Cravotto Giancarlo, Boffa Luisa, Mantegna Stefano, Perego Patrizia, Avogadro Milvio, Cintas Pedro
Dipartimento di Scienza e Tecnologia del Farmaco, Università di Torino, Via P. Giuria 9, 10125 Torino, Italy.
Ultrason Sonochem. 2008 Jul;15(5):898-902. doi: 10.1016/j.ultsonch.2007.10.009. Epub 2007 Nov 9.
Ultrasound-assisted extraction (UAE) and microwave-assisted extraction (MAE) techniques have been employed as complementary techniques to extract oils from vegetable sources, viz, soybean germ and a cultivated marine microalga rich in docosahexaenoic acid (DHA). Ultrasound (US) devices developed by ourselves, working at several frequencies (19, 25, 40 and 300 kHz), were used for US-based protocols, while a multimode microwave (MW) oven (operating with both open and closed vessels) was used for MAE. Combined treatments were also studied, such as simultaneous double sonication (at 19 and 25 kHz) and simultaneous US/MW irradiation, achieved by inserting a non-metallic horn in a MW oven. Extraction times and yields were compared with those resulting from conventional procedures. With soybean germ the best yield was obtained with a 'cavitating tube' prototype (19 kHz, 80 W), featuring a thin titanium cylinder instead of a conventional horn. Double sonication, carried out by inserting an immersion horn (25 kHz) in the same tube, improved the yield only slightly but halved the extraction time. Almost comparable yields were achieved by closed-vessel MAE and simultaneous US/MW irradiation. Compared with conventional methods, extraction times were reduced by up to 10-fold and yields increased by 50-500%. In the case of marine microalgae, UAE worked best, as the disruption by US of the tough algal cell wall considerably improved the extraction yield from 4.8% in soxhlet to 25.9%. Our results indicate that US and MW, either alone or combined, can greatly improve the extraction of bioactive substances, achieving higher efficiency and shorter reaction times at low or moderate costs, with minimal added toxicity.
超声辅助提取（UAE）和微波辅助提取（MAE）技术已被用作从植物源（即大豆胚芽和富含二十二碳六烯酸（DHA）的养殖海洋微藻）中提取油脂的互补技术。我们自行开发的工作频率为19、25、40和300kHz的超声（US）设备用于基于超声的提取方案，而多模式微波（MW）炉（可在开放和封闭容器中操作）用于MAE。还研究了联合处理，例如通过在MW炉中插入非金属喇叭实现的同时双超声处理（19和25kHz）以及同时的US/MW辐照。将提取时间和产率与传统方法得到的结果进行了比较。对于大豆胚芽，使用“空化管”原型（19kHz，80W）获得了最佳产率，该原型具有薄钛圆柱体而非传统喇叭。通过在同一管中插入浸入式喇叭（25kHz）进行双超声处理，产率仅略有提高，但提取时间减半。封闭容器MAE和同时的US/MW辐照获得了几乎相当的产率。与传统方法相比，提取时间减少了多达10倍，产率提高了50 - 500%。对于海洋微藻，UAE效果最佳，因为超声对坚韧的藻类细胞壁的破坏大大提高了提取产率，从索氏提取法的4.8%提高到25.9%。我们的结果表明，超声和微波单独或联合使用都可以极大地改善生物活性物质的提取，以低或中等成本实现更高的效率和更短的反应时间，且添加的毒性最小。
