Effects of whole seaweed consumption on humans: current evidence from randomized-controlled intervention trials, knowledge gaps, and limitations.

Seaweed is often recognized for its potential health benefits, attributed to its abundance of dietary fibers, protein, and polyphenols. While human observational studies have shown promise, the collective evidence from human intervention trials remains limited. This narrative review aims to comprehensively analyze the effects of seaweed intake on humans, while critically assessing the methodology, including Cochrane risk-of-bias assessment. A search was conducted in online databases, including PubMed, Scopus, and Google Scholar, covering the period from 2000 to May 2023. The focus was on randomized controlled clinical trials (RCTs) evaluating the impact of whole seaweed, either consumed as capsules, integrated into food products or as part of meals. Various health outcomes were examined, including appetite, anthropometric measures, cardiometabolic risk factors, thyroid function, markers of oxidative stress, and blood mineral concentrations. Out of the 25 RCTs reviewed, the findings revealed limited yet encouraging evidence for effects of seaweed on blood glucose metabolism, blood pressure, anthropometric measures, and, to a lesser extent, blood lipids. Notably, these favorable effects were predominantly observed in populations with type-2 diabetes and hypertension. Despite most trials selecting a seaweed dose aligning with estimated consumption levels in Japan, considerable variability was observed in the pretreatment and delivery methods of seaweed across studies. Moreover, most studies exhibited a moderate-to-high risk of bias, posing challenges in drawing definitive conclusions. Overall, this review highlights the necessity for well-designed RCTs with transparent reporting of methods and results. Furthermore, there is a need for RCTs to explore seaweed species cultivated outside of Asia, with a specific emphasis on green and red species. Such studies will provide robust evidence-based support for the growing utilization of seaweed as a dietary component in regions with negligible seaweed consumption, e.g., Europe.

Structural and functional properties of collagen isolated from lumpfish and starfish using isoelectric precipitation vs salting out.

The possibility of replacing the very time and resource demanding salting out (SO) method with isoelectric precipitation (IP) during collagen extraction from common starfish and lumpfish was investigated. The effect of IP on yield, structural and functional properties of the collagens was therefore compared with SO. Application of IP resulted in a higher or similar collagen mass yield compared with SO from starfish and lumpfish, respectively. However, the purity of collagens recovered with IP was lower than those recovered with SO. Replacing SO with IP did not affect polypeptide pattern and tropohelical structural integrity of collagen from the two resources as revealed with SDS-PAGE and FTIR analysis. Thermal stability and fibril formation capacity of collagens recovered with IP were also well preserved. Overall, the results showed that the IP can be a promising resource smart alternative for the classic SO precipitation during collagen extraction from marine resources.

Pilot-Scale Antioxidant Dipping of Herring (Clupea harengus) Co-products to Allow Their Upgrading to a High-Quality Mince for Food Production.

To enable production of high-quality mince from herring backbones, a scalable antioxidant strategy is needed due to the high susceptibility of herring muscle to lipid oxidation. We here measured the stabilizing effect of lab-/pilot-scale predipping of herring backbones (30-500 kg) in antioxidant solutions prior to production of mechanically separated mince (MSM). The antioxidants were (i) Duralox MANC, a mixture of rosemary extract, ascorbic acid, α-tocopherol, and citric acid, and (ii) rosemary extract with or without isoascorbic acid. Delivery of the key rosemary-derived antioxidant components carnosol and carnosic acid was monitored during the dipping process and ice/frozen storage. Predipping in 2% Duralox MANC gave MSM with 26.7-31.7 mg/kg carnosol + carnosic acid and extended the oxidation lag phase from <1 to 12 days during ice storage and from <1 to 6 months during frozen storage compared to control. Dipping in 0.2% rosemary extract with or without 0.5% isoascorbic acid solution gave MSM with 20.6-28.2 mg/kg carnosol + carnosic acid and extended the lag phase to 6 days and 9 months during ice and frozen storage, respectively. Our results confirmed, in pilot scale, that predipping herring coproducts in antioxidant solutions is a promising strategy to utilize these raw materials for, e.g., mince and burger production rather than for low value products as fish meal.

