To conduct bi-objective optimization for the sensory properties and chlorogenic acid content of Lonicera japonica and Siraitia grosvenorii tea, determine the optimal processing parameters.

Single-factor experiments and Box-Behnken response surface design were firstly applied to explore the extraction process of Lonicera japonica. On this basis, response surface methodology combined with non-dominated sorting genetic algorithm II (NSGA-II) algorithm was adopted to perform the bi-objective optimization of Lonicera japonica and Siraitia grosvenorii tea in terms of sensory quality and chlorogenic acid content. The 2 prediction models (Y₁ and Y₂)were established correspondingly. Furthermore, the chlorogenic acid content, total phenolic content and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging rate of the tea infusion prepared under optimal conditions were determined and analyzed.

The optimal processing conditions were determined as follows: Siraitia grosvenorii addition of 1.3 g/500 mL, brewing time of 22.3 min, brewing temperature of 88.1 ℃ and Lonicera japonica addition of 2.3 g/500 mL. Under the optimized conditions, the sensory score of the prepared tea reached 9.4, and the chlorogenic acid content was 162.6 μg/g. The predicted sensory score and chlorogenic acid content of the models were 9.72 and 159.25 μg/g, respectively. The relative errors of all models were less than 5%, which verified the reliable predictive validity of the established models. In the tea infusion prepared under optimal conditions, the chlorogenic acid content decreased slightly within the first 3 days and decreased significantly after the third day. In addition, the total phenolic content and radical scavenging rate showed a trend of first increasing and then decreasing with the prolongation of storage time.

This study realizes the synchronous improvement of active ingredient content and sensory quality of Lonicera japonica and Siraitia grosvenorii tea, which provides a systematic method for the process optimization and quality improvement of the tea product.