Using either freshly pulped or preserved seaweed biomass for the extraction of protein can have a great effect on the amount of protein that can be extracted. In this study, the effect of four preservation techniques (frozen, freeze-dried, and air-dried at 40 and 70 °C) on the protein extractability, measured as Kjeldahl nitrogen, of four seaweed species, Chondrus crispus (Rhodophyceae), Ascophyllum nodosum, Saccharina latissima (both Phaeophyceae) and Ulva lactuca (Chlorophyceae), was tested and compared with extracting freshly pulped biomass. The effect of preservation is species dependent: in all four seaweed species, a differenttreatment resulted in the highest protein extractability. The pellet (i.e., the non-dissolved biomass after extraction) was also analyzed as in most cases the largest part of the initial protein ended up in the pellet and not in the supernatant. Of the four species tested, freeze-dried A. nodosum yielded the highest overall protein extractability of 59.6% with a significantly increased protein content compared with the sample before extraction. For C. crispus extracting biomass air-dried at 40 °C gave the best results with a protein extractability of 50.4%. Preservation had little effect on the protein extraction for S. latissima; only air-drying at 70 °C decreased the yield significantly. Over 70% of the initial protein ended up in the pellet for all U. lactuca extractions while increasing the protein content significantly. Extracting freshly pulped U. lactuca resulted in a 78% increase in protein content in the pellet while still containing 84.5% of the total initial total protein. These results show the importance of the right choice when selecting a preservation method and seaweed species for protein extraction. Besides the extracted protein fraction, the remainingpellet also has the potential as a source with an increased protein content.
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Seaweeds from the genus Porphyra play a big economic role in seaweed aquaculture, mainly in Asia. In Europe, resources are put towards seaweed cultivation, but without attention to the Porphyra species which is also native to Europe. Different nomenclature and specifications are used to describe Porphyra, due to taxonomical reclassification and difficult phenotypical identification. Abiotic & biotic together with seasonal factors make for major variance in chemical compositions that are reported. This is also fueled by differences in chemical analytical methods and procedures followed. Combining taxonomical challenges, variance due to seasonal factors and differences in analysis, overviewing published research on Porphyra constituents such as protein, polysaccharides and fatty acids is warranted. Within this review, cellular consitutents found in Porphyra are discussed, including proteins, polysaccharides, fatty acids and mycosporine-like amino acids (MAA’s). MAA's are considered amongst the strongest UV-photoprotectants found in nature and feature possible applications in cosmetics. As global interest in seaweeds as food, feed and industrial resource is emerging, opportunities for Porphyra constituents is rising.
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Vanuit het ZEEVIVO project werd in werkpakket B, Bioraffinage, onderzoek gedaan naar het opwaarderen van eiwit uit zeewier. De hoofdvraag was: Hoe is uit zeewier een commercieel interessant eiwitconcentraat te extraheren met een eiwitgehalte van tenminste 60%? Om deze vraag te beantwoorden zijn optimalisatieproeven uitgevoerd in het laboratorium. Daarnaast zijn er extractieproeven op pilotschaal gedaan, gevolgd door het concentreren en zuiveren van de eiwitten in deze extracten met behulp van membraanfiltratie.
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Understanding taste is key for optimizing the palatability of seaweeds and other non-animal-based foods rich in protein. The lingual papillae in the mouth hold taste buds with taste receptors for the five gustatory taste qualities. Each taste bud contains three distinct cell types, of which Type II cells carry various G protein-coupled receptors that can detect sweet, bitter, or umami tastants, while type III cells detect sour, and likely salty stimuli. Upon ligand binding, receptor-linked intracellular heterotrimeric G proteins initiate a cascade of downstream events which activate the afferent nerve fibers for taste perception in the brain. The taste of amino acids depends on the hydrophobicity, size, charge, isoelectric point, chirality of the alpha carbon, and the functional groups on their side chains. The principal umami ingredient monosodium l-glutamate, broadly known as MSG, loses umami taste upon acetylation, esterification, or methylation, but is able to form flat configurations that bind well to the umami taste receptor. Ribonucleotides such as guanosine monophosphate and inosine monophosphate strongly enhance umami taste when l-glutamate is present. Ribonucleotides bind to the outer section of the venus flytrap domain of the receptor dimer and stabilize the closed conformation. Concentrations of glutamate, aspartate, arginate, and other compounds in food products may enhance saltiness and overall flavor. Umami ingredients may help to reduce the consumption of salts and fats in the general population and increase food consumption in the elderly.
