Near-Infrared Spectroscopy and Chemometrics for Effective Online Quality Monitoring and Process Control during Pelagic Fishmeal and Oil Processing.

Near-infrared spectroscopy has become a common quality assessment tool for fishmeal products during the last two decades. However, to date it has not been used for active online quality monitoring during fishmeal processing. Our aim was to investigate whether NIR spectroscopy, in combination with multivariate chemometrics, could actively predict the changes in the main chemical quality parameters of pelagic fishmeal and oil during processing, with an emphasis on lipid quality changes. Results indicated that partial least square regression (PLSR) models from the NIR data effectively predicted proximate composition changes during processing (with coefficients of determination of an independent test set at RCV2 = 0.9938, RMSECV = 2.41 for water; RCV2 = 0.9773, RMSECV = 3.94 for lipids; and RCV2 = 0.9356, RMSECV = 5.58 for FFDM) and were successful in distinguishing between fatty acids according to their level of saturation (SFA (RCV2=0.9928, RMSECV=0.24), MUFA (RCV2=0.8291, RMSECV=1.49), PUFA (RCV2=0.8588, RMSECV=2.11)). This technique also allowed the prediction of phospholipids (PL RCV2=0.8617, RMSECV=0.11, and DHA (RCV2=0.8785, RMSECV=0.89) and EPA content RCV2=0.8689, RMSECV=0.62) throughout processing. NIR spectroscopy in combination with chemometrics is, thus, a powerful quality assessment tool that can be applied for active online quality monitoring and processing control during fishmeal and oil processing.

Protein Characteristics and Bioactivity of Fish Protein Hydrolysates from Tra Catfish (Pangasius hypophthalmus) Side Stream Isolates.

Enzymatic hydrolysis is a novel method to recover highly potent bioactive fish protein hydrolysates (FPHs) from fish processing side-streams. The common way of producing FPHs directly from fish side-streams may be inappropriate due to the excess of lipids and pro-oxidants, especially in lipid-rich streams, as obtained from Tra catfish. This study aimed to optimise the hydrolysis conditions for a commercial enzyme (Alcalase® 2.4 L) (enzyme concentrate, temperature, and time) in FPH production from the fish protein isolate obtained from Tra catfish dark muscle (DM-FPI) using the pH-shift method. The degree of hydrolysis (DH), protein recovery (PR), and antioxidant properties, including DPPH radical scavenging activity (DPPH-RSA) and total reducing power capacity (TRPC), were measured to evaluate the effects of the hydrolysis conditions on the FPHs. Optimal hydrolysis was obtained at an enzyme/substrate protein ratio of 3% (v/w) and a hydrolysis temperature of 50 °C for 3 h. The FPHs obtained from different substrates, including DM-FPI, abdominal cut-off (ACO) FPI, and head and backbone blend (HBB) FPI, had similar DHs under these optimum conditions, ranging from 22.5% to 24.0%. However, the FPH obtained from abdominal cut-off isolate (ACO-FPH) showed the highest PR of 81.5 ± 4.3% and the highest antioxidant properties, with a DPPH-RSA of 86.1 ± 1.6% and a TRPC of 6.4 ± 0.4 equivalent mg vitamin C/g protein. The resulting FPHs present a natural source of antioxidants with great potential for food applications, especially the ACO-FPH. In addition, all FPHs had excellent amino acid profiles, indicating strong potential for their use as supplements. Tra catfish protein-rich side-streams can thus be processed into high-value bioactive FPHs using Alcalase for human consumption.

Protein Recovery of Tra Catfish (Pangasius hypophthalmus) Protein-Rich Side Streams by the pH-Shift Method.

