Process

Sesame Oil Refining Process

Sesame Oil Refining Process: Complete Guide to Refining Sesame Oil

Introduction

Sesame oil is valued for its distinctive flavor, nutritional properties, and high content of unsaturated fatty acids. However, crude sesame oil obtained after pressing still contains various impurities that can affect its appearance, flavor, stability, and storage life.

The sesame oil refining process is designed to remove these unwanted substances while preserving as much of the valuable oil as possible. Depending on the quality of the crude oil and the requirements of the final product, the refining process may include degumming, neutralization, bleaching, deodorization, and optional winterization.

For a commercial sesame oil factory, choosing the right refining process and equipment is important because refining affects not only final oil quality but also oil loss, energy consumption, operating costs, and production capacity.

This guide explains how sesame oil is refined, what equipment is required, and how to choose a suitable sesame oil refinery plant for different production requirements.

Why Does Sesame Oil Need to Be Refined?

Freshly pressed sesame oil is not composed solely of triglycerides. It also contains various natural impurities and minor components, including phospholipids, free fatty acids, pigments, trace metals, suspended solids, waxes, oxidation products, and volatile compounds that may contribute to undesirable odors. While these substances are naturally present in crude sesame oil, excessive amounts can negatively affect the oil’s appearance, flavor, storage stability, and market value.

The refining process is designed to remove or reduce these unwanted components, resulting in a higher-quality product. By eliminating pigments and fine impurities, refining improves the clarity and visual appeal of the oil, giving it a cleaner and more uniform appearance. The removal of trace metals and oxidation products helps slow down oxidative deterioration, enhancing the oil’s storage stability and extending its shelf life. In addition, deodorization reduces undesirable volatile compounds, creating a more balanced flavor profile and minimizing excessive odors.

From a commercial perspective, refined sesame oil is often preferred for bottled cooking oil, supermarket retail products, food manufacturing applications, and export markets where consistent quality standards are required. However, the level of refining should be determined by the intended market and product positioning. Many traditional sesame oil producers deliberately preserve part of the oil’s natural color, aroma, and characteristic roasted flavor to meet consumer preferences. Therefore, an appropriate sesame oil refining process should be customized according to the desired product quality, flavor profile, and market requirements.

Where Does Crude Sesame Oil Come From?

Before entering the refinery, sesame oil is generally produced through mechanical extraction.

The two common production routes are:

Cold Press Sesame Oil

Cold pressing uses relatively low-temperature mechanical extraction and is commonly selected for premium and minimally processed sesame oil.

Read our detailed guide:

Cold Press Sesame Oil Process

Hot Press Sesame Oil

Hot pressing uses controlled seed roasting before mechanical extraction. It generally provides higher oil recovery and develops a stronger roasted sesame aroma.

Read our detailed guide:

Hot Press Sesame Oil Process

Both types of crude oil can be further processed in a sesame oil refinery, although the refining conditions may need to be adjusted according to crude oil quality.

Sesame Oil Refining Process Flow

A typical sesame oil refining process may follow this sequence:

Crude Sesame Oil → Degumming → Neutralization → Bleaching → Filtration → Deodorization → Refined Sesame Oil

Depending on the raw oil and final product requirements, some plants may add additional treatment such as winterization or specialized filtration.

Each stage has a different purpose.

Step 1: Degumming

Degumming is usually the first major refining stage.

Crude sesame oil may contain phospholipids and other gum-forming substances. If they remain in the oil, they can cause:

  • Cloudiness
  • Sedimentation
  • Darkening
  • Poor storage stability
  • Problems during downstream refining

During degumming, water and/or suitable conditioning agents are introduced under controlled conditions to hydrate or separate the gums.

The separated gums are then removed from the oil.

Main Objectives of Degumming

The process helps:

  • Reduce phospholipid content
  • Improve oil stability
  • Prepare the oil for subsequent refining
  • Reduce fouling of downstream equipment

For some crude oils, the degumming process may be adjusted according to the phospholipid content and the desired final oil quality.

