Echium oil as a vegetable source of omega 3 fatty acids for human supplementation

• Grant number: 24/03253-1
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: September 01, 2024
• End date: August 31, 2025
• Field of knowledge: Agronomical Sciences - Food Science and Technology - Food Science
• Principal Investigator: Inar Castro Erger
• Grantee: Ana Júlia Martins Silva
• Host Institution: Faculdade de Ciências Farmacêuticas (FCF). Universidade de São Paulo (USP). São Paulo , SP, Brazil

Abstract

The ingestion of omega-3 fatty acids (n-3 FA), mainly eicosapentaenoic acid (EPA; C20:5) and docosahexaenoic acid (DHA; C22:6), has been associated with the prevention of cardiovascular diseases. Except for genetically modified plants, vegetable oils do not contain EPA or DHA. But, they can be biosynthesized from ±-linolenic acid (ALA; C18:3 n-3) and stearidonic acid (SDA; C18:4 n-3), with the conversion of the latter being much more efficient. Echium plantagineum L. seeds naturally contain about 38% n-3 FA, of which 9 to 16% is SDA, making it an alternative to fish oil, the main source of EPA/DHA for human supplementation. However, due to the high content of polyunsaturated fatty acids (PUFA), echium oil is highly susceptible to oxidation, which can be catalyzed by enzymes or occur directly through the action of reactive species. The oxidation of PUFA in echium oil reduces its nutritional value and forms volatile products with an unpleasant odor, compromising its acceptability to consumers, as well as its incorporation into other foods. Therefore, the main objective of this study is to investigate the main mechanisms involved in the lipid oxidation of echium oil, enabling the design of better strategies to reduce this reaction, making the oil more stable and palatable. Initially, the seeds were subjected to a thermal treatment similar to that applied to soybean seeds to inactivate oxidizing enzymes, especially lipoxygenases. The formation of volatile compounds was determined by gas chromatography before and after the treatment. No activity of any lipoxygenase isoform was observed in echium oil, leading to the conclusion that oxidation would primarily be caused by reactive species. (E)-2-octenal, 3,5-octadien-3-one, and hexanal were the main volatile compounds observed in echium seed and associated with undesirable odors. Based on this result, the second step of this study aimed to control the oxidative reaction during oil extraction, combining the extraction process with supercritical fluid extraction (CO2-SFE) involving lower temperatures, along with the addition of natural antioxidants during the seed disruption (±-tocopherol) and during the oil storage (rosemary extract/citric acid). In this step, the oxidative stability of the samples was evaluated every week in an open container for 30 days, simulating consumption. It will be also evaluated every 30 days in a closed container for 6 months, simulating the product's shelf life. In addition, the conversion rate to produce EPA and DHA in vivo will be evaluated and compared with other vegetable oils, including the ahiflower oil, that is also rich in SDA. In the experimental model, mice will be fed with diets containing 4% of soybean, echium, chia and ahiflower oils for 6 weeks. The proportion of EPA and DHA will be determined in several tissues, using GC-MS method. In the final step of this project, nano and microcapsules of echium oil will be produced using electrospraying and spray-drying, respectively, and the oxidative stability will be compared. Overall, the results of this project could contribute to obtaining an alternative source of n-3 FA for human consumption and food formulation, in accordance with official guidelines for cardiovascular health.