Radial discharge high shear homogenization and ultrasonication assisted pH-shift processing of herring co-products with antioxidant-rich materials for maximum protein yield and functionality.

Cross-processing herring co-products with antioxidant-rich helpers including lingonberry-press-cake, shrimp-shells and seaweed was reported to mitigate lipid oxidation but reduce protein yield. Here, four strategies were used to counteract such yield-reduction; optimizing solubilization/precipitation pH, increasing raw-material-to-water-ratio, replacing single-stage-toothed- by radial-discharge- high-shear-mechanical-homogenization (RD-HSMH) and ultrasonication (US). The effects of RD-HSMH and US on lipid oxidation, protein structural and functional properties were studied. Combining four strategies improved total protein yield by 5-12 %, depending on helper type. More than the confirmed antioxidant effects, cross-processing also improved protein water solubility and emulsification activity but reduced gelation properties. RD-HSMH generally improved protein emulsifying and gelation properties but reduced protein water solubility. US reduced protein water solubility and gelation properties. Altogether, it was recommended for all helpers to increase solubilization pH to 12 and raw-material-to-water-ratio to 1:6 followed by RD-HSMH at 8000 rpm for 90 s, aiming for maximum protein yield and emulsifying and gelation properties.

Lower Non-Heme Iron Absorption in Healthy Females from Single Meals with Texturized Fava Bean Protein Compared to Beef and Cod Protein Meals: Two Single-Blinded Randomized Trials.

Meat analogs based on plant protein extracts are rising in popularity as meat consumption declines. A dietary shift away from meat, which has a high iron bioavailability, may have a negative effect on the amount of iron absorbed from the diet. Iron absorption from legumes cultivated in regions not suitable for soy production, such as fava bean, has not yet been explored. The aim of this study was to evaluate non-heme iron absorption from a meal with texturized fava bean protein compared to beef and cod protein meals. The study included two single-blinded iron isotope trials in healthy Swedish women of the ages 18-45 years, each of whom served as their own control. The participants were served matched test meals containing beef and fava bean protein (Study 1) or cod and fava bean protein (Study 2) with radiolabeled non-heme iron 55Fe and 59Fe. The absorption of non-heme iron from test meals was measured by whole-body counting and erythrocyte incorporation. The absorption of non-heme iron, measured as erythrocyte incorporation ratio, from beef protein meal was 4.2 times higher compared to texturized fava bean meal, and absorption from cod protein meal was 2.7 times higher compared to the fava bean meal. The adjusted non-heme iron absorption, normalized to a 40% reference dose uptake, was 9.2% for cod protein meal, 21.7% for beef protein meal, and 4.2% for texturized fava bean meal. A fava bean protein meal has markedly lower iron bioavailability in healthy females compared with a meal of beef or cod protein. Therefore, a dietary shift from meat and fish protein to fava bean protein may increase the risk of iron deficiency.

Pilot-Scale Ensilaging of Herring Filleting Co-Products and Subsequent Separation of Fish Oil and Protein Hydrolysates.