Step 2: Neutralization

Neutralization is primarily used to reduce free fatty acids (FFA) in crude oil.

High levels of free fatty acids can negatively affect:

  • Taste
  • Odor
  • Oxidative stability
  • Final product quality

In conventional chemical refining, an alkaline solution such as caustic soda is added under controlled conditions.

The alkali reacts with free fatty acids and converts them into soapstock, which can then be separated from the oil.

Key Factors Affecting Neutralization

The process needs to consider:

  • Initial FFA content
  • Oil temperature
  • Alkali concentration
  • Mixing intensity
  • Reaction time
  • Desired final FFA level

Over-treatment can increase neutral oil loss, while insufficient treatment may leave excessive free fatty acids in the product.

Therefore, accurate process control is essential for achieving a good balance between oil quality and refining yield.

Step 3: Washing and Drying

After neutralization, the oil may contain residual soap and other water-soluble impurities.

Water washing can help remove these substances.

The oil is then dried to remove residual moisture before entering the bleaching stage.

Effective drying is important because excessive moisture can reduce bleaching efficiency and negatively affect the performance of bleaching earth.

Step 4: Bleaching

Bleaching is one of the most important stages in sesame oil refining.

Despite its name, bleaching does not simply “wash” the oil. It mainly uses adsorbent materials to remove unwanted color bodies and trace impurities.

Common adsorbents include:

  • Activated bleaching earth
  • Activated carbon
  • Other specialized adsorbents

What Does Bleaching Remove?

Depending on the crude oil quality and adsorbent used, the bleaching stage can help reduce:

  • Carotenoid pigments
  • Chlorophyll
  • Trace metals
  • Residual soap
  • Oxidation products
  • Other polar impurities

The oil and adsorbent are mixed under controlled temperature and vacuum conditions.

After sufficient contact time, the spent bleaching earth is removed through filtration.

Step 5: Filtration

After bleaching, the oil contains spent adsorbent that must be removed efficiently.

A leaf filter or another suitable filtration system is commonly used for this purpose.

Good filtration is important because residual bleaching earth can affect:

  • Oil clarity
  • Color
  • Oxidative stability
  • Downstream deodorization equipment

The filtration system should also minimize the amount of oil retained in the spent bleaching earth to reduce refining losses.

Common Equipment

  • Pressure leaf filter
  • Fine filter
  • Safety filter

For larger plants, multiple filtration units may be configured to maintain continuous or semi-continuous operation.

Step 6: Deodorization

Deodorization is usually the final major stage of physical refining.

Even after previous refining stages, sesame oil may contain volatile compounds that contribute to unwanted odors or flavors.

Deodorization uses:

  • High temperature
  • High vacuum
  • Steam stripping

to remove volatile odor compounds.

Main Functions

Deodorization helps reduce:

  • Unwanted odors
  • Volatile flavor compounds
  • Residual free fatty acids
  • Certain low-boiling impurities

The final oil becomes cleaner in taste and odor and more suitable for applications where a neutral sensory profile is required.

However, sesame oil is often valued for its characteristic aroma. Therefore, deodorization conditions should be carefully selected rather than simply maximizing odor removal.

Step 7: Optional Winterization

Winterization is not required for every sesame oil product.

It may be considered when the final product needs better low-temperature clarity.

The process selectively removes higher-melting components that may crystallize when the oil is exposed to lower temperatures.

Winterization can be useful when:

  • The oil must remain clear during cold storage.
  • The product is intended for specific markets.
  • The final application requires improved cold stability.

Whether this stage is necessary should be determined by crude oil characteristics and product specifications.

Does Every Sesame Oil Require Full Refining?

Not all sesame oil needs to undergo a complete refining process. The appropriate processing method depends on the product’s positioning, quality requirements, and target market. For traditional or premium sesame oil products, manufacturers often adopt a simple process of pressing, filtration, and storage, which helps preserve the natural aroma, flavor, and nutritional characteristics of sesame oil. This type of oil is especially popular among consumers who value authentic taste and traditional production methods.

