| 1. |
- Stedt, Kristoffer, 1991, et al.
(författare)
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Cultivation in wastewater increases growth and nitrogen content of seaweeds: A meta-analysis
- 2022
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Ingår i: Journal of Algal Research. - : Elsevier BV. - 2211-9264. ; 61
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Tidskriftsartikel (refereegranskat)abstract
- The growing world population demands sustainably produced proteins and cultivation of seaweeds may become an important solution for this so-called protein-shift. To increase the biomass yield and protein content of seaweeds, nutrient-rich wastewaters originating from different processes and activities such as aquaculture, industrial food processing, and municipal wastewater management could be used. Our aim was to synthesize previous literature to assess the impact that different wastewaters have on seaweed growth and protein content, and to identify research gaps. We show, by using standardized and quantitative methods, that cultivation in wastewaters increases both growth and nitrogen content (often used as an approximation for protein) of seaweeds. We further show that all groups of seaweeds (green, brown, and red) benefit from cultivation in wastewater, that the effect is similar between ocean- and land-based seaweed cultivations, and that seaweed cultivation with wastewater is not limited to only fish aquaculture wastewaters. Our results clearly demonstrate that seaweeds can be cultivated in a wide range of wastewaters to generate protein-rich biomass with increased growth and biomass yields. These results can be valuable when searching for sustainably produced proteins for the growing human population.
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| 2. |
- Stedt, Kristoffer, 1991, et al.
(författare)
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Cultivation of seaweeds in food production process waters: Evaluation of growth and crude protein content
- 2022
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Ingår i: Algal Research. - : Elsevier BV. - 2211-9264. ; 63
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Tidskriftsartikel (refereegranskat)abstract
- There is an increasing demand for sustainably produced, protein-rich, and nutritious food. Seaweeds are promising protein sources for the future if their protein content can be optimized, something which can be achieved by cultivation in elevated nutrient concentrations. Cultivation of seaweeds in integration with fish farms have received much attention lately, but using nutrient-rich process waters from other food industries as feed stock for seaweed has rarely been studied. Here, we demonstrate a simple and sustainable strategy to answer the increasing world demand for food rich in plant-based proteins by connecting food production process waters with seaweed cultivation. We compared growth rates and crude protein content of four different seaweed species, the brown species Saccharina latissima, and the green species Ulva fenestrata, Ulva intestinalis, and Chaetomorpha linum, when cultivated in two dilutions (providing 20 and 200 μM ammonium) of eight different process waters emerging from recirculating salmon aquaculture systems as well as from herring, shrimp and oat processing. Growth rates of the green seaweeds were up to 64% higher, and crude protein content was almost up to four times higher when cultivated in the food production process waters, compared to seawater controls. Growth rates were generally higher in presence of 20 μM compared to 200 μM ammonium, while crude protein content was either unaffected or positively affected by the increasing ammonium concentration. This study indicates the potential for cultivating seaweeds with food production process waters to generate additional protein-rich biomass while nutrients are being circulated back to the food chain. A new nutrient loop is thus illustrated, in which the costly disposal of food production process waters is instead turned into value by seaweed cultivation.
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| 3. |
- Stedt, Kristoffer, 1991, et al.
(författare)
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Cultivation of Ulva fenestrata using herring production process waters increases biomass yield and protein content
- 2022
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Ingår i: Frontiers in Marine Science. - : Frontiers Media SA. - 2296-7745. ; 9:988523
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Tidskriftsartikel (refereegranskat)abstract
- Ulva spp. (sea lettuce) has recently gained attention as a sustainable protein source due to its high productivity and many nutritional properties interesting for the food industry. In this study, we explored a possible industrial symbiosis between herring production processing industries and Ulva fenestrata cultivation. We show that U. fenestrata cultivated in herring production process waters had four to six times higher biomass yields (27.17 - 37.07 g fresh weight vs. 6.18 g fresh weight) and three times higher crude protein content (> 30% dry weight vs. 10% dry weight) compared to U. fenestrata cultivated in seawater. Along with the elevation of protein, the herring production process waters also significantly increased levels of all essential amino acids in the seaweed biomass. The content of some heavy metals (arsenic, mercury, lead, and cadmium) was well below the maximum allowed levels in foodstuff. Therefore, quantities of biomass around 100 g dry weight could be consumed daily following the US Environmental Protection Agency’s reference doses. Combined, the results show that cultivation of U. fenestrata in herring production process waters has great potential to produce sustainable proteins for the growing world population. At the same time, nutrients of currently discarded process waters are circulated back to the food chain.