In this study, ensilaging of herring (Clupea harengus) filleting co-products was taken from lab-scale to pilot scale (1500 L) while monitoring the protein degree of hydrolysis (DH) and lipid oxidation. Subsequently, the possibility of recovering fish oil and protein hydrolysates using batch centrifugation at different g-forces/times was investigated. Around 38% DH was recorded after 2-day pilot-scale ensilaging of herring co-products at ambient temperature (i.e., ~ 22 °C), which was similar to the DH found in lab-scale (40% after 2 days; 22 °C). The lipid oxidation marker 2-thiobarbituric acid reactive substances (TBARS) reached 20 µmole TBARS/kg silage after 2-day ensilaging. Centrifugation of the silage at 3000-8500 × g for 2-20 min revealed successful separation into fish oil and protein hydrolysates. Heat-treating the silage (85 °C; 30 min) prior to centrifugation resulted in significantly higher oil and hydrolysates recoveries; the same being true for increased g-force. At 8500 × g, the recovery of oil and hydrolysates were 9.7 and 53.0% w/w, respectively, from heat-treated silage, while recoveries were 4.1 and 48.1% w/w, respectively, from non-heat treated silage. At 4500 × g, being a more scalable approach, corresponding numbers were 8.2 and 47.1% (w/w) as well as 2.0 and 40.2% (w/w). The recovered fish oil contained 8% EPA and 11% DHA of total fatty acids. Free fatty acids (FFA), peroxide value (PV), p-anisidine value (p-AV), and total oxidation (TOTOX) values of oils were in the range of 4-7% (FFA), 3.6-3.7 meq/kg oil (PV), 2.5-4.0 (p-AV), and 9.9-11.1 (TOTOX), respectively, which were within the acceptable limits for human consumption specified by the GOED voluntary monograph. The recovered protein hydrolysates contained peptides in the molecular weight range 0.3-6 kDa (~ 37%) and 11-34 kDa (~ 63%). Also, the remaining solids contained 15-17% (w/w) protein, having 44-45% essential amino acids. Overall, the results suggest that herring co-product silage is a valuable source of fish oil and protein hydrolysates, paving the way for ensilaging based-biorefining of herring co-products into multiple products. Supplementary Information: The online version contains supplementary material available at 10.1007/s11947-022-02870-9.

Pro-oxidative activity of trout and bovine hemoglobin during digestion using a static in vitro gastrointestinal model.

The degradation of trout and bovine hemoglobin (Hb) and their pro-oxidant activities in washed cod muscle mince (WCM) were studied using simple pH-shifts to simulate gastrointestinal (GI) conditions (pH 7 â†’ 6 â†’ 3 â†’ 7), as well as full static in vitro GI digestion. Following gastric acidification to pH 6, metHb formation increased, especially for trout Hb. Subsequent acidification to pH 3 promoted Hb unfolding and partial or complete heme group-loss. During full GI digestion, polypeptide/peptide analyses revealed more extensive Hb-degradation in the gastric than duodenal phase, without any species-differences. When digesting WCM +/-Hb, both Hbs strongly promoted malondialdehyde (MDA), 4-hydroxy-2-hexenal (HHE), and 4-hydroxy-2-nonenal (HNE) formation, peaking at the end of the gastric phase. Trout-Hb stimulated MDA and HHE more than bovine Hb in the first gastric phase. Altogether, partially degraded Hb, and/or free hemin -both mammal and fish-derived- stimulated oxidation of PUFA-rich lipids under GI-conditions, especially gastric ones.

Resource efficient collagen extraction from common starfish with the aid of high shear mechanical homogenization and ultrasound.

Processes currently used for collagen extraction are complicated requiring a great deal of time and chemicals. Here, high shear mechanical homogenization (HSMH) and ultrasound (US) were integrated in the pretreatment step of collagen extraction from common starfish to reduce chemical use and time consumption. Effects of the assistant technologies on yield, structural integrity and functionality of collagen were also investigated. HSMH reduced the deproteinization time from 6 h to 5 min and its required amount of alkali 4 times, compared with classic methods. HSMH + US reduced the demineralization time from 24 h to 12 h and improved its efficiency in extraction of minerals. Collagen extraction with HSMH and HSMH + US resulted in similar yield as the classic method and did not affect triple helical structural integrity, polypeptide pattern, thermal stability or fibril-formation capacity of the collagens. Altogether, HSMH and US can effectively improve resource efficiency during collagen extraction without imposing negative effect on collagen quality.