In some cases, producers choose a partial refining process, applying only selected refining stages to remove impurities, improve clarity, and enhance storage stability while retaining much of the oil’s original flavor profile. This approach provides a balance between product quality and natural sensory characteristics.

For large-scale commercial cooking oils, export-grade products, and standardized bottled sesame oil, full refining is often the preferred solution. A complete refining process can effectively remove free fatty acids, pigments, odors, trace impurities, and other undesirable components, resulting in a cleaner appearance, longer shelf life, and more consistent product quality.

When determining the most suitable refining configuration, several factors should be carefully evaluated, including the quality of the raw sesame seeds, the oil extraction method, free fatty acid (FFA) content, oil color, target market requirements, product specifications, and local food regulations. Selecting the right refining process ensures that the final sesame oil meets both quality expectations and commercial objectives.

Batch vs Semi-Continuous vs Continuous Sesame Oil Refinery

The refining process itself can be configured in different ways.

Batch Sesame Oil Refinery

Batch refining processes a fixed quantity of oil at a time.

Advantages

  • Lower initial investment
  • Flexible production
  • Easy to change between different oils
  • Suitable for smaller factories

Batch systems are often suitable for small-scale sesame oil businesses and projects with variable production volumes.

Semi-Continuous Sesame Oil Refinery

A semi-continuous refinery combines batch-style processing with more continuous material handling.

Advantages

  • Higher production efficiency
  • Better process stability
  • Reduced manual operation
  • Flexible capacity
  • Easier expansion

It is suitable for medium-sized sesame oil processing plants that need higher efficiency without the investment level of a large continuous refinery.

Continuous Sesame Oil Refinery

Continuous refining is designed for large-scale plants requiring stable and high-volume production.

Advantages

  • High processing capacity
  • Consistent process conditions
  • High level of automation
  • Lower labor requirements per ton
  • Suitable for long operating hours

Continuous refining is generally more appropriate for large commercial edible oil manufacturers.

How to Choose the Right Sesame Oil Refinery

There is no single refinery configuration suitable for every project.

The decision should consider:

1. Processing Capacity

For example:

  • Small projects: approximately 1–20 TPD
  • Medium projects: approximately 20–50 TPD
  • Large projects: 50 TPD and above

These ranges are only general planning references. The actual equipment configuration should be determined from the required daily throughput and operating schedule.

2. Crude Oil Quality

The initial:

  • FFA
  • Phosphorus
  • Moisture
  • Color
  • Impurity level

will affect the required refining process.

3. Final Product

A premium traditional sesame oil may require a different process from neutral cooking oil.

4. Investment Budget

Small businesses may start with a batch refinery and upgrade capacity later.

Larger manufacturers may benefit from semi-continuous or continuous systems from the beginning.

5. Utility Availability

The refinery design should consider:

  • Steam supply
  • Electricity
  • Cooling water
  • Vacuum system
  • Process water
  • Fuel availability

These utilities have a direct impact on operating costs and plant layout.

Main Equipment in a Sesame Oil Refinery

A typical sesame oil refinery may include:

Degumming System

Used for phospholipid and gum removal.

Neutralization System

Used for free fatty acid reduction in chemical refining.

Bleaching System

Used for pigment and trace impurity adsorption.

Leaf Filter

Used to separate spent bleaching earth from oil.

Deodorization System

Used to remove volatile compounds under vacuum and steam stripping conditions.

Vacuum System

Maintains the required vacuum during drying, bleaching, and deodorization.

Heat Exchanger

Used for controlled heating and heat recovery between process streams.

Storage Tanks

Used for crude oil, intermediate oil, and refined oil storage.

The final equipment list should be customized according to the selected refining technology and production capacity.

How to Reduce Oil Loss During Refining

Oil loss is one of the most important economic factors in refinery operation.

Major sources of loss may include:

  • Soapstock
  • Spent bleaching earth
  • Filtration losses
  • Deodorizer distillate
  • Oil remaining in pipelines and equipment

To improve refining yield, manufacturers should focus on:

Accurate Chemical Dosing

Excessive alkali or adsorbent can increase neutral oil loss.

