Microbiological Food Safety of Seaweeds

Improving Meat Quality, Safety and Sustainability in Monogastric Livestock with Algae Feed Additives

Integrating algae (microalgae and seaweeds) into monogastric animal diets presents significant opportunities to improve meat quality, safety, and sustainability. This review synthesizes current knowledge on the nutritional and bioactive compounds found in key microalgae (e.g., Chlorella vulgaris, Spirulina, and Nannochloropsis) and seaweeds (e.g., Ascophyllum nodosum, Ulva), emphasizing their potential benefits for animal health and meat production. Algae-enriched diets substantially increase meat omega-3 fatty acid content and antioxidant capacity, thereby enhancing nutritional value, sensory appeal, and shelf life by mitigating lipid and protein oxidation during storage. Additionally, bioactive compounds in algae demonstrate potent antimicrobial activities capable of reducing pathogenic bacteria such as Salmonella, Escherichia coli, and Campylobacter, significantly contributing to improved meat safety. Environmentally, algae cultivation reduces dependency on arable land and freshwater, promotes nutrient recycling through wastewater use, and substantially decreases greenhouse gas emissions compared to traditional livestock feeds. Nevertheless, challenges persist, including high production costs, scalability concerns, variability in nutrient composition, potential contamination with heavy metals and other toxins, and regulatory constraints. Overcoming these limitations through advancements in cultivation technologies, optimized inclusion strategies, and comprehensive market and regulatory analyses is essential to fully realize the potential of algae in sustainable monogastric livestock feeding systems.

Expanding our food supply: underutilized resources and resilient processing technologies

Many underutilized food resources have been traditionally used by regional and poor communities. The history of their consumption makes them potential new food sources for incorporation into the wider food supply. The ability to tap the potential of undervalued and underutilized food sources will reduce the world's reliance on a limited number of food sources and improve food security and sustainability. The expansion of the food diversity of the food supply to include underutilized food resources will require overcoming challenges in the efficient and profitable production of the raw material, application of suitable postharvest handling procedures to maintain the quality of perishable produce, and the use of appropriate traditional and emerging food processing technologies for conversion of the raw material into safe, nutritious and consumer-acceptable foods. Improvement of food processing technologies, particularly resource-efficient resilient food processes, are required to ensure the safety, quality and functionality of the whole food or extracts, and to develop ingredient formulations containing new foods for manufacture of consumer food products. Factors that help facilitate the social acceptance of new underutilized foods include increasing consumer knowledge and understanding of the contribution of new underutilized food resources to diet diversity for good nutrition, confidence in the safety and value of new foods, and their low environmental impact and importance for future sustainable food. The introduction of new underutilized food resources will increasingly require collaboration along the whole food value chain, including support from government and industry. © 2024 The Author(s). Journal of the Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Microbial Level and Microbiota Change of Laver in Dried Laver Processing Line During Production Seasons

To understand better the high microbial load in dried laver (Porphyra yezoensis or nori), this study analyzed the aerobic plate count (APC), coliform count, temperature change, and microbiota of processing water, laver materials, and food contact surface (FCS) samples from three processing plants during the dried laver processing season from December 2023 to April 2024. The seawater used for the first washing had a low microbial load (APCs < 1-2.85 log CFU/g; coliform < 1 log CFU/g) and was dominated by Proteobacteria, Firmicutes, and Bacteroidota. The microbial load of fresh laver (4.21-4.76 log CFU/g) remained unchanged after seawater washing, but significantly increased after continuous shredding, sponge dehydration, first drying, and with the seasonal temperature rise. The microbiota of laver before drying was vulnerable between processing steps and seasons, but consistently shifted back to fresh laver microflora and was dominated by Flavobacteriaceae after drying. The FCSs (except for the curtain), which had a high microbial load (APCs 5.25-8.26 log CFU/g; coliform 1.52-4.84 log CFU/g) with similar microbiota to seawater, caused the secondary contamination of laver during processing. This study revealed the microbial proliferation of laver and seawater microflora in the continuous processing line with high nutrients and with the seasonal processing water temperature rise caused by the local weather, highlighting the need for routine cleaning and sanitizing, better washing of fresh laver, and low temperature control for future dried laver production.

