Montmorillonite-enhanced Carboxymethylcellulose/Polyethyleneimine aerogel: A highly efficient and reusable adsorbent for caffeine removal from tea infusions

Excessive consumption of caffeine presents health risks, necessitating the development of effective decaffeination methods in the food industry. This study introduced an innovative CMP aerogel that incorporated montmorillonite into a carboxymethylcellulose/polyethyleneimine framework to selectively decaffeinate without compromising the food's original flavor. The CMP aerogel achieved a caffeine adsorption capacity of 18.59 mg/g, primarily driven by electrostatic interactions and hydrogen bonding, as well as additional processes such as chelation, cation exchange, and complexation. The adsorption kinetics followed a pseudo-second-order model, with the adsorption data fitting the Langmuir isotherm, indicating monolayer adsorption. Notably, the CMP aerogel demonstrated excellent stability and reproducibility, maintaining over 90 % of its initial adsorption capacity after seven cycles. Importantly, it effectively reduced caffeine content in black tea infusions while preserving key attributes such as tea color, catechins, and aroma. The retention rate of catechins was 66.2 %, the number of flavor compounds decreased from 109 to 91 and the total retention rate was 58.7 %. These findings highlight the aerogel's promising potential as a practical decaffeination solution, providing valuable insights into alternative methods for caffeine removal, particularly in the tea industry.