2. Material and Methods

2.1. Reagents

The commercial castor bean seeds were bought from the Brazilian company BRSeeds, and the Crambe oil was donated by the research company MS Foundation, located in Maracaju - MS, Brazil. Ethyl ether, ethanol, hexane, acetone, sodium hydroxide, and phenolphthalein were used with minimum purities of 99%.

2.2. Preparation of Castor Seed Particles

2.2.1. In Natura Seeds

In natura castor seeds were ground with a blender, and the seed particles smaller than 4.8 mm were collected after sieving.

2.2.2. Oil-Free Seeds

To prepare the oil-free seeds, a methodology reported elsewhere was used with slight modifications (Cavalcanti et al., 2007). Approximately 10 g of castor bean seeds were peeled and ground, then 50 cm3 of acetone was added to the particles and were left under constant stirring at 4oC for 16 h. Subsequently, the seeds were filtered under vacuum and left to dry at room temperature for 24 h. Particles of less than 1 mm were collected after sieving. The average of oil extracted following this methodology was 47.4 ± 1.3%.

2.3. Quantification of FFA

Titration with NaOH solution was performed to quantify the FFA (free fatty acids) following the AOCS official method (Ca 5a-40) (AOCS, 1996).Equation 1 was employed to calculate the mass percentage of FFA in the samples.