Filtration for Flavor, Beauty, and Cosmetics Extracts

Flavor and aroma extracts are extremely valuable to consumers and manufacturers in the flavor, beauty, and cosmetics industries, so let’s look at how to control turbidity and remove color, particulates, and solids.

Purifying Botanical Extracts

Extraction is the obvious first step; however, conventional methods like maceration and modern techniques like supercritical fluid extraction co-extract residual plant particulates, waxes, lipids, and pigments, which need to be filtered out.

Turbidity is the cloudiness or haze you see when fine particles scatter light in a liquid. It is a direct indicator of suspended load and is commonly measured in NTU using a nephelometer. Elevated turbidity drives instability, visible haze, and customer complaints, even when the color looks acceptable.

These substances may compromise the final product by causing instability, off-colors, precipitation, and browning. For example, Polyphenols containing catechol groups can oxidize and polymerize to form a yellow-brown color in the end product. To prevent this, we reduce the polyphenol load and lower turbidity so the product stays clear and stable.

Chlorophylls are another example. These green pigments in plants are highly soluble in many standard extractions like supercritical CO2. They are responsible for the green hue in an extract, which can be problematic in cosmetics and clear beverages. Chlorophyll may also interfere with lab tests used for quality control, leading to wrong or inconsistent results. For a stable and visually appealing product, you must filter your crude oil.

The Filtration and Purification Approach

The strategy often used for purifying botanical extracts involves several stages, each targeting different issues. First, we remove the coarse solids; second, we filter out the finer particles; and third, we make adjustments to the color and flavor. Doing it in this order is the best way to prevent premature clogging the blinding of finer filters, and turbidity. By the end, you will have a fully filtered product.

Stage One: Removing Coarse Solids and Particulates

The first step in clarifying a botanical extract is the removal of coarse plant material and other large suspended solids. This step reduces the particulate load on the finer filters, extending their lifespan and making the entire process more efficient. This first pass typically delivers a measurable drop in NTU and sets up downstream filters to remove the colloidal fraction that drives residual turbidity.

Bag Filtration

A standard method for the first stage is bag filtration, which involves passing the extract through felt polypropylene bags. These bags are available in various micron ratings, typically from one to five microns, and can be placed in-line after the extractor to capture any residual plant matter. Doing this prevents suspended solids from prematurely clogging the later-stage filters. Selecting the right micron rating will control early-stage turbidity.

Continuous Drum Filtration

For more challenging extractions that contain materials prone to filter fouling, such as gums or waxes, more advanced systems are required. Continuous drum filtration is often the solution for these applications. This filter device features an adjustable skiving knife that continuously removes the accumulated filter cake from the drum screen with each revolution. This method eliminates the downtime required for manual filter changes, which is perfect for operators seeking automated filtration.

Stage Two: Removing Fine Particulates, Waxes, and Lipids

Once the larger solids are removed, the next step is eliminating the finer, sub-micron particulates, waxes, and lipids. This step is designed to remove lipids and colloids that the previous filtration was unable to remove.

Winterization and Vacuum Filtration

Winterization involves mixing the crude extract with ethanol and chilling it to low temperatures. The cold treatment causes waxes and lipids to coagulate and precipitate out of the solution, making them easier to filter. The winterized solution then passes through a vacuum filtration unit to filter out the particulates, waxes, and lipids. This particular filter machine functions as a large Buchner funnel with a vacuum forcing the extract through the media at a much faster rate than gravity alone.

Depth Filtration

After the initial solids and waxes are removed, the clarified liquid is often passed through a depth filtration stage for a final run. Lenticular filtration is a widely used depth filtration method that employs a housing loaded with media modules available in various grades to remove particles.

Stage Three: Decolorization and Flavor Adjustment

The final phase of purification focuses on appearance and clarity, specifically removing undesireable colors and adjusting the flavor and aroma profiles. Unwanted coloration can stem from pigments like chlorophylls or from the oxidation of polyphenols.

Carbon Filtration

Carbon filtration is where activated carbons adsorb pigments and other compounds, affecting color and flavor. This method is accomplished with carbon-embedded lenticular modules or over a vacuum filtration unit. Carbon treatment should be performed after the initial filtration, as any suspended solids will quickly clog the carbon media.

