Abstract: Using red elephant grass (Pennisetum purpureum Schumab) as the raw material and anthocyanin content as the response value. Based on a single factor test, three independent variables including ethanol concentration, liquid-material ratio, and extraction time were selected to design a response surface optimization experiment with three factors and three levels using Box-Behnken methodology to optimize the extraction process of anthocyanins from red elephant grass and assess its antioxidant capacity. The results indicated that the optimal conditions for anthocyanin extraction from red elephant grass were a 49% ethanol concentration, an extraction time of 30 minutes, and a liquid-solid ratio of 49∶1. Under these conditions, the extracted anthocyanin content was 2.09 mg·g^-1, with only a slight deviation of 1.8% from the theoretical value. The maximum scavenging rates of anthocyanins from red elephant grass on hydroxyl radical and DPPH radical were found to be 121.3% and 97.5%, respectively. While the maximum total antioxidant capacity against ABTS⁺ radical reached up to 2.6 mmol·g^-1, demonstrating significant antioxidant activity. This study can offer a reliable theoretical foundation and important technical support for the extraction and processing of anthocyanins from red elephant grass.

Key words: Pennisetum purpureum Schumab, Anthocyanin, Process optimization, Antioxidant activity

摘要： 以红象草(Pennisetum purpureum Schumab)为原材料，花青素含量为响应值，在单因素试验的基础上，选择乙醇浓度、液料比和提取时间3个因素作为自变量，基于Box-Behnken设计3因素3水平的响应面优化试验，确定红象草花青素的最佳提取工艺，并测定其抗氧化能力。结果表明：红象草花青素的最佳提取工艺条件为乙醇浓度49%，提取时间30 min，液料比49∶1，在此条件下提取得到的花青素含量为2.09 mg·g^-1，相对于理论值误差为1.8%。红象草花青素对羟自由基、DPPH自由基的清除率最高分别为121.3%和97.5%，对ABTS⁺自由基的总抗氧化能力最高可达2.6 mmol·g^-1，具有较强的抗氧化活性。本研究可为红象草花青素的提取及其加工利用提供可靠的理论依据和重要的技术支持。

关键词: 红象草, 花青素, 工艺优化, 抗氧化活性