{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,23]],"date-time":"2026-10-23T21:08:47Z","timestamp":1792789727201,"version":"4.5.0"},"reference-count":42,"publisher":"MDPI AG","issue":"9","license":[{"start":{"date-parts":[[2026,9,20]],"date-time":"2026-09-20T00:00:00Z","timestamp":1789862400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Agriculture and Food Research Initiative Competitive","award":["2021-69014-34501"],"award-info":[{"award-number":["2021-69014-34501"]}],"id":[{"id":"https:\/\/ror.org\/03n17ds51","id-type":"ROR","asserted-by":"crossref"}]},{"award":["2021-69014-34501"],"award-info":[{"award-number":["2021-69014-34501"]}],"id":[{"id":"https:\/\/ror.org\/03n17ds51","id-type":"ROR","asserted-by":"publisher"}]},{"name":"Cynthia and George Mitchell Foundation","id":[{"id":"https:\/\/ror.org\/017qdky13","id-type":"ROR","asserted-by":"crossref"}]},{"id":[{"id":"https:\/\/ror.org\/017qdky13","id-type":"ROR","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Microorganisms"],"abstract":"<jats:p>The sustainability limitations of fishmeal and fish oil have increased interest in nutrient- rich microalgal co-products for aquafeeds. This study evaluated the effects of processing on the nutritional composition and apparent digestibility of a defatted Nannochloropsis sp. QH25 co-product in rainbow trout (Oncorhynchus mykiss). Experiment 1 assessed the effects of extrusion at 90 \u00b0C or 127 \u00b0C, with or without precooking, and enzymatic treatment with protease, xylanase, and \u03b2-glucanase. Based on nutrient composition, the 90 \u00b0C extrusion treatment without precooking was selected for Experiment 2, which compared a reference diet with three diets containing 30% raw, extruded, or enzyme-treated co-product, using four replicate tanks per diet. Extrusion at 127 \u00b0C reduced crude protein, gross energy, and methionine concentrations, whereas extrusion at 90 \u00b0C largely preserved nutrient composition. Precooking reduced several essential amino acids but increased methionine and did not affect tryptophan. Crude protein digestibility was numerically higher in the extruded co-product than in the raw co-product, although the difference was not statistically significant. Most essential amino acids showed similar digestibility in the raw and extruded treatments, whereas enzymatic processing resulted in lower crude protein and amino acid digestibility. Omega-3 fatty acid digestibility remained high across diets. Overall, the raw co-product showed high nutrient digestibility, while extrusion resulted in only small, generally non-significant numerical differences and enzymatic processing generally resulted in lower nutrient digestibility under the conditions evaluated.<\/jats:p>","DOI":"10.3390\/microorganisms14092104","type":"journal-article","created":{"date-parts":[[2026,9,21]],"date-time":"2026-09-21T10:25:43Z","timestamp":1789986343000},"page":"2104","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Evaluating the Processing and Nutrient Digestibility of Defatted Nannochloropsis sp. QH25 Co-Product for Sustainable Rainbow Trout Aquaculture Diets"],"prefix":"10.3390","volume":"14","author":[{"ORCID":"https:\/\/orcid.org\/0009-0009-0475-8189","authenticated-orcid":false,"given":"Pallab K.","family":"Sarker","sequence":"first","affiliation":[{"name":"Environmental Studies Department, University of California Santa Cruz, Santa Cruz, CA 95064, USA"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"conceptualization","vocabulary":"credit"},{"role":"methodology","vocabulary":"credit"},{"role":"resources","vocabulary":"credit"},{"role":"formal-analysis","vocabulary":"credit"},{"role":"writing-original-draft","vocabulary":"credit"},{"role":"writing-review-editing","vocabulary":"credit"},{"role":"supervision","vocabulary":"credit"},{"role":"software","vocabulary":"credit"},{"role":"project-administration","vocabulary":"credit"},{"role":"funding-acquisition","vocabulary":"credit"}]},{"given":"Benjamin V.","family":"Schoffstall","sequence":"additional","affiliation":[{"name":"Environmental