Side streams from wheat processing, such as the bran and gluten fractions, show great potential as a feedstock for the production of novel food ingredients and materials. In this study, we prepared hybrid polysaccharide-protein hydrogels via enzymatic crosslinking of wheat bran arabinoxylan and gluten fractions. Arabinoxylan was first isolated from wheat bran via subcritical water extraction, which preserved the covalently bound ferulic acid moieties to the arabinoxylan core amenable for laccase crosslinking. Gluten was fractionated into its main protein components (glutenin and gliadin) via treatment with aqueous ethanol. Hydrogels with different contents of arabinoxylan and gluten were prepared, demonstrating the integration of the protein fractions within the polysaccharide gel network. Increased addition of gluten led to gradually softer hydrogels, suggesting that the gluten fractions were not involved in the covalent crosslinking with the ferulic acid moieties to any noticeable level. Freeze-drying and regeneration of the hydrogels led to a 3-fold–10-fold increase in the storage and loss moduli, depending on the sample. Analysis of the structure of the hydrogels revealed that the addition of gluten upon enzymatic crosslinking impacted the physical interactions and crystallinity of the arabinoxylan populations, resulting in phase separation of the protein and polysaccharide components. This study demonstrates that tunable hydrogels can be prepared from cereal side streams, with potential as functional plant-based food hydrocolloids with improved nutritional properties, combining dietary fibre and protein components.

Side streams from wheat processing constitute a widely available renewable resource from biomass rich in carbohydrate polymers and proteins, with great potential as biopolymeric matrices for the production of biobased films for food packaging applications. In this study, arabinoxylan (AX) was extracted with high purity from wheat bran via alkaline extraction and was combined with wheat gluten for the preparation of AX-gluten glycoprotein films using citric acid (CA) as a crosslinker and glycerol as plasticizer. Self-standing and flexible films were prepared via solvent casting and further cured at 150 °C to initiate crosslinking. FTIR analysis and solubility tests revealed that chemical crosslinking had occurred to some extent involving both the AX and gluten components, suggesting the formation of glycoprotein structures. However, the evaluation of the mechanical and barrier properties of the films showed that CA mainly works as a plasticizing agent rather than a crosslinking agent at the conditions used in the study. UV–Vis spectroscopy measurements showed that the films had an excellent ability to block UV-light. This study demonstrates the successful preparation of AX-gluten glycoprotein films with excellent mechanical and barrier properties, which can be tuned by the protein content and CA addition balancing both plasticizing and crosslinking effects.

Seaweed biomass is a renewable resource with multiple applications. Sea-based cultivation of seaweeds can provide high biomass yields, low construction, operation, and maintenance costs and could offer an environmentally and economically sustainable alternative to land-based cultivations. The biochemical profile of sea-grown biomass depends on seasonal variation in environmental factors, and the optimization of harvest time is important for the quality of the produced biomass. To identify optimal harvest times of Swedish sea-based cultivated sea lettuce (Ulva fenestrata), this study monitored biomass yield, morphology, chemical composition, fertility, and biofouling at five different harvesting times in April - June 2020. The highest biomass yields (approximately 1.2 kg fw [m rope](-1)) were observed in late spring (May). The number and size of holes in the thalli and the amount of fertile and fouled tissue increased with prolonged growth season, which together led to a significant decline in both biomass yield and quality during summer (June). Early spring (April) conditions were optimal for obtaining high fatty acid, protein, biochar, phenolic, and pigment contents in the biomass, whereas carbohydrate and ash content, as well as essential and non-essential elements, increased later in the growth season. Our study results show that the optimal harvest time of sea-based cultivated U. fenestrata depends on the downstream application of the biomass and must be carefully selected to balance yield, quality, and desired biochemical contents to maximize the output of future sea-based algal cultivations in the European Northern Hemisphere.

