Aceite De Canola

Canola Oil:
Physical and Chemical Properties
by Dr. Roman Przybylski
Canola oil produced in Canada is obtained from the seeds of Brassica napus and Brassica rapa. These cultivars, low in erucic acid and glucosinolates, are very different from high erucic acid rapeseed oil in chemical, physical and nutritional properties.

PHYSICAL PROPERTIES
Selected physical properties for canola oil areshown in Table 1.
Table 1. Physical Properties of Canola Oil

Crismer Value
The Crismer Value measures the miscibility of an oil in a standard solvent mixture, composed of t-amyl alcohol, ethyl alcohol and water in the volume proportion 5:5:0.27. Crismer value (CV) is one of the specification criteria used for international trade, mostly in Europe. Characteristic values are usually within anarrow limit (AOCS, 1992). The miscibility of an oil is related to the solubility of glycerides, and is affected mainly by the unsaturation and chain length of the constituent fatty acids. Little data is available describing the solubility characteristics of canola oil. Sahasrabudhe (1977) found that the Crismer value decreased from 82.0 to 76.8 with the reduction of erucic acid content from 54 to0.1%.

Parameter

Value

Relative Density (g/cm3; 20˚C/water at 20˚C) Refractive Index (nD 40˚C) Crismer Value Viscosity (Kinematic at 20˚C, mm2/sec) Cold Test (15 Hrs at 4˚C) Smoke Point (˚C) Flash Point, Open cup (˚C) Specific Heat (J/g at 20˚C) Thermal Conductivity (W/m˚K)

0.914 - 0.917 1.465 - 1.467 67 - 70 78.2 Passed 220 - 230 275 - 290 1.910 - 1.916 0.179 - 0.188

ViscosityViscosity values estimate an oil’s relative thickness or resistance to flow. Viscosity of refined, bleached and deodorized (RBD) canola is higher than soybean oil (Figure 2).
Figure 2: Effect of Temperature on Viscosity of Canola and Selected Oils. Adapted from Lang et al. (1992), Vadke et al. (1988) and Noureddini et al. (1992)

Relative Density
The relative density of canola oil was first reportedby Ackman and Eaton in 1977 and later confirmed by Vadke et al. (1988) and Lang et al. (1992). Noureddini et al. (1992) reported a density for high erucic acid rapeseed oil of 0.9073 g/cm3 while Appelqvist & Ohlson (1972) reported a range from 0.906 g/cm3 to 0.914 g/cm3. Ackman and Eaton (1977) indicated that a different proportion of eicosenoic (C20:1) and C18 polyunsaturated acids could be amajor factor for the increase in relative density of canola oil. The higher specific gravity of 0.9193 g/cm3 observed for soybean oil can be attributed to the higher content of linoleic acid (Ackman and Eaton, 1977). As for other liquids, the density of vegetable oils is temperature dependent and decreases in value when temperature increases (Figure 1).
Figure 1: Effect of Temperature on Density ofSelected Oils. Adapted from Lang, et al (1992) and Noureddini, et al (1992)

Lang et al. (1992) and Noureddini et al. (1992a) found that the viscosity of canola and other vegetable oils, like other liquids, was affected by temperature and proposed an equation to calculate viscosity in the temperature range from 4 to 100˚C. Figure 2 shows the relation between temperature and viscosity for canolaand selected vegetable oils. Rapeseed oil exhibited a higher viscosity than canola, corn and soybean oils. This can be directly related to the contribution of saturated fatty acids (Noureddini et al., 1992a).

1

Smoke Point
Smoke point is the temperature at which a fat or oil produces a continuous wisp of smoke when heated. This provides a useful characterization of its suitability forfrying. The Canadian Government specifications define that frying oil should have a smoke point above 200˚C. Table 1 indicates that canola oil fulfills this requirement. A similar smoke point was observed for rapeseed oil (Appelqvist & Ohlson, 1972). The heating technique used in the standard method for smoke point determination is well-defined (AOCS Method Cc 9a-48). Arens et al. (1977) reported...