Author: Kristín Edda Gylfadóttir

The red alga Palmaria palmata ("dulse"; Palmariaceae, Rhodophyta) has been used as food since the fifth century, especially in the North Atlantic region. Dulse is a good alternative to cereals due to its high content nutritional profile. A critical review based on scientific and gray literature of dulse bioactive compounds and their activity identified key knowledge gaps. The review synthesis emphasizes the importance of species delimitation, microbial community characterization and multi-omics in the research of P. palmata. Recent advances and uncertainty in delimiting P. palmata are introduced in a phylogenetic context, and recommendations are given for the future phytochemicals studies. We refer to the concept of "seaweed holobiont" as the functional entity encompassing the seaweed and its associated microbiota, and call for action to characterize the microbial communities, since their interactions with the environment and seaweed are important in seaweed well-being and postharvest quality changes (eg microbial spoilage and degradation of algal matrices). Finally, we discuss the status and trends of using multi-omics to address important research questions P. palmata, and to help us understand the source, biosynthesis and function of it bioactive compounds.

Atlantic mackerel (Scomber scombrus) caught during the summer months in Icelandic waters after intensive feeding is rich in lipids and, thus, sensitive to lipid degradation. Recent studies have led to improved cooling and handling on board, ensuring high-quality raw material. However, studies on the development of high-quality products for human consumption are lacking. The study aimed to investigate the effects of hot-smoking on the physicochemical, microbial, and sensory quality of deep-skinned Atlantic mackerel fillets during chilled storage (1 ± 0.6°C). In addition, the quality of smoked mackerel from frozen–thawed fillets (9 months at −25 ± 1.8°C) was compared to that of fresh-smoked fillets to evaluate the possibility of the industry being able to provide smoked fillets throughout the year, despite the short fishing season. Brining and hot-smoking reduced total viable counts and inactivated Listeria monocytogenes. Hot-smoking positively affected the sensory attributes of the fillets and sensory quality was largely maintained for at least 21 days of chilled storage. Although slightly lower sensory and texture scores were obtained for frozen–thawed smoked fillets, they remained within acceptable limits throughout the period of cold storage. The shelf-life of smoked Atlantic mackerel deep-skinned fillets stored at 1°C is, therefore, assessed to be at least 21 days. Well-fed Atlantic mackerel is suitable for developing high-quality and stable smoked fillet products from both fresh and frozen–thawed raw materials.

The current expansion of seaweed farming to North America and Europe can be a cornerstone in a new "blue bioeconomy" in the Northern Hemisphere. In this domain, the focus of R&D efforts is on creating value-added products through new biorefining processes for valorizing the unique polysaccharides of seaweeds. Apart from direct consumption of seaweeds as food—particularly in the Asian cuisine—commercial seaweed products are primarily natural hydrocolloids used to make viscous suspensions and gels, but new valuable products exerting bioactivity are coming into focus. This recent development rests on targeted, gentle extraction and modification of the seaweed polysaccharides using tailor-made bioprocessing enzyme technologies. Since brown seaweed cultivation is rising in the Northern Hemisphere, this article provides an overview of recent advances and prospects in brown seaweed biorefining.

Alternative protein sources are gaining attraction in the food industry and consumers. Proteins obtained by single-cell organisms, such as torula yeast, are of enormous interest, as they are highly scalable, efficient, and sustainable, and the production costs are comparably low. Nevertheless, proteins obtained from yeasts are still mostly known and studied for feed applications, despite their nutritional, functional, and sensory benefits for various food applications. Testing consumer acceptance of products, especially products containing alternative proteins provides insights into, eg, market success, consumer perception, and optimization potential. In this study, the development of two vegan spread powders, high in protein and containing torula yeast as an alternative protein source, is introduced. The result of food product development using torula yeast were "Leberwurst"-style (14.7% protein) and a "Balkan"-style (9.7% protein) spreads both meeting the criteria "at least 20% kcal from proteins of total product kcal" and thus claimable as "high-protein." The application of the alternative protein from torula yeast within the final products was studied by a consumer acceptance test (n= 123) within three different countries (Germany, Iceland, and Sweden). Consumers also rated their trust in food production actors, the food industry in particular, and their willingness to try new foods. Overall, both spreads received acceptance values in the range of "like slightly." It is noticeable that the consumers liked the spread "Balkan style" more than "Leberwurst"-style. The background variables revealed higher neophobic characteristics of Icelandic consumers compared with Swedish or German consumers. However, German consumers felt transparency, and communication was missing, but Icelandic consumers, in general, had more trust in the overall food value chain. This knowledge allows for the development of strategies that address cultural-specific barriers and capitalize on cultural values that promote openness to culinary innovation. The identification of cultural variations in consumer preferences emphasizes the need for customized approaches to product development and marketing. These findings could have implications for businesses and policymakers in understanding and catering to the preferences and concerns of consumers in these respective countries. Businesses might benefit from emphasizing transparency and improving communication strategies. This could involve providing clear information about the sourcing, production, and other aspects of the food value chain.

Analysis of volatile compounds in various marine resources and seafood during storage has shown that compounds derived from oxidation of polyunsaturated fatty acids are responsible for the characteristic fish odor. Their origin and formation have been partially elucidated, where membrane bound phospholipids play a key role as precursors. Volatile microbial metabolites as indicators of spoilage can be monitored to determine the quality of fish products. Profiles of volatiles offer possibilities to perform multivariate prediction of quality. However, different handling and processing influences the proliferation of volatiles, depending on the dominating specific spoilage organisms and oxidative processes during storage. As a result, varying levels of volatiles develop in different marine resources and seafood causing different characteristic aromas. Here are some examples to demonstrate the role of key volatile compounds in odor quality changes in chilled cod and haddock, boiled cod, and in washed cod model system. Additionally, the influence of processing on key volatiles and odor development in smoked salmon and salted cod are presented, and key volatiles of seaweed contributing to characteristic marine flavors are highlighted.

An uncharacterized gene encoding a glycoside hydrolase family 43-like enzyme from Clostridium boliviensis strain E-1 was identified from genomic sequence data, and the encoded enzyme, CbE1Xyn43-l, was produced in Escherichia coli. CbE1Xyn43-l (52.9 kDa) is a two-domain endo-β-xylanase consisting of a C-terminal CBM6 and a GH43-like catalytic domain. The positions of the catalytic dyad conserved in GH43, the catalytic base (Asp74), and proton donor (Glu240) were identified in alignments including GH43-enzymes of known 3D-structure from different subfamilies. CbE1Xyn43-l is active at pH 7.0–9.0, with optimum temperature at 65°C, and a more than 7 days' half-life in irreversible deactivation studies at this temperature. The enzyme hydrolyzed birchwood xylan, quinoa stalks glucuronoarabinoxylan, and wheat arabinoxylan with xylotriose and xylotetraose as major hydrolysis products. CbE1Xyn43-l also released xylobiose from pNPX₂ with low turnover (k_cat over 0.044 s⁻¹) but was inactive on pNPX, showing that a degree of polymerization of three (DP3) was the smallest hydrolyzable substrate. Divalent ions affected the specific activity on xylan substrates, which depending on the ion could be increased or decreased. In conclusion, CbE1Xyn43-l from C. boliviensis strain E-1 is the first characterized member of a large group of homologous hypothetical proteins annotated as GH43-like and is a thermostable endo-xylanase, producing xylooligosaccharides of high DP (xylotriose and xylotetraose) producer.