We report (1) successful extraction and characterization of cellulose from northern hemisphere green macroalgae Ulva lactuca (Ulva fenestrata) collected along the Swedish west coast and cultivated indoors under controlled conditions, followed by (2) its utilization in the production of lignin-free cellulose nanofibrils (CNF). Cellulose was extracted by sequential treatment with ethanol, hydrogen peroxide, sodium hydroxide, and hydrochloric acid, yielding a cellulose-rich insoluble fraction. The extracted cellulose was disintegrated into CNF using a mechanical homogenization process without any further enzymatic pre-treatments. In addition, regenerated cellulose was prepared. XRD characterization of the CNF showed characteristic peaks for the cellulose I allomorph and confirmed that the nanofibrils were semicrystalline with a crystallinity index of 48%. Regenerated cellulose was mostly amorphous with an XRD pattern indicating the presence of the cellulose II allomorph. The cellulose fractions were essentially free from inorganic substances and thermally stable up to around 260 degrees C. Structural mapping with CP-MAS C-13-NMR sustains the cellulose content of CNF and regenerated cellulose, respectively, yet ion chromatography identified the presence of 10-15% xylose in the fractions. Optotracing was used as a novel and non-disruptive tool to selectively assess the polysaccharide composition of the cellulose fractions and produced CNF aiming to shed light on this hitherto non-resolved origin of xylose in Ulva cell wall matter. Fluorescence excitation and emission spectra of a panel of 4 oligothiophenes identified and verified the presence of cellulose and sustain the conclusion that the isolated fractions consist of cellulose intertwined with a small amount of a xylose-containing glucan copolymer.

The cell wall polysaccharide ulvan was isolated from two species of the seaweed Ulva collected along the Swedish west coast. Acidic extraction was benchmarked against hot water extraction with enzymatic purification and against commercial ulvan. Extracted ulvan contained 11-18 % g/g of ash, some protein (up to 1.3 % g N/g) but minimal colored impurities. The ulvans had high molecular weights (660,000-760,000 g/mol) and were composed of 77-79 % g/g carbohydrates, mainly rhamnose, xylose, glucose, glucuronic acid, and iduronic acid. The extraction protocol and the ulvan source strongly impact the molecular weight and the chemical composition. Acidic extraction caused almost complete desulfation of the isolated ulvan while the other method preserved a significant degree of SO3 substituents. Elemental analysis of ash remaining after thermal degradation showed presence of common mineral elements such as Na, Ca, Mg, Al, and K, but none of the heavy metals Pb, Hg, or As.

In recent years, the interest in using seaweed for the sustainable production of commodities has been increasing as seaweeds contain many potentially worthwhile compounds. Thus, the extraction and refining processes of interesting compounds from seaweeds is a hot research topic but has been found to have problems with profitability for novel applications. To increase the economic potential of refining seaweed biomass, the content of the compounds of interest should be maximized, which can potentially be achieved through optimization of cultivation conditions. In this study, we studied how the monosaccharide composition of the green seaweed species Ulva fenestrata is influenced by the abiotic factors; irradiance, temperature, nitrate, phosphate, and pCO2. It was evident that lower nitrate concentration and cultivation at elevated temperature increased monosaccharide contents. A 70% increase in iduronic acid and a 26% increase in rhamnose content were seen under elevated irradiance and temperature conditions, though the absolute differences in monosaccharide concentration were small. Irradiance and nitrate impacted the ratio between iduronic and rhamnose, which is an indicator of the ulvan structure. These results could potentially be utilized to coax the ulvan towards specific bioactivities, and thus have a considerable impact on a potential biorefinery centered around Ulva.

Ulva fenestrata is an economically and ecologically important green algal species with a large potential in seaweed aquaculture due to its high productivity, wide environmental tolerance, as well as interesting functional and nutritional properties. Here, we performed a series of manipulative cultivation experiments in order to investigate the effects of irradiance (50, 100, and 160 μmol photons m−2 s−1), temperature (13 and 18 °C), nitrate (< 5, 150, and 500 μM), phosphate (< 1 and 50 μM), and pCO2 (200, 400, and 2500 ppm) on the relative growth rate and biochemical composition (fatty acid, protein, phenolic, ash, and biochar content) in indoor tank cultivation of Swedish U. fenestrata. High irradiance and low temperature were optimal for the growth of this northern hemisphere U. fenestrata strain, but addition of nutrients or changes in pCO2 levels were not necessary to increase growth. Low irradiance resulted in the highest fatty acid, protein, and phenolic content, while low temperature had a negative effect on the fatty acid content but a positive effect on the protein content. Addition of nutrients (especially nitrate) increased the fatty acid, protein, and phenolic content. High nitrate levels decreased the total ash content of the seaweeds. The char content of the seaweeds did not change in response to any of the manipulated factors, and the only significant effect of changes in pCO2 was a negative relationship with phenolic content. We conclude that the optimal cultivation conditions for Swedish U. fenestrata are dependent on the desired biomass traits (biomass yield or biochemical composition).