Studies Department, University of California Santa Cruz, Santa Cruz, CA 95064, USA"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"investigation","vocabulary":"credit"},{"role":"resources","vocabulary":"credit"},{"role":"formal-analysis","vocabulary":"credit"},{"role":"writing-original-draft","vocabulary":"credit"},{"role":"writing-review-editing","vocabulary":"credit"},{"role":"data-curation","vocabulary":"credit"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-7576-0889","authenticated-orcid":false,"given":"Anne R.","family":"Kapuscinski","sequence":"additional","affiliation":[{"name":"Environmental Studies Department, University of California Santa Cruz, Santa Cruz, CA 95064, USA"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"conceptualization","vocabulary":"credit"},{"role":"methodology","vocabulary":"credit"},{"role":"writing-review-editing","vocabulary":"credit"}]},{"given":"Devin","family":"Fitzgerald","sequence":"additional","affiliation":[{"name":"California Sea Grant Extension Program, University of California San Diego, San Diego, CA 92093, USA"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"investigation","vocabulary":"credit"},{"role":"resources","vocabulary":"credit"},{"role":"formal-analysis","vocabulary":"credit"},{"role":"methodology","vocabulary":"credit"},{"role":"data-curation","vocabulary":"credit"}]},{"given":"Anindita","family":"Datta","sequence":"additional","affiliation":[{"name":"Environmental Studies Department, University of California Santa Cruz, Santa Cruz, CA 95064, USA"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"writing-original-draft","vocabulary":"credit"},{"role":"writing-review-editing","vocabulary":"credit"},{"role":"visualization","vocabulary":"credit"}]},{"ORCID":"https:\/\/orcid.org\/0009-0002-1460-5871","authenticated-orcid":false,"given":"Duncan","family":"Gwynne","sequence":"additional","affiliation":[{"name":"Environmental Studies Department, University of California Santa Cruz, Santa Cruz, CA 95064, USA"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"writing-original-draft","vocabulary":"credit"},{"role":"writing-review-editing","vocabulary":"credit"},{"role":"formal-analysis","vocabulary":"credit"},{"role":"software","vocabulary":"credit"},{"role":"data-curation","vocabulary":"credit"}]},{"given":"Connor","family":"Greenwood","sequence":"additional","affiliation":[{"name":"Monterey Bay Salmon and Trout Project, Big Creek Rd., Davenport, CA 95017, USA"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"investigation","vocabulary":"credit"},{"role":"methodology","vocabulary":"credit"}]}],"member":"1968","published-online":{"date-parts":[[2026,9,20]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"551","DOI":"10.1038\/s41586-021-03308-6","article-title":"A 20-Year Retrospective Review of Global Aquaculture","volume":"591","author":"Naylor","year":"2021","journal-title":"Nature"},{"key":"ref_2","unstructured":"National Research Council (NRC), Division on Earth and Life Studies, Board on Agriculture and Natural Resources, and Committee on the Nutrient Requirements of Fish and Shrimp (2011). Nutrient Requirements of Fish and Shrimp, National Academies Press. [1st ed.]."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"1068","DOI":"10.1038\/s43016-025-01254-4","article-title":"Unstable Supply and Future Shortages of Wild Forage Fish Heighten Risks to Global Fed Aquaculture Production","volume":"6","author":"Liu","year":"2025","journal-title":"Nat. Food"},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"95","DOI":"10.1038\/s41586-020-2616-y","article-title":"The Future of Food from the Sea","volume":"588","author":"Costello","year":"2020","journal-title":"Nature"},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"eadn5650","DOI":"10.1126\/sciadv.adn5650","article-title":"A Review of the Global Use of Fishmeal and Fish Oil and the Fish In: Fish Out Metric","volume":"10","author":"Majluf","year":"2024","journal-title":"Sci. Adv."