Effect of antioxidants on lipid oxidation in herring (Clupea harengus) co-product silage during its production, heat-treatment and storage.

Provided high product quality, ensilaging can be used to valorize fish filleting co-products into a silage suitable for food applications. However, a documented challenge for products from hemoglobin-rich fish raw materials is the high susceptibility to lipid oxidation, calling for stabilization by antioxidants. In a comparison among different rosemary-containing antioxidants and isoascorbic acid, we here found that the commercial mixture Duralox MANC-213 (MANC) provided the best protection against peroxide value and 2-thiobarbituric acid reactive substances (TBARS) development during ensilaging of herring filleting co-products (0-7 days, 22 °C), and also during subsequent heat-treatment (30 min, 85 °C). Increasing MANC concentration from 0.25 and 0.75 to 1.25% lowered TBARS values from 43.53 and 25.12 to 18.04 µmole TBARS/Kg silage, respectively, after 7 days of ensilaging. During storage at 4 °C/22 °C in presence of MANC, 1.25% provided the highest protection with 87-90% and 66-73% lower TBARS, at 4 °C and 22 °C, respectively, at 6 months compared to the controls. At this time point, heat-treated silages had lower protein degree of hydrolysis and free amino acids values than the non-heat-treated one. Regardless of antioxidant addition, total volatile basic nitrogen (TVB-N) formation still increased during the storage, but, overall, TVB-N values in silages were below the acceptable limit of 30 mg TVB-N/100 g fish for human consumption. Together with lipid oxidation data, this suggest that herring silage produced in presence of antioxidants can be used both for high quality feed and food applications.

Lipid oxidation and antioxidant delivery systems in muscle food.

Lipid oxidation accelerates quality deterioration in muscle-based foods (fish, red meat, and poultry), resulting in off-odors/flavors, color problems, texture defects, and safety concerns. Adding antioxidants is one approach to control lipid oxidation, and several delivery strategies have been applied, such as supplementing antioxidants to the feed, direct mixing into minces, or, for whole muscle pieces; spraying, glazing, and injection. However, some issues linked to these technologies hinder their wide utilization, such as low effectiveness, noncompatibility with clean label, and off-flavor. These shortcomings have promoted the development of new antioxidant delivery technologies. In this review, the main focus is on the principles, characteristics, and implementation of five novel antioxidant delivery methods in different types of muscle food products. Their advantages and drawbacks are also summarized, plus comments about future trends in this area. Among novel routes to deliver antioxidants to muscle foods are, for whole tissues, recyclable dipping solutions; for minces, encapsulation; and, for both minces and whole tissues, cross-processing with nonmuscle antioxidant-containing raw materials as well as applications of edible films/coatings and active packaging. Advantages of these technologies comprise, for example, low price, the possibility to control the antioxidant release rate, overcoming strong aromas from natural antioxidants, and allowing antioxidant-containing raw materials from the food industry to be valorized, providing an opportunity for more circular food production.

Effect of recovery technique, antioxidant addition and compositional features on lipid oxidation in protein enriched products from cod- salmon and herring backbones.

The influence of recovery technique (pH-shift processing vs mechanical separation), antioxidant addition and endogenous factors on lipid oxidation in protein-enriched products from herring, salmon and cod backbones was investigated. Salmon-derived products were very stable during both ice and -20 °C storage. Contrary, peroxide value and TBA-reactive substances in herring- and cod-derived products increased rapidly during ice storage, with the pH-shift-produced protein isolates (PI) being most susceptible to oxidation in case of cod. Duralox MANC (0.5%) however largely increased the oxidation lag phase in both PI and mechanically separated meat (MSM); from <1 day to >15 days. At -20 °C, mainly the herring products oxidized, and particularly the MSM. Pearson correlation tests showed that endogenous levels of Hb, total Fe, ascorbic acid and α-tocopherol correlated significantly (p < 0.05) with lipid oxidation development. Evaluating the role of pre-processing storage indicated that fish co-products should be processed immediately after the filleting process unless antioxidants are added.