Increasing protein demand has led to growing attention being given to the full utilization of proteins from side streams in industrial fish processing. In this study, proteins were recovered from three protein-rich side streams during Tra catfish (Pangasius hypophthalamus) processing (dark muscle; head-backbone; and abdominal cut-offs) by an optimized pH-shift process. Physicochemical characteristics of the resulting fish protein isolates (FPIs) were compared to industrial surimi from the same raw material batch. The pH had a significant influence on protein extraction, while extraction time and the ratio of the extraction solution to raw material had little effect on the protein and dry matter recoveries. Optimal protein extraction conditions were obtained at pH 12, a solvent to raw material ratio of 8, and an extraction duration of 150 min. The resulting FPI contained <10% of the fat and <15% of the ash of the raw material, while the FPI protein recovery was 83.0−88.9%, including a good amino acid profile. All FPIs had significantly higher protein content and lower lipid content than the surimi, indicating the high efficiency of using the pH-shift method to recover proteins from industrial Tra catfish side streams. The FPI made from abdominal cut-offs had high whiteness, increasing its potential for the development of a high-value product.

Added Value of Ascophyllum nodosum Side Stream Utilization during Seaweed Meal Processing.

Ascophyllum nodosum contains many valuable compounds, including polyphenols, peptides, and carotenoids that have been shown to exhibit biological activities. These compounds are not a priority ingredient in seaweed meal products for the current users. Hence, the aim of the study was to investigate the chemical and bioactive characteristics of A. nodosum as affected by seasonal variation and evaluate the potential benefits of alternative processing and the utilization of side streams for product development. The analysis of raw materials, press liquid, and press cake from alternative processing and the commercial seaweed meal at different harvesting periods indicated that the chemical composition is linked to the reproductive state of the algae. Phenolic content and ORAC activity increased following the seaweed's fertile period, making alternative processing more promising in July and October compared to June. Several valuable ingredients were obtained in the press liquid, including polyphenols, which can be used in the development of new high-value bioactive products. The suggested alternative processing does not have a negative effect on the composition and quality of the current seaweed meal products. Hence, the extraction of valuable ingredients from the fresh biomass during the processing of seaweed meal could be a feasible option to increase the value and sustainability of seaweed processing.

Biochemical characteristics of zooplankton entering Atlantic mackerel processing plants in Iceland as side-catch.

The Northeast Atlantic mackerel (Scomber scombrus) is a zooplanktivorous fish with its main summer feeding grounds in the waters around Iceland. The zooplankton in the stomachs of the caught fish causes several problems during processing due to the high enzyme activity of the zooplankton. The aim of the study was to evaluate the chemical characteristics of zooplankton that accompanies mackerel as a side-catch and stomach fullness as affected by catching year, season, catching zone, and catching method over three mackerel seasons from 2016 to 2018. Species identification by the fatty acid tropic marker method (FATM) was also applied within the zooplankton rich side-stream. FATM analysis indicated that the majority of the zooplankton mass belonged to Calanus finmarchicus. The lipid composition of the zooplankton rich side-stream varied between years but was rich in monounsaturated, as well as polyunsaturated fatty acids (PUFA), such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). The results suggest that the zooplankton rich side-stream from mackerel caught in Icelandic waters has the potential for further sustainable processing into valuable nutrients.

Onboard Evaluation of Variable Water Flow and Recirculation Effects on Bleeding of Atlantic Cod (Gadus morhua).

The aim of the study was to explore the effects of different design variables in the onboard bleeding process of cod on bleeding efficiency and the resulting product quality. A time- and flow-controlled process was used to create variable bleeding conditions for whole gutted cod onboard a wet-fish trawler. Two main design variables influencing the bleeding process are the pump flow recirculation (PFR) and the water replacement ratio (WRR); they were studied in five different combinations (groups). The effects of different bleeding conditions were evaluated by measurements of free fatty acids (FFAs), phospholipids (PLs), and total heme iron (HI) content during freezer storage for up to four months. The results for PL content and the regression model indicate that the enzyme activity in the fish muscle is lower in cases where PFR exerts greater influence in the bleeding process than WRR. The effects of successful blood removal also seem to be most noticeable after one month of freezer storage, rather than in fresh cod after seven days or after four months of simulated frozen food-chain storage. The study indicates that, with the bleeding medium to fish ratio of around 3:1 and enough WRR (over 100% replacement in 20 min), the PFR becomes the limiting design parameter regarding efficient blood removal and should be at least 10% of the tank volume per minute to ensure enough recirculation and flow of water in the bleed-out tanks.

