Camellia Oil Molecular Distillation: How Low Can the Acid Value Go?
The global demand for high-quality edible oils is rising, driven by increasing health consciousness among consumers. Among these, tea oil, a time-honored nutritional treasure, has gained recognition for its exceptional fatty acid profile and bioactive compounds.
However, traditional processing methods often compromise its quality and nutrient retention. As a leading manufacturer of molecular distillation equipment, we provide cutting-edge solutions that redefine tea oil refining standards. This article explores how molecular distillation technology addresses historical challenges and unlocks unprecedented value for producers and consumers alike.
What Does Molecular Distillation Actually Remove from Camellia Oil?
For camellia oil refining, the most defensible target is usually free fatty acids (FFAs).
FFAs are more volatile than the triglycerides that make up most of the edible oil.
Under reduced pressure and controlled temperature, part of the FFA fraction can evaporate from the wiped liquid film and move toward the condenser, while the less volatile triglyceride-rich oil remains primarily in the residue.
Depending on feed composition and process design, molecular distillation may also remove some:
- water;
- light volatile compounds;
- odor-related volatile fractions;
- other relatively volatile low-molecular-weight components.
But molecular distillation should not be presented as a universal refining process.
It does not automatically remove all:
- gums;
- phospholipids;
- pigments;
- metals;
- suspended solids;
- pesticides;
- nonvolatile contaminants.
Those require degumming, filtration, adsorption, washing, bleaching or another refining step.
Camellia Oil Deacidification Results
The strongest peer-reviewed reference for this application is the 2019 LWT study on supercritical-fluid-extracted camellia oil.
The authors specifically investigated the influence of:
- evaporation temperature;
- system vacuum;
- wiper speed;
- feed flow rate
on molecular-distillation performance.
The final reported comparison was:
| Parameter | Before MD | After MD |
|---|---|---|
| Acid value | 2.93 ± 0.01 mg KOH/g | 0.63 ± 0.01 mg KOH/g |
| Acid-value reduction | — | ≈78.5% |
| Fatty-acid composition | Baseline | No significant change reported |
| γ-Tocopherol | Present | Effectively retained |
| β-Sitosterol | Present | Effectively retained |
| Squalene | Present | Effectively retained |
These results are useful because they show that molecular distillation can reduce FFA content without automatically implying that the complete triglyceride fraction must be heavily altered.
However, these values apply to the specific camellia oil and equipment used in that study.
They should be treated as a published process reference, not as a guaranteed commercial result.
What Operating Parameters Have Been Published for Camellia Oil?
Besides peer-reviewed studies, several published patents provide useful engineering ranges for staged camellia-oil molecular distillation.
One staged process describes three different duties rather than trying to perform all refining at one temperature and pressure.
Stage 1: Dehydration and Degassing
Published range:
| Parameter | Range |
|---|---|
| Evaporation temperature | 70–100°C |
| Pressure | 2,000–3,000 Pa |
| Feed rate | 5–15 mL/min |
| Condenser temperature | 0–10°C |
| Wiper speed | 200–500 rpm |
The objective of this stage is mainly to remove water and dissolved/light gases before deeper-vacuum treatment.
Stage 2: Deodorization and Partial Deacidification
Published range:
| Parameter | Range |
|---|---|
| Evaporation temperature | 120–150°C |
| Pressure | 600–1,200 Pa |
| Feed rate | 4–12 mL/min |
| Condenser temperature | 0–10°C |
| Wiper speed | 200–500 rpm |
This stage handles more volatile odor components and part of the FFA load.
Stage 3: Deeper Refining
Published range:
| Parameter | Range |
|---|---|
| Evaporation temperature | 160–230°C |
| Pressure | 0.1–20 Pa |
| Feed rate | 3–9 mL/min |
| Condenser temperature | 0–25°C |
| Wiper speed | 200–500 rpm |
One example in the patent used approximately:
160°C / 0.1 Pa / 200 rpm / 3 mL/min
in the final stage and reported a product recovery of about 94.14%.
These are patent examples, not universal recommended settings.
Why Use Different Conditions in Different Stages?
This is one of the most useful lessons from the published camellia-oil processes.
A crude oil simultaneously contain:
- water;
- dissolved gases;
- odor components;
- free fatty acids;
- valuable triglycerides;
- minor unsaponifiable compounds.
Trying to remove everything at one extremely low pressure and high temperature is not necessarily efficient.
A more practical process is:
Feed Preparation → Dehydration/Degassing → FFA Removal → Deep-Vacuum Polishing if Required
Each stage can then operate only as aggressively as necessary.
Stage 1 Reduces Vacuum Load
Water creates a large vapor load.
If a wet feed is sent directly into a deep-vacuum molecular still, the evaporator, condenser, cold trap and vacuum system all need to handle that water vapor.
