The use of tunicate (Ciona intestinalis) as a sustainable protein source in fish feed – Effects on the extrusion process, physical pellet quality and microstructure

The aim of this research was to study the effect of the replacement of fishmeal (FM) or soy protein concentrate (SPC) by tunicate meal (Ciona intestinalis) on the extrusion process, physical pellet quality, pellet expansion, and microstructure. The experiment was based on a 3-component simplex-centroid mixture design. Models with R2 in the range of 0.574–0.999 (P = 0.03 to < 0.0001) were established for specific mechanical energy (SME), temperature behind extruder die (Tdie), apparent dough viscosity in the extruder die (Vdie), pellet hardness, durability, expansion, and microstructure parameters. Increase in SME and Tdie were mainly explained by the reduced lipid content in the feed mix due to the replacement of FM with tunicate or SPC. Reduced Vdie was mainly an effect of increased tunicate level and with the lowest value found for the pure tunicate blend. There was an increase in volumetric expansion and open porosity by replacement of SPC with tunicate, explained by this decrease in Vdie. Reduced hardness and durability were found for blends high in SPC due to incomplete plasticisation. Extrudate expansion, fat adsorption capacity and leakage were explained by the extrudate microstructure measured by X-ray microtomography. Within the boundary of the chosen design, 64% of the FM can be replaced by tunicate meal without compromising physical feed quality. Due to its viscosity behaviour, tunicate meal can improve pellet expansion and fat absorption capacity of extruded feed.publishedVersio

Sensory Properties and Chemical Composition of Fish Solubles Obtained from Upcycling of Fish Filleting Side Streams

The whitefish processing industry igenerates large amounts of food-grade side streams consisting of trimmings, head-backbone-skin (HBS), and viscera. Several factory fishing vessels have fishmeal plants to utilize the residues after onboard processing of the fish, however, at present, the protein-rich solubles is discarded. . In this study, fish solubles based on side streams from cod, saithe, haddock, and golden redfish were produced based on cooking, mechanical dewatering, centrifugation, and membrane filtration. All products had high flavor intensity, and only minor differences between fish species on sensory attributes were observed, suggesting a potential application as broth and flavor enhancer.Sensory Properties and Chemical Composition of Fish Solubles Obtained from Upcycling of Fish Filleting Side StreamspublishedVersio

Fractionation of Oil from Black Soldier Fly Larvae (Hermetia illucens)

Black soldier fly larvae (BSFL; Hermetia illucens) are subjected to a conventional fishmeal process, or room-temperature formic acid hydrolysis, and lipid yield and composition between the two processes compared. Acid hydrolysis of BSFL results in higher protein yield in the meal and higher oil yield. Oils separated after acid hydrolysis have a lower trilaurin content (triacyglycerol with lauric acid (12:0) in all sn-positions) and a lower melting point (23 °C) compared to oils separated after conventional (fishmeal) processing (26 °C). Further reduction of trilaurin content and melting point (20 °C) are achieved by dry-fractionation (winterization) of the oil. Practical Applications: Fractionation of black soldier fly larvae oil could yield products with targeted levels of trilaurin and melting points adapted to different applications in feeds, foods, and cosmetics.publishedVersio

Intake of residuals from Atlantic cod attenuated blood pressure increase but did not delay development of kidney damage in obese Zucker fa/fa rats

Background: Documentation of health effects of residuals after fish filleting may motivate both consumers and producers to increase the use of this under-utilised protein source. Objectives: The primary objective of the present study was to investigate the effects of a diet containing residuals from Atlantic cod (Gadus morhua) filleting on the development of high blood pressure in obese Zucker fa/fa rats, which spontaneously develop hypertension and proteinuria. The secondary objectives were to investigate any changes in kidney morphology, kidney function and organ damage, and to determine the potential inhibition of cod residuals on renin and angiotensin-converting enzyme (ACE) activities in vitro. Methods: Male rats were fed diets containing protein powder prepared from head, backbone and skin fraction (HBS, n = 6) from Atlantic cod as 25% of total protein with the remaining 75% as casein, or casein as the sole protein source (Control group, n = 6) for 4 weeks. Blood pressure was measured on day 0, 14 and 26. Kidneys were analysed morphologically, and markers for renal function and organ damage were analysed biochemically. Results: The HBS diet attenuated the blood pressure increase compared to the Control group, but kidney damage and dysfunction were similar between the two groups. Conclusion: A diet containing a protein powder consisting of HBS fraction from cod attenuated the blood pressure increase in obese Zucker fa/fa rats, without preventing kidney damage.publishedVersio