The use of the so-called 'tubs' for transporting and storing fresh fishery products.

On-land transport/storage of fresh fishery products (FFP) for up to 3 days in 'tubs' of three-layered poly-ethylene filled with freshwater and ice was compared to the currently authorised practice (fish boxes of high-density poly-ethylene filled with ice). The impact on the survival and growth of biological hazards in fish and the histamine production in fish species associated with a high amount of histidine was assessed. In different modelling scenarios, the FFP are stored on-board in freshwater or seawater/ice (in tubs) and once on-land they are 'handled' (i.e. sorted or gutted and/or filleted) and transferred to either tubs or boxes. The temperature of the FFP was assumed to be the most influential factor affecting relevant hazards. Under reasonably foreseeable 'abusive' scenarios and using a conservative modelling approach, the growth of the relevant hazards (i.e. Listeria monocytogenes, Aeromonas spp. and non-proteolytic Clostridium botulinum), is expected to be < 0.2 log10 units higher in tubs than in boxes after 3 days when the initial temperature of the fish is 0°C ('keeping' process). Starting at 7°C ('cooling-keeping' process), the expected difference in the growth potential is higher (< 1 log10 for A. hydrophila and < 0.5 log10 for the other two hazards) due to the poorer cooling capacity of water and ice (tub) compared with ice (box). The survival of relevant hazards is not or is negligibly impacted. Histamine formation due to growth of Morganella psychrotolerans under the 'keeping' or 'cooling-keeping' process can be up to 0.4 ppm and 1.5 ppm higher, respectively, in tubs as compared to boxes after 3 days, without reaching the legal limit of 100 ppm. The water uptake associated with the storage of the FFP in tubs (which may be up to 6%) does not make a relevant contribution to the differences in microbial growth potential compared to boxes.

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.

Developing a Sustainable and Circular Bio-Based Economy in EU: By Partnering Across Sectors, Upscaling and Using New Knowledge Faster, and For the Benefit of Climate, Environment & Biodiversity, and People & Business.

This paper gives an overview of development of the EU-bioeconomy, 2014-2020. The Vision of the new Circular Bio-based Economy, CBE is presented: Unlocking the full potential of all types of sustainably sourced biomass, crop residues, industrial side-streams, and wastes by transforming it into value-added products. The resulting product portfolio consists of a wide spectrum of value-added products, addressing societal and consumer needs. Food and feed, bio-based chemicals, materials, health-promoting products; and bio-based fuels. The pillars of CBE are described, including biotechnology, microbial production, enzyme technology, green chemistry, integrated physical/chemical processing, policies, conducive framework conditions and public private partnerships. Drivers of CBE are analyzed: Biomass supply, biorefineries, value chain clusters, rural development, farmers, foresters and mariners; urgent need for climate change mitigation and adaptation, and stopping biodiversity loss. Improved framework conditions can be drivers but also obstacles if not updated to the era of circularity. Key figures, across the entire BBI-JU project portfolio (2014-2020) are provided, including expansion into biomass feedstocks, terrestrial and aquatic, and an impressive broadening of bio-based product portfolio, including higher-value, health-promoting products for man, animal, plants and soil. Parallel to this, diversification of industrial segments and types of funding instruments developed, reflecting industrial needs and academic research involvement. Impact assessment is highlighted. A number of specific recommendations are given; e.g., including international win/win CBE-collaborations, as e.g., expanding African EU collaboration into CBE. In contrast to fossil resources biological resources are found worldwide. In its outset, circular bio-based economy, can be implemented all over, in a just manner, not the least stimulating rural development.

The influence of lipid content and pretreatment methods on protein conformation in fish (capelin, Mallotus villosus) during smoking and drying.

