Emulsion and Surface-Active Properties of Fish Solubles Based on Direct Extraction and after Hydrolysis of Atlantic Cod and Atlantic Salmon Backbones

publishedVersio

Utbyttetall og næringsstoffinnhold i hvitfiskmel og olje basert på restråstoff fra torsk, hyse og sei

Rapporten gir en oversikt over innhold av næringsstoffer og uønskede forbindelser i hvitfiskmel fremstilt av restråstoff etter opparbeidelse av torsk, hyse og sei til hodekappet og sløyd fisk (HG) og skinn og beinfri filet. Nivåene er rapportert på basis av fettfritt tørrstoff i presskake og limvann eller på lipidbasis for å kunne sammenligne på tvers av råstoffslag og sesong uten å ta hensyn til variasjon i fett og tørrstoff. Basert på labskalaforsøk er det beregnet massebalanser og fordeling av protein, aske og fett mellom presskake og væskefase i en fiskemelprosess. Dette muliggjør beregning av effekt på utbytte og nivå i mel avhengig av om limvannet inkluderes eller ikke. Nivåene kan konverteres til et typisk hvitfiskmel med 5 % vann og 9 % fett ved å multiplisere med en faktor på 0,86. Kartleggingen inkluderer følgende næringsstoffer: protein og aminosyrer, totale lipider og fettsyrer, aske, vitaminer (A, B, D, E), mineraler (Na, K, Ca, Mg, P, Cu, Fe, I, Mn, Se, Zn), tungmetaller (As, Cd, Hg, Pb) og organiske miljøgifter (PCDD/F, DL-PCB og NDL-PCB). I rapporten påvises effekt av råstofftype, sesong (høst vs. vår), prosess (HG vs. filetproduksjon) og tilsetting av limvann på utbytte og sammensetning av hvitfiskmel.Utbyttetall og næringsstoffinnhold i hvitfiskmel og olje basert på restråstoff fra torsk, hyse og seipublishedVersio

Emulsion and Surface-Active Properties of Fish Solubles Based on Direct Extraction and after Hydrolysis of Atlantic Cod and Atlantic Salmon Backbones

The focus on natural foods and “clean” labeled products is increasing and encourages development of new biobased ingredients. Fish solubles derived from downstream processing of side stream materials in the fish filleting industries have potential as emulsifiers based on their surface-active and emulsion stabilizing properties. The aim of this study was to evaluate and compare emulsion properties and critical micelle concentration (CMC) of direct protein extracts and protein hydrolysates based on fish backbones, and to identify associations between molecular weight distribution and process yield with the studied physicochemical properties. Protein extracts and enzymatic protein hydrolysates were produced based on two raw materials (cod and salmon backbones), two enzymes with different proteolytic specificity, and varying hydrolysis time. Emulsion activity index (EAI), emulsion stability index (ESI) and CMC were measured and compared with casein as a reference to protein-based emulsifiers. Protein hydrolysis was found to have negative impact on EAI and CMC, likely due to generation of small peptides disrupting the amphiphilic balance. The direct protein extracts had comparable EAI with casein, but the latter had superior ESI values. Protein hydrolysates with acceptable EAI could only be obtained at the expense of product yield. The study emphasizes the complexity of physicochemical properties of protein hydrolysates and discusses the challenges of achieving both good surface-active properties and high product yield

Sensory and physicochemical properties of enzymatic protein hydrolysates : Influence of raw material, protease, and downstream processing

