Corn Germ Oil Production Line

1. 🌾 Pretreatment Section

This section is the foundation for ensuring oil yield and quality. It creates critical conditions for subsequent oil extraction through physical processing:

• Cleaning: Uses vibrating screens, stone removers, and magnetic separators to remove impurities such as sand, stems, leaves, stones, and metal shavings, protecting downstream equipment and ensuring oil purity.
• (Optional) Crushing: Uses a toothed roller crusher to break flaxseeds into fine particles, increasing surface area for better flaking performance.
• Flaking: Uses a double-roll flaker to roll flaxseeds into uniform flakes of 0.3-0.5mm, maximizing cell structure disruption to ensure efficient oil release.

2. ⚙️ Oil Extraction Section - Three Flexible Routes

Route A: Cold Pressing Process

• Core Equipment: Low-temperature screw oil press.
• Process Principle: Directly presses at low temperature without heat treatment or only with low-temperature (<60°C) conditioning.
• Product Features: Maximally retains heat-sensitive nutrients such as α-linolenic acid and lignans, with light color and mild flavor. Residual oil in cake is approximately 5%.

Route B: Hot Pressing Process

• Core Equipment: Layered steam cooker, screw oil press.
• Process Principle: Uses moist heat treatment (usually 100-120°C) to enhance flaxseed aroma, denature proteins, and coagulate oils before pressing.
• Product Features: Rich oil aroma with traditional flavor.

Route C: Pre-pressing & Solvent Extraction Process

• Core Equipment: Layered steam cooker, screw pre-press, extractor (rotary/loop type).
• Process Principle: The steamed and cooked flakes are first processed by a pre-press to extract most of the oil, yielding a pre-pressed cake with residual oil of approximately 12-18%.
• Commercial Decision Point: This cake can be sold directly as a high-protein feed ingredient for quick returns.
• Extraction Option: For maximum oil yield, the pre-pressed cake can be sent to an extractor to recover residual oil using solvent, reducing final residual oil to around 0.5%.

3. 🧪 Refining Section

Pressed or extracted crude oil requires refining to become safe, stable, and standard-compliant edible oil:

• Degumming: Uses hydration/acid refining combined with a disc centrifuge to remove gum-soluble impurities such as phospholipids and mucilage.
• Deacidification: Removes free fatty acids and reduces acid value through alkali refining (neutralization) or physical refining (distillation).
• Bleaching: Adds activated bleaching earth/activated carbon in a vacuum bleaching tower to adsorb pigments and improve oil color.
• Deodorization: Uses high-temperature, high-vacuum steam distillation to remove off-flavors and peroxides, improving smoke point and oxidative stability.
• (Optional) Winterization & Dewaxing: Freezes, crystallizes, and filters to prevent sedimentation in finished oil at low temperatures, improving visual clarity.

🎯 Process Comparison & Selection Guide

1. 🌾 Pretreatment Section

Pretreatment directly impacts oil yield and quality. Core steps include:

• Cleaning: Removes dirt, stones, metal shavings and other impurities from rapeseed using magnetic separators, vibrating screens and stone removers. Protects downstream equipment, reduces wear and prevents foreign matter contamination.
• Flaking: Uses roller mills to crush rapeseed into thin flakes, maximizing surface area and completely disrupting oilseed cell structure for easier extraction in subsequent processes.
• Cooking: A critical step for hot pressing and pre-press solvent extraction processes. Typically uses a stacked cooker for moist cooking. Adjusts moisture and temperature of the flaked material to unlock rapeseed aroma, denature proteins, coagulate oils and prepare the material for optimal pressing conditions.

2. ⚙️ Pressing Process

Pressing methods are classified as hot pressing or cold pressing based on whether cooking is applied:

• Hot Pressing Process: Cooked flakes are fed into a screw press for extraction under high temperature and pressure. Features higher oil yield and rich oil aroma, but high temperatures may cause some nutrient loss.
• Cold Pressing Process: Cleaned rapeseed is directly pressed by a screw press or dedicated cold press at lower temperatures (e.g., 60-70°C) without heat treatment or only with low-temperature conditioning. Better retains natural nutrients like vitamin E, sterols and polyphenols, producing oil with light color and fresh flavor.
• Filtration: Crude oil from pressing is filtered using equipment such as plate-and-frame filters to remove solid meal residues.

3. 🔬 Solvent Extraction Process

For maximum oil yield, large-scale production often uses the "pre-press + solvent extraction" method:

• Pre-Pressing: Cooked flakes are first pre-pressed by a screw press to extract most of the oil, yielding a pre-pressed cake with residual oil content of approximately 12%-18%.
• Extraction: Pre-pressed cake is fed into extractors (rotary, annular, or drag-chain type) and soaked with solvents like n-hexane to dissolve residual oil.
• Solvent Recovery: The oil-solvent miscella is heated via evaporators and stripping towers to separate the solvent and obtain crude extracted oil. Solvent vapors are condensed and recycled. Wet meal is desolventized in a DTDC desolventizer to produce finished meal.

Extraction System Technical Parameters:

• Residual Oil Content: ≤ 0.5% (extremely high extraction rate)
• Solvent Consumption: ≈ 1.5 kg/t (very low consumption, high economic efficiency)
• System Recovery Rate: ≥ 99.5% (safe and environmentally friendly)
• Thermal Energy Efficiency: 10%–15% improvement (energy-saving and cost-reducing)

4. 🧪 Refining Section

Crude oil from pressing or extraction requires refining before consumption. Typical processes include:

• Degumming: Heated crude oil is treated with water or dilute acid to remove gum-soluble impurities such as phospholipids via hydration or acid refining.
• Deacidification: Food-grade sodium hydroxide solution is added, or physical distillation is applied, to neutralize and remove free fatty acids.
• Bleaching: Activated bleaching earth or activated carbon is added in a bleaching tower to adsorb pigments (e.g., chlorophyll), residual soapstock and trace contaminants.
• Deodorization: Under high temperature (220-240°C) and high vacuum, effectively removes odor-causing substances and peroxides, significantly improving the oil's smoke point and oxidative stability, achieving "zero trans fatty acids" and "zero glycidyl esters" standards.
• Winterization (Optional): Oil is cooled, crystallized and filtered to remove solid fats, improving clarity and appearance.

🎯 Process Comparison & Selection Guide