https://doi.org/10.17113/ftb.64.03.26.9473

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Improving the Polyphenol Profile, Antioxidant and Antiglycation Activity of Onion Outer Scales with Chamomile Treatment

Valerija Vujčić Bok^1*, Sanja Gagić¹, Lucija Rubinić¹, Ivana Šola², Petra Kašnjar Perković¹, Nika Celinić¹, Sandra Jurić³ and Željan Maleš¹

¹University of Zagreb Faculty of Pharmacy and Biochemistry, Department of Pharmaceutical Botany, A. Kovačića 1, 10000 Zagreb, Croatia

²University of Zagreb Faculty of Science, Department of Biology, Horvatovac 102a, 10000 Zagreb, Croatia

³University of Zagreb Faculty of Pharmacy and Biochemistry, Department of Organic Chemistry, A. Kovačića 1, 10000 Zagreb, Croatia

Copyright © 2024 This is a Diamond Open Access article published under CC-BY licence. Copyright remains with the authors, who grant third parties the unrestricted right to use, copy, distribute and reproduce the article as long as the original author(s) and source are acknowledged.

Food Technol. Biotechnol. 2026; 64(3).

Article history:

Received: 12 November 2025

Accepted: 14 May 2026

Keywords:

Allium cepa L.; Matricaria chamomilla L.; inhibition of BSA glycation; antioxidant activity; in vitro digestion; polyphenols

The content of this publication has not been approved by the United Nations and does not reflect the views of the United Nations or its officials or Member States.

Summary:

Research background. Outer scales of common onion (Allium cepa L.) are often discarded as biological waste but can be an interesting source of polyphenols with antioxidant and antidiabetic properties that can be used in the food and pharmaceutical industries.

Experimental approach. The study goal is to use dried chamomile flowers (Matricaria camomilla L.) containing 6 % flavonoid apigenin in the form of water extract to improve the polyphenol profile, antioxidant and antiglycation activity of onion outer scales. “Red Carmen” onion bulbs with roots were exposed to deionized water (control) and chamomile water extract (test treatment) in a phytotron (23 °C/16 h day/8 h dark). From dried and pulverized outer scales and chamomile, Fourier transform infrared (FTIR) analysis was performed. Also, pure standards of polyphenols (apigenin, quercetin and caffeic acid) was used for FTIR spectra comparison.

Results and conclusions. In the initial phase, the salivary, gastric, and intestinal phase; THA (total hydroxycinnamic acids), TFL (total flavonols), antioxidant (ABTS; (2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonicacid and FRAP; ferric reducing antioxidant power) activity, and inhibition of BSA (bovine serum albumin) glycation activity of on-ion scales extract was measured. Chamomile treatment improved THA, TFL, antioxidant (FRAP) and antiglycation activity (BSA method) in almost all in vitro digestion phases. Treatment of onions with chamomile water extract is good method of enrichment of biological waste. This is confirmed by FTIR analysis. Enricht onion scales represent good sources of bioaccessible polyphenols with high antioxidant (ABTS>85 % and FRAP>95 %) and moderate antiglycation activity (43–62 %).

Novelty and scientific contribution. The enrichment of the phytochemical composition and biological potential of onions had potential applications of this technique for health and nutritional purposes. Since the method does not require genetic modification but relies on natural absorption mechanisms and stress induction, it could become a valuable tool for enriching the nutritional and therapeutic composition of herbs. These results represent a foundation for future research, which should further elucidate the mechanisms of transmission, long-term effects, and potential industrial applications of this phenomenon.