Estabilidade de componentes da fração lipídica durante o armazenamento de grãos, óleo bruto, óleo refinado e biodiesel de arroz, canola e girassol

Abstract

In the last decade a worldwide trend in the demand for renewable energy has been observed. In Brazil, soybean oil is the main feedstock for biodiesel production. Apart from diversification of raw materials, other needs for the supply chain of grain, oils and biodiesel is stored for longer periods, principally for the manufacture of biofuels and their derivatives. The main problem ofthe supply chain is the storage stage, as there are few data regarding lipid stability of grain and oils, and the stability of methyl esters (biodiesel), mainly medium and long periods, maintaining technological characteristics at acceptable levels for the production and marketing of biodiesel, as are also scarce when it comes to foodconsumption. This study analyzed the effects of storage of rice, canola and sunflower grains, crude oil, refined oil, their methyl esters, their fatty acid profile and the antioxidant content and physical-chemical characteristics of the oil and biodiesel stored at 25°C and 55 % relative humidity. It was found that: (a) prolonged storage promoted the degradation of total and individual tocopherols, reducing its content in all grains, oil and biodiesel; (b) both primary and secondary oxidation were increased for all grains, oils and biodiesel during storage, with the exception of crude sunflower oil (for secondary oxidation); (c) the acidity was also increasing during the period of grains storage, crude and refined oil, but was stable for biodiesel during the 6 months of storage, with the exception of crude rice and canola; (d) the highest lipid stability in thisstudy was found in canola grains.