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In werkpakket A, Zeewierteelt, werd onderzocht wat het effect is van de nitraatconcentratie op de groei en eiwitgehalte van de zeewiersoorten Saccharina latissima en Ulva lactuca. Bij de laatste soort werd ook gekeken naar de aminozuursamenstelling. Hogere nitraatconcentraties zorgden bij beide zeewiersoorten voor een hogere groeisnelheid en een hogere eiwitgehalte. De totale aminozuurhoeveelheid van Ulva lactuca was hoger bij blootstelling aan een hogere nitraatconcentratie. Alle gemeten aminozuurgehaltes waren hoger, behalve die van methionine, die gelijk was ten opzichte van de Ulva lactuca die gekweekt werd onder lage nitraatconcentraties. Het is dus mogelijk om tijdens het groeiproces, de aminozuur- en eiwitgehalte van zeewier te verhogen. De toename in eiwitgehalte was zelfs zo snel, dat het mogelijk is om zeewier te verrijken door het twee weken voor de oogst onder verhoogde nitraatconcentraties te laten groeien.
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Hoe bestrijden we energiearmoede die ontstaat in de private huursector? Hoe versterk je de cyberweerbaarheid van het mkb? En hoe kunnen we afgeschreven windmolens hergebruiken als nieuw bouwmateriaal? Het zijn slechts drie van de talloze voorbeelden van actueel praktijkgericht onderzoek aan hogescholen. Onderzoek dat direct is verbonden met grote maatschappelijke opgaven, bijvoorbeeld op het gebied van energie, klimaat, technologisering en kansengelijkheid. Voor die opgaven hebben we nieuwe kennis nodig die we snel kunnen omzetten in nieuwe producten en oplossingen. Het praktijkgericht onderzoek aan hogescholen is daarvoor een onmisbare schakel tussen fundamenteel onderzoek en onze samenleving.
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Op de HAS Hogeschool wordt al een aantal jaren voer voor vis en schaaldieren op basis van insecten vergeleken met regulier voer op basis van vismeel en/of visolie. Dit onderzoek wordt uitgevoerd in samenwerking met New Generation Nutrition. Resultaten laten zien dat garnalen gevoerd met voer op basis van insecten even goed groeien als bij regulier voer. Tot op heden is onbekend of het voer op basis van insecten gezondheidsrisico’s met zich meebrengt en dergelijk onderzoek komt na het aanstellen van Olga Haenen als lector Gezonde en Duurzame eiwitten in een stroomversnelling.
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Bitterness has been suggested to be the main reason for the limited palatability of several vegetables. Vegetable acceptance has been associated with preparation method. However, the taste intensity of a variety of vegetables prepared by differentmethods has not been studied yet. The objective of this study is to assess the intensity of the five basic tastes and fattiness of ten vegetables commonly consumed in the Netherlands prepared by different methods using the modified Spectrum method. Intensities of sweetness, sourness, bitterness, umami, saltiness and fattiness were assessed for ten vegetables (cauliflower, broccoli, leek, carrot, onion, red bell pepper, French beans, tomato, cucumber and iceberg lettuce) by a panel (n = 9) trained in a modified Spectrum method. Each vegetable was assessed prepared by different methods (raw, cooked, mashed and as a cold pressed juice). Spectrum based reference solutions were available with fixed reference points at 13.3 mm (R1), 33.3mm(R2) and 66.7mm(R3) for each tastemodality on a 100mmline scale. For saltiness, R1 and R3 differed (16.7 mm and 56.7 mm). Mean intensities of all taste modalities and fattiness for all vegetables were mostly below R1 (13.3 mm). Significant differences (p b 0.05) within vegetables between preparation methods were found. Sweetness was the most intensive taste, followed by sourness, bitterness, fattiness, umami and saltiness.In conclusion, all ten vegetables prepared by different methods showed low mean intensities of all taste modalities and fattiness. Preparation method affected taste and fattiness intensity and the effect differed by vegetable type.
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