Reduction of Tannins in Black Tea Using Rice Husk Ash: An Innovation to Reduce The Risk of Iron Deficiency Anemia

Rengganis Wulan Kinasih, Nadira Mais Fayyaza, Binar Panunggal, Nurmasari Widyastuti, Dewi Marfu'ah Kurniawati

Abstract

Background: Iron deficiency anemia may result from inadequate iron intake or hindered iron absorption. Black tea is known to contain tannins, compounds that can interfere with the body’s ability to absorb iron. Rice husk ash, which is rich in silica, has the potential to lower the tannin content in black tea. Objective: This study aimed to examine the impact of rice husk ash supplementation on the tannin content of black tea. Methods: An experimental study was carried out using a completely randomized design involving four treatment groups: control (P0), soaking (P1), boiling followed by soaking (P2), and boiling plus soaking with 15% rice husk ash (P3). The tea samples were prepared in the Culinary Dietetics Laboratory, Department of Nutrition Science, Faculty of Medicine, Universitas Diponegoro. Analysis of tannin and phenolic content was performed at Chemix Pratama Laboratory in Yogyakarta using spectrophotometric techniques. The study took place between December 2024 and April 2025. Results: The highest tannin concentration was observed in the control group (P0), averaging 9.05% ± 0.09, while the lowest was recorded in the P3 group (treated with rice husk ash), with an average of 4.66% ± 0.14. A statistically significant difference in tannin levels was found between the P2 and P3 groups (p < 0.05). Additionally, a very strong positive correlation between tannin and phenolic content was identified (r = 0.99; p < 0.05). Conclusion: The combined treatment of boiling and soaking black tea with 15% rice husk ash effectively reduces tannin content. The most notable decrease in tannin levels was seen in the boiling plus soaking with 15% rice husk ash group, indicating this method's potential in reducing compounds that inhibit iron absorption.