Effect of Solvent Type, Extraction Temperature, Agitation Speed and Microwave Power on Phenolic Compound Extraction and Antioxidant Activity of Apricot Kernels ((Prunus armeniaca L.)

Abstract

Background: Prunus armeniaca L. is widely cultivated around the world. High consumption of its fruit produces a large quantity of the apricot kernel. The valorization of this byproduct in terms of polyphenol compounds seems to be important. Objective: The aim of the present study is to investigate the best conditions of phenolic compound extraction from apricot kernels in order to determine the effects of different parameters, namely time, stirring speed, solvent type, temperature, and microwave power, on polyphenol yield. Methods: In this study, the effect of many parameters, such as the type of solvent (ethanol, methanol, acetone and water), the acetone concentration (40-70%, v/v), the extraction time, power of the microwave (100-900 W) and stirring speed on the extraction of Total Phenolic Content (TPC) from apricot kernels was studied, using the approach of single factor experiments. Results: The importance of agitation speed was determined for polyphenol compound extraction from apricot kernels besides time, temperature and microwave power, whereas the linear agitation in the water bath had no significant effect on the extraction of phenolic compounds. The best extraction conditions were 60% acetone, 300 W of microwave power for 5 min of extraction time, which gave a high TPC of 249.44 ±15.83 mg GAE/g DW. All the extraction conditions showed a significant effect (p <0.05) on the TPC. The antioxidant capacity (DPPH-RSA) of the extract was positively correlated with TPC in all tested methods. Conclusion: It can be concluded that the importance of agitation speed was determined for the extraction of phenolic compounds from apricot kernels by maceration. However, the linear agitation in the water bath had no significant effect on the extraction. Apricot kernel seems to be a good source of polyphenols compared to other sources mentioned in the previous studies present in literature.