Deep Eutectic Solvents Extraction of Polyphenols from Tieguanyin Tea Optimized by Response Surface Method
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摘要:
目的 探索一种绿色、环保、安全、高效的铁观音茶多酚提取新方法,为茶多酚绿色提取提供新的技术参考。 方法 以铁观音成品茶为原料,采用新型绿色溶剂——低共熔溶液提取茶多酚;首先筛选出最优的低共熔溶液提取体系,然后在单因素试验的基础上,通过响应面法优化,研究时间、温度、溶液含水率对提取率的影响,得出最佳提取条件并分析其主要成分;最后通过测定DPPH自由基清除率分析茶多酚的抗氧化能力。 结果 筛选出最适的茶多酚低共熔溶液提取体系为:乳酸-甜菜碱,其次得到最佳单因素提取条件为提取时间40 min、提取温度60℃、含水率30%、摩尔比2 ∶ 1、固液比1 ∶ 40(g : mL);响应面优化分析得到最佳提取条件为:时间46.79 min、温度62.48℃、溶液含水率32.15%,在此条件下茶多酚提取率为15.42%。通过高效液相色谱分析茶多酚组分,其中没食子酸含量占1.40%,儿茶素类物质占84.99%,其他组分占13.61%。低共熔溶液法提取的茶多酚DPPH自由基半清除浓度(IC50)值73.89 μg·mL−1,比抗坏血酸提高了37.80%。 结论 采用响应面法优化得出的低共熔溶液提取茶多酚最佳工艺条件,可有效提高铁观音茶多酚提取率。 Abstract:Objective A green, environmentally friendly, safe and efficient process to extract polyphenols from tea was explored and optimized using the response surface method. Methods Tieguanyin tea was used for the extraction with deep eutectic solvents (DESs). After the DES was selected and a single factor experiment conducted, the time, temperature and water content in solvent were optimized for the process with respect of polyphenol extraction rate by a response surface experimentation. Antioxidant capacity of the extract was determined according to the DPPH radical scavenging rate. Results Lactic acid and betaine of a molar ratio of 2:1 with a water content of 30% and a substrate-to-solvent ratio of 1:40 (g:mL) were chosen for the extraction at 60oC for 40 min. The response surface method optimized the process to apply a moisture content of 32.15% of DESs for a 46.79 min-extraction at 62.48℃ with a yield of polyphenols at 15.42%. The polyphenol extract was analyzed by HPLC to show a gallic acid content of 1.40%, catechins of 84.99%, and the remainders of 13.61%. The semi-scavenging concentration (IC50) of the extract was 73.89 μg·mL-1, which was 37.80% higher than that of ascorbic acid. Conclusion The newly developed DESs extraction significantly improved the polyphenol extraction rate from Tieguanyin tea over the conventional process. -
Key words:
- deep eutectic solvents /
- Tieguanyin /
- tea polyphenol /
- antioxidant activity /
- chemical analysis
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表 1 Box-Behnken试验因素水平及编码
Table 1. Factors and coding levels in Box-Behnken experiment
水平
Levels因素 Factors A时间
Time/minB温度
Temperature/℃C溶液含水率
Water raito of solvent/%−1 20 50 20 0 40 60 30 1 60 70 40 表 2 不同低共熔溶液体系提取茶多酚
Table 2. DESs for polyphenol extraction
名称
Name提取率
Extraction ratio/%相对水提取提高
Aqueous extraction ratio exceeded by DES/%水 Water 8.61±0.27Aa 果糖/氯化胆碱
Fructose/Choline chloride12.47±0.74Bb 44.90 乳酸/氯化胆碱
Lacticacid/Choline chloride12.69±0.81Bb 47.36 苹果酸/甜菜碱
Malicacid/Choline chloride12.68±0.68 Bb 47.24 柠檬酸/甜菜碱
Citricacid/Betaine12.79±0.54Bb 48.59 乳酸/甜菜碱
Lacticacid/Betaine14.40±0.53 Cc 67.29 注:同列数据后不同大、小写字母表示差异极显著(P<0.01)或差异显著(P<0.05)。
Note: Different uppercase and lowercase letters in the same column indicate extremely significant differences (P<0.01) and significant differences (P<0.05).表 3 响应面优化结果
Table 3. Response surface experiment and results
序号
NumberA时间
TimeB温度
TemperatureC含水率
Water ratioY提取率
Extraction ratio/%1 0 0 0 15.46 2 −1 0 1 14.68 3 0 0 0 15.33 4 0 0 0 15.40 5 −1 0 −1 13.93 6 0 −1 −1 13.62 7 −1 −1 0 14.37 8 1 0 −1 14.63 9 0 0 0 15.27 10 1 1 0 15.07 11 1 −1 0 14.74 12 0 1 1 14.88 13 0 1 −1 14.57 14 −1 1 0 14.86 15 0 −1 1 14.76 16 0 0 0 15.39 17 1 0 1 15.01 表 4 方差分析
Table 4. Regression statistical analysis
来源
Source平方和
Sum of square自由度
Degree of freedom均方
Mean squareF值
F valueP值
P value显著性
Significance模型 Model 4.13 9 0.46 48.03 <0.000 1 ** A时间 Time 0.32 1 0.32 33.89 0.000 6 ** B温度 Temperature 0.45 1 0.45 46.7 0.000 2 ** C含水率 Water raito 0.83 1 0.83 87.03 <0.000 1 ** AB 6.40×10−3 1 6.40×10−3 0.67 0.440 2 AC 0.034 1 0.034 3.58 0.100 4 BC 0.17 1 0.17 18.01 0.003 8 ** A2 0.27 1 0.27 28.08 0.001 1 ** B2 0.54 1 0.54 56.29 0.000 1 ** C2 1.3 1 1.3 135.65 <0.000 1 ** 残差 Resdual 0.067 7 9.561×10−3 失拟项 Lack of fit 0.046 3 0.015 2.92 0.164 纯误差 Pure error 0.021 4 5.250×10−3 总和 Cor total 4.2 16 注:*,P<0.05,表示显著差异;**,P<0.01,表示极显著差异。
Note: *, P<0.05, indicating significant difference; **, P<0.01, indicating extremely significant difference. -
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