The influence of lipid content and pretreatment methods (blanching and brining) on proteins conformation in fish (Capelin, Mallotus villosus) during drying and smoking were assessed. Soluble protein fractions were examined through changes in salt-soluble proteins, sulfhydryl groups, and disulfide bonds contents. The salt level and moisture content were also evaluated. Conformational changes in muscle protein were significant (p < 0.05) after blanching and during initial drying when moisture content and dryness rates were high. Salt-soluble proteins and total sulfhydryl groups contents reduced, whereas available sulfhydryl group and disulfide bonds contents intensified. The conformational changes were explained by muscle protein denaturation and aggregation ascribed to high temperature and dehydration during processing. The study reports fish protein denaturation to have reduced protein solubility as well as the nutritional value (loss of thermolabile compounds) and yield after smoking. More so, protein aggregation that was significantly (p < 0.05) higher in dried blanched fish could have reduced the dried fish sensory quality. Blanching pretreatment is thus not suitable for commercial capelin drying. Lipids were found to have protective effect against fish protein conformation.

Low field nuclear magnetic resonance and multivariate analysis for prediction of physicochemical characteristics of Atlantic mackerel as affected by season of catch, freezing method, and frozen storage duration.

Fast and non-destructive prediction of the quality characteristics of food products during frozen storage are of great value both for the food industry and the consumers. The current study investigated the potential of using low field Nuclear Magnetic Resonance (NMR) along with multivariate chemometric methods to predict various important physicochemical quality parameters in Atlantic mackerel during frozen storage, as affected by season of catch, freezing method and temperature, as well as frozen storage duration. The obtained results clearly showed that transverse relaxation data obtained by low field NMR can be effectively used to simultaneously predict multiple quality characteristics of the mackerel fillets through storage, including water and lipid content, water holding capacity, lipid oxidation (peroxide value (PV), and thiobartituric reactive substances (TBARS)) and lipid hydrolysis (free fatty acids (FFA)) content within the muscle. The NMR data could furthermore be used to predict variations in the muscle due to season of catch, the frozen storage duration of the mackerel samples when all samples were used, and whether the fish had been headed and gutted or stored whole, which freezing equipment had been used, and the frozen storage temperature for mackerel samples caught at the end of July. Simplified monitoring and optimization of these quality parameters in frozen mackerel with a fast and non-destructive analytical technique like low field NMR is thus of great value for the fishing industry.

Stability of Golden redfish (Sebastes marinus) during frozen storage as affected by raw material freshness and season of capture.

Physicochemical changes of Icelandic golden redfish (Sebastes marinus) as affected by seasonal variation (June and November) and raw material freshness (processed 4 and 9 days postcatch) during frozen storage (at -25°C for 20 months) were studied to find optimal conditions for production of high-quality frozen products. Thawing loss, cooking yield, and color of the fillets as well as chemical composition, water holding capacity, pH, total volatile basic nitrogen, lipid oxidation, and hydrolysis of the light and dark muscle were analyzed every 4 months of frozen storage. Lipid hydrolysis was the main degradation process in the light muscle, while the dark muscle was more affected by lipid oxidation. Fish caught in November showed greater instability in the analyzed parameters during storage than fish caught in June, which could be linked to differences in individual poly unsaturated fatty acids between the two seasons. The quality attributes of fish processed on day 9 were similar to fish processed 4 days postcatch, except slightly higher thawing loss and yellowness, were observed in fish processed 9 days postcatch. Stability of golden redfish through frozen storage was higher in the fish caught in June than in November.

Influence of smoking and packaging methods on lipid stability and microbial quality of Capelin (Mallotus villosus) and Sardine (Sardinella gibossa).