The world aquaculture, fisheries and poultry sectors generate large amounts of residual raw materials, such as heads, backbones, and carcasses. Almost 85% of the residual materials from Norwegian aquaculture and fisheries were utilized in 2019, but over 150 000 metric tons were wasted. This is not compatible with the aim of a circular bioeconomic food production where all the biomass should be utilized. Furthermore, the majority of utilized raw materials were used as low-value feed ingredients. The residual raw materials are excellent food-grade sources of protein and have high potential for further upgrading. However, the materials are not directly applicable for human consumption, but through enzymatic protein hydrolysis, the proteins will be cleaved into more water-soluble peptides and made accessible for use and valorisation. Enzymatic protein hydrolysates may be utilized within human consumption as protein enrichment of food products and/or as a functional ingredient. However, the sensory properties of protein hydrolysates are considered a major limitation for hydrolysate inclusion in foods. Peptides, free amino acids, minerals, and other water-soluble molecules will follow the hydrolysate phase and contribute to the overall sensory profile. Increased knowledge of the flavour development in protein hydrolysates is imperative when producing products destined for human consumption. Furthermore, the potential amphiphilicity of the peptides generates surface-active properties which is important to understand for their use as functional ingredients in food applications. The main objective of this study was to assess hydrolysate properties, important for food formulations, of products based on species generating a substantial fraction of residual raw materials. Sensory profiles of the hydrolysates were evaluated using a trained panel and combined with metabolite composition, based on 1H NMR. Both enzyme specificity and new membrane filtration technology were assessed to reduce the sensory properties of the hydrolysates. Furthermore, the effects of hydrolysis parameters on important physicochemical properties, i.e. emulsion activity index (EAI), emulsion stability index (ESI) and critical micelle concentration (CMC) were evaluated. In Paper I, the use of nuclear magnetic resonance (NMR) spectroscopy as a new tool in sensory assessment of protein hydrolysates were evaluated. Hydrolysates were produced based on muscle tissue from cod, salmon, and chicken with two different enzymes (Bromelain and FoodPro PNL) and hydrolysis times (10 and 50 min). Metabolite composition of the 12 hydrolysates were determined by NMR and the sensory profiles assessed by a trained sensory panel. The results showed that raw material had a major effect on attribute intensity and metabolite variation. The formation of bitter taste was not affected by raw material, indicating a comparable release of bitter peptides independent of substrate. Partial least squares regression on 1H NMR and sensory data provided models for 11 of the 17 evaluates attributes, and significant metaboliteattribute associations were identified based on the obtained models. The study confirmed a potential for prediction of sensory properties based on 1H NMR data. In Paper II, the effect of hydrolysis parameters on emulsion and surface-active properties were assessed. Direct protein extracts from salmon and cod backbones were compared to hydrolysates based on two different enzymes (Bromelain and FoodPro PNL) with increasing hydrolysis time. EAI, ESI, and CMC were measured for all products. Protein hydrolysis was found to have a negative impact on ESI and CMC, while the ESI generally increased. The direct protein extracts had comparable EAI to that of the commercial emulsifier casein but considerably lower ESI values. The study emphasized the complexity of functional properties in protein hydrolysates and the challenges of achieving high protein yield simultaneously with high surface-activity. In Paper III, the effect of membrane filtration on sensory properties were evaluated. Heads and backbones from cod and salmon were hydrolysed for 50 min with either Bromelain or FoodPro PNL. The hydrolysates were purified by microfiltration and further refined by nanofiltration and diafiltration. Sensory profiles and metabolite compositions were assessed prior to, and after each nanofiltration step. Metabolite composition were determined and quantified by 1H NMR and sensory profiles were evaluated by a trained sensory panel. The results showed a substantial reduction in metabolite concentration by nanofiltration, with a concomitant reduction in the intensity of several sensory attributes. Bitterness, however, increased as small peptides associated with bitter taste (MW range 0.5−2 kDa) were rejected by the membrane. About 19-24% of the raw material protein were recovered in the nanofiltered product and the main loss was attributed to the removal of bones and solids in the crude hydrolysates. Considerable amounts of protein were also retained in the microfiltration retentate, emphasizing the need for process optimization. In Paper IV, the sensory, nutritional, and chemical quality properties of protein hydrolysates based on backbones, heads, and viscera from salmon and mackerel were assessed. The hydrolysates were produced using FoodPro PNL and hydrolysed for 50 min. All products were high in essential amino acids and had low biogenic amines content. The raw material fractions caused most of the variation in sensory properties, where viscera products had highest attribute intensities. Mackerel was perceived as the most taste intense of the species, mostly due to high ash content giving strong salty taste of the mackerel hydrolysates. This illustrated the importance of salt removal when producing products for human consumption