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"43","DOI":"10.1080\/23308249.2019.1649634","article-title":"Trends in Global Aquaculture and Aquafeed Production: 2000\u20132017","volume":"28","author":"Tacon","year":"2020","journal-title":"Rev. Fish. Sci. Aquac."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"43","DOI":"10.1007\/s00726-008-0171-1","article-title":"New Developments in Fish Amino Acid Nutrition: Towards Functional and Environmentally Oriented Aquafeeds","volume":"37","author":"Li","year":"2009","journal-title":"Amino Acids"},{"key":"ref_8","unstructured":"Davis, D.A. (2015). 8\u2014Replacing Fishmeal and Fish Oil in Industrial Aquafeeds for Carnivorous Fish. Feed and Feeding Practices in Aquaculture, Woodhead Publishing. Woodhead Publishing Series in Food Science, Technology and Nutrition."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"5","DOI":"10.1525\/elementa.404","article-title":"Towards Sustainable and Ocean-Friendly Aquafeeds: Evaluating a Fish-Free Feed for Rainbow Trout (Oncorhynchus mykiss) Using Three Marine Microalgae Species","volume":"8","author":"Sarker","year":"2020","journal-title":"Elem. Sci. Anthr."},{"key":"ref_10","first-page":"7949782","article-title":"Algal and Vegetable Oils as Sustainable Fish Oil Substitutes in Rainbow Trout Diets: An Approach to Reduce Contaminant Exposure","volume":"2018","author":"Sarker","year":"2018","journal-title":"J. Food Qual."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"56","DOI":"10.1111\/anu.12533","article-title":"Digestibility of the Defatted Microalgae Nannochloropsis sp. and Desmodesmus sp. When Fed to Atlantic Salmon, Salmo salar","volume":"24","author":"Gong","year":"2018","journal-title":"Aquac. Nutr."},{"key":"ref_12","doi-asserted-by":"crossref","unstructured":"Kiron, V., S\u00f8rensen, M., Huntley, M., Vasanth, G.K., Gong, Y., Dahle, D., and Palihawadana, A.M. (2016). Defatted Biomass of the Microalga, Desmodesmus sp., Can Replace Fishmeal in the Feeds for Atlantic Salmon. Front. Mar. Sci., 3.","DOI":"10.3389\/fmars.2016.00067"},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"109","DOI":"10.1111\/anu.12230","article-title":"Nile Tilapia (Oreochromis niloticus) Show High Digestibility of Lipid and Fatty Acids from Marine Schizochytrium sp. and of Protein and Essential Amino Acids from Freshwater Spirulina sp. Feed Ingredients","volume":"22","author":"Sarker","year":"2016","journal-title":"Aquac. Nutr."},{"key":"ref_14","doi-asserted-by":"crossref","unstructured":"Sarker, P.K., Kapuscinski, A.R., Bae, A.Y., Donaldson, E., Sitek, A.J., Fitzgerald, D.S., and Edelson, O.F. (2018). Towards Sustainable Aquafeeds: Evaluating Substitution of Fishmeal with Lipid-Extracted Microalgal Co-Product (Nannochloropsis oculata) in Diets of Juvenile Nile Tilapia (Oreochromis niloticus). PLoS ONE, 13.","DOI":"10.1371\/journal.pone.0201315"},{"key":"ref_15","doi-asserted-by":"crossref","unstructured":"S\u00f8rensen, M., Gong, Y., Bjarnason, F., Vasanth, G.K., Dahle, D., Huntley, M., and Kiron, V. (2017). Nannochloropsis oceania-Derived Defatted Meal as an Alternative to Fishmeal in Atlantic Salmon Feeds. PLoS ONE, 12.","DOI":"10.1371\/journal.pone.0179907"},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"19328","DOI":"10.1038\/s41598-020-75289-x","article-title":"Microalgae-Blend Tilapia Feed Eliminates Fishmeal and Fish Oil, Improves Growth, and Is Cost Viable","volume":"10","author":"Sarker","year":"2020","journal-title":"Sci. Rep."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"1109","DOI":"10.1007\/s10811-014-0428-x","article-title":"Chemical Composition and Nutritional Properties of Freshwater and Marine Microalgal Biomass Cultured in Photobioreactors","volume":"27","author":"Tibbetts","year":"2015","journal-title":"J. Appl. Phycol."