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| 4. |
- Stedt, Kristoffer, 1991, et al.
(författare)
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Determination of nitrogen content in Ulva fenestrata by color image analysis – a rapid and cost-efficient method to estimate nitrogen content in seaweeds
- 2022
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Ingår i: Frontiers in Marine Science. - : Frontiers Media SA. - 2296-7745. ; 9
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Tidskriftsartikel (refereegranskat)abstract
- There is an increasing interest in the cultivation of seaweeds for food and feed, and the seaweed aquaculture industry is rapidly developing. The nutritional status of the seaweeds is important to ensure a good quality crop. Cost-efficient and straightforward methods for farmers to analyze their crop are essential for the successful development of the industry. In this study, we developed non-destructive, labor- and cost-efficient models to estimate the nitrogen content in the crop seaweed Ulva fenestrata by color image analysis. We quantified tissue nitrogen content and thallus color in sea-farmed seaweed every week throughout a whole cultivation season (15 consecutive weeks) and analyzed data with linear regression models. We showed that color image analysis accurately estimated the nitrogen content in the seaweed (R2 = 0.944 and 0.827 for fresh tissue and dried powder, respectively), and through tenfold cross validation we showed that the developed models were robust and precise. Based on these models, we developed a web-based application that automatically analyzes the nitrogen content of the seaweeds. Furthermore, we produced a color guide that can easily be brought to the farm for onsite crude estimation of seaweeds’ nitrogen content. Our results demonstrate that color can be a powerful tool for seaweed farmers (and researchers) to estimate seaweeds’ nutritional status. We anticipate that similar models can be developed for other commercially interesting seaweed species.
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| 5. |
- Stedt, Kristoffer, 1991, et al.
(författare)
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Post-harvest cultivation with seafood process waters improves protein levels of Ulva fenestrata while retaining important food sensory attributes
- 2022
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Ingår i: Frontiers in Marine Science. - : Frontiers Media SA. - 2296-7745.
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Tidskriftsartikel (refereegranskat)abstract
- Seaweed aquaculture can provide the growing human population with a sustainable source of proteins. Sea-based cultivation is an effective method for farming seaweeds on a large scale and can yield high biomass output. However, the quality and biochemical composition of the biomass is seasonally dependent, which limits the harvests to certain periods of the year. Here we show the possibility to extend the sea-based cultivation season of Ulva fenestrata when aiming for high protein levels, by post-harvest treatment in herring production process waters. We harvested U. fenestrata at an optimal period in terms of yield, but suboptimal in terms of protein content. We then cultivated the seaweed in onshore tank systems with the nutrient-rich process waters for 14 days. We monitored biomass yield, crude protein content, amino acid composition, and content of the health concerning metals arsenic, mercury, lead, and cadmium, as well as the sensory properties of the dried biomass. After cultivation in the process waters, biomass yields were 30 - 40% higher (210 – 230 g fresh weight) compared to in seawater (160 g fresh weight). Also, the crude protein and amino acid content increased three to five times in the process waters, reaching 12 - 17 and 15 – 21% dry weight, respectively. The protein enriched biomass followed food graded standards for heavy metal content, and consumption of the biomass does not exceed health based reference points. Additionally, no sensory attributes regarded as negative were found. This rapid, post-harvest treatment can help extend the cultivation season of sea-based seaweed farms, maximizing their output of sustainable proteins.
