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Analytical Chemistry

More productive seeds

Magnetic resonance measures the concentration and quality of oilseeds for producing biodiesel

Eduardo CesarSunflower, cashew nuts, Brazil nuts and Barbados nutsEduardo Cesar

New technology developed in the laboratories of Embrapa Agricultural & Livestock Instrumentation in São Carlos, in inner state São Paulo, should strengthen Brazil’s position in the worldwide production of biofuels. Researchers from this organization created a nuclear magnetic resonance device for super-fast measurement of the quantity and quality of vegetable oils found the seeds of soybean, castor-oil, palm oil, sunflower, peanut, cotton and other oil-bearing plants that have already been used for, or are candidates for, the manufacture of biodiesel. The equipment has the potential for analyzing the oil content of more than 10,000 seeds an hour, whereas the fastest conventional chemical methods available in the market produce only 60 analyses in the same amount of time. Though the equipment also measures the quality of oil at the rate of only 300 samples an hour, this is still dozens of times faster than the currently available techniques.

Analytical speed is important because it allows varieties of commercial and wild plants, like the pinhão-manso [Barbados nut], macaúba [macaw palm], pequi and tucumã, other candidates for biodiesel, which are highly productive, to be chosen more quickly and therefore to speed up the genetic improvement programs of the crops involved in the production of biofuels. “In order for the new plant selection programs to be fast, thousands of analyses of the concentration of oil in seeds are needed every year. Today’s oil analysis methods don’t meet this requirement”, explained biochemist Luiz Alberto Colnago, who coordinated the research. According to the researcher from the Brazilian Agriculture & Livestock Research Company (Embrapa), although Brazil, thanks to its pioneering work, is in a relatively comfortable position in the global biofuels” market, it is still necessary to increase the productivity of crops used for producing biodiesel so that future demand is met without any risk of product scarcity. “Today only palm oil is highly productive, at about 5 t./ha a year. Soybeans and the majority of the other commercial crops are around 1 t./ha a year. This means that the energy produced is only slightly greater than the energy spent producing it”, he says.

In addition to speed, the new magnetic resonance technique has another important advantage. Unlike traditional methods, where it is necessary to dry and crush the seeds that are going to be analyzed, thus destroying them, the magnetic resonance technology leaves the sample intact. “With this technique the very same seed that has been analyzed can be planted”, say the Embrapa researcher. In conventional techniques, oil extraction uses a solvent derived from petroleum oil, which harms the environment. By this method, it is necessary to extract the oil for 24 hours, evaporate the solvent and then weigh how much liquid was extracted. “This method generates chemical waste that needs to be treated.”

The equipment created at Embrapa Agriculture & Livestock Instrumentation works in a similar way to a nuclear magnetic resonance device used for medical purposes in the country’s clinics and hospitals. The seeds are placed sequentially, one behind the other, on a belt that runs through a magnet, whose function is to magnetize the sample. A small sensor is attached to this magnet. When the seed reaches the sensor it is stimulated by radio waves at a fixed frequency of 85 megahertz for just 10 micro-seconds.

“At the end of the irradiation, the seed starts emitting a signal on the same frequency. The intensity of this signal is proportional to the concentration of oil in the seed. The stronger the signal the more oil the seed has”, explains Colnago. The measure of quality, on the other hand, is given by the time the signal reflected back from the seed takes to disappear. The faster the signal disappears the greater the viscosity of the oil. Viscosity is one of the quality parameters of vegetable oils and is directly associated with its chemical composition and its cetane number. In turn, this number is an indicator of the diesel’s ignition quality, something akin to octane for gasoline engines. For Colnago, improving the quality of the vegetable oils produced in Brazil is fundamental because some of them are yet to meet international specification norms. “Soybean, sunflower and cotton have high concentrations of polyunsaturated fatty acids that are undesirable for use as a fuel, because they are chemically unstable and have a low cetane number”, says the researcher.

Commercial modules
The resonance device received funding from FAPESP and from the Studies and Projects Financer (Finep). Researchers from the Department of Physics of the Federal University of Pernambuco (UFPE), from the São Carlos Institute of Chemistry of the University of São Paulo (USP) and from Embrapa Soils, Rio de Janeiro, also took part. Colnago explains that the device was not fully developed by his team. “We assembled it using commercial modules and only built those parts that are not available in the world market. We used a magnet from a magnetic resonance tomograph and the electronic part from a transmitter and receiver of a conventional device. The sample movement system – the conveyor belts – and the bobbins where the samples are placed in the magnet were built by us”, says Colnago.

“The most important thing in this work was the development of new analysis methodologies using nuclear magnetic resonance for measuring both the quantity and the quality of the oil directly in the seeds. It’s these fast procedures that are unheard of.” These methodologies started being developed in 1998 and were the topic of two master’s degree dissertations and of two doctoral theses for which the researcher from USP’s São Carlos Institute of Chemistry was the tutor. The research also provided material for publication in scientific articles in the journals Analytical Chemistry and Analytica Chimica Acta, in February and July this year, respectively.

Within six months to a year, Colnago hopes to have a prototype of the device in a more user-friendly and cheaper version. The current equipment would cost US$ 500,000 because it uses a magnet from a tomograph that is very large and expensive. The biochemist from Embrapa believes that if this were to be replaced by a small magnet this figure would drop by a factor of almost 20, so that the cost of the device would be around US$70,000, excluding taxes and the manufacturer’s profit margin. Gil Equipamentos Industriais, from Ribeirão Preto, which acquired some other magnetic resonance technology developed by the Embrapa group ten years ago, has already shown an interest in producing this equipment commercially. “Although it’s likely to come onto the market costing twice as much as the traditional methods, it’s going to offer far greater productivity (number of analyses over time). This will be its unique selling point”, says Colnago.

The projects
1. Development of instrumentation and the application of NMR in the analysis of food (nº 04/11904-9); Modality Regular Line of Aid to Research; Coordinator Luiz Alberto Colnago – Embrapa; Investment R$ 36,750.00 and US$ 33,000.00 (FAPESP)
2. Development of super-fast NMR technology for determining the quantity and quality of vegetable oils in whole seeds; Modality Regular Line of Aid to Research (nº 06/06111-5); Coordinator Luiz Alberto Colnago – Embrapa; Investment R$ 115,500.00 (FAPESP)
3. On-line evaluation of the quality of agri-industrial products using NMR; Modality Brazil Technology Network; Coordinator Luiz Alberto Colnago – Embrapa; Investment R$ 270,000.00 (Finep)