The authors regret that the original version of this article unfortunately contained a mistake. All the words and "carrageenan-rich fraction" should be replaced by "porphyranrich fraction" Also, "κ-carrageenan", "ι-carrageenan" and "λ- carrageenan" should be replaced by "porphyran" The correct Figures and associated text are given below. The authors would like to apologize for any inconvenience caused. The following tables from the Supporting Information file have been corrected:. (Figure Presented) (Table Presented).

Cultivation of seaweed has been conducted for centuries in Asia, but is largely undeveloped in Sweden even though there is potential for this industry. Seaweed offers benefits compared with land-based biomass cultivation. Cultivation of seaweed does not occupy land areas and does not require irrigation or fertilizers, which contributes to avoid coastal eutrophication. Seaweed contains polysaccharides and is a potential feedstock for production of bio-based materials. The aim of this thesis was to extract and map the chemical structure of polysaccharides from macroalgae collected along the Swedish west coast. Another aim was to use the extracted polysaccharides to design new bio-based materials. In the first study, a fractionation strategy was developed to sequentially extract proteins and polysaccharides from the red macroalgae Porphyra. The fractionation yielded one protein fraction and three polysaccharide fractions. In the second study, the polysaccharide ulvan was extracted from two species of the green macroalgae Ulva. Two different extraction protocols were tested. Parameters such as the yield, molecular weight and monosaccharide composition of the extracted ulvan depended on the extraction protocol and the specie of Ulva used for the extraction. In the third study, ulvan extracted from Ulva was used to prepare hydrogels, which were tested as an adsorbent for heavy metals and the dye methylene blue. Ulvan was first oxidized into ulvan dialdehyde and mixed with gelatin, yielding hydrogels. The hydrogels showed high water-uptake capacity and a high adsorption capacity of methylene blue. The hydrogels also adsorbed heavy metal ions. In the fourth study, cellulose was extracted from Ulva and further used to prepare cellulose nanofibrils (CNF). Chemical analysis of the CNF showed that it contains mostly cellulose but also a smaller amount of a xylose-glucose copolymer. The CNF had a crystallinity index of 48% and showed typical peaks for the cellulose I allomorph.

Algodling är en stor industri i Asien, men i stort sett outvecklad i Sverige. Algodling erbjuder många fördelar jämfört med odling av landbaserad biomassa. Algodlingar upptar inte värdefulla landområden och kräver ingen konstbevattning eller gödningsmedel vilket förebygger övergödning i kustnära miljöer. Alger är en potentiell råvara för framställning av biobränslen och biobaserade material. Syftet med detta avhandlingsarbete var att utveckla metoder för att extrahera och strukturbestämma polysackarider från makroalger som odlats på västkusten i Sverige. De extraherade polysackariderna användes sedan för att framställa några olika biobaserade material. I den första studien utvecklades en metod för att fraktionera proteiner och polysackarider från den röda makroalgen Porphyra. En proteinfraktion och tre polysackaridfraktioner erhölls vid fraktioneringen. I den andra studien utvecklades två olika protokoll för att extrahera polysackariden ulvan från två olika arter den gröna makroalgen Ulva. Extraktion med saltsyralösning gav ett högre utbyte av ulvan än extraktion med vatten. Sammansättningen av monosackarider hos det extraherade ulvanet varierade beroende på vilken extraktionsmetod som användes och även på vilken art av Ulva som användes. I den tredje studien tillverkades hydrogeler av ulvan som extraherats från Ulva. Ulvan oxiderades först till ulvan dialdehyd och blandades sedan med gelatin vilket ledde till bildningen av hydrogeler. Hydrogelerna visade en god svällningsförmåga i vatten och god förmåga att adsorbera färgämnet metylenblått. Hydrogelerna adsorberade också tungmetalljoner i viss utsträckning. I den fjärde studien extraherades cellulosa från Ulva och den extraherade cellulosan användes sedan vidare för att tillverka nanocellulosa (CNF) och regenererad cellulosa. Kemisk analys av nanocellulosan visade att den innehåller mest cellulosa, men även en mindre mängd av en xylos-glukossampolymer. Kristalliniteten uppmättes till 48% och det uppmätta XRD difraktogrammet indikerade förekomst av allomorfen cellulosa I.