Lipid and microbial quality of smoked capelin (two groups differing in lipid content) and sardine was studied, with the aim of introducing capelin in the smoked sardine markets. Lipid hydrolysis (phospholipid and free fatty acids) and oxidation index (hydroperoxides and thiobarbituric acid-reactive substances), fatty acid composition, and total viable count were measured in raw and packaged smoked fish during chilled storage (day 2, 10, 16, 22, 28). Lipid hydrolysis was more pronounced in low lipid capelin, whereas accelerated lipid oxidation occurred in high lipid capelin. Muscle lipid was less stable in sardine than capelin. Essential polyunsaturated fatty acids (eicosapentaenoic acid and docosahexaenoic acid) constituted 12% of fatty acids in capelin and 19% in sardine. Vacuum packaging as well as hot smoking retarded bacterial growth, recording counts of ≤log 5 CFU/g compared to ≥log 7CFU/g in cold smoked air packaged. Smoked low lipid capelin was considered an alternative for introduction in smoked sardine markets.

The effects of pre-salting methods on salt and water distribution of heavily salted cod, as analyzed by (1)H and (23)Na MRI, (23)Na NMR, low-field NMR and physicochemical analysis.

The effect of different pre-salting methods (brine injection with salt with/without polyphosphates, brining and pickling) on the water and salt distribution in dry salted Atlantic cod (Gadus morhua) fillets was studied with proton and sodium NMR and MRI methods, supported by physicochemical analysis of salt and water content as well as water holding capacity. The study indicated that double head brine injection with salt and phosphates lead to the least heterogeneous water distribution, while pickle salting had the least heterogeneous salt distribution. Fillets from all treatments contained spots with unsaturated brine, increasing the risk of microbial denaturation of the fillets during storage. Since a homogeneous water and salt distribution was not achieved with the studied pre-salting methods, further optimizations of the salting process, including the pre-salting and dry salting steps, must be made in the future.

Effect of thermal treatment and frozen storage on lipid decomposition of light and dark muscles of saithe (Pollachius virens).

Lipid decomposition of saithe (Pollachius virens) light and dark muscles was monitored during frozen storage at -25°C of raw (up to 18 months) and cooked products. Samples were cooked after 0, 6 and 12 months raw storage then refrozen and stored at -25°C for 12 months to determine the stability of cooked-then-stored samples. Fatty acid profiles, formation of hydroperoxides (PV), thiobarbituric acid reactive substances (TBARS), fluorescence compounds (OFR) and free fatty acids (FFA) were evaluated throughout the storage for all samples. In general, results indicated that enzymatic lipolysis was the driving factor influencing the quality of saithe over raw storage and it mostly affected polyunsaturated lipids in the light muscle. Cooking, however, inhibited FFA formation and induced formation of PV and TBARS. This behavior was more evident in samples cooked after long raw storage periods. The initial quality of the raw material before cooking is therefore critical with regard to oxidative stability of cooked fish products.

The application of near infrared spectroscopy to study lipid characteristics and deterioration of frozen lean fish muscles.

Near infrared spectroscopy (NIR) was applied to estimate lipid composition and degradation of two lean fish species, saithe (Pollachius virens) and hoki (Macruronus novaezelandiae). Calibration models were developed, using partial least squares (PLS) regression, for total lipid content and composition, free fatty acids (FFA), thiobarbituric acid reactive substances (TBARS) and fluorescent interaction compounds (OFR). Coefficients of determination for calibration (R(2)cv) and root-mean-square error of cross validation (RMSECV) ranged from 0.82 to 0.99 and 0.66 to 3.69 for hoki and from 0.64 to 0.99 and 0.06 to 2.65 for saithe, respectively. The validations of the calibrations indicated that lipid composition and FFA of hoki and saithe can be estimated by NIR with good accuracy. Furthermore, NIR differentiate fish muscles with low, medium and high concentration of OFR and TBARS. Overall, the results demonstrate the potential for use of NIR spectroscopy as an objective and non-destructive method to inspect the lipid characteristics and quality of frozen lean fish.

Effects of temperature during frozen storage on lipid deterioration of saithe (Pollachius virens) and hoki (Macruronus novaezelandiae) muscles.