Characterization, Bio-Prospection, and Comparative Metagenomics of Bacterial Communities Revealing the Predictive Functionalities in Wild and Cultured Samples of Industrially Important Red Seaweed Gracilaria dura

The present study explores the microbial community associated with the industrially important red seaweed Gracilaria dura to determine the diversity and biotechnological potential through culture and metagenomics approaches. In the first part of the investigation, we isolated and characterized 75 bacterial morphotypes, with varied colony characteristics and metabolic diversity from the wild seaweed. Phylogenetic analysis identified isolates in Proteobacteria, Firmicutes, and Actinobacteria, with Bacillus sp. being prevalent. B. licheniformis and Streptomyces sp. were notable in producing important enzymes like L-asparaginase, and polysaccharide lyases. Antimicrobial activity was significant in 21% of isolates, effective against seaweed pathogens such as Vibrio and Xanthomonas. Rhodococcus pyridinivorans showed strong pyridine degradation, suggesting bioremediation potential. Several isolates exhibited phosphate solubilization and nitrate indicating the roles of bacteria as algal growth promoters and biocontrol agents. Subsequent metagenome analysis of wild and cultured samples provides insights into bacterial communities associated with G. dura, revealing their distribution and functional roles. Proteobacteria (~ 95%) dominated the communities, further bacterial groups involved in algal growth, carpospore liberation, stress resistance, biogeochemical cycles, and biomedical applications were identified. A notable difference in bacteriomes was observed between the samples, with 25% remaining stable. The samples are cultured in the lab to generate seedlings for farming and serve as germplasm storage during the monsoon season. Microbiome surveys are crucial for understanding the association of pathogens and the overall health of the seedlings, supporting successful seaweed farming. Our findings provide valuable insights into G. dura-associated microbial communities and their role in algal growth, which has aquacultural implications.

Effect of Biomass Drying Protocols on Bioactive Compounds and Antioxidant and Enzymatic Activities of Red Macroalga Kappaphycus alvarezii

Kappaphycus alvarezii is a red seaweed used globally in various biotechnological processes. To ensure the content and stability of its bioactive compounds postharvest, suitable drying protocols must be adopted to provide high-quality raw materials for industrial use. This study aimed to analyze the influence of freeze-drying and oven-drying on the total phenolic content (TPC), total flavonoid content (TFC), antioxidant activity (FRAP and DPPH assays), total carotenoid content (TC), and lipase (LA) and protease activity (PA) of K. alvarezii samples collected over the seasons in sea farms in southern Brazil. The freeze-drying technique was found to be more effective regarding superior contents of TPC (39.23 to 127.74 mg GAE/100 g) and TC (10.27 to 75.33 μg/g), as well as DPPH (6.12 to 8.91 mg/100 g). In turn, oven-drying proved to be the best method regarding the TFC (4.99 to 12.29 mg QE/100 g) and PA (119.50 to 1485.09 U/g), with better performance in the FRAP (0.28 to 0.70 mmol/100 g). In this way, it appears that the drying process of the algal biomass can be selected depending on the required traits of the biomass for the intended industrial application. In terms of cost-effectiveness, drying the biomass using oven-drying can be considered appropriate.

The green seaweed Ulva: tomorrow's "wheat of the sea" in foods, feeds, nutrition, and biomaterials

Ulva, a genus of green macroalgae commonly known as sea lettuce, has long been recognized for its nutritional benefits for food and feed. As the demand for sustainable food and feed sources continues to grow, so does the interest in alternative, plant-based protein sources. With its abundance along coastal waters and high protein content, Ulva spp. have emerged as promising candidates. While the use of Ulva in food and feed has its challenges, the utilization of Ulva in other industries, including in biomaterials, biostimulants, and biorefineries, has been growing. This review aims to provide a comprehensive overview of the current status, challenges and opportunities associated with using Ulva in food, feed, and beyond. Drawing on the expertise of leading researchers and industry professionals, it explores the latest knowledge on Ulva's nutritional value, processing methods, and potential benefits for human nutrition, aquaculture feeds, terrestrial feeds, biomaterials, biostimulants and biorefineries. In addition, it examines the economic feasibility of incorporating Ulva into aquafeed. Through its comprehensive and insightful analysis, including a critical review of the challenges and future research needs, this review will be a valuable resource for anyone interested in sustainable aquaculture and Ulva's role in food, feed, biomaterials, biostimulants and beyond.

Modified Atmosphere Packaging (MAP) for Seaweed Conservation: Impact on Physicochemical Characteristics and Microbiological Activity

Conventional conservation techniques such as drying, salting or freezing do not allow for preserving the original characteristics of seaweeds. The present work aims to study the impact of minimal processing, in particular "Modified Atmosphere Packaging" (MAP), on the physicochemical characteristics and food safety of two seaweed species, "laver" (Porphyra umbilicalis) and "sea-lettuce" (Ulva lactuca), stored at 6 °C for 15 days. Different parameters were evaluated using analytical methods, namely the composition of headspace gases, color, texture, microorganisms, and volatile organic compounds (VOCs). The main findings of this study were that the MAP treatment was able to inhibit the respiration rate of minimally processed seaweeds, also preserving their color and texture. There was a remarkable reduction in the microbial load for P. umbilicalis treated under modified and vacuum atmospheres, and U. lactuca exhibited relatively steady values with no notable differences between the treatments and the control. Therefore, during the 15-day study period, both seaweeds met the requirements for food safety. GC-TOF-MS allowed to conclude that both MAP and vacuum treatments were more efficient in maintaining the odor characteristics of U. lactuca compared to P. umbilicalis with no significant differences throughout the storage days. Metabolic responses to diverse sources of abiotic stress seemed to account for most of the changes observed.