A novel cold biorefinery approach for isolation of high quality fish oil in parallel with gel-forming proteins.

The pH-shift process for isolation of gel-forming proteins from fish processing by-products was extended to allow parallel isolation of fish oil. Subjecting the floating emulsion layer formed during pH-shift processing of salmon by-products to pH-adjustment or freeze/thawing efficiently released the emulsified oil at 4 °C. However, for herring by-products higher temperature (10 °C) and a combination of the emulsion-breaking techniques was required for efficient oil release. Oil recovery yield using the adjusted pH-shift process was lower than with classic heat-induced oil isolation (90 °C/20 min), but pH-shift-produced oils had higher amounts of n-3 polyunsaturated fatty acids (n-3 PUFA). Also, alkaline pH-shift processing produced oils with remarkably less oxidation products and free fatty acids compared with acid pH-shift process or heat-induced isolation. Extending the pH-shift process with emulsion breaking techniques can thus be a promising biorefinery approach for parallel cold production of high-quality fish oil and gel-forming proteins from fish by-products.

Effect of antioxidants on the sensory quality and physicochemical stability of Atlantic mackerel (Scomber scombrus) fillets during frozen storage.

This study aimed to evaluate the shelf-life of mechanically filleted well-fed Atlantic mackerel during frozen storage at -25 °C and effect of treatment with antioxidants (sodium erythorbate and a polyphosphate mixture) and different antioxidant application methods (dipping, spraying and glazing). Both physicochemical measurements and sensory analysis were applied. Antioxidant treatments prolonged shelf-life of mackerel. Sensory analysis indicated that untreated fillets had a shelf-life of less than 2.5 months, while all antioxidant treated fillets exceeded that. The most effective treatment, dipping fillets into a sodium erythorbate solution, yielding a shelf-life of 15 months. Physicochemical methods used to evaluate degradation of lipids in the fillets were free fatty acids (FFA), lipid hydroperoxides (PV) and thiobarbituric acid reactive substances (TBARS). They did not correlate with sensory results and might therefore be a questionable choice for evaluation of oxidation and development of rancid flavour and odour in complex matrixes such as Atlantic mackerel.

Stabilization of herring (Clupea harengus) by-products against lipid oxidation by rinsing and incubation with antioxidant solutions.

To allow value adding into foods, stabilizing strategies for fish by-products are needed based on their high susceptibility to hemoglobin (Hb)-mediated lipid oxidation. Here, three strategies for preventing lipid oxidation in herring (Clupea harengus) by-products during ice-storage were studied: (i) rinsing away Hb with water or 0.9% NaCl with/without antioxidants (Duralox-MANC, erythorbate and ethylenediamine-tetraacetic acid (EDTA)), (ii) incubation in water/0.9% NaCl with/without antioxidants, (iii) mincing with subsequent addition of the mentioned antioxidants. Only 10-18% Hb was rinsed away in (i), and the effect of this rinsing on peroxide value (PV) or TBA-reactive substances (TBARS) development was limited. Rinsing or incubating by-products in antioxidant solutions however significantly (p ≤ 0.05) increased shelf life from <1 day to >12 days; Duralox-MANC was particularly efficient. The presented strategies could hereby facilitate more diversified end-use of herring by-products from being 100% feed, to include also high-quality minces, protein isolates or oils for the food industry.

Oxidation of marine oils during in vitro gastrointestinal digestion with human digestive fluids - Role of oil origin, added tocopherols and lipolytic activity.

