Biomass soaking treatments to reduce potentially undesirable compounds in the edible seaweeds sugar kelp (Saccharina latissima) and winged kelp (Alaria esculenta) and health risk estimation for human consumption

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Perspectives on the Use of Algae in Agriculture and Animal Production

Algae have been used in agriculture as fertilizers for a long time. Recently, they have also been applied to crops as biostimulants that target plant growth promotion and tolerance to biotic (herbivores, fungi, bacteria, viruses) or abiotic stresses. In addition, algae contain bioactive compounds that have been shown to maintain the health of domestic animals or aquaculture species. This opinion piece highlights different aspects of the present use of algae in agriculture and animal production and their future perspectives

Antiallergic properties

International audienceA brief introduction gives the state of the art concerning allergies related to the consumption of seafoods. In this type of product, allergenic substances are mainly muscle proteins and thus largely concern fish, shellfish, mollusks, and crustaceans. The literature available regarding food intolerance caused by eating seaweeds is very restricted. Paradoxically, many works have been carried out on the antiallergic properties of macroalgae. This chapter deals with the species shown to be active against allergies and the specific compounds involved, including phenols, in particular phlorotannins in Phaeophyceae, and polysaccharides, such as alginates and porphyrans. Perspectives for using some seaweeds in the development of functional foods are discussed. The harmlessness of most edible seaweeds is also mentioned

Interactions of the mix-linked beta-(1,3)/beta-(1,4)-D-xylans in the cell walls of Palmaria palmata (Rhodophyta)

International audienceAlgal cell wall mechanical properties, crucial for biological functions and commercial applications, rely on interactions in macromolecular assemblies. In an effort to better understand the interactions of the matrix-phase beta-(1,3)/(1,4)-d-xylan in the edible seaweed Palmaria palmata ((L.) O. Kuntze, Rhodophyta, Palmariales), sequential extractions by saline, alkaline, and chaotropic solutions were done. The chemical composition and structure and the physicochemical properties of the isolated xylan revealed that it was partly acidic, probably due to the presence of sulfate (up to 5%) and phosphate groups (up to 4%). Although such acidity suggested ionic interactions of xylan in the cell walls, the high yields of polysaccharide extracted by alkali and particularly by 8 M urea and 4.5 M guanidium thiocyanate demonstrated that it was mainly hydrogen bonded in the cell wall. H-bonds did not appear to be related to the mean proportions of beta-(1,3) and beta-(1,4)-d-xylose linkages because these did not differ between extracts of increasing alkalinity. However, the decreasing molar weight and intrinsic viscosity of extracts obtained by alkaline solution containing a reducing agent used to prevent polysaccharide degradation suggested the presence of an alkali-labile component in the xylan. These results are discussed with regard to the role of potential wall proteins as a means of control of these interactions

Purification et caractérisation du pigment bleu-vert "marennine" synthétisé par la diatomée marine Haslea ostrearia (Gaillon/Bory) Simonsen (propriétés physico-chimiques et activités biologiques)

Haslea ostrearia est une diatomée marine qui synthétise un pigment bleu-vert appelé "marennine". Il existe une localisation intracellulaire (IMn) et extracellulaire (EMn) du pigment. Cette diatomée est responsable de la coloration verte des branchies d'huîtres de culture.Une méthode de purification et de quantification de l'IMn et de l'EMn est mise au point. Elle fait appel à l'ultrafiltration sur membranes et à la CLHP (exclusion-diffusion et échange d'anions), couplée à un détecteur UV-visible à barrette de diodes. La caractérisation des molécules purifiées révèle la nature polyphénolique de la marennine. L'étude comparée des paramètres physico-chimiques, masses moléculaires et propriétés spectrales notamment, montre que l'IMn et l'EMn possèdent des structures moléculaires distinctes. Par alleurs, l'IMn et l'EMn présentent des activités cytostatiques in vitro à l'encontre de cellules cancéreuses, de bactéries et de microalgues, ainsi que des propriétés anti-UV et antioxydantes.Haslea ostrearia is a marine diatom that synthesizes a blue-green pigment called "marennine". This pigment is found under an intra- (IMn) and an extracellular form (EMn). The diatom is responsible for the blue colour of the cultured oyster gills. A method for the purification and the quantification of IMn and EMn is perfected. It uses an ultrafiltration process through membranes and a gel-filtration / anion-exchange HPLC interfaced with a photodiode-array detector. The characterisation of the purified molecules reveals the polyphenolic nature of marennine. The comparative analysis of physico-chemical parameters, molecular weights and spectral properties among others, shows that IMn and EMn have distinct molecular structures. Moreover, IMn and EMn display in vitro cytostatic activities against cancerous cell lines, bacteria and microalgae, as well as anti-UV and antioxidative properties.NANTES-BU Sciences (441092104) / SudocSudocFranceF