From Lab to Industry - Enzymes from Undifferentiated Marine Rest Raw Material

The aim of this project was to optimize the extraction of esterase enzymes from undifferentiated herring rest raw material. This was conducted by comparing, in laboratory scale, the outcome of using homogenised and non-homogenised raw material, and by extracting with buffers of different pH. Further on, clarification experiments of flocculation were performed on the optimal extract. The focus was to define methods enabling a large-scale production, with regards to one of the esterases found, and also determined in a previous project, to be of particular commercial interest

Sensory and Chemical Properties of Protein Hydrolysates Based on Mackerel (Scomber scombrus) and Salmon (Salmo salar) Side Stream Materials

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Reduction in flavor-intense components in fish protein hydrolysates by membrane filtration

Enzymatic protein hydrolysates based on side stream materials from the fish-filleting industry are increasingly explored as food ingredients. However, intense sensory properties, and high salt contents, are often a limiting factor. Most of the sensory attributes, such as fish flavor and salty taste, can be ascribed to low-molecular-weight, water-soluble components, whereas bitterness is associated with small hydrophobic peptides. In this study, protein hydrolysates based on head and backbone residuals from Atlantic salmon (Salmo salar) and Atlantic cod (Gadus morhua) were produced using two different enzymes. The effects of micro- and nanofiltration on the chemical composition, protein recovery, and sensory properties of the final products were investigated. The choice of raw material and enzyme had negligible effects, whereas nanofiltration caused a considerable reduction in metabolites, ash, and the intensity of several sensory attributes. The intensity of bitterness increased after nanofiltration, indicating that small peptides associated with bitter taste were retained by the membrane. Total protein yield after microfiltration was 24%–29%, whereas 19%–24% were recovered in the nanofiltration retentate.publishedVersio

Sensory and Chemical Properties of Protein Hydrolysates Based on Mackerel (Scomber scombrus) and Salmon (Salmo salar) Side Stream Materials

publishedVersio

Sensory Assessment of Fish and Chicken Protein Hydrolysates. Evaluation of NMR Metabolomics Profiling as a New Prediction Tool

Nuclear magnetic resonance (NMR) metabolomics profiling was evaluated as a new tool in sensory assessment of protein hydrolysates. Hydrolysates were produced on the basis of different raw materials (cod, salmon, and chicken), enzymes (Food Pro PNL and Bromelain), and hydrolysis time (10 and 50 min). The influence of raw material and hydrolysis parameters on sensory attributes was determined by traditional descriptive sensory analysis and 1H NMR spectroscopy. The raw material had a major influence on the attribute intensity and metabolite variation, followed by enzyme and hydrolysis time. However, the formation of bitter taste was not affected by the raw material. Partial least-squares regression (PLSR) on 1H NMR and sensory data provided good models (Q2 = 0.55–0.89) for 11 of the 17 evaluated attributes, including bitterness. Significant metabolite–attribute associations were identified. The study confirms the potential prediction of the sensory properties of protein hydrolysates from cod, salmon, and chicken based on 1H NMR metabolomics profiling.submittedVersio

Reduction in flavor-intense components in fish protein hydrolysates by membrane filtration

Enzymatic protein hydrolysates based on side stream materials from the fish-filleting industry are increasingly explored as food ingredients. However, intense sensory properties, and high salt contents, are often a limiting factor. Most of the sensory attributes, such as fish flavor and salty taste, can be ascribed to low-molecular-weight, water-soluble components, whereas bitterness is associated with small hydrophobic peptides. In this study, protein hydrolysates based on head and backbone residuals from Atlantic salmon (Salmo salar) and Atlantic cod (Gadus morhua) were produced using two different enzymes. The effects of micro- and nanofiltration on the chemical composition, protein recovery, and sensory properties of the final products were investigated. The choice of raw material and enzyme had negligible effects, whereas nanofiltration caused a considerable reduction in metabolites, ash, and the intensity of several sensory attributes. The intensity of bitterness increased after nanofiltration, indicating that small peptides associated with bitter taste were retained by the membrane. Total protein yield after microfiltration was 24%–29%, whereas 19%–24% were recovered in the nanofiltration retentate