Pre-dehydration can therefore make the later stages much more stable.
Stage 2 Removes Easier Volatiles First
Odor compounds and easier-to-evaporate fractions do not necessarily need sub-Pa pressure.
Removing them upstream prevents them from consuming high-vacuum capacity later.
Final Stage Targets More Difficult FFA Separation
Only after the easier volatile load has been reduced does it make sense to evaluate deeper vacuum and higher evaporator temperature.
This is why the correct molecular distillation process should be designed around the feed rather than around one fixed operating condition.
Which Parameters Have the Biggest Effect on Camellia Oil Deacidification?
1. Evaporation Temperature
Temperature strongly affects FFA evaporation.
Increasing the evaporator temperature generally increases FFA vapor pressure and therefore helps deacidification.
But the objective is not simply:
Higher temperature = better separation.
Higher temperature also increases thermal exposure to the oil.
The appropriate temperature depends on pressure, feed rate, film thickness, starting acid value and required final acid value.
Published edible-oil molecular-distillation studies use very different evaporation temperatures depending on feed and process objective; recent research across vegetable oils reports temperatures from roughly 100°C to above 200°C in different applications.
2. Operating Pressure
Reducing absolute pressure allows FFA removal at a lower evaporator temperature.
But the relevant number is the pressure while material is actually being fed, not just the ultimate pressure of the vacuum pump.
HJCHEM standard systems typically provide a complete-system no-load vacuum of approximately 0.1–1 Pa, while an optional high-vacuum configuration can reach approximately 0.01–0.1 Pa no-load.
Those values describe the equipment capability.
They do not mean camellia oil will necessarily operate at 0.1 Pa.
Actual operating pressure depends on:
- water content;
- FFA concentration;
- feed rate;
- evaporation temperature;
- vapor generation;
- condenser load;
- cold trap;
- vacuum-system configuration.
The difference between operating pressure and no-load vacuum should therefore be confirmed before comparing equipment quotations.
3. Feed Rate
Feed rate changes the residence behavior of the oil.
At a higher feed rate:
- the film may become thicker;
- effective thermal exposure may decrease;
- vapor load increases;
- throughput increases;
- FFA removal per pass may decrease.
So the highest feed rate is not necessarily the best production point.
4. Wiper Speed
The wiper continuously renews the liquid film on the evaporator wall.
Published camellia-oil processes report ranges of approximately 200–500 rpm, depending on the apparatus and stage.
The optimum speed depends strongly on equipment geometry.
A literature value from a small test unit should therefore not simply be transferred to a larger industrial rotor.
5. Feed Temperature
Preheating lowers viscosity and reduces the heating duty inside the evaporator.
One published camellia-oil process used feed preheating in the approximately 60–80°C range before staged molecular distillation.
The correct value still depends on the actual feed.
Is Molecular Distillation Better Than Alkali Deacidification?
Not automatically.
Conventional alkali refining can be effective for many edible oils.
Molecular distillation becomes attractive when the manufacturer specifically wants to evaluate physical separation of FFAs under vacuum and potentially reduce dependence on alkali neutralization.
But the decision should consider:
- starting acid value;
- product recovery;
- desired final acid value;
- pretreatment requirements;
- energy consumption;
- equipment cost;
- valuable minor components;
- required production capacity.
A very low starting acid value may not justify a complex molecular-distillation process.
Conversely, a higher FFA load may require upstream treatment or multiple passes.
Which Fraction Is the Final Camellia Oil?
For deacidification, the main edible-oil product is typically the heavier residue fraction, while more volatile FFAs are enriched in the distillate.
That means system design should consider not only the evaporator, but also:
- residue discharge;
- distillate collection;
- heating of high-viscosity product lines if needed;
- condenser temperature;
- cold-trap duty;
- vacuum protection.
If the customer instead wants to recover a valuable component from a deodorizer distillate—for example tocopherols—the desired product and operating strategy is completely different.
Published patents, for example, describe molecular-distillation processing of camellia-oil deodorizer distillate for tocopherol recovery, rather than deacidifying the edible oil itself.
These are two different applications and should not be mixed together.
One Stage or Multiple Stages?
A single molecular-distillation pass is sufficient for some feeds.
But staged processing becomes more reasonable when:
- water content is significant;
- the FFA load is high;
- odor removal is also required;
- the final acid-value target is low;
- one pass cannot achieve acceptable product quality and recovery.
Published camellia-oil patents use two- and three-stage approaches precisely because different volatile fractions are easier to remove under different temperature and pressure conditions.
That does not mean every customer needs three molecular stills.
We should instead use:
existing dehydration / vacuum evaporation → one molecular-distillation polishing stage
depending on the existing production line.
How Should Camellia Oil Molecular Distillation Equipment Be Sized?
Do not select equipment from feed capacity alone.
