Extraction of flavonoids and phenolic acids from poplar-type propolis: optimization of maceration process, evaluation of antioxidant and antimicrobial activities
Meifei Zhu, Jiayi Bao, Pengbo Liang, Cuiping Zhang, Shanshan Li, Fuliang Hu
Abstract
Propolis is a traditional food with significant health benefits owing to its rich polyphenol content. An extraction process is essential to obtain bioactive ingredients, including flavonoids and phenolic acids. This study aimed to optimize the extraction of polyphenol-rich compounds from poplar-type propolis and evaluate their antioxidant and antibacterial effects. By employing two Box-Behnken design experiments, four key variables − extraction time, temperature, ethanol concentration, and solid-to-liquid ratio – were systematically optimized to maximise the yields of phenolic acids and flavonoids. Subsequently, a two-step extraction method was developed to maximise the recovery of phenolic acids and flavonoids via response surface optimization. The results showed that a high concentration of ethanol (85 %) was optimal for extracting non-polar polyphenols, such as flavonoids, whereas a low concentration of ethanol (23 %) was more effective for extracting polar polyphenols, such as phenolic acids. The two-step method combined these ethanol extracts to maximise polyphenol yield. The optimal extraction conditions were 23/25 h extraction time, 46/41 °C temperature, and 1:14/1:11 (g/mL) solid-to-liquid ratio for 85 % and 23 % ethanol, respectively. This approach yielded a total flavanoid content of 471 ± 13 mg rutin/g propolis extract and a total phenolic content of 157 ± 2 mg gallic acid/g propolis extract. Moreover, the two-step extraction method showed better antioxidant and antibacterial ability. In summary, optimized extraction methods can be readily translated into more efficient production processes for high-quality propolis. • Optimized extraction factors (temperature, time, solid-liquid ratio and ethanol concentration) for yield, TPC and TFC. • Developed a two-step ethanol extraction method for propolis. • Two-step extraction yielded higher phenolic acids and flavonoids than single-phase method. • Two-step extract exhibited higher antioxidant capacity and antibacterial efficacy.