An overview on the nutritional and bioactive components of green seaweeds

Green seaweed, as the most abundant species of macroseaweeds, is an important marine biological resource. It is a rich source of several amino acids, fatty acids, and dietary fibers, as well as polysaccharides, polyphenols, pigments, and other active substances, which have crucial roles in various biological processes such as antioxidant activity, immunoregulation, and anti-inflammatory response. In recent years, attention to marine resources has accelerated the exploration and utilization of green seaweeds for greater economic value. This paper elaborates on the main nutrients and active substances present in different green seaweeds and provides a review of their biological activities and their applications for high-value utilization.

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The Controlled Semi-Solid Fermentation of Seaweeds as a Strategy for Their Stabilization and New Food Applications

For centuries, macroalgae, or seaweeds, have been a significant part of East Asian diets. In Europe, seaweeds are not considered traditional foods, even though they are increasingly popular in Western diets in human food applications. In this study, a biological processing method based on semi-solid fermentation was optimized for the treatment of the seaweed Gracilaria gracilis. For the first time, selected lactic acid bacteria and non-conventional coagulase-negative staphylococci were used as starter preparations for driving a bio-processing and bio-stabilization of raw macroalga material to obtain new seaweed-based food prototypes for human consumption. Definite food safety and process hygiene criteria were identified and successfully applied. The obtained fermented products did not show any presence of pathogenic or spoilage microorganisms, thereby indicating safety and good shelf life. Lactobacillus acidophilus-treated seaweeds revealed higher α-amylase, protease, lipase, endo-cellulase, and endo-xylanase activity than in the untreated sample. This fermented sample showed a balanced n-6/n-3 fatty acid ratio. SBM-11 (Lactobacillus sakei, Staphylococcus carnosus and Staphylococcus xylosus) and PROMIX 1 (Staphylococcus xylosus) treated samples showed fatty acid compositions that were considered of good nutritional quality and contained relevant amounts of isoprenoids (vitamin E and A). All the starters improved the nutritional value of the seaweeds by significantly reducing the insoluble indigestible fractions. Preliminary data were obtained on the cytocompatibility of G. gracilis fermented products by in vitro tests. This approach served as a valid strategy for the easy bio-stabilization of this valuable but perishable food resource and could boost its employment for newly designed seaweed-based food products.

Bioextractive aquaculture as an alternative nutrient management strategy for water resource recovery facilities

Advanced nutrient removal in water resource recovery facilities (WRRFs) can reduce coastal eutrophication, but can increase economic costs and indirect environmental impacts associated with energy and materials usage for WRRF construction and operation. A strategy of interest to reduce coastal eutrophication is the cultivation of seaweeds in proximity to WRRF discharge plumes to bioextract nutrients from coastal waters. We report economic and environmental trade-offs of this proposed strategy for a 1,170 m³·d^-1 (0.31 mgd) WRRF in Boothbay Harbor, Maine, targeting a Water Environment Research Federation (WERF) level 2 effluent nitrogen goal of 3 mg-N·L^-1. The scenarios investigated include WRRF upgrade and year-round nutrient bioextractive aquaculture (Saccharina latissima and Gracilaria tikvahiae cultivation) with end uses of bioenergy feedstock, fertilizer, or food. Based on biomass production characteristics and tissue nitrogen contents in Boothbay Harbor, an aquaculture site of 5.4 hectares would bioextract equivalent nitrogen mass as WRRF upgrade to meet level 2 nitrogen effluent goals. Using a techno-economic analysis, the cost of a WRRF upgrade was estimated to be $0.31 m^-3 wastewater treated. The cost of bioextractive seaweed aquaculture depended on beneficial use of seaweed. If dried and sold as sea vegetables (for human consumption), a net revenue of $0.72 m^-3 wastewater treated could be generated. If dried and sold as commercial fertilizer, the net cost of nutrient removal would be $0.26 m^-3 wastewater treated, less than the WRRF upgrade. However, if anaerobically digested to produce biogas, the net cost of treatment was estimated to be $0.499 m^-3 wastewater treated. WRRF upgrade and bioextractive aquaculture significantly reduced marine eutrophication. Bioextractive aquaculture with use as biofuel feedstock had the best performance on human carcinogenic toxicity, global warming, and fossil resource scarcity, marine ecotoxicity, and freshwater ecotoxicity. Use of seaweed product as sea vegetables was favorable considering human non-carcinogenic toxicity, marine eutrophication, freshwater eutrophication, and terrestrial ecotoxicity. The study results imply that nutrient bioextraction by seaweed aquaculture may be attractive as an alternative to advanced nutrient removal technologies in small coastal WRRFs, providing potential economic and environmental benefits for nutrient management.