Microalgae have attracted considerable interest due to their ability to produce a wide range of valuable compounds. Pulsed Electric Fields (PEF) has been demonstrated to effectively disrupt the microalgae cells and facilitate intracellular extraction. To increase the commercial viability of microalgae, the entire biomass should be exploited with different products extracted and valorized according to the biorefinery scheme. However, demonstrations of multiple component extraction in series are very limited in literature. This study aimed to develop an effective lipid extraction protocol from wet Scenedesmus almeriensis after PEF-treatment with 1.5 MJ·kgDW−1. A cascade process, i.e., the valorization of several products in row, was tested with firstly the collection of the released carbohydrates in the water fraction, then protein enzymatic hydrolysis and finally lipid extraction. Biomass processed with high pressure homogenization (HPH) on parallel, served as benchmark. Lipid extraction with ethanol:hexane (1:0.41 vol/vol) offered the highest yields from the different protocols tested. PEF-treatment promoted extraction with almost 70% of total lipids extracted against 43% from untreated biomass. An incubation step after PEF-treatment, further improved the yields, up to 83% of total lipids. Increasing the solvent volume by factor 2 offered no improvement. In comparison, extraction with two other systems utilizing only ethanol at room temperature or elevated at 60 °C were ineffective with less than 30% of total lipids extracted. Regarding cascade extraction, carbohydrate release after PEF was detected albeit in low concentrations. PEF-treated samples displayed slightly better kinetics during the enzymatic protein hydrolysis compared to untreated or HPH-treated biomass. The yields from a subsequent lipid extraction were not affected after PEF but were significantly increased for untreated samples (66% of total lipids), while HPH displayed the lowest yields (~ 49% of total lipids). PEF-treatment successfully promoted lipid extraction from S. almeriensis but only in combination with a polar:neutral co-solvent (ethanol:hexane). After enzymatic protein hydrolysis in cascade processing; however, untreated biomass displayed equal lipid yields due to the disruptive effect of the proteolytic enzymes. Therefore, the positive impact of PEF in this scheme is limited on the improved reaction kinetics exhibited during the enzymatic hydrolysis step.

中文翻译：

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阿尔美栅藻生物精炼级联工艺中脂质提取性能分析


微藻由于能够产生多种有价值的化合物而引起了人们的极大兴趣。脉冲电场 (PEF) 已被证明可以有效破坏微藻细胞并促进细胞内提取。为了提高微藻的商业可行性，应根据生物精炼方案提取和增值的不同产品来利用整个生物质。然而，文献中对串联多组分萃取的演示非常有限。本研究旨在开发一种有效的从湿栅藻中经 1.5 MJ·kgDW−1 PEF 处理后的脂质提取方案。测试了级联过程，即连续几种产品的增值，首先收集水部分中释放的碳水化合物，然后进行蛋白质酶水解，最后进行脂质提取。采用高压均质 (HPH) 并行处理的生物质作为基准。在所测试的不同方案中，使用乙醇：己烷（1:0.41 体积/体积）提取脂质的产量最高。 PEF 处理促进了提取，提取了近 70% 的总脂质，而未处理的生物质中提取的总脂质为 43%。 PEF 处理后的孵育步骤进一步提高了产量，高达总脂质的 83%。将溶剂体积增加 2 倍并没有改善。相比之下，在室温或 60 °C 下仅使用乙醇的另外两个系统的提取效果不佳，提取的总脂质不足 30%。关于级联提取，PEF 后检测到碳水化合物释放，尽管浓度较低。与未处理或 HPH 处理的生物质相比，PEF 处理的样品在酶促蛋白质水解过程中表现出稍微更好的动力学。 PEF 后后续脂质提取的产量未受影响，但未经处理的样品显着增加（占总脂质的 66%），而 HPH 的产量最低（约占总脂质的 49%）。 PEF 处理成功地促进了阿尔美瑞沙门氏菌的脂质提取，但仅与极性：中性共溶剂（乙醇：己烷）结合使用。经过级联处理的酶促蛋白质水解后；然而，由于蛋白水解酶的破坏作用，未经处理的生物质显示出相同的脂质产量。因此，该方案中 PEF 对酶水解步骤中反应动力学改善的积极影响有限。