Athirojthanakij Weerawich, Rashidinejad Ali
School of Food and Advanced Technology Massey University Palmerston North New Zealand.
Riddet Institute Massey University Palmerston North New Zealand.
Food Sci Nutr. 2024 Apr 8;12(7):5121-5130. doi: 10.1002/fsn3.4161. eCollection 2024 Jul.
This study aimed to develop an efficient method for the extraction of bioactive compounds from green tea waste (GTW) toward its potential application in the food industry. GTW, which is generated during the harvesting and processing of green tea products, accounts for a global annual loss of nearly 1 million tonnes. Notably, this waste is rich in polyphenolic compounds, particularly catechins, which are renowned for their significant health benefits. We assessed the optimization of catechin extraction from GTW employing hot water extraction (HWE), ultrasound-assisted extraction (UAE), and ethanol extraction (EthE) techniques at different sample-to-solvent ratios (1:100, 1:50, and 1:20 w/v). The extraction temperature was set at 80°C for both HWE and UAE; however, for EthE, the temperature was slightly lower at 70°C, adhering to the boiling point of ethanol. High-performance liquid chromatography was used to determine the extraction efficiency by quantifying various catechins (i.e., catechin, epicatechin [EC], epicatechin gallate [ECG], epigallocatechin [EGC], and epigallocatechin gallate [EGCG]). In terms of the concentration for individual catechins, EC was found to be the highest concentration detected, ranging from 30.58 ± 1.17 to 37.95 ± 0.84 mg/L in all extraction techniques and ratios of solvents, followed by EGCG (9.71 ± 1.40-20.99 ± 1.11 mg/L), EGC + C (7.95 ± 0.66-12.58 ± 0.56 mg/L), and ECG (1.85 ± 0.71-6.05 ± 0.06 mg/L). The findings of DPPH (2,2-diphenyl-1-picryl-hydrazyl) free radical assay illustrated that HWE demonstrated the highest extraction efficiency at all ratios, ranging from 61.41 ± 1.00 to 70.36 ± 1.47 mg/L. The 1:50 ratio exhibited the highest extraction yield (25.98% ± 0.75%) compared to UAE (24.16% ± 0.95%) and EthE (22.59% ± 0.26%). Moreover, this method of extraction (i.e., HWE) produced the highest total catechins and %DPPH reduction. Consequently, HWE was the most efficient method for extracting catechins from GTW, underscoring its potential for valorizing waste within the food manufacturing industry.
本研究旨在开发一种高效的从绿茶废弃物（GTW）中提取生物活性化合物的方法，以实现其在食品工业中的潜在应用。GTW是在绿茶产品的收获和加工过程中产生的，全球每年损失近100万吨。值得注意的是，这种废弃物富含多酚类化合物，尤其是儿茶素，它们因具有显著的健康益处而闻名。我们评估了采用热水提取（HWE）、超声辅助提取（UAE）和乙醇提取（EthE）技术，在不同样品与溶剂比例（1:100、1:50和1:20 w/v）下从GTW中提取儿茶素的优化情况。HWE和UAE的提取温度均设定为80°C；然而，对于EthE，温度略低，为70°C，这是乙醇的沸点。采用高效液相色谱法通过定量各种儿茶素（即儿茶素、表儿茶素[EC]、表儿茶素没食子酸酯[ECG]、表没食子儿茶素[EGC]和表没食子儿茶素没食子酸酯[EGCG]）来确定提取效率。就单个儿茶素的浓度而言，发现EC是检测到的最高浓度，在所有提取技术和溶剂比例中，其浓度范围为30.58±1.17至37.95±0.84 mg/L，其次是EGCG（9.71±1.40 - 20.99±1.11 mg/L）、EGC + C（7.95±0.66 - 12.58±0.56 mg/L）和ECG（1.85±0.71 - 6.05±0.06 mg/L）。DPPH（2,2 - 二苯基 - 1 - 苦基肼）自由基测定的结果表明，HWE在所有比例下均表现出最高的提取效率，范围为61.41±1.00至70.36±1.47 mg/L。与UAE（24.16%±0.95%）和EthE（22.59%±0.26%）相比，1:50的比例表现出最高的提取率（25.98%±0.75%）。此外，这种提取方法（即HWE）产生的总儿茶素含量最高，%DPPH还原率也最高。因此，HWE是从GTW中提取儿茶素的最有效方法，突出了其在食品制造业中使废弃物增值的潜力。