},{"key":"ref_18","doi-asserted-by":"crossref","unstructured":"Sarker, P.K., Schoffstall, B.V., Kapuscinski, A.R., McKuin, B., Fitzgerald, D., Greenwood, C., O\u2019Shelski, K., Pasion, E.N., Gwynne, D., and Gonzalez Orcajo, D. (2025). Towards Sustainable Aquafeeds: Microalgal (Nannochloropsis sp. QH25) Co-Product Biomass Can Fully Replace Fishmeal in the Feeds for Rainbow Trout (Oncorhynchus mykiss). Foods, 14.","DOI":"10.3390\/foods14050781"},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"47","DOI":"10.1016\/j.aquaculture.2015.08.027","article-title":"Microalgae and Organic Minerals Enhance Lipid Retention Efficiency and Fillet Quality in Atlantic Salmon (Salmo salar L.)","volume":"451","author":"Kousoulaki","year":"2016","journal-title":"Aquaculture"},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"6","DOI":"10.1186\/2241-5793-21-6","article-title":"An Overview: Biomolecules from Microalgae for Animal Feed and Aquaculture","volume":"21","author":"Yaakob","year":"2014","journal-title":"J. Biol. Res. Thessalon."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"46073","DOI":"10.1007\/s11356-024-34136-6","article-title":"Towards Cleaner Environment: Recycling Microalgal Co-Product to Reduce Emissions and Impacts While Eliminating Fishmeal in Rainbow Trout Feed for Sustainable Aquaculture","volume":"31","author":"Sarker","year":"2024","journal-title":"Environ. Sci. Pollut. Res."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"103295","DOI":"10.1016\/j.algal.2023.103295","article-title":"Extrusion Processing Improves Rainbow Trout Digestibility of Microalgal Nannochloropsis oculata Co-Product Biomass for More Sustainable Aquaculture Diets","volume":"75","author":"Sarker","year":"2023","journal-title":"Algal Res."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"00119","DOI":"10.1525\/elementa.2023.00119","article-title":"Enzyme-Treated Microalgal Co-Product Diets for Rainbow Trout Aquaculture: Supporting Fish Growth, Phosphorus Digestibility, and Reducing Phosphorus Waste Emission","volume":"12","author":"Andrade","year":"2024","journal-title":"Elem. Sci. Anth."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"e70002","DOI":"10.1111\/raq.70002","article-title":"The State-of-the-Art of Aquafeed Extrusion: Mechanisms, Challenges and Opportunities","volume":"17","author":"Pennells","year":"2025","journal-title":"Rev. Aquac."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"419","DOI":"10.1111\/anu.12258","article-title":"Supplementing Enzymes to Extruded, Soybean-Based Diet Improves Breakdown of Non-Starch Polysaccharides in Rainbow Trout (Oncorhynchus mykiss)","volume":"22","author":"Dalsgaard","year":"2016","journal-title":"Aquac. Nutr."},{"key":"ref_26","doi-asserted-by":"crossref","unstructured":"B\u00e9langer, A., Sarker, P.K., Bureau, D.P., Chouinard, Y., Vandenberg, G.W., Rombenso, A., Ara\u00fajo, B., Li, E., and Olivotto, I. (2021). Apparent Digestibility of Macronutrients and Fatty Acids from Microalgae (Schizochytrium sp.) Fed to Rainbow Trout (Oncorhynchus Mykiss): A Potential Candidate for Fish Oil Substitution. Animals, 11.","DOI":"10.3390\/ani11020456"},{"key":"ref_27","first-page":"25","article-title":"Bioenergetics of Salmonid Fishes: Energy Intake, Expenditure and Productivity","volume":"73","author":"Cho","year":"1982","journal-title":"Comp. Biochem. Physiol. B Biochem. Mol. Biol."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"17","DOI":"10.1111\/j.1365-2095.2007.00450.x","article-title":"A Feed Is Only as Good as Its Ingredients\u2014A Review of Ingredient Evaluation Strategies for Aquaculture Feeds","volume":"13","author":"Glencross","year":"2007","journal-title":"Aquac. Nutr."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"103","DOI":"10.1016\/j.aquaculture.2006.01.028","article-title":"Letter to the Editor of Aquaculture","volume":"252","author":"Bureau","year":"2006","journal-title":"Aquaculture"},{"key":"ref_30","unstructured":"Farrell, A.P. (2011). ENERGETIC MODELS | Bioenergetics in Aquaculture Settings. Encyclopedia of Fish Physiology, Academic Press."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"8779","DOI":"10.1021\/jf071769z","article-title":"Retention of Essential Amino Acids during Extrusion of Protein and Reducing Sugars","volume":"55","author":"Singh","year":"2007","journal-title":"J. Agric. Food Chem."