Seasonal composition of lipids, fatty acids, and sterols in the edible red alga Grateloupia turuturu

International audienceComposition of lipids, sterols, fatty acids (FA), and phospholipids in the edible Rhodophyta Grateloupia turuturu from Britanny, France, was investigated over four seasons in order to identify compounds with potential benefits in health and nutrition. The lipid content was found to vary from 3.3 to 4.1 % dry weight. No marked variations were observed for glycolipids accounting for 42.3-46.8 %, whereas neutral lipids and phospholipids fluctuated from 20.1 % (summer) to 41.8 % (winter), and 11.2 % (winter) to 33.4 % (summer), respectively. Polyunsaturated FA of the total lipids were found from 20.4 % (winter) to 31.1 % (summer), including 20:5 omega 3 acid as the major one (up to 16.3 % in summer). Phosphatidylcholine (20.0-43.7 %) and phosphatidylserine (24.6-37.5 %) were the dominant phospholipids in all seasons. Compounds of interest were identified in minor amounts such as squalene, alpha-tocopherol, phytonadione (vitamin K-1), cholesteryl formate, cholest-4-en-3-one, and cholesta-4,6-dien-3-one. Cholesterol was the major sterol with a lower content in spring and summer

Nutritional value of the kelps Alaria esculenta and Saccharina latissima and effects of short-term storage on biomass quality

Storage of macroalgae in seawater, prior to further processing, is a standard initial pre-treatment step after harvest to avoid rapid degradation of the biomass. In the context of using seaweeds in human food and animal feed products, such practice may affect the nutritional value and the overall quality of the biomass. The effects of seawater storage on the chemical composition (i.e., mineral fraction, carbohydrates, proteins, polyphenols, and fucoxanthin) and surface color of two cultivated kelps (Phaeophyceae), Alaria esculenta and Saccharina latissima, were investigated over a 22-h period. Storage treatments resulted in a rapid decrease in dry weight during the first 2 h (−21.4 and −20.4% in A. esculenta and S. latissima, respectively) with subsequent stabilization. Although it is not clear whether the reduction of dry weight was caused by the release of nutritional compounds from seaweed biomass or water uptake during storage treatment, the results from chemical analyses suggest the combined effect of both mechanisms. Seawater storage increased the ash and sodium contents and reduced carbohydrate and polyphenol levels in both species. Among carbohydrates, the levels of mannitol and glucose (laminaran) were particularly reduced in S. latissima samples while the fucose level, reflecting fucoidans, was reduced in A. esculenta. The protein content remained relatively stable in both species. These results provide evidence of the effect of seawater storage on the quality of the edible kelps A. esculenta and S. latissima. The results will contribute to selecting postharvest strategies adequate for maintaining biomass quality, minimizing losses of valuable compounds and increasing profitability for industrial stakeholders.acceptedVersion© Springer Science+Business Media Dordrecht 2017. This is the authors' accepted and refereed manuscript to the article. Locked until 29 March 2018 due to copyright restriction

Effects of drying on the nutrient content and physico-chemical and sensory characteristics of the edible kelp Saccharina latissima

The effects of convective air-drying at 25, 40, and 70 °C and freeze-drying on the quality of the edible kelp Saccharina latissima to be used for food were investigated. Based on the analysis of the carbohydrate and amino acid profiles, as well as polyphenol, fucoxanthin, and ash contents, no significant differences were detected among sample groups, and air-drying up to 70 °C results in equally nutritious products at shorter processing times. Only the iodine content was found lower in freeze-dried compared to air-dried samples. The swelling capacity of the air-dried samples was significantly lower than in freeze-dried samples, particularly at high temperatures (40 and 70 °C), reflecting alteration of the physico-chemical properties of the seaweed during air-drying (attributed to product shrinkage) and reduced capacity of the final product to rehydrate. Structural differences between air-dried products at 25 and 70 °C may explain the differences in mouthfeel perception (dissolving rate) among the two sample groups observed during a sensory evaluation. Overall, the drying temperature within this range did not alter neither the aroma (i.e. odor) nor the flavor intensity of the product. In food applications where the product’s mechanical properties (e.g. porosity) are essential, freeze-drying, and to a lesser extent, air-drying at low temperatures, will result in higher quality products than air-drying at higher temperatures.acceptedVersio