Lipid deterioration of two lean fish species, saithe (Pollachius virens) and hoki (Macruronus novaezelandiae), during frozen storage at -20 and -30°C (up to 18months) was studied. Lipid composition, lipid oxidation and hydrolysis, and sensory attributes were evaluated on both light and dark muscles of the fish species. Results showed significant lipid deterioration with extended storage time, but lower storage temperature showed significantly more preservative effects. A marked difference was observed between the composition of dark muscle of hoki and saithe. Polyunsaturated fatty acids were the predominant lipids in dark muscle of saithe, while monounsaturated fatty acids were predominant in dark muscle of hoki. Further, the hydrolytic activity differed greatly between dark muscle of hoki and saithe, with significantly lower activity observed in hoki. Present results indicate that both tertiary lipid oxidation and hydrolysis products are appropriate for assessing lipid deterioration of saithe and hoki light muscle during frozen storage.

Injection of fish protein solutions of fresh saithe (Pollachius virens) fillets studied by low field Nuclear Magnetic Resonance and physicochemical measurements.

Low field Nuclear Magnetic Resonance was used in comparison to yield and physicochemical measurements to assess the effects of salt and protein injection on the properties of saithe (Pollachius virens) fillets during chilled and frozen storage. Saithe fillets injected with various combinations of salt, homogenized fish proteins, gelatine and fish protein hydrolyzate, were compared to the properties of untreated fillets. Addition of salt or fish protein hydrolyzate resulted in increased yield after cooking and water holding capacity compared to other treatments. Transversal relaxation data fitting resulted in three water populations with relaxation times of 27-45 ms, 60-99 ms and 187-341 ms. Relaxation times and respective populations showed significant correlation to various physicochemical properties, that muscle water behaviour was changed by salt and protein injection and indicated protein denaturation during frozen storage. Fish protein hydrolyzate injected fillets were most stable through storage, while gelatine injected fillets were most denatured during frozen storage.

Shelf life of air and modified atmosphere-packaged fresh tilapia (Oreochromis niloticus) fillets stored under chilled and superchilled conditions.

Optimal packaging and storage conditions for fresh tilapia fillets were established by evaluating sensory and microbiological changes, as well as monitoring physicochemical properties. Nile tilapia (Oreochromis niloticus) farmed in recirculation aquaculture system was filleted, deskinned, and packaged in air and 50% CO2/50% N2 prior to chilling and superchilling storage at 1°C and -1°C. Sensory analysis of cooked samples revealed a shelf life of 13-15 days for air-packaged fillets during storage at 1°C and 20 days at -1°C. At the end of shelf life in air-packaged fillets, total viable counts (TVC) and pseudomonads counts reached log 8 colony-forming units (CFU) g(-1). In 50% CO2/50% N2-packaged fillets, the lag phase and generation time of bacteria were extended and recorded counts were below the limit for consumption (

Characteristics of freeze-dried fish protein isolated from saithe (Pollachius virens).

Fish proteins isolated from by-products or low commercial/underutilized species using pH-shift process is a new source of proteins that may be used as wet or dried ingredients to develop value-added convenience foods. This paper reports the effects of freeze-drying on characteristics of fish protein isolates (FPI) from saithe (Pollachius virens) with or without lyoprotectants. Freeze-dried saithe mince from the same lot and without additives was used as a control. The resulting fish protein powders contained 71-93% protein, 1.5-3% moisture, 0-21% carbohydrate and 0.5-2% fat. Lipid oxidation (assessed by TBARS) of FPI powder groups was higher than that of fish mince powder. The results revealed that oxidation started during the pH-shift process and was increased by freeze-drying. Functional properties and sensory attributes were influenced by the advanced oxidation. However, the mince powder was less oxidized and had higher functional properties such as water binding capacity, gel forming ability, emulsification, foaming properties and colour and lower sensory scores for rancid odour and flavour than the FPI powders. Further studies on how to prevent oxidation of fish flesh during pH-shift and drying processes are recommended.