Andiroba (Carapa guianensis Aubl.) is a tree native to the Amazon region, which is widely used in traditional medicine of the area, being utilized in the treatment of skin conditions, muscle and throat inflammations, and also as an insect repellent 1,2.
Natura, through plant extraction in cooperatives around the city of Belém (PA), obtains andiroba seeds, the raw material for the extraction of the oil widely used in our products.
After being harvested, the andiroba seeds (with an average moisture content of 60%) exhibit a high enzymatic activity of hydrolases, which accelerate the hydrolysis of the oil present inside the seeds. Due to this, the seeds must undergo a drying process before the extraction process begins to ensure lower hydrolase activity and thus obtain oil with low acidity, thereby avoiding the need for chemical refining of the final raw material to achieve acceptable acidity levels for cosmetic use.
The drying of the seeds usually takes place in electric greenhouses; however, due to high energy consumption, there was a need to develop alternatives that were locally available for cooperatives to dry andiroba seeds. With this goal, artisanal greenhouses were developed, built in the style of stilts with materials available in the region, such as wood and plastic (Figure 1).
Figure 1. Artisanal greenhouses built with wood and covered with plastic in the andiroba seed extraction cooperatives.
Due to the hot climate of the Amazon region, the internal temperature of the artisanal greenhouses remained naturally between 25 and 35ºC, which is an ideal temperature for drying the seeds.
To evaluate the effectiveness of drying in the artisanal greenhouses and the quality of the seeds after drying, seed samples were taken every 5 days over a drying period of 20 days.
The samples were subjected to moisture analysis, and oil was also extracted from the seeds via mechanical pressing, a more environmentally friendly process, at Natura's Benevides Industrial Unit (UIB). After extraction, the content of free fatty acids (FFA) was evaluated by acid-base titration3 of the obtained oil (Figure 2).
Figure 2. A) Moisture measurement of andiroba seeds according to the drying period in the artisanal greenhouses. B) Content of free fatty acids in andiroba oil whose seeds remained in the greenhouse for different periods.
It was observed that the artisanal greenhouses were effective in reducing the moisture of the seeds, having a reduction from 62% to 11.94% moisture at the end of the 20-day study (Figure 2 A).
However, the FFA content of the andiroba oil saw a significant increase after the 20-day study, rising from 0.85% at the beginning of the study to 9.1% on the 20th day. This increase in FFA, and the consequent increase in the acidity of the oil, is due to the action of hydrolases inside the seeds during the drying period. Despite this increase in FFA content after drying, the acidity level is within the recommended levels (<10%) 4. Thus, it was recommended to partner cooperatives that the drying of the seeds be done for 20 days before being sent to the industrial plant for oil extraction.
In addition to this study, a size exclusion chromatography analysis 5 (HPSEC – High pressure size exclusion chromatography) was also conducted on two samples of andiroba oil, one of which had seeds that underwent drying control in the artisanal greenhouse (controlled drying), and in the other sample, the seeds were not subjected to any control during drying (uncontrolled drying).
It was observed that when the drying of the andiroba seeds was not controlled, the level of triacylglycerols decreased, while the level of free fatty acids increased, evidencing that the increase in the acidity of the oil is caused by the hydrolysis of triacylglycerols.
These data show the importance of proper processing of andiroba seeds in order to avoid the enzymatic degradation of the oil and to obtain high-quality oil, ensuring its use by the cosmetic industry without the need for chemical refining of the oil.
In addition to increasing the quality of andiroba oil, this study provided other benefits for the cooperatives, as the drying reduced the water content of the seeds, with only the dry material now being transported instead of water, reducing transportation costs and increasing the profits of the cooperatives.
References:
Lorenzi, H. Brazilian Trees: A Manual for Identification and Cultivation of Native Tree Plants of Brazil. Plantarum: Nova Odessa, 1998.
Vieira, L.S. Phytotherapy of the Amazon: Manual of Medicinal Plants, 2nd ed. Agronômica Ceres: São Paulo, 1992.
AOCS Official Method, American Oil Chemists’ Society, Official Methods and Recommended Practices Ca 5a -40. Fifth Edition. Editors of Analytical Methods. Washington, D.C., 1997.
Dorsa, R. Technology of Vegetable Oils, 1st ed. Ideal: Campinas, 2004.
AOCS Official Method, American Oil Chemists’ Society, Official Methods and Recommended Practices Fifth Edition. Editors of Analytical Methods. Washington, D.C., 2004.
