Research Group on EcoIndustrial System Analysis, Department of Environmental Science, Aarhus University, Frederiksborgvej 399, Postboks 358, DK-4000, Roskilde, Denmark; Aarhus University Centre for Circular Bioeconomy, Denmark.
Toulouse Biotechnology Institute (TBI), INSA, INRAE UMR792, and CNRS UMR5504, Federal University of Toulouse, 135 Avenue de Rangueil, F-31077, Toulouse, France.
J Environ Manage. 2021 Feb 15;280:111832. doi: 10.1016/j.jenvman.2020.111832. Epub 2020 Dec 23.
This study presents a critical overview of reported essential oil (EO) extractions from citrus peel wastes (CPW), including harmonized data on the various citrus species and cultivars. Harmonization is vital to enable sustainable management practices. The review only includes eco-efficient extraction techniques. In total, the review contains 66 quantified examples using i) mechanical cold press ii) thermal extraction with water or steam media iii) thermal microwave-assisted extraction iv) other innovative methods (such as ultrasound). The technologies were assessed for their potential use in cascading production to achieve economies of scope, particularly considering the use of extraction residues for subsequent fermentation to produce various products from energy carriers to enzymes. Two techniques were found insufficient for direct use in fermentation. Cold press extracts an inadequate amount of EO (average yield 2.85% DW) to ensure suitable fermentation, while solvent extraction contaminates the residues for its subsequent use. Extractions using water media, such as hydrodistillation and microwave-assisted hydrodistillation (average EO yield 2.87% DW), are feasible for the liquid-based fermentation processes, such as submerged fermentation. Steam extraction is feasible for any type of fermentation. Our review highlighted solvent-free microwave extraction (average EO yield 5.29% DW) as the most effective method, which provides a high yield in a short extraction time. We also uncovered and discussed several inconsistencies in existing yields and energy consumption published data.
本研究对从柑橘皮废弃物（CPW）中提取的精油（EO）进行了综述，包括对各种柑橘属物种和品种的协调数据。协调对于实现可持续管理实践至关重要。本综述仅包括生态高效的提取技术。总共包含 66 个使用以下技术进行量化的例子：i）机械冷榨；ii）水或蒸汽介质的热提取；iii）热微波辅助提取；iv）其他创新方法（如超声）。评估了这些技术在级联生产中的潜在用途，以实现范围经济，特别是考虑到提取残渣可用于后续发酵，以从能源载体到酶等各种产品。发现有两种技术不适用于直接发酵。冷榨提取的精油量不足（平均产量为 2.85%DW），无法确保合适的发酵，而溶剂提取会污染残渣，使其无法后续使用。使用水介质的提取方法，如水蒸馏和微波辅助水蒸馏（平均精油产量为 2.87%DW），适用于液体发酵工艺，如浸没式发酵。蒸汽提取适用于任何类型的发酵。我们的综述强调了无溶剂微波提取（平均精油产量为 5.29%DW）是最有效的方法，它在短时间内提供了高产量。我们还发现并讨论了现有产量和能源消耗发表数据中的几个不一致之处。
