Sunflower Oil Overview and Composition

Study Notes

Sunflower seed size varies based on the cultivar and position within the seed head.
Seed position affects oil content; internal seeds have less oil than those in the intermediate or external zones.
The fatty acid composition, including linoleic, palmitic, and oleic acids, changes depending on the seed's position and harvest time.

Hull composition: 31% N-free extract, 61% fiber, 3% ash and 3% protein, 3% oil.
Kernel composition: 67% oil, 21% protein, 3% ash, and 6% N-free extract.
Fatty Acids: Sunflower oil is predominantly composed of linoleic acid followed by oleic acid.
Other notable fatty acids include palmitic and stearic acids.

Harvesting Time: Linoleic acid content increases with time after flowering, while oleic acid decreases.
Temperature and Light: Linoleic acid content increases proportionally with temperature difference.
Maturity: Lower temperatures result in decreased linoleic acid content and increased oleic acid content.
Oxidative stability: Low content of linolenic acid leads to good oxidative stability.
Chemical and Physical Properties: Saponification value ranges from 188-194 mg KOH/g oil; iodine value ranges from 118-141.
Refractive Index: Ranges from 1.461-1.468 at 40°C
Density: Ranges from 0.918-0.923 (20°C/water at 20°C.
Viscosity: Varies with temperature, decreasing with increasing temperatures
Specific Heat: 2.197 J/kg°C
Combustion Heat: Major parameter when using oil as energy.
Smoke Point, Flash Point, and Fire Point: For refined sunflower oil with 0.10% free fatty acids: Smoke point = 209°C, flash point = 316°C, fire point = 341°C
Triacylglycerol composition: The TAG distribution contributes to a low solidification point of regular sunflower oil at 16-19°C.

Tocopherols and tocotrienols are present in concentrations from 403-935 ppm for alpha-tocopherol.
Content levels vary depending on cultivar or growing conditions.

The main component in sunflower oil is beta-sitosterol, followed by gamma-sitosterol.
Sterol content helps differentiate oil types and detect adulteration.

Aliphatic compounds and terpenoids in sunflower oil, with squalene as the main terpenoid, are notable components.
Squalene content is 0.008–0.019% or 15–20 mg/100 g in regular sunflower oils.
Carotenoids and chlorophylls contribute to the color of the oil.

Varieties with modified fatty acid compositions, including increased SFA and High-oleic content are available.

High-oleic sunflower oil has a high percentage of oleic acid.
High-oleic sunflower oil is appropriate for various applications where oxidative stability is essential.

Cold-pressed sunflower oil offers a clear appearance, a golden-yellow color, and a characteristic light flavor.
The processing method preserves the natural flavors with a low level of chlorophylls and carotenoids.

Regular sunflower oil doesn't need hydrogenation for stabilizing it.
Hydrogenated sunflower oil can be used for margarine and shortenings, but it can have disadvantages relating to texture.

Crude sunflower oil requires treatment before other uses.
Treatment steps include degumming, alkali refining, bleaching, dewaxing, and deodorization to improve its physical properties.

Dewaxing is needed to remove or adjust the wax content in the oil.
This process involves cooling the oil and separating the wax by crystallization.

Physical refining is crucial for removing phosphatides and other components.
Deodorization and Deacidification are important steps to remove volatile components and improve the oil flavor.