Garden cress oil as a vegan source of PUFA: Achieving through optimized supercritical carbon dioxide extraction

Abstract

With more people shifting to healthier and environment-friendly lifestyles, the vegan diet has recently gained popularity. Nevertheless, this kind of diet comes with its own limitations in terms of adequate availability of nutrients, for example, essential fatty acids. The primary source for these includes fish and other marine animals, hence not accepted by the vegan population. The plant source is limited. The present work focuses on exploring garden cress (GC) seed oil - an easily available seed, with considerable polyunsaturated fatty acids (PUFA). Conventionally, Soxhlet extraction of vegetable oils is done using solvents like hexane. However, selective extraction of PUFA, phytosterols, and tocopherols could be done by supercritical-CO2 (SC-CO2) extraction of oil from the GC seeds with proper optimization of extraction parameters. The PUFA content was found to be 38% in the case of oil extracted with n-hexane. This was enriched to nearly 50% PUFA, when extracted at 350 bar pressure, 60 °C temperature, and 30 g/min flow rate in case of SC-CO2 extraction. At similar conditions, even tocopherol contents were improved significantly from 486 to 1138 ppm. Further, oil enriched with unsaponifiable matter (2.3%) containing major phytosterols like campesterol, stigmasterol, β-sitosterol, and isofucosterol was obtained at 20 g/min flow rate itself. Another major advantage of SC-CO2 extraction is the selective extraction of oil from the seed, leaving behind the phospholipids. This in turn eliminates one step of refining, thereby making the process economically viable. The use of co-solvents resulted in nutritionally enriched GC seed oil at a pressure of 250 bar. It is quite evident from the findings of this study that, careful selection of process parameters of SC-CO2 extraction of GC seed oil can result in a nutritionally enriched vegan source of PUFA, using an emerging cleaner and greener technology. Industrial relevanceThere is a huge demand for newer vegan sources of PUFA. GC seed oil can be one of them. This investigation aimed at process development for extracting PUFA and tocopherol, phytosterol enriched GC oil using eco-friendly SC-CO2 extraction. SC-CO2 extraction is becoming more popular and the economic feasibility is proven for the higher scale of operation. As this oil can be encapsulated and sold at a reasonably good price, this work has significant industrial relevance.