SUPERCRITICAL EXTRACTION OF LYOPHILIZED STRAWBERRY ANTHOCYANINS WITH PULSED ELECTRIC FIELDS PRETREATMENT

The lyophilized strawberry anthocyanins were extracted using a supercritical extraction (SE) process. The effect of pulsed electric fields (PEF) as pretreatment and the influence of the addition of ethanol as a cosolvent on the percentage of extraction yield (EY) and the total anthocyanin concentration (TAC) were analyzed. The effect of PEF was evaluated at 0.5 and 1.0 kV/cm, while the effect of the cosolvent was studied in mixtures of supercritical carbon dioxide - ethanol (SCCO2 + ethanol) at 1.6 and 3.3% by weight. The best results (% EY = 0.506, TAC = 0.428 g /100 g of lyophilized strawberry) were obtained with a PEF pretreatment of 1.0 kV cm-1, 3.3%wt. ethanol at 200 bar and 333.15 K. The experimental results of solubility were suitably adjusted with the Kumar and Johnston model. The maximum solubility (0.114 g/100 g of solvent mixture) was obtained at 300 bar and 313.15 K.

本研究采用超临界萃取（supercritical extraction, SE）工艺提取冻干草莓花色苷，考察了脉冲电场（pulsed electric fields, PEF）预处理以及添加乙醇作为助溶剂对萃取率（extraction yield, EY）与总花色苷浓度（total anthocyanin concentration, TAC）的影响。其中，PEF预处理的电场强度设置为0.5与1.0 kV/cm，助溶剂的添加量则以超临界二氧化碳-乙醇（SCCO2 + ethanol）混合体系中乙醇的质量分数1.6%与3.3%进行考察。当采用1.0 kV·cm⁻¹的PEF预处理、体系中乙醇添加量为3.3%wt.、萃取压力200 bar、温度333.15 K时，可获得最优实验结果（萃取率为0.506，总花色苷浓度为0.428 g/100 g冻干草莓）。本研究采用库马尔-约翰斯顿模型（Kumar and Johnston model）对溶解度实验数据进行拟合，拟合效果良好；在300 bar、313.15 K条件下可获得最大溶解度，其值为0.114 g/100 g混合溶剂。