Abstract A conventional evaporation is known to involve high temperature process which could destroy the heat-sensitive compound in a plant extract. In this study, a green and low-cost alternative concentration technique namely progressive freeze concentration (PFC) has been introduced to concentrate broccoli extract. A stirred cylindrical crystallizer was used to freeze the added solvent (water) in the extraction process. The changes in effective partition constant (K), antioxidant activity (AA) and total phenolic content (TPC) of the extract, were analysed at a different reading of coolant temperature, freezing time and stirring rate. From the findings, it was found that an amount of 0.003180 mg GAE/g of total phenolic content and 86.10% of antioxidant activity were retained through the PFC process at a coolant temperature of −6 °C, freezing time of 45 min and stirring rate of 100. Besides, the lowest K value achieved was 0.08 which outstandingly portrays an efficient PFC process.

中文翻译：

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渐进冷冻浓缩对西兰花提取物浓度中总酚含量和抗氧化活性的保留

摘要 众所周知，常规蒸发涉及高温过程，可能会破坏植物提取物中的热敏化合物。在这项研究中，引入了一种绿色且低成本的替代浓缩技术，即渐进冷冻浓缩 (PFC) 来浓缩西兰花提取物。在萃取过程中使用搅拌的圆柱形结晶器冻结添加的溶剂（水）。在冷却剂温度、冷冻时间和搅拌速率的不同读数下分析提取物的有效分配常数 (K)、抗氧化活性 (AA) 和总酚含量 (TPC) 的变化。结果表明，在-6°C的冷却剂温度下，通过PFC工艺保留了0.003180 mg GAE/g总酚含量和86.10%的抗氧化活性，