Supercritical CO2 extraction of uxi (Endopleura uchi) oil: Global yield isotherms, fatty acid profile, functional quality and thermal stability
Graphical abstract
Introduction
Uxi (Endopleura uchi) is a native species from the Amazon region, and its fruits are widely consumed by the local population [[1], [2], [3]]. Uxi wood is commercially desirable by the civil construction industry (manufacture of posts and beams), which contributes to the indiscriminate extraction of its species' trees, causing deforestation in the Amazon region [4]. The fruits have potential for edible vegetable oil production, due to their chemical composition [5]. The study by Berto et al. [6] showed that the lipid fraction of the uxi fruit contains a predominance of unsaturated fatty acids. Other characteristic compounds in the uxi oil include phytosterols, tocopherols and carotenoids [[7], [8], [9]]. The phytochemical profile of the species also indicates the presence of bergenin in the bark of its trunk [10].
Unsaturated fatty acids are structural components of cell membranes, incorporated into phospholipids, which regulate the fluidity and function of the membrane, in addition to having the role of metabolites precursors with biological properties of interest. A major effect attributed to linoleic acid (n-6) is the decrease in cholesterol levels in the blood, due to the reduction in the levels of low-density plasma lipoproteins, contributing to the prevention of cardiovascular diseases [11]. The benefits of linoleic acid (n-6) include the reduction of atherosclerosis, carcinogenesis, obesity, diabetes and inflammatory processes [12].
Obtaining high quality lipid products depends on factors related to the extraction process, such as temperature, nature of the solvent, solvent/raw material ratio, extraction period, atmospheric composition and preparation of the raw material. The compounds degradation can be accelerated by the mechanical pressing system, while the use of organic solvents can increase the oils toxicity. Conventional methods, although allowing high yields, are lengthy, exposing raw materials to hydrolytic and oxidative rancidity processes, contributing to the loss of the quality of the final product [13,14].
Considering this scenario, the application of supercritical fluid turn out to be an alternative to obtain high quality vegetable oil, preserving the nature of the characteristic compounds, as in the case of unsaturated fatty acids and other substances of interest (bioactive compounds). Extraction with supercritical CO2 is considered to be a green technique, environmentally friendly, due to the characteristics of the used solvent, especially because it is non-corrosive, non-toxic, non-flammable, presents low cost and easy removal of the extracted product, besides allowing high profitability in mass and shorter process time [15,16].
In this context, extraction with supercritical CO2 represents an important tool to replace conventional methods, and it can be applied for the production of uxi oil. This proposal allows the development of a new product and the valorization of the species, especially in terms of environmental preservation. In this research, uxi (Endopleura uchi) oil was obtained via supercritical CO2 extraction in order to promote the valorization of the species in the industrial scenario, showing the potential of its oil as a functional food.
Section snippets
Uxi samples
The uxi fruits were collected in the municipality of Bujaru, Pará, Brazil (-01°64′09″S, -48°02′73″W), in March 2018. After 48 h of ripening, the material was transported to the Extraction Laboratory of the Federal University of Pará, where manual pulping was performed. The pulp was frozen in an ultra-freezer at −80 °C for 24 h. Dehydration was carried out in a freeze dryer (Alpha, 2–4 LD Plus, Germany) for 72 h. The dehydrated pulp was crushed in a processor (Croydon, LR03, Brazil) and stored
Freeze-dried uxi pulp characteristics
The real density of the uxi pulp was 1200 ± 10 kg/m3, while the apparent density was equal to 504.48 ± 9.36 kg/m3. The bed porosity was 0.58 ± 0.01. The average diameter of the pulp particles was 0.82 ± 0.02 mm. The centesimal composition of the dehydrated uxi pulp showed moisture equal to 6.96 ± 0.02 %; ash content of 1.49 ± 0.01 %; lipid content equal to 25.61 ± 0.02 %; protein content of 3.87 ± 0.05 % and total carbohydrates of 62.07 %.
Global yield
The extraction performance and global yields of uxi oil
Conclusion
The process parameters analyzed in this study showed that the density of supercritical CO2 was the main factor to obtain high mass yield of uxi oil, with the use of temperature close to the CO2 critical point, which contributed to the quality of the obtained product. The fatty acids and triglycerides profiles (by prediction) and the thermogravimetric study showed that uxi oil has interesting functional quality due to the majority composition of unsaturated fatty acids that can be used to
Acknowledgements
This study was financed in part by the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior – Brasil (CAPES) – Finance Code 001.
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