The formation of malondialdehyde (MDA), 4-hydroxy-2-hexenal (HHE), 4-hydroxy-2-nonenal (HNE), and 4-oxo-2-nonenal (ONE) in cod liver-, anchovy-, krill-, and algae oil during in vitro digestion with human gastrointestinal fluids was investigated. Adding rabbit gastric lipase, lipase inhibitor (orlistat) and tocopherols to cod liver oil, lipolysis and oxidation was also studied. Among the marine oils, the highest aldehyde levels (18 µM MDA, 3 µM HHE and 0.2 µM HNE) were detected after digestion of cod liver oil, while the lowest levels were detected in krill and algae oils. Addition of rabbit gastric lipase significantly increased the release of HNE during the digestion. Orlistat significantly reduced lipolysis and MDA formation. Formation of MDA and HHE was delayed by tocopherols, the tocopherol mix Covi-ox® T 70 EU being more effective than pure α-tocopherol.

Correction: Formation of reactive aldehydes (MDA, HHE, HNE) during the digestion of cod liver oil: comparison of human and porcine in vitro digestion models.

Correction for 'Formation of reactive aldehydes (MDA, HHE, HNE) during the digestion of cod liver oil: comparison of human and porcine in vitro digestion models' by Cecilia Tullberg et al., Food Funct., 2016, 7, 1401-1412.

Malondialdehyde and 4-hydroxy-2-hexenal are formed during dynamic gastrointestinal in vitro digestion of cod liver oils.

Marine long-chain polyunsaturated fatty acids (LC n-3 PUFA) are associated with reduced risk for inflammatory diseases, such as cardiovascular diseases and rheumatoid arthritis. These fatty acids, however, are rapidly oxidized, generating highly reactive malondialdehyde (MDA), 4-hydroxy-2-hexenal (HHE) and 4-hydroxy-2-nonenal (HNE). These oxidation products may interact with DNA and proteins, thus possibly leading to impaired cell functions. Little is known about the formation of MDA, HHE and HNE in fish oil in the gastrointestinal (GI) tract. In this study, the effect of dynamic in vitro digestion of cod liver oil on the generation of MDA, HHE and HNE was evaluated using the TNO Gastro-Intestinal Model (tiny-TIM). Effects of pre-formed oxidation products, pre-emulsification of the oil, and addition of oxidants (EDTA and hemoglobin, Hb) on GI oxidation were evaluated. Formation of aldehydes occurred during GI digestion. However, only emulsified oil fortified with 11.5 µM Hb oxidized to a degree that overcame the dilution induced by gastric secretion, which caused increased aldehyde concentrations in gastric lumen up to 90 min. The maximum levels of aldehydes generated in this study were 24.5 µM MDA, 1.6 µM HHE and 0.07 µM HNE. Oils containing different amounts of pre-formed lipid oxidation products maintained the same oxidation ranking order during digestion, even though the relative changes were not directly proportional. Emulsification of the oil had an unclear effect in the gastric phase, but a pro-oxidative effect in the intestinal phase. In general, higher aldehyde levels were reached in the intestinal lumen than in the initial meal, demonstrating that GI digestion promotes oxidation. Hence, epithelial cells may be exposed to elevated amounts of reactive aldehydes for several hours after a meal containing fish oil.

Formation of reactive aldehydes (MDA, HHE, HNE) during the digestion of cod liver oil: comparison of human and porcine in vitro digestion models.

In this work, we investigated lipid oxidation of cod liver oil during gastrointestinal (GI) digestion using two types of in vitro digestion models. In the first type of model, we used human GI juices, while we used digestive enzymes and bile from porcine origin in the second type of model. Human and porcine models were matched with respect to factors important for lipolysis, using a standardized digestion protocol. The digests were analysed for reactive oxidation products: malondialdehyde (MDA), 4-hydroxy-trans-2-nonenal (HNE), and 4-hydroxy-trans-2-hexenal (HHE) by liquid chromatography/atmospheric pressure chemical ionization-mass spectrometry (LC/APCI-MS), and for free fatty acids (FFA) obtained during the digestion by gas chromatography-mass spectrometry (GC-MS). The formation of the oxidation products MDA, HHE, and HNE was low during the gastric digestion, however, it increased during the duodenal digestion. The formation of the oxidation products reached higher levels when digestive juices of human origin were used (60 µM of MDA, 9.8 µM of HHE, and 0.36 µM of HNE) [corrected] compared to when using enzymes and bile of porcine origin (0.96, and 1.6 µM of MDA; 0.16, and 0.23 µM of HHE; 0.026, [corrected] and 0.005 µM of HNE, respectively, in porcine models I and II). In all models, FFA release was only detected during the intestinal step, and reached up to 31% of total fatty acids (FA). The findings in this work may be of importance when designing oxidation oriented lipid digestion studies.