Efficient Filtration

Good filter design reduces oil retained in spent bleaching earth.

Optimized Deodorization

Excessive temperature, steam, or residence time can increase unnecessary losses.

Proper Process Control

Temperature, vacuum, flow rate, and chemical dosage should be monitored consistently.

A well-designed refinery should balance oil quality, refining yield, energy consumption, and operating cost rather than focusing on only one parameter.

Sesame Oil Refinery for Different Production Scales

Small Sesame Oil Refinery

Suitable for:

  • Small oil mills
  • Start-up businesses
  • Local brands
  • Agricultural cooperatives

A batch-type system is often a practical choice because it provides flexibility with relatively low investment.

Medium-Scale Sesame Oil Refinery

Suitable for:

  • Regional edible oil manufacturers
  • Growing sesame oil brands
  • Commercial processing plants

A semi-continuous refinery can provide a useful balance between investment and production efficiency.

Large Sesame Oil Refinery

Suitable for:

  • Industrial edible oil manufacturers
  • Export-oriented factories
  • Large food processing companies

Continuous refining offers higher automation and stable high-volume production.

Cold Press, Hot Press, or Refining: How Do They Work Together?

These processes are not necessarily competing technologies.

They can form different parts of the same sesame oil production project.

Option 1: Premium Cold-Pressed Sesame Oil

Cleaning → Cold Pressing → Filtration → Bottling

Suitable for premium and minimally processed products.

Option 2: Commercial Hot-Pressed Sesame Oil

Cleaning → Roasting → Hot Pressing → Filtration → Bottling

Suitable for products where strong flavor and high oil recovery are priorities.

Option 3: Refined Sesame Oil

Cleaning → Hot/Cold Pressing → Crude Oil Treatment → Refining → Bottling

Suitable for manufacturers requiring standardized appearance, stability, and shelf life.

For more information about the extraction stage, see:

Cold Press Sesame Oil Process and Hot Press Sesame Oil Process

How We Can Customize a Sesame Oil Refinery

Every sesame oil project has different requirements.

The refinery can be customized according to:

  • Processing capacity
  • Sesame seed variety
  • Crude oil quality
  • Extraction method
  • Desired final oil quality
  • Automation level
  • Available factory space
  • Local steam and power conditions

Before selecting equipment, it is recommended to evaluate the complete process rather than choosing individual machines based only on capacity.

A properly designed system should coordinate oil extraction, refining, utilities, storage, filtration, and finished-product handling as one integrated production line.

Frequently Asked Questions

Can sesame oil be refined after cold pressing?

Yes. Cold-pressed sesame oil can be further refined when the target market requires improved color, stability, or shelf life.

Can hot-pressed sesame oil be refined?

Yes. Hot-pressed sesame oil can undergo conventional refining after mechanical extraction.

Is deodorization always necessary?

No. It depends on the desired flavor profile and final product specifications. Traditional sesame oil may intentionally retain its characteristic aroma.

What is the best refinery type for a small sesame oil factory?

A batch-type refinery is often a practical choice because of its flexibility and relatively lower initial investment.

What is the difference between batch and continuous refining?

Batch refining processes oil in separate quantities, while continuous refining is designed for uninterrupted material flow and higher production capacity.

Can the sesame oil refinery process be customized?

Yes. Refining conditions and equipment configuration should be selected according to crude oil characteristics, capacity, product requirements, and local utility conditions.

Conclusion

The sesame oil refining process plays an important role in converting crude pressed sesame oil into a more stable and commercially standardized edible oil. Degumming, neutralization, bleaching, filtration, and deodorization each target different impurities and quality parameters.

However, the most advanced refinery is not necessarily the best choice for every business. A small local producer may benefit from a flexible batch system, while a large export-oriented factory may require a semi-continuous or continuous refinery.

The right solution should be based on raw oil quality, production capacity, target market, desired oil characteristics, investment budget, and available utilities.

Whether your project starts with cold pressing or hot pressing, a properly designed sesame oil refining system can help improve product consistency, marketability, and overall production efficiency.