Abstract: In order to improve the quality of vacuum freeze-dried Lonicera edulis powder, five freeze-dried L. edulis powders were prepared using different cryoprotectants, namely, maltodextrin and its binary mixtures with sodium carboxymethyl cellulose, sodium alginate, gum arabic, and β-cyclodextrin. Based on the color, yield and anthocyanin content of freeze-dried L. edulis powder, the optimal addition levels of carboxymethyl sodium cellulose, sodium alginate, gum arabic and β-cyclodextrin were determined to be 2.5%, 1.5%, 2%, and 1%, respectively. The anthocyanin content of freeze-dried L. edulis powder with 2% gum arabic was the highest, (18.09 ± 0.98) mg/g, and it had the strongest ability to scavenge 2,2’-azinobis(3-ethylberizothiazoline-6-sulfonic acid) (ABTS) radical cation, (93.04 ± 0.30)%. Freeze-dried L. edulis powder with 1% β-cyclodextrin added had the highest contents of total polyphenols and total flavonoids. Compared with the single protective agent, L. edulis powders with the mixed protective agents showed a rounder and smoother spherical shape under a scanning electron microscope (SEM). The anthocyanins in L. edulis powder were more stable to gastric digestion than to intestinal digestion. As the in vitro digestion proceeded, the anthocyanin content showed a downward trend, and the retention rate of anthocyanins in L. edulis powder with the mixed protective agents was higher than that in L. edulis powder with malt alone. The retention rate of anthocyanins in the maltodextrin/sodium carboxymethylcellulose (D1) and maltodextrin/gum arabic (D3) groups was higher.

Key words: vacuum freeze-drying; Lonicera edulis; cryoprotectant; anthocyanin; in vitro digestion