Abstract:

Granny Smith apple, an apple cultivar with high acidity, is rich in polyphenols, such as procyanidins. In this study,
the extraction of polyphenols from Granny Smith apple by multi-enzymatic hydrolysis was optimized by the combined use
of single factor method and Box-Behnken design. A mixture of cellulose and pectinase (2:1, m/m) was found to be the most
efficient enzyme for the extraction of polyphenols. The maximum yield of polyphenols of 5.07% was obtained when the
enzymatic extraction was done at 62.5 ℃ for 82.9 min with an initial pH of 3.7. According to the statistical analysis, the
response surface model developed could be used to analyze and predict the extraction of polyphenols from Granny Smith
apple effectively. Additionally, the polyphenols extracted from Granny Smith apple exhibited significant Fe3+ reducing
capacity and DPPH free radical scavenging activity and the half-inhibition concentration (IC50) for scavenging of DPPH free
radical was 22.72 μg/mL, showing that the extract is a good source of antioxidants, and could be further utilized and explored
as a useful food additive or antioxidant.

Key words: Granny Smith apple, polyphenol, multi-enzymatic extraction, response surface methodology, antioxidant activity