Macaúba: native raw material with potential for biodiesel production

According to the National Agroenergy Plan, launched by the Ministry of Agriculture, Livestock and Supply, research should seek new levels of oil yield with greater energy density of oilseed species, going from the current level of 500 to 700 kg of oil/ha obtained with traditional crops, in which there is technological mastery, such as soybeans and castor beans, for approximately 5.000 kg of oil/ha, providing increasing competitiveness to biodiesel and promoting national energy security.

In this search for higher levels of productivity in terms of quantity of oil produced per hectare, perennial species are being studied and used, such as, for example, oil palm trees (dendê, macaúba and buritis) and jatropha, which have a high oil yield, with productivity exceeding 4.000 kg of oil/ha and adapted to different edapho-climatic conditions, including different biomes, mainly cerrado, caatinga and Amazon forest.

There are, therefore, real prospects for using macaúba as a raw material for biodiesel production in Brazil. This palm tree stands out for its potential for producing large quantities of oil per unit area, in addition to the possibility of use in agrosilvopastoral systems.

The macaúba (Acrocomia aculeata (Jacq.) Lood. ex Mart) is a palm tree native to the Tropical Forests. It is widely distributed in Brazil and neighboring countries such as Colombia, Bolivia and Paraguay. In Brazil, natural settlements occur in almost the entire territory, but the largest concentrations are located in Minas Gerais, Goiás, Mato Grosso and Mato Grosso do Sul, being widely spread throughout the Cerrado areas.

This species has a vast popular synonym in Brazil: macaúba, mucajá, mocujá, mocajá, macaíba, macaiúva, bacaiúva, mouthiúva, umbocaiúva, imbocaiá, coco-de-catarro or coco-de-espinho.

The fruit is the most important part of the plant, whose pulp is consumed fresh or used to extract edible fat; almonds provide clear oil with similar qualities to olives. Given their wide usefulness, these palm trees have been used by man since prehistoric times (around 9.000 years BC). Research published in Revista FAPESP in December 2002 showed that the peels, dried and crushed, can be used as a valuable source in the fight against child malnutrition, as they have an iron content four times higher than the multi-mixture, in addition to reasonable concentrations of calcium. and phosphate. Thus, macaúba bark can replace some components of this food supplement normally distributed by Pastoral do Menor, such as sunflower and peanut seeds, which are scarce in the northeast region during the drought, a period in which child malnutrition increases.

There are several reports of traditional use of macaúba as a source of oil for food purposes, soap making and burning for lighting and heating purposes. This palm tree has significant production potential due to its high oil content and ability to adapt to dense populations. Potential productivity per area is similar to that of oil palm, reaching more than 4 t of oil/ha.

The fruits are made up of around 20% skin, 40% pulp, 33% endocarp and 7% almond. The oil content is slightly higher in the pulp (60%) compared to the almond (55%). Just like palm oil, two types of oil are extracted from macaúba. A fine oil is removed from the almond, representing around 15% of the plant's total oil, rich in lauric acid (44%) and oleic acid (26%), with potential for noble uses in the food, pharmaceutical and cosmetics industries. .

The oil extracted from the pulp, with the greatest potential for the manufacture of biodiesel, is dominated by oleic acid (53%) and palmitic acid (19%) and has good characteristics for industrial processing, but presents serious problems of loss of quality with storage. . As with palm oil, the fruits must be processed immediately after harvesting, as they degrade quickly, increasing acidity and harming biofuel production. The cakes produced from the processing of pulp and almonds can be used in animal feed with excellent nutritional characteristics and good palatability. An important by-product is also charcoal produced from the endocarp (rigid shell that surrounds the almond), which has a high calorific value.

In order to facilitate the commercial use of macaúba and make it a truly attractive species for the production of biodiesel, Embrapa Agroenergia has coordinated research, development and innovation (RD&I) projects involving this crop. In one of them, with funding from the Ministry of Agriculture, Livestock and Supply and in partnership with Embrapa Cerrados, surveys are being carried out on the occurrence of native macaúba masses in Minas Gerais, Goiás and the Federal District. With the results of this study, it is possible to establish regions where there are large native macaúba masses and also to survey the productive potential of the identified masses.

To avoid the rapid depletion of the energy source, sustainable extractivism practices are studied, carrying out a detailed inventory in the area covered by the massifs, planning the conservation and use of available genetic resources, defining the types of permitted activities and preparing rules for use of the area, according to the potential of the zoning for each activity.

Studies are also carried out to develop production systems, where macaúba will be grown in rational plantations. To this end, research is being carried out on genetic improvement, planting, fertilization, spacing between plants and obtaining the necessary information to establish sustainable production systems. A great advantage of macaúba is the possibility of intercropped production with other species. Food (beans, corn) can be produced during the implementation of the crop and after four years, when the palm trees reach a height of 7 to 10 meters and are producing normal fruit, grass can be planted to raise livestock. It is an integrated system with good performance, as the cattle feed on the grass and fruits that eventually fall from the trees and the manure produced by the animals fertilizes the palm trees.

With the available knowledge, it is known that macaúba cannot be used as the only raw material to feed a profitable biodiesel plant, as the fruit is not harvested all year round. In order for the plant to operate for at least eleven months a year, it will be necessary to use other oilseeds, such as soybeans, sunflower, cotton, castor beans and also beef tallow. Each combination of raw materials requires specific studies and research and possible adaptations in industrial processing.

A proposal presented by Embrapa Agroenergia is the establishment of Local Production Arrangements (APLs) that can meet the need for a continuous supply of raw materials for biodiesel production and that allow optimizing land use and the global energy balance. In this type of APL, it will be advantageous to form associations or cooperatives of producers that install raw material crushing units. The extracted vegetable oil will be transported to the biodiesel plant and the cake resulting from the extraction will be used by the oilseed producers themselves, both for animal feed and for use as fertilizer. With this scheme, the production radius of raw materials to supply the biodiesel plant can be expanded, which would not be economically viable if the whole grains were transported to the biodiesel plant and the cakes transported back to the producing regions.

Leonardo Bhering

Researcher at Embrapa Agroenergia (Brasília - DF)

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