Sunflower Oil Overview and Composition

Sunflower Oil Overview

• Sunflower oil is extracted from sunflower seeds.
• Two main types of sunflower seeds exist: oilseed and non-oil types.
• Oilseed types have a higher oil content (40%) than non-oil types (30%).

Introduction to Sunflower Oil

• 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.

Composition of Sunflower Oil

• 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.

Properties of Sunflower Oil

• 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

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

Sterols

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

Other Components

• 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.

Modified Fatty Acid Composition

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

High-Oleic Sunflower

• 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

• 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.

Hydrogenation

• 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.

Storage and Deterioration

• Sunflower oil storage conditions influence shelf life.
• Factors influencing oxidative stability include time, temperature, and light.

Treatment of Crude Oil

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

Dewaxing/Winterization

• 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.

Refining Procedures

• 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.

Degumming

• Degumming removes non-hydratable phospholipids using water.
• Phospholipids are essential components in the refining process.

Deodorization

• Deodorization procedures for sunflower oil do not differ significantly from those of other vegetable oils.