Functional Category
Emollient; lubricant; oleaginous vehicle
Applications in Pharmaceutical Formulation
Canola oil is a refined rapeseed oil obtained from particular species of rapeseed that have been genetically selected for their low erucic acid content.(4) In pharmaceutical formulations, canola oil is used mainly in topical preparations such as soft soaps and liniments. It is also used in cosmetics.
Description
A clear, light yellow-colored oily liquid with a bland taste.
Stability and Storage Conditions
Canola oil is stable and should be stored in an airtight, lightresistant container in a cool, dry place. The USP32–NF27 specifies that contact between canola oil and metals should be avoided. Containers should be filled to the top, while partially filled containers should be flushed with nitrogen. During storage, grassy, paintlike, or rancid off-flavors can develop. Flavor deterioration has been attributed mainly to secondary oxidation products of linolenic acid, which normally makes up 6–14% of the fatty acids in canola oil. Storage tests of canola oil showed sensory changes after 2–4 days at 60–658C in comparison to 16 weeks at room temperature. Canola oil seems to be more stable to storage in light than cottonseed oil and soybean oils, but is less stable than sunflower oil.(5) In addition, the effects of various factors on sediment formation in canola oil have been reported.(6) It has been reported that oils stored at 28C showed the highest rate of sediment formation, followed by those stored at 68C.(5) All samples showed little sediment formation, as measured by turbidity, during storage at 128C. Removal of sediment from canola oil prior to storage by cold precipitation and filtration did not eliminate this phenomenon, which still developed rapidly at 28C. A study on the effect of heating on the oxidation of low linolenic acid canola oil at frying temperatures under nitrogen and air clearly showed that a significantly lower development of oxidation was evident for the low linolenic acid canola oil. Reduction in the linolenic acid content of canola oil reduced the development of room odor at frying temperatures. The thermal oxidation of canola oil studied during oven heating revealed an increase in peroxide values of pure and antioxidant treated oils. Peroxide values were shown to differ between pure and antioxidant-treated canola oil during the initial stages of microwave heating (6 minutes). Formation of secondary products of oxidation, which contribute to off-flavors, were also observed.(7
Safety
Canola oil is generally regarded as an essentially nontoxic and nonirritant material, and has been accepted by the FDA for use in cosmetics, foods, and pharmaceuticals. Rapeseed oil has been used for a number of years in food applications as a cheap alternative to olive oil. However, there are large amounts of erucic acid and glucosinolates in conventional rapeseed oil, both substances being toxic to humans and animals.(7) Canola oil derived from genetically selected rapeseed plants that are low in erucic acid content has been developed to overcome this problem. The FDA specifies 165.55 mg as the maximum amount for each route or dosage form containing the ingredient. Feeding studies in rats have suggested that canola oil is nontoxic to the heart, although it has also been suggested that the toxicological data may be unclear.(8)