Effects of novel ingredients on growth performance in european sea bass, dicentrarchus labrax

publishedVersio

Nordic Centre of Excellence Network in Fishmeal and Fish oil

The main objective of this work was to summarise current knowledge on fishmeal and fish oil as well as identify the research needs and create a roadmap for future industry-driven research. The main conclusion was that the quality of raw material, fishmeal and - oil are not yet well defined. The real focus by the industry has mainly been limited to nutrients, such as proteins and fats and other components that makeup fishmeal. There has been less focus on the health benefits of dietary contents of fishmeal and –oil and the relationship between processing methods and the nutritional and technical properties of fishmeal. In addition, to proactively strengthen the market position and competitiveness, it is crucial for the industry to achieve a common understanding of the needs of their customers in line with a clear profile of the benefits of their products. A communication strategy as well as a research strategy is needed. Finally, the identity of the industry needs to be clear and transparent to promote a story about the industry to provide a clear and positive image of the industry to be communicated to the society. This means, that a communication strategy as well as a research strategy must be established, as there is a lack of communication along the value chain from the industry to the consumers. There is still a lack of understanding by the consumers of why fishmeal is produced, the reasons must be communicated in such a way that it reaches the average consumer. The industry members are interested in moving forward to sustain the future growth of the industry. Fishmeal and fish oil production has been prosperous for a very long time, but to remain so, cooperation among all stakeholders is crucial for continued progress

Growth and nitrogen recovery efficiency of potato (Solanum tuberosum) fertilised with shrimp shell pellets

In organic plant production, nitrogen (N) availability is often a growth-limiting factor. Under such conditions, off-farm waste-derived nutrient resources may be an alternative to meet the N demand. In this study, we described a production method for a shrimp shell (SS) pellet Product and evaluated the N fertiliser effect and N recovery efficiency (NRE) in a controlled climate pot experiment with potatoes. The experiment was set up with low, medium and high N levels of SS pellets in comparison with a standard mineral fertiliser (MF) at 9°C, 15°C and 21°C. In a separate study, we examined the loss of N as N2O from SS pellets in comparison with SS powder in a 100 days incubation experiment. The results documented the possibility to formulate a fertiliser pellet product from SS, and that SS pellets were an effective N fertiliser in potato at all Growth temperatures. Nevertheless, a slightly slower development and lower tuber yields than for MF indicated a delayed N-availability from SS pellet fertiliser. NRE after use of MF was around 90%, and about 70% for the different levels of SS pellets. The incubation experiment showed a higher rate of available N for SS powder than for pellets (67% and 39%, respectively) after 100 days of incubation at constant humidity and temperature. This difference was attributed to a lower degree of dissolved materials and a higher rate of denitrification and N2O emissions for pellets than for powder, probably caused by differences in physical properties, occurrence of anoxic hotspots and higher microbial activity around and inside the SS pellets.Growth and nitrogen recovery efficiency of potato (Solanum tuberosum) fertilised with shrimp shell pellet

Fishmeal physicochemical properties. Impact on the fish feed extrusion process, phase transitions and physical pellet quality

