Antioxidant phenolic compounds from Pinus morrisconicola using compressional-puffing pretreatment and water–ethanol extraction : Optimization of extraction parameters

This study is aimed to increase the extraction yield and efficiency of the antioxidant phenolic compounds from Pinus morrisonicola. The optimum extraction conditions for the phenolic compounds from pine needles are determined by using response surface methodology with a central-composite design. Effects of ethanol concentration, extraction temperature and liquid–solid ratio on the extraction yield (total flavonoids content and total phenolic content) and antioxidant activity (2,2′-diphenyl-1-picryhydrazyl (DPPH) scavenging activity, ferric reducing antioxidant power (FRAP) and 2,2′-Azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) scavenging activity) are investigated. The optimum conditions to maximize the extraction yields and antioxidant activity of the pine needles extracts are: 36.1% v/v of ethanol, 70 ºC and 50 ml/g of liquid–solid ratio. The pine needles extracts are shown to be free of 311 tested pesticide residues or certain heavy metals and exhibit comparable quantities of total flavonoids contents, total phenolic contents and the antioxidant activities with commercial products.