MICROWAVE-ASSISTED EXTRACTION AND LC/MS ANALYSIS OF PHENOLIC ANTIOXIDANTS IN SWEET APRICOT (PRUNUS ARMENIACA L.) KERNEL SKINS

Abstract

Sweet apricot kernel skins, the byproduct of sweet apricot kernel processing, contain high levels of phenolic antioxidants. This research aimed at optimizing the extraction procedure of antioxidants from sweet apricot kernel skins, investigating the relationship of antioxidant activity with total phenolic content (TPC) and preliminarily analyzing the composition of phenolic compounds in extract with LC/MS. The extraction condition at the assistance of microwave was optimized with response surface methodology both for antioxidant activity and TPC. The study results showed that the antioxidant activity of extract is higher than those of ascorbic acid and Butylated hydroxytoluene and correlated with TPC although a difference was existent in optimized extraction conditions. Compared with ultrasonic-assisted extraction and solvent soak extraction, microwave-assisted extraction had much higher extraction yield of TPC. HPLC-MS analysis revealed that the phenolic compounds in the extract of sweet apricot kernel skins were mainly chlorogenic acids, procyanidins, and propelargonidins.

Keywords:

• antioxidant
• LC-MS analysis
• microwave-assisted extraction
• polyphenol
• response surface methodology
• sweet apricot kernel skins

ACKNOWLEDGMENT

The project was supported by the National Natural Science Fund of China (No. 21145003) and the Key Development Fund for Agriculture of Shaanxi Province, China (No. 2008K01-23).

Notes

^a Numbers in bracket are the coded values of the independent variables in the experimental design.

For TPC R² = 0.9976; CV% = 3.06; Adeq Precision = 75.835.

For RSA R² = 1.0000; CV% = 0.032; Adeq Precision = 4422.966.

^a DF, degree of freedom.

^b Significant, P < 0.05.