Functional Herbal Tea Blends: Phenolic Profiles, Antioxidant Activities, and In Vitro Digestibility Assessment by SOTAX Dissolution Test
VIII. INTERNATIONAL AGRICULTURAL BIOLOGICAL & LIFE SCIENCE CONFERENCE (AGBIOL 2026), İstanbul, Türkiye, 6 - 09 Eylül 2026, ss.1-18, (Tam Metin Bildiri)
- Yayın Türü: Bildiri / Tam Metin Bildiri
- Basıldığı Şehir: İstanbul
- Basıldığı Ülke: Türkiye
- Sayfa Sayıları: ss.1-18
- İstanbul Üniversitesi Adresli: Evet
Özet
Interest in herbal teas is steadily increasing due to their potential health benefits. In this study, fennel (Foeniculum vulgare), lemon balm (Melissa officinalis L.), hibiscus (Hibiscus sabdariffa L.), green tea (Camellia sinensis L.), freeze-dried Ottoman strawberries, and lavender (Lavandula angustifolia) were used to develop three functional herbal tea prototypes, and their antioxidant activities, FTIR spectral characteristics, and in vitro dissolution behaviours were evaluated. Three prototypes were prepared based on their targeted effects on the digestive system. Prototype 1 (P1), formulated with fennel (30%), lemon balm (24%), hibiscus (16%), green tea (14%), freeze-dried strawberry (12%), and lavender (4%), was designed to promote balanced digestion. Prototype 2 (P2) contained fennel (26%), lemon balm (20%), hibiscus (24%), green tea (12%), freeze-dried strawberry (14%), and lavender (4%) and was formulated to stimulate bowel activity. Prototype 3 (P3) was formulated with fennel (34%), lemon balm (30%), hibiscus (10%), green tea (10%), freeze-dried strawberry (12%), and lavender (4%), emphasising digestive comfort through increased proportions of fennel and lemon balm and reduced proportions of hibiscus and green tea. Fourier Transform Infrared Spectroscopy (FTIR) spectra revealed characteristic absorption bands associated with the diverse phytochemical and structural components of the plant mixtures. Antioxidant activity was evaluated using ABTS and DPPH radical-scavenging assays. P3 exhibited the strongest antioxidant performance among the three formulations, showing the highest ABTS radical-scavenging activity and the lowest IC₅₀ value (9.65 and 9.71). The DPPH IC₅₀ values were measured as 10.26, 9.73, and 9.71; and ABTS IC₅₀ values were 10.26, 10.75 and 9.65, for P1, P2, and P3, respectively. The Trolox-equivalent antioxidant capacity determined by the ABTS assay exceeded 90 µmol TE g⁻¹ in all tested formulations. The SOTAX dissolution test demonstrated rapid and extensive in vitro release under simulated gastrointestinal pH conditions (pH 1.2, 4.5, and 6.8), with cumulative dissolution values approaching 99-100% after 30 min. Consequently, P3, in which the proportions of fennel and lemon balm were increased while those of hibiscus and green tea were reduced, emerged as the most promising formulation based on its antioxidant performance and dissolution behaviour. These findings suggest that combining plant-based ingredients in appropriate ratios may influence the functional characteristics of herbal tea blends. The results provide a basis for further studies involving simulated
gastrointestinal digestion, bioaccessibility, and bioavailability of the bioactive compounds.
Keywords: Functional herbal tea, antioxidant activity, phenolic content, digestibility.