Formation of malondialdehyde (MDA), 4-hydroxy-2-hexenal (HHE) and 4-hydroxy-2-nonenal (HNE) in fish and fish oil during dynamic gastrointestinal in vitro digestion.

Marine lipids contain a high proportion of polyunsaturated fatty acids (PUFA), including the characteristic long chain (LC) n-3 PUFA. Upon peroxidation these lipids generate reactive products, such as malondialdehyde (MDA), 4-hydroxy-2-hexenal (HHE) and 4-hydroxy-2-nonenal (HNE), which can form covalent adducts with biomolecules and thus are regarded as genotoxic and cytotoxic. PUFA peroxidation can occur both before and after ingestion. The aim of this study was to determine what levels of MDA, HHE and HNE can evolve in the gastric and intestinal lumen after ingesting meals containing fish or fish oil using a dynamic gastrointestinal (GI) model (TIM). The impact of the fish muscle matrix, lipid content, fish species, and oven baking on GI oxidation was evaluated. MDA and HHE concentrations in gastric lumen increased for all meals during digestion, with the highest level found with herring mince; ∼ 25 µM MDA and ∼ 850 nM HHE. Aldehyde concentrations reached in intestinal lumen during digestion of fish containing meals were generally lower than in gastric lumen, while isolated herring oils (bulk and emulsified) generated higher MDA and HHE values in intestinal lumen compared to gastric lumen. Based on aldehyde levels in gastric lumen, meals containing herring lipids were ranked: raw herring (17% lipid) = baked herring (4% lipid) > raw herring (4% lipid) ≫ herring oil emulsion > herring oil. Herring developed higher concentrations of MDA and HHE during gastric digestion compared to salmon, which initially contained lower levels of oxidation products. Cooked salmon generated higher MDA concentrations during digestion than raw salmon. Low levels of HNE were observed during digestion of all test meals, in accordance with the low content of n-6 PUFA in fish lipids.

The ability of in vitro antioxidant assays to predict the efficiency of a cod protein hydrolysate and brown seaweed extract to prevent oxidation in marine food model systems.

BACKGROUND: The ability of different in vitro antioxidant assays to predict the efficiency of cod protein hydrolysate (CPH) and Fucus vesiculosus ethyl acetate extract (EA) towards lipid oxidation in haemoglobin-fortified washed cod mince and iron-containing cod liver oil emulsion was evaluated. The progression of oxidation was followed by sensory analysis, lipid hydroperoxides and thiobarbituric acid-reactive substances (TBARS) in both systems, as well as loss of redness and protein carbonyls in the cod system. RESULTS: The in vitro tests revealed high reducing capacity, high DPPH radical scavenging properties and a high oxygen radical absorbance capacity (ORAC) value of the EA which also inhibited lipid and protein oxidation in the cod model system. The CPH had a high metal chelating capacity and was efficient against oxidation in the cod liver oil emulsion. CONCLUSION: The results indicate that the F. vesiculosus extract has a potential as an excellent natural antioxidant against lipid oxidation in fish muscle foods while protein hydrolysates are more promising for fish oil emulsions. The usefulness of in vitro assays to predict the antioxidative properties of new natural ingredients in foods thus depends on the knowledge about the food systems, particularly the main pro-oxidants present.