Aquaculture Europe 2021

October 4 - 7, 2021

Funchal, Madeira

Add To Calendar 07/10/2021 15:50:0007/10/2021 16:10:00Europe/LisbonAquaculture Europe 2021ANTIOXIDATIVE ACTIVITIES, PHENOLIC COMPOUNDS AND MARINE FOOD ALLERGENS IN THE MACROALGAE Saccharina latissima PRODUCED IN INTEGRATED MULTI-TROPHIC AQUACULTURE SYSTEMSMezzanine-CasinoThe European Aquaculture Societyalistair@aquaeas.eufalseanrl65yqlzh3g1q0dme13067DD/MM/YYYY

ANTIOXIDATIVE ACTIVITIES, PHENOLIC COMPOUNDS AND MARINE FOOD ALLERGENS IN THE MACROALGAE Saccharina latissima PRODUCED IN INTEGRATED MULTI-TROPHIC AQUACULTURE SYSTEMS

 

C. Rebours *, J. Mildenberger and J.K. Stangeland

 

Møreforsking AS, Borgundveien 340, 6009 Ålesund, Norway

 E-mail: Celine.Rebours@moreforsking.no

 



INTRODUCTION

 The concept of "Integrated Multi-Trophic Aquaculture" (IMTA) has been given great interest in recent decades and is one of several strategies to increase biomass production from the sea by reducing the environmental impact of fish farming and by increased production of low-level trophic organisms such as macroalgae. However, due to lack of data and scientific evidence, appropriate food regulations are lacking for IMTA to guide the production of macroalgae and their application as food products. Macroalgae are however  recognized to  have valuable bioactivities including antioxidative activity. Due to variations in bioactivities between species, geographic location and season, characterization of  the quality of  specific  IMTA products will be important for further marketing purposes. Besides valuable compounds, macroalgae can also contain elements with unwanted effects such as allergens. Thus, there is a growing concern from the food industry and food safety authorities regarding the potential occurrence of contaminating marine allergens in seaweed food products. A s seaweed is produced in the ocean, allergens of marine species, such as crustaceans, molluscs or even fish might find their way into the production line and these hazards must be monitored to evaluate the risk for allergenic incidents and the need for appropriate labelling for future food products. Here, the occurrence of marine food allergens as well as total phenolic compounds and antioxidant activity have been assessed in  S. latissima  produced in three different locations in 2020 in the vicinity of salmonids farms  in Norway.

MATERIALS AND METHODS

 In 2020, 10 kg of seaweed was collected at three different  Norwegian IMTA farms located at three different sites (Bjønnspjotneset, Dyrholmen Vest, Furholmen) owned respectively by Osland Havbruk AS, Sulefisk AS and Engesund Fiskeoppdrett.  The seaweed was washed, freeze dried and ground. Extractions and analyses were conducted in triplicates.

 For analysis of phenolic compounds and  antioxidants,  seaweed  samples were dissolved at 25 mg/ml in dH2O  or MeOH:dH2O (4:1) , incubated in an ultrasonic water bath (Branson 2200, 40kHz) for 30 min where indicated, and filtered. Phenolic compounds were measured by the Folin-Ciocalteu method

 with g allic acid (Sigma Aldrich G7384) standard  curve and undiluted samples. Antioxidative activity was assessed by ORAC assay, according to the BioTek Application Note 2006

. Samples were diluted to 25 µg/ml (1:1000) for MeOH extracts and to 5 mg/ml (1:5) for water extracts.

 For allergen detection, ELISA kits for the antigens fish parvalbumin, mollusc tropomyosin or crustacean tropomyosin (Demeditec DEFISE1, DEMOLE1 and DECRUE1) were used. Dried and grinded seaweed (0.2 g, exact weight) was dissolved in 20 ml extraction buffer , filtered, and diluted 2-times to limit matrix effects.

RESULTS

The content of phenolic compounds was in a range of 1-2 mg GAE/g dry weight for all three locations and all three extraction methods . Antioxidative capacity was significantly increased when extracted in aqueous methanol as compared to water extracts in all samples. In the methanol extracts, t he seaweed from Osland contained the significantly  highest antioxidative activity with 1665.1 ± 39.4 µmol TE/g, followed by Sulefisk with 1243.2 ± 68.9 and Engesund with 630.9 ± 31.5 µmol TE/g. The difference in ORAC values between Osland and Sulefisk was not consistent for all extraction methods, while the sample from Engesund had the overall significantly lowest values.  The treatment in an ultrasonic water bath did not  have a significant effect on  the content of phenolic compounds  or antioxidant capacity but decreased the  viscosity of water extracts.

 Further, the seaweed samples were tested for  the established food allergens crustacean, mollusc and fish. Values for crustacean tropomyosin were  for all samples  above the lower detection limit of 20 ppm in the assay (corresponding to 0.2 mg/kg sample) and ranged from 0.442 ± 0.05 mg/kg for Osland to 1.005 ± 0.39 mg/kg at Sulefisk. The measured values were not significantly different between the three IMTA sites, although the lowest values were all detected in the samples from Osland. The m ollusc tropomyosin concentrations in the seaweed samples were  numerically above, but very near the lower detection limit of 10 ppm in the assay or 0.1 mg/kg sample. Fish allergens, provided as cod concentrations, were below the lower detection limit of 4 ppm in the assay (or 40 mg/kg sample) for the seaweed samples from Sulefisk and Engesund. The concentration measured in the samples from Osland was above, but near the detection limit. Osland was also the location with the highest fish production in 2020. According to literature, cod contains parvalbumin at 2 mg/g

 with higher concentrations in muscle

 . Based on this, 40 mg cod per kg as the detection limit would translate to 0.08 mg parvalbumin per kg.

CONCLUSIONS

Products with relatively high market value such as food and feed ingredients are predicted to play an important role in creating value from Norwegian-grown seaweed and kelp

 . This work confirmed the presence of phenolic compounds and antioxidative activity in S. latissima, produced in IMTA systems,  in a similar range for all assessed locations and comparable to previous studies, indicating  that this species and production method can play a role for the development of  natural food additives,  functional food or health products from seaweed. The here reported bioactivities should  be  further investigating to fully understand the potential and limit of using S. latissima as functional ingredients in food or feed formulas.

 Our analyses of S. latissima bulk samples with commercial sandwich ELISA kits  for known food allergens  have shown  acceptable detection limits, linearity and recovery. Only crustacean allergens could be detected in all tested locations in this study,  while mollusc tropomyosin was very near the detection limit, thus assumed as not detectable. Cod parvalbumin was detected slightly above detection limit only in one location. In the context of realistic incorporation in final food products and resulting daily ingestion, the presence of contaminating marine species in seaweed raw products does not seem to be critical, but should be further followed through seasons, locations and productions as more processed products are developed.

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