolysate from rest raw material, or 100 % protein from CAS for 4 weeks. The fatty acid compositions were similar in the experimental diets, and none of them contained any long-chain n-3 PUFA. Ratios of lysine:arginine and methionine:glycine were lower in HER and SAL diets when compared with CAS, and taurine was detected only in fish protein hydrolysate diets. Motifs with reported hypocholesterolemic or antidiabetic activities were identified in both fish protein hydrolysates. Rats fed HER diet had lower serum HDL-cholesterol and LDL-cholesterol, and higher serum TAG, MUFA and n-3:n-6 PUFA ratio compared with CAS-fed rats. SAL rats gained more weight and had better postprandial glucose regulation compared with CAS rats. Serum lipids and fatty acids were only marginally affected by SAL, but adipose tissue contained less total SFA and more total n-3 PUFA when compared with CAS. To conclude, diets containing hydrolysed rest raw material from herring or salmon proteins may affect growth, lipid metabolism, postprandial glucose regulation and fatty acid composition in serum and adipose tissue in obese Zucker rats.

In the Norwegian oceanic fleet, whitefish onboard processing creates a great amount of rest raw materials. Cod heads are nutritious and a good source for production of high-quality marine peptides. Frozen cod heads, captured by trawl or longline, were evaluated based on the lightness and redness in the neck cut to compare the quality in heads from the different fishing gears. The heads were subjected to enzymatic hydrolysis. The hydrolysates have been chemically and sensory characterized. There was no significant difference in quality or chemical and sensory characteristics based on type of fishing gear. The resulting hydrolysates were of high quality, although moderately bitter. The study demonstrates that frozen cod heads from the oceanic fleet can be an excellent source of high-quality proteins for human consumption. [ABSTRACT FROM AUTHOR]

Cod heads were hydrolysed using different enzymes (Alcalase, Flavourzyme, Papain, Bromelain, and Protamex) at concentration of 0.1% for 1 hour and different water/raw material ratios. The most promising processing conditions were further verified in large-scale trials in a pilot plant. The results showed that the water/raw material ratios had little effect on hydrolysis yield, protein content, or the molecular weight distribution in hydrolysate. However, different enzymes led to differences in chemical composition and molecular weight distribution. Protein recovery was lower in the pilot trial, primarily because pilot and industrial processing equipment must be adapted and optimized to the raw material and process. Upscaling proved that high-quality protein powder can be produced from cod heads. The product has a neutral smell, light color, contains more than 80% protein, and could serve as an excellent source of protein for human consumption. [ABSTRACT FROM AUTHOR]

Chicken protein hydrolysates (CPHs) generated from rest raw materials through enzymatic hydrolysis using Corolase PP or Alcalase were shown to reduce inflammation and stimulate hepatic mitochondrial fatty acid oxidation in high‐fat‐fed mice. This study investigates the effect of CPH diets in atherosclerosis‐prone apolipoprotein E‐deficient (Apoe−/−) mice. Apoe−/− mice were divided into three groups of 12 animals and fed high‐fat diets with casein (control), Alcalase CPH, or Corolase PP CPH. After 12 weeks, mice were sacrificed, blood samples were collected, and aorta was dissected for subsequent én face analysis. Mice fed Corolase PP CPH but not Alcalase CPH had significantly lower % atherosclerotic plaque area in the aortic arch compared to controls (p =.015 and p =.077, respectively). Plasma and liver cholesterol and triacylglycerol remained constant, but levels of the fatty acid C20:5n‐3 were increased, accompanied by an elevated delta‐5 desaturase index in both CPHs groups. Moreover, a significant reduction of plasma MCP‐1 was detected in Corolase PP CPH compared to control. Overall, our data show that protein hydrolysates from chicken reduced atherosclerosis and attenuated systemic risk factors related to atherosclerotic disorders, not related to changes in the level of plasma cholesterol. [ABSTRACT FROM AUTHOR]

Background: In Norway, 3 million discarded egg-laying hens are destructed annually, which equals 1500 tons pure hen meat. Due to the slaughter methods used, this raw material is handled as a high-risk waste, while in reality it constitutes a source of valuable components like proteins and lipids. Methods: This study assess different processing methods (thermal treatment, enzymatic hydrolysis and silaging) for utilization of discarded egg-laying hens for the production of ingredients for human consumption and animal feed. The processing methods were evaluated on the basis of quantity and quality of the obtained products. Results: Thermal treatment and enzymatic hydrolysis resulted in extraction of good quality lipids from the raw material. The separated oil (50.1–82.3% of the total lipid content in the raw material) was of high quality based on the content of free fatty acids (≤ 1.0%) and total oxidation value (≤ 3.9). Enzymatic hydrolysis also enabled separation of protein in the form of protein hydrolysate. Addition of Protamex and Papain+Bromelain significantly (p ≤ 0.05) increased the protein content (85.1–94.6%) and decreased the lipid content (0.3–1.1%) in the hydrolysate compared to autolysis (protein content: 64.8–72.3%, lipid content: 1.0–2.6%). Silaging increased the protein digestibility (63.2–79.7% compared to 57.3–66.2% for untreated raw material), and thus constitutes a good method for utilizing the protein content of the raw material for animal feed. Conclusion: The biotechnological processing methods thermal treatment, enzymatic hydrolysis and silaging can be used to increase the utilization of discarded egg-laying hens for production of ingredients for human consumption and animal feed. [ABSTRACT FROM AUTHOR]

There is an increasing demand for omega-3 containing fish oils. By-products from fish fillet production can be utilized for the production of fish oils and be a valuable source of omega-3 for human consumption. The aim of this work was to evaluate industrial processes for production of quality oil for human consumption made from Norwegian spring spawning herring by-products. A mobile production plant was used to compare two industrial processes, thermal treatment (wet rendering) and enzymatic protein hydrolysis, for production of oil from herring by-products immediately after filleting. Results show that high quality herring oil can be produced from fresh by-products. The use of by-products immediately after filleting resulted in a low amount of free fatty acids for all the produced oils (below 0.4%). Thermal treatment at 70°C resulted in an oil with lower oxidation status and higher stability compared to the oils produced by enzymatic protein hydrolysis. Nevertheless, both processing methods gave a crude oil of high quality compared to crude oils on the market. [ABSTRACT FROM PUBLISHER]