Resin Adsorption

To address browning caused by polyphenols, resin adsorption is a viable solution. This technique uses chromatography, where extracts are passed through macroporous polymeric resins, such as D301 resin, which selectively adsorbs and removes polyphenols. For example, you can typically see 83% of polyphenols removed from Sapindus mukurossi extract, which significantly improves color stability.

Advanced Degreening Techniques for Chlorophyll Removal

When chlorophyll is the primary pigment of concern, several advanced “degreening” methods are available.

Oxidative Decolorization

Oxidative decolorization utilizes an agent, such as hydrogen peroxide, to chemically break the conjugated double bonds, or chromophores, within pigment molecules. This process decolorizes without introducing new impurities and is well-suited for industrial production.

Solid-Phase Extraction

Solid-phase extraction uses polymeric hydrophilic–lipophilic balance cartridges. The dual nature of the SPE absorbent enables it to interact with the hydrophobic tail and hydrophilic head of chlorophyll molecules, removing over 85% of chlorophylls in as little as 10 minutes. The cartridges for this process can also be regenerated and reused, which makes it a sustainable option.

Countercurrent Separation

Countercurrent separation techniques, such as the Centrifugal Partition Chromatography technique, utilize a biphasic liquid solvent system to selectively partition chlorophylls into one phase, resulting in a degreened extract.

Electrocoagulation

An innovative technique known as electrocoagulation is also often a viable option. An electrical current is passed through sacrificial electrodes, typically aluminum, to generate coagulating species in the extract. These species bind with pigments to form “flocs,” which can then be easily filtered out. This green technology has been demonstrated to remove approximately 76% of chlorophyll and 70% of carotenoids from seaweed extract, and also eliminates polymeric compounds that can interfere with HPLC analysis.

Real-World Examples of Extract Filtration

Filtration is applied in various markets. Let’s look at examples in the flavor, beauty, and cosmetics industries.

Purifying Sapindus mukurossi Extract for Shampoos

Sapindus mukurossi is a source of natural surfactants that people use as an ingredient in soap products. Because the crude extract contains polyphenols that oxidize and polymerize, it causes the product to turn brown over time. A two-step purification process solves this issue. For this application, you treat it with a selective macroporous resin (D301) that uses mechanisms like hydrogen bonding and π-π stacking, which remove over 83% of the browning-causing polyphenols. Then the extract undergoes oxidative decolorization using an agent like hydrogen peroxide to destroy the remaining pigments. Combined, these create a stable extract for shampoos.

Removing Chlorophyll from Leaf Extracts for Cosmetics

Leaf extracts contain a high amount of chlorophyll, which absorbs light and can affect the stability of the product. Solid-phase extraction (SPE) protocol using polymeric hydrophilic–lipophilic balance (HLB) cartridges is a viable solution. The dual nature of the cartridge material enables it to interact with and trap chlorophyll molecules, removing over 85% of chlorophyll while preserving the desired compounds.

Clarifying Osmanthus Extract for Fragrance and Aroma

The Osmanthus aroma is often used in perfumes, and its extracts are thick, containing not only the desired aromatic compounds but also waxes. The crude is washed with ethanol, which dissolves the fragrant compounds and leaves the waxes behind. After the solids are filtered out, the ethanol is removed through a process like vacuum fractionation. The result is a beautiful Osmanthus fragrance.

How to Choose the Right Filtration Setup

When selecting the proper setup, consider your batch size, desired extract quality, and constraints on time and labor. For operations of both large and small scales, we’ve seen success using vacuum filtration, continuous drum filtration, and carbon filtration.

Measure and Control Turbidity

Set a turbidity target that matches your application and validate each stage against it. Record NTU before and after coarse filtration, after winterization or depth filtration, and after color or flavor adjustments. Clear beverages often require very low NTU, while cosmetic bases may tolerate slightly higher values if appearance is still bright and uniform.

Run a Pilot Test

Conducting a pilot run is highly recommended for those looking to invest in filtration equipment. Testing the systems eliminates the risk of purchasing equipment that is not suitable for your application. Simply provide an extract to your equipment supplier, and with the result, you will be able to decide if it’s a fit.

Talk to Extraction and Filtration Experts

Consult with experts who have dealt with a wide range of botanical materials and sizes of operation. extraktLAB can help you select the right filtration equipment and conduct pilot runs tailored to your application.

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