REQUIMTE-Departamento de Química e Bioquímica, Faculdade de Ciências, Universidade do Porto, Porto, Portugal.
Anal Bioanal Chem. 2012 May;403(4):1019-29. doi: 10.1007/s00216-011-5703-y. Epub 2012 Jan 26.
This paper reports a novel application of microwave-assisted extraction (MAE) of polyphenols from brewer's spent grains (BSG). A 2(4) orthogonal composite design was used to obtain the optimal conditions of MAE. The influence of the MAE operational parameters (extraction time, temperature, solvent volume and stirring speed) on the extraction yield of ferulic acid was investigated through response surface methodology. The results showed that the optimal conditions were 15 min extraction time, 100 °C extraction temperature, 20 mL of solvent, and maximum stirring speed. Under these conditions, the yield of ferulic acid was 1.31 ± 0.04% (w/w), which was fivefold higher than that obtained with conventional solid-liquid extraction techniques. The developed new extraction method considerably reduces extraction time, energy and solvent consumption, while generating fewer wastes. HPLC-DAD-MS analysis indicated that other hydroxycinnamic acids and several ferulic acid dehydrodimers, as well as one dehydrotrimer were also present, confirming that BSG is a valuable source of antioxidant compounds.
本文报道了一种利用微波辅助提取（MAE）从啤酒糟（BSG）中提取多酚的新方法。采用 2(4)正交复合设计获得 MAE 的最佳条件。通过响应面法研究了 MAE 操作参数（提取时间、温度、溶剂体积和搅拌速度）对阿魏酸提取率的影响。结果表明，最佳条件为提取时间 15 min、提取温度 100°C、溶剂 20 mL 和最大搅拌速度。在此条件下，阿魏酸的得率为 1.31±0.04%（w/w），是传统固液萃取技术的五倍。开发的新提取方法大大缩短了提取时间，减少了能源和溶剂的消耗，同时产生的废物更少。HPLC-DAD-MS 分析表明，BSG 中还存在其他羟基肉桂酸和几种阿魏酸脱氢二聚体以及一种脱氢三聚体，这证实了 BSG 是一种有价值的抗氧化化合物来源。
