Spruce bark represents a reservoir of bioactive compounds. The aim of this study was to investigate the effect of independent variables (temperature, liquid to solid ratio, time and methanol content) and their interaction within the extraction process by the response surface methodology (RSM). The effect of conventional (solvent extraction; SE) and modern (ultrasound-assisted extraction; UAE) methods for the extraction of antioxidants (antioxidant capacity; AC) and polyphenols (total polyphenol content; TPC) was compared. Maximum yields of AC and TPC by SE and UAE were obtained at modified optimal conditions of 63 °C, methanol content of 53 % (v/v) and 38 mL of extraction solvent per gram of dry material. Two-step extraction process consisting of the fast washing and slow diffusion steps was suitable described by Peleg and Patricelli mathematic models. The HPLC fingerprints of both extracts did not show significant differences while the content of phenolic compounds extracted by UAE was 1.1- to 7.1-times higher than that obtained by SE, quantified by HPLC.

中文翻译：

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超声波辅助从云杉皮中提取多酚和抗氧化剂。

云杉的树皮代表生物活性化合物的库。这项研究的目的是通过响应面方法（RSM）研究自变量（温度，液固比，时间和甲醇含量）的影响及其在萃取过程中的相互作用。比较了传统方法（溶剂萃取； SE）和现代方法（超声波辅助萃取； UAE）对抗氧化剂（抗氧化剂容量； AC）和多酚（总多酚含量； TPC）的萃取效果。在改良的最佳条件下，温度为63°C，甲醇含量为53％（v / v），每克干物质38 mL的萃取溶剂，通过SE和UAE获得的AC和TPC的最大收率。Peleg和Patricelli数学模型适合描述由快速洗涤和缓慢扩散步骤组成的两步​​提取过程。两种提取物的HPLC指纹图谱均未显示出显着差异，而通过UAE提取的酚类化合物含量比SE提取的酚类化合物含量高出1.1至7.1倍（通过HPLC定量）。