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| 6. |
- Stedt, Kristoffer, 1991
(författare)
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Seaweeds as a future protein source: innovative cultivation methods for protein production
- 2023
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- As the global population is projected to reach approximately 10 billion people by 2050, it is estimated that we will need to produce up to 60% more food compared to 2010. Although the current food production system contributes to 25% of greenhouse gas emissions worldwide, accounts for 70-80% of eutrophication and freshwater usage, and occupies half of all ice- and desert-free land, it fails to meet the global nutritional needs. Furthermore, with extreme weather events and heat waves affecting terrestrial food production systems, it is evident that we need to look elsewhere to produce sustainable, protein-rich, and nutritious food. Recently, seaweeds have emerged as a promising part of this solution. Cultivating seaweeds requires no arable land, freshwater supply, or high nutrient input. Furthermore, seaweeds have high productivity that outperforms many terrestrial crops such as wheat, seeds, and soybeans. The protein often contains all the essential amino acids, making seaweeds a favorable protein source for human consumption. However, even though seaweeds often have protein contents in the range of some beans and pulses, it is lower than in soybeans. Therefore, their protein content needs to be increased if seaweeds are to become a competitive protein source in the future. This thesis aims to explore the potential of seaweeds as a sustainable future protein source. It specifically focuses on optimizing seaweed cultivation to boost both growth rates and protein content. To achieve this, the effects of different cultivation conditions and the potential of one kelp and three green seaweed species are investigated. A novel nutrient loop is explored, wherein industrial food production process waters (FPPWs) are used as seaweed growth media. By conducting a meta-analysis, as well as land-based experiments that combine physiological, biochemical, chemical, and sensory analyses, the thesis aims to establish the potential for seaweed cultivation in nutrient-rich process waters. The findings from this thesis show that seaweeds can become a promising alternative food source in the ongoing dietary protein shift. The results show that all groups of seaweeds (brown, green, and red) can be cultivated in various nutrient-rich process waters; but green seaweeds have the highest potential. After identifying the green seaweed species Ulva fenestrata, which usually has a crude protein content of 10-20% dry weight, as a promising candidate, its cultivation in FPPWs yielded protein content of up to 37% dry weight. Furthermore, the biomass yield was up to six times higher compared to when grown in seawater. The safety aspects of consuming the biomass were confirmed by showing that large quantities of the biomass can be consumed every day without exceeding health-based reference points for heavy metals. Also, no sensory attributes regarded as negative were found after cultivation in the FPPWs. In conclusion, this thesis illustrates a novel nutrient loop, where the disposal of industrial food production process waters can be turned into nutrient-rich and valuable biomass through seaweed cultivation.
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| 7. |
- Steinhagen, Sophie, et al.
(författare)
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A step towards closing the food-waste gap in novel protein sources: Post-harvest protein boost of the seaweed crop Ulva by herring production tub water
- 2024
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Ingår i: Future Foods. - 2666-8335.
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Tidskriftsartikel (refereegranskat)abstract
- Sea lettuce (Ulva) species have been identified as a future protein source, and post-harvest techniques, including the sustainable integration of liquid food side streams, have been developed to further increase their protein content and commercial market value. This study explores the post-harvest treatment of commercially produced seaweed biomass from large-scale, sea-based cultivations of U. fenestrata with residual water streams emerging from industrial storage of herring – so called herring production tub water (TUB). Growth rates of U. fenestrata were significantly higher in TUB treated seaweeds compared to controls. Further, the crude protein content was 71.26% higher when cultivated in TUB, compared to controls, reaching a crude protein content of 37.37 ± 1.83 % dry weight. Notably, there were no limiting amino acids, nor fish-related allergenic activity in the seaweed biomass. Our study demonstrates a new nutrient loop turning food waste into protein-rich biomass by applying sustainable seaweed cultivation.
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| 8. |
- Trigo, João Pedro, 1995, et al.
(författare)
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Mild blanching prior to pH-shift processing of Saccharina latissima retains protein extraction yields and amino acid levels of extracts while minimizing iodine content
- 2023
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Ingår i: Food Chemistry. - : Elsevier BV. - 0308-8146 .- 1873-7072. ; 404
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Tidskriftsartikel (refereegranskat)abstract
- The seaweed Saccharina latissima is often blanched to lower iodine levels, however, it is not known how blanching affects protein extraction. We assessed the effect of blanching or soaking (80/45/12 °C, 2 min) on protein yield and protein extract characteristics after pH-shift processing of S. latissima. Average protein yields and extract amino acid levels ranked treatments as follows: blanching-45 °C ∼ control > soaking ∼ blanching-80 °C. Although blanching-45 °C decreased protein solubilization yield at pH 12, it increased isoelectric protein precipitation yield at pH 2 (p < 0.05). The former could be explained by a higher ratio of large peptides/proteins in the blanched biomass as shown by HP-SEC, whereas the latter by blanching-induced lowering of ionic strength, as verified by a dialysis model. Moreover, blanching-45 °C yielded a protein extract with 49 % less iodine compared with the control extract. We recommend blanching-45 °C since it is effective at removing iodine and does not compromise total protein extraction yield.
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