},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"5456","DOI":"10.1038\/s41467-024-49277-y","article-title":"Implicating the Red Body of Nannochloropsis in Forming the Recalcitrant Cell Wall Polymer Algaenan","volume":"15","author":"Gee","year":"2024","journal-title":"Nat. Commun."},{"key":"ref_33","doi-asserted-by":"crossref","unstructured":"Zhao, K., Zhang, M., Tian, H., Lei, F., He, D., Zheng, J., and Zhang, L. (2022). Effects of Structural and Compositional Changes of Nanochloropsis Oceania after Enzyme Treatment on EPA-Rich Lipids Extraction. Mar. Drugs, 20.","DOI":"10.3390\/md20030160"},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"339","DOI":"10.1016\/j.energy.2017.10.061","article-title":"Microalgal Cell Disruption via Extrusion for the Production of Intracellular Valuables","volume":"142","author":"Wang","year":"2018","journal-title":"Energy"},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"4877","DOI":"10.1002\/fsn3.1775","article-title":"Effect of Processing on the Contents of Amino Acids and Fatty Acids, and Glucose Release from the Starch of Quinoa","volume":"8","author":"Wu","year":"2020","journal-title":"Food Sci. Nutr."},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"76","DOI":"10.1016\/j.algal.2016.11.010","article-title":"In Vitro Prediction of Digestible Protein Content of Marine Microalgae (Nannochloropsis granulata) Meals for Pacific White Shrimp (Litopenaeus vannamei) and Rainbow Trout (Oncorhynchus mykiss)","volume":"21","author":"Tibbetts","year":"2017","journal-title":"Algal Res."},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"741209","DOI":"10.1016\/j.aquaculture.2024.741209","article-title":"Impact of Extrusion Temperature and Moisture Incorporation on Nutrient Digestibility in Barramundi (Lates calcarifer) Diet","volume":"592","author":"Chung","year":"2024","journal-title":"Aquaculture"},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"1792","DOI":"10.1111\/raq.12410","article-title":"Bile Acid Metabolism in Fish: Disturbances Caused by Fishmeal Alternatives and Some Mitigating Effects from Dietary Bile Inclusions","volume":"12","author":"Romano","year":"2020","journal-title":"Rev. Aquac."},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"43","DOI":"10.1111\/anu.12136","article-title":"Apparent Digestibility of Asian Carp- and Common Carp-Derived Fish Meals in Feeds for Hybrid Striped Bass Morone saxatilis \u2640 \u00d7 M. chrysops \u2642 and Rainbow Trout Oncorhynchus mykiss","volume":"21","author":"Bowzer","year":"2015","journal-title":"Aquac. Nutr."},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"1450","DOI":"10.1128\/EC.00183-14","article-title":"Ultrastructure and Composition of the Nannochloropsis gaditana Cell Wall","volume":"13","author":"Scholz","year":"2014","journal-title":"Eukaryot. Cell"},{"key":"ref_41","doi-asserted-by":"crossref","first-page":"312","DOI":"10.1016\/j.biortech.2016.10.063","article-title":"Aqueous Enzymatic Process for Cell Wall Degradation and Lipid Extraction from Nannochloropsis sp","volume":"223","author":"Wu","year":"2017","journal-title":"Bioresour. Technol."},{"key":"ref_42","doi-asserted-by":"crossref","first-page":"114344","DOI":"10.1016\/j.anifeedsci.2019.114344","article-title":"Parameters Monitored during the Pelleting Process and Their Relationship to Xylanase Activity Loss","volume":"259","author":"Pope","year":"2020","journal-title":"Anim. Feed Sci. Technol."}],"container-title":["Microorganisms"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2076-2607\/14\/9\/2104\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,9,22]],"date-time":"2026-09-22T04:37:12Z","timestamp":1790051832000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2076-2607\/14\/9\/2104"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,9,20]]},"references-count":42,"journal-issue":{"issue":"9","published-online":{"date-parts":[[2026,9]]}},"alternative-id":["microorganisms14092104"],"URL":"https:\/\/doi.org\/10.3390\/microorganisms14092104","relation":{},"ISSN":["2076-2607"],"issn-type":[{"value":"2076-2607","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,9,20]]}}}