Abstract:

To obtain hawthorn fruit juices with high nutritional value and powerful health benefits, freeze-thawing softening
combined with enzymatic extraction was applied for the preparation of hawthorn fruit juices, and the optimum preparation
conditions for the highest content of total flavonoids was obtained by using Box-Behnken experimental design and response
surface methodology. Results indicated that pretreatment with freeze-thawing improved the enzymatic extraction of
flavonoids from hawthorn fruit, and thereby it was favorable for the preparation of flavanoids-rich hawthorn fruit juice.
Among the factors which influence the content of flavonoids , the duration and temperature for enzymatic extraction as
well as freezing time affected significantly the content of flavonoids in hawthorn fruit juices (P < 0.05), while the amount of
enzyme had minor effect. The optimum preparation conditions were freezing for 10 h followed by enzymatic extraction for 2.15 h
at 60 ℃ with addition of 1.0 mL/kg pectinase. Under these conditions, the content of flavonoids in hawthorn fruit juice was
241.59 mg/100 g as experimental value, which agreed well with the predicted value according to the regression model.

Key words: hawthorn, freeze-thawing, fruit juice, flavonoids, optimization, response surface methodology