Walnut kernel pellicle polyphenols: subcritical water extraction, digestive characteristics, and their effect on gut microbiota and metabolites.

Xinyu Yuan, Qiqi Feng, Qing Wang, Tao Wang, Zhu Qiao, Hongyu Pan, Yujie Zhong, Yongliang Zhuang

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Article in Food chemistry: X, 2025. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Not yet cited in PubMed.

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5 · Who and what money

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8 authors.

Xinyu YuanFaculty of Food Science and Engineering, Kunming University of Science and Technology, Kunming, Yunnan Province 650500, China.

Qiqi FengFaculty of Food Science and Engineering, Kunming University of Science and Technology, Kunming, Yunnan Province 650500, China.

Qing WangFaculty of Food Science and Engineering, Kunming University of Science and Technology, Kunming, Yunnan Province 650500, China.

Tao WangFaculty of Food Science and Engineering, Kunming University of Science and Technology, Kunming, Yunnan Province 650500, China.

Zhu QiaoSchool of Biological and Food Processing Engineering, Huanghuai University, Zhumadian, Henan Province 463000, China.

Hongyu PanFaculty of Food Science and Engineering, Kunming University of Science and Technology, Kunming, Yunnan Province 650500, China.

Yujie ZhongFaculty of Food Science and Engineering, Kunming University of Science and Technology, Kunming, Yunnan Province 650500, China.

Yongliang ZhuangFaculty of Food Science and Engineering, Kunming University of Science and Technology, Kunming, Yunnan Province 650500, China.

Funding

No grant is acknowledged in the PubMed record.

6 · The paper itself

Abstract

Walnut kernel pellicle, a by-product of the walnut industry, is rich in polyphenols. However, research on walnut kernel pellicle polyphenols (WPP) remains limited, and the composition and bioactivity of WPP are influenced by extraction methods, gastrointestinal digestion, and colonic fermentation. Therefore, this study aimed to optimize subcritical water extraction (SWE) and NKA-9 resin purification of WPP. Next, the changes in WPP throughout simulated gastrointestinal digestion and colonic fermentation were evaluated. The results demonstrated that SWE achieved higher polyphenol yield compared to ultrasound-assisted extraction, with ellagic acid and ellagitannins as the main components. Although digestion and fermentation reduced WPP contents and antioxidant activities, they facilitated the biotransformation of ellagic acid and ellagitannins into urolithins. Meanwhile, WPP modulated the gut microbiota by promoting beneficial bacteria. Additionally, WPP enhanced beneficial microbial metabolites, including short-chain fatty acids and indole derivatives. These findings highlighted the potential of WPP as a functional ingredient for gut health.

Indexed as

Colonic fermentationGastrointestinal digestionIndole derivativesIntestinal microbiotaShort-chain fatty acidsWalnut pellicle polyphenols

Identifiers

PMID41049094

DOI10.1016/j.fochx.2025.103020

PMCPMC12489916

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LicenceCC BY-NC-ND

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Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.