Valorization of Chrysanthemum morifolium Ramat. cv. “Hangbaiju” stems for phenolic compounds production by steam explosion pretreatment

Chrysanthemi Flos, as one of the medicinal and edible herbals, contains phenols, flavonoids, and other physiologically active substances that contribute to health benefits. The stem residues also contained abundant phenolic compounds of high significance to the pharmaceutical and food industries. To valorize the currently underutilized stem residues, steam explosion (SE) pretreatment was exploited to extract the polyphenolics from Hangbaiju (HBJ) stems. After the SE pretreatment, the total phenolic and flavonoid contents of the stems were maximally increased by 1.64 and 8.71 times, respectively. The antioxidant activity also increased significantly. Notably, 3,5-CQA, linarin, luteolin, apigenin, and acacetin, which were not detected in the raw stems, could be obtained through SE. The simulated in vitro gastrointestinal digestion demonstrated that the bioaccessibility of luteolin-7-O-glucoside and apigenin-7-O-glucoside could be enhanced by SE. This study highlights that SE can promote more effective extraction of phenolics and greater antioxidant activity of HBJ stems.