Norway is the world largest producer of Atlantic salmon (Salmo salar). In 2013 the Norwegian aquaculture industry produced 1.2 million metric tons salmon with the use of 1.5 million metric tons of commercial feeds. The feeds are delivered to the farms in big bags or in bulk and are conveyed pneumatically to the sea cages. Such harsh treatments expose pellets to stress that may give product loss due to abrasion and fragmentation. Feed loss in pneumatic feeding systems is estimated to be in the range of 0.3% to 1.5%. This equals a yearly additional expense of around 40 to 200 million NOK for the Norwegian salmon industry. To minimize product loss the feed has to be of a consistent and high physical quality. Extrusion processing is a technology that enables production of such feed quality. Physical pellet quality is normally improved by the addition of starch and other binders, but recent research has shown that the protein ingredients in the feed mix also impact the physical quality of extruded feed products. During the last decade several new plant derived protein ingredients has been introduced and partly replaced fishmeal. This has introduced new challenges in fish feed extrusion and stressed the importance to improve the knowledge related to the technical properties of the individual ingredients. The main objectives of this work have been to quantify fishmeal physicochemical properties with significant effects on the extrusion cooking process and physical pellet quality, and to study the plasticization effect of water solubles in fishmeal. Various multivariate analytical techniques have been applied in the studies, such as principal component analysis, partial least squares -and multiple linear regression. In Paper I and II, the impact of variation in fishmeal physicochemical properties were assessed based on standardized extrusion, drying and coating conditions. In Paper III the effect of water-soluble protein level and moisture content on the extrusion process, extrudate phase transitions and physical quality of feed were studied. In Paper IV the influence of fishmeal water solubles and added moisture on glass transition and flow-starting temperature were quantified. The studies in Paper I and II document the complexity of fishmeal as a protein ingredient with significant impact on the extrusion process, starch gelatinization and physical pellet quality. Large differences in technical quality within and between the studied fishmeal types (i.e. herring and sand eel) were observed. The research quantifies a positive effect of increased levels of water-soluble protein on pellet durability and hardness. This can be explained by two different mechanisms: a crosslinking effect of large polypeptides and a plasticizing effect of smaller peptides and amino acids. Differences in peptide size distribution between the two studied groups were identified with the highest level of large polypeptides for herring meal. At an equal level of water-soluble protein, extruded feed containing fishmeal from sand eel had significantly lower physical quality than feed containing herring meal. This can be attributed to differences in thermal and rheological properties between the two studied groups, and improper cooking in the extruder barrel for sand eel based feed mixes. Incomplete cooking or transformation may result in increased levels of particles in the extrudates and poor physical feed quality. The studies also document that fishmeal specifications normally used on the world commodity market inadequately describe the technical properties of fishmeal. In Paper III the effects of water-soluble protein level in fishmeal on extrusion behaviour, phase transitions and physical feed quality were studied. The plasticizing effect of water-soluble protein was comparable to that of moisture. However, in contrast to moisture, addition of water-soluble protein had a positive effect on specific mechanical energy and physical pellet quality. No loss of water-soluble protein during the extrusion process could be observed, confirming that the amino acids and peptides do not form any new covalent bonds in the extrusion process. A non-volatile plasticizer like water-soluble protein will not be removed in the drying process. It will therefore influence the viscoelastic properties of the final product and have a positive effect on physical pellet quality by establishment of an intermolecular binding network through hydrogen-, ionic bond, and hydrophobic interactions. It can be concluded from the study that water-soluble protein can be used as a processing aid for the fish feed industry, serving multiple purposes as nutrient, plasticizer and binder in extruded fish feed. In Paper IV significant effects of fishmeal water solubles and moisture level on the glass transition and flow-starting temperatures have been documented. The effect of solubles level on the glass transition temperature could be modelled based on the Gordon-Taylor equation. The documented plasticizing effect of water solubles was lower than the effect of moister addition per unit mass, but higher on a molar basis. The plasticization effect can be attributed to the content of low molecular nitrogencompounds. The studied fishmeal model system showed a large composition region of water solubles and moisture with a higher difference between the flow-starting and glass transition temperature than for other reported protein components (i.e. casein, gluten and soya protein isolate). This indicates a reduced temperature effect on viscosity reduction in the rubbery phase for fishmeal in this region. Combined with significantly lower glass transition temperatures, such differences in physicochemical properties may contribute to explain the unique functional properties of fishmeal compared to plant based proteins and casein. This will have positive impact on physical pellet quality and open up the possibility to obtain a satisfactory thermomechanical transformation in the extrusion process at reduced moisture level

A novel approach to determine optimal protein texturization conditions - A critical moisture level with increased effect of temperature on viscosity reduction in the rubbery state

publishedVersio

High lipid microalgae (Schizochytrium sp.) inclusion as a sustainable source of n-3 long-chain PUFA in fish feed — Effects on the extrusion process and physical pellet quality

The aim of this research was to investigate effects on the extrusion process and physical pellet quality of high lipid microalgae (HL-microalgae) inclusion level as a source of n-3 long-chain polyunsaturated fatty acids (n-3 LC-PUFA) in fish feed. The experiment was based on a 3-component mixture design on commercially relevant feed blends by varying the content of dried HL-microalgae Schizochytrium sp. meal, vital wheat gluten (WG), and soy protein concentrate (SPC). Mixture models with R2 in the range of 0.881–0.998 (P < 0.01) were established for specific mechanical energy (SME), feed melt viscosity and temperature behind die, expansion parameters, and pellet hardness and durability. The mixture components affected SME, melt viscosity and viscous heat dissipation with the highest values observed for SPC followed by WG, and lowest for HL-microalgae rich blends. Increase in viscous heat dissipation and feed melt temperature increased the steam flashing rate and consequently pellet expansion and fat adsorption capacity. Lowest pellet hardness and durability were found for blends high in HL-microalgae or SPC level due to incomplete cooking. HL-microalgae addition up to 132 g/kg DM in SPC rich blends gave favourable processing effects with respect to improved plasticisation and physical pellet quality. This study documents that HL-microalgae has a potential to be used as an alternative and sustainable source of n-3 LC-PUFA in aquaculture feeds without compromising physical pellet attributes.submittedVersio