{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,4,10]],"date-time":"2026-04-10T11:48:07Z","timestamp":1775821687312,"version":"3.50.1"},"reference-count":11,"publisher":"MDPI AG","issue":"4","license":[{"start":{"date-parts":[[2026,4,10]],"date-time":"2026-04-10T00:00:00Z","timestamp":1775779200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Metabolites"],"abstract":"<jats:p>Background\/Objectives: Citrus peels are widely utilized as functional ingredients in health foods; however, their functional value is often assumed based on botanical classification rather than verified chemical composition. Bushukan (Citrus medica var. sarcodactylis) was selected as it lacks developed edible pulp; consequently, the usable portion consists almost entirely of peel tissue, making it a suitable model for evaluating peel-specific functional components. This commentary highlights the importance of species- and origin-specific evaluation through a case study of Bushukan (Citrus medica var. sarcodactylis) whole fruit powder cultivated in Japan. Methods: Dried whole-fruit powder samples of bushukan, prepared by freeze-drying and hot-air drying at 50 \u00b0C, were analyzed, and the contents of hesperidin and nobiletin were quantified using high-performance liquid chromatography (HPLC) following methanol reflux extraction. Results: Hesperidin was detected at 75 mg\/100 g under both drying conditions, whereas nobiletin was below the practical limit of quantification (approximately 1 mg\/100 g). No reduction in hesperidin content was observed after drying at 50 \u00b0C. These levels were markedly lower than those reported for commonly used citrus peels, such as satsuma mandarin, in previous studies. Conclusions: This commentary demonstrates that Japanese-grown bushukan samples do not necessarily provide substantial levels of commonly expected citrus flavonoids. These findings underscore the need for species- and origin-specific compositional verification before the use of citrus peels as raw materials for health food applications, illustrating this need through a practical, cautionary case study.<\/jats:p>","DOI":"10.3390\/metabo16040254","type":"journal-article","created":{"date-parts":[[2026,4,10]],"date-time":"2026-04-10T10:20:16Z","timestamp":1775816416000},"page":"254","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Citrus Peels in Health Foods: A Case Study of Pulp-Free Japanese-Grown Bushukan (Citrus medica var. sarcodactylis)"],"prefix":"10.3390","volume":"16","author":[{"ORCID":"https:\/\/orcid.org\/0009-0009-7100-8935","authenticated-orcid":false,"given":"Jun","family":"Nakahigashi","sequence":"first","affiliation":[{"name":"Wellness Development Research Center, AIR WATER INC., 1-7, Tsukisamu Higashi 2-jo 16-chome, Toyohi-ra-ku, Sapporo 062-0052, Hokkaido, Japan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-8617-3778","authenticated-orcid":false,"given":"Eiji","family":"Kobayashi","sequence":"additional","affiliation":[{"name":"Kobayashi Regenerative Research Institute, LLC, 1 Chayano-cho, Wakayama-shi 640-8263, Wakayama, Japan"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2026,4,10]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"81","DOI":"10.12691\/jfnr-10-2-1","article-title":"Structurally Diverse Flavonoids from Citrus medica L. var. sarcodactylis Swingle and Their Multiple Bioactivities: A review","volume":"10","author":"Chen","year":"2022","journal-title":"J. Food Nutr. Res."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"690","DOI":"10.1007\/978-94-007-4053-2_85","article-title":"Citrus medica var. sarcodactylis","volume":"Volume 4","author":"Lim","year":"2012","journal-title":"Edible Medicinal and Non-Medicinal Plants"},{"key":"ref_3","doi-asserted-by":"crossref","unstructured":"Nakahigashi, J., Kurikami, M., Iwai, S., Iwamoto, S., Kobayashi, S., and Kobayashi, E. (2024). Exploring the pharmacokinetics and gut microbiota modulation of hesperidin and nobiletin from mandarin orange peel in experimental dogs: A pilot study. Metabolites, 15.","DOI":"10.3390\/metabo15010003"},{"key":"ref_4","doi-asserted-by":"crossref","unstructured":"Yonezawa, T., Marasigan, C.N.B.B., Komori, M., Fujiwara, N., Nakahigashi, J., and Kobayashi, E. (2026). Preliminary Safety Assessment for Mandarin Orange Peel Administration to Dogs Based on Physical Conditions and Blood Examination Parameters. Metabolites, 16.","DOI":"10.3390\/metabo16030213"},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"1247","DOI":"10.1007\/s11101-023-09865-0","article-title":"Citrus medica var. sarcodactylus (Siebold ex Hoola van Nooten) Swingle: An insight into its botany, traditional uses, phytochemistry, and pharmacological properties","volume":"22","author":"Ma","year":"2023","journal-title":"Phytochem. Rev."},{"key":"ref_6","unstructured":"National Institute of Biomedical Innovation, Health and Nutrition (NIBIOHN) (2026, March 15). Chenpi Assay Method: Hesperidin Quantification Using Methanol Reflux. Medicinal Plant Database of Japan. Available online: http:\/\/mpdb.nibiohn.go.jp\/mpdb-bin\/view_jp_assay_data.cgi?id=42."},{"key":"ref_7","doi-asserted-by":"crossref","unstructured":"Mai, D.-S., Chen, C.-X., Cao, J.-M., Chen, Y.-C., Liang, T.-T., Zhao, Z.-X., and Yang, W.-Q. (2025). A new limonoid from the Fruits of Citrus medica var. sarcodactylus (Siebold ex Hoola van Nooten) Swingle. 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Sci., 10.","DOI":"10.3389\/fenvs.2022.1062333"},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"835","DOI":"10.1093\/ee\/nvaf051","article-title":"Pesticide drift into field margins threatens bee pollinators and other beneficial insects","volume":"54","author":"Graham","year":"2025","journal-title":"Environ. Entomol."}],"container-title":["Metabolites"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2218-1989\/16\/4\/254\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,4,10]],"date-time":"2026-04-10T10:52:40Z","timestamp":1775818360000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2218-1989\/16\/4\/254"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,4,10]]},"references-count":11,"journal-issue":{"issue":"4","published-online":{"date-parts":[[2026,4]]}},"alternative-id":["metabo16040254"],"URL":"https:\/\/doi.org\/10.3390\/metabo16040254","relation":{},"ISSN":["2218-1989"],"issn-type":[{"value":"2218-1989","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,4,10]]}}}