For example:
500 kg/h camellia oil at acid value 0.8
and
500 kg/h camellia oil at acid value 5.0
have very different FFA evaporation loads.
Useful sizing information includes:
| Process Data | Why It Matters |
|---|---|
| Initial acid value | Defines starting FFA load |
| Target acid value | Defines separation duty |
| Water content | Determines initial vapor load |
| Feed rate | Determines overall capacity |
| Feed temperature | Affects viscosity and heating duty |
| Maximum oil temperature | Defines thermal limit |
| FFA composition | Affects volatility |
| Desired oil recovery | Defines acceptable distillate cut |
| Existing pretreatment | Determines what MD stage must do |
| Current refining data | Provides scale-up reference |
The molecular distillation system size should then be based on evaporation area and validated process performance, not only on a nominal kg/h figure.
Why Material Testing Makes Sense for Camellia Oil
This application is particularly suitable for material trials because the key question is measurable:
Under what temperature, pressure, feed rate and wiper speed can the required acid value be reached without unacceptable oil loss?
Literature gives a useful starting point, but actual camellia oils vary in:
- initial acid value;
- moisture;
- fatty-acid composition;
- unsaponifiable content;
- previous extraction method;
- oxidation condition;
- required final specification.
HJCHEM Material Trial Service
HJCHEM has laboratory molecular distillation equipment available for customer material trials.
Customers can send their actual camellia oil when the required process conditions have not yet been established.
During a paid trial, parameters such as:
- evaporator temperature;
- operating pressure;
- wiper speed;
- feed rate;
- condenser condition;
- distillate/residue ratio
can be adjusted while the customer analyzes the acid value and other required quality parameters of the collected fractions.
The test is chargeable because it involves equipment preparation, operation, cleaning and engineering time.
If the customer subsequently places the corresponding equipment order with HJCHEM, the trial fee can be credited back against the equipment purchase.
This is more reliable than selecting a full production system directly from a literature temperature and vacuum value.
HJCHEM Equipment Options for Camellia Oil
LABORATORY
Laboratory Glass Molecular Distillation
0.06–0.50 m²
Borosilicate Glass
Up to 20 kg/h*
For R&D, feasibility testing, and process development.
PILOT SCALE
Pilot Stainless Steel Molecular Distillation
0.06–0.50 m²
SS316L
Up to 50 L/h*
For process scale-up, validation, and pilot production.
INDUSTRIAL
Industrial Wiped Film Molecular Distillation
1–10 m²
SS316L
Up to 600 L/h*
For continuous industrial production and higher throughput.
For initial process development, a laboratory glass wiped-film molecular distillation system allows direct observation of:
- film formation;
- feed behavior;
- light/heavy fraction generation;
- foaming or entrainment;
- condenser performance.
Once the process window has been established, it can be transferred to pilot SS316L equipment for continuous trials and scale-up.
Validated processes can then be developed toward larger industrial SS316L systems.
A complete molecular distillation system can include:
- feed tank;
- metering feed pump;
- wiped-film evaporator;
- internal condenser;
- distillate receiver;
- residue receiver or continuous discharge pump;
- cold trap;
- vacuum system;
- heating/cooling circulators;
- PLC/HMI control where required.
For edible-oil applications, the system configuration should be based on the specific refining duty rather than simply specifying the deepest vacuum available.
What Should You Send for a Camellia Oil Trial or RFQ?
Before recommending equipment, HJCHEM needs:
- raw material: crude camellia oil, pressed oil, extracted oil or pre-refined oil;
- initial acid value;
- target acid value;
- water content;
- feed capacity;
- current refining process;
- maximum acceptable product temperature;
- desired oil recovery;
- any GC/HPLC or fatty-acid composition data;
- required analysis of tocopherol, squalene or sterols if relevant;
- available sample quantity for testing.
These buyer checks help determine whether one-stage molecular distillation, staged processing, or another refining route is more appropriate.
Conclusion
Molecular distillation has a real, published application in camellia oil deacidification.
Peer-reviewed research has reported a reduction in acid value from 2.93 to 0.63 mg KOH/g, while other published work has reported similarly significant reductions under different processes.
Published camellia-oil processes also show why there is no single universal setting: dehydration may occur at several thousand Pa, while the final deacidification stage can operate from tens of Pa down into the sub-Pa range.
The more useful engineering question is therefore not:
“What is the standard temperature for camellia oil molecular distillation?”
but:
“What temperature, pressure, feed rate and cut ratio achieve my target acid value with acceptable product recovery?”
That operating window should be validated before industrial scale-up.
Have Camellia Oil to Test?
Send HJCHEM your initial acid value, target acid value, water content, feed capacity and available process data.
If the molecular-distillation conditions are not yet known, paid material testing can be arranged using HJCHEM laboratory equipment.
If you later place the equipment order, the trial fee can be credited back against the purchase.