Is Glycerine a Preservative?


Image by Daria Nepriakhina via Unsplash

You may have noticed the word “glycerine” in the ingredient list of some of the products you use. With so many unpronounceable chemicals and combinations on food and skincare labels, including added preservatives, you may wonder if there are reasons to be concerned.  

Glycerine is a naturally occurring, non-toxic preservative sourced from either animals or plants. It is used in products ranging from food and cosmetics to cleaning agents and pharmaceuticals. However, most commonly, it is utilized as a sweetener in the food industry and a humectant — or moisturizing agent — in skincare products.

Keep reading to learn more about glycerine as a natural preservative and how producers utilize it in foods, soaps, creams, herbal extracts, and many other products we encounter daily.

What is Glycerine?

Glycerine is a simple organic compound that is water-soluble, colorless, odorless, viscous — a thickening characteristic or quality — and surprisingly sweet tasting at a lower caloric cost than sugar. 

Occurring naturally, it can be obtained from both animal and plant sources, where it is found in triglycerides, which are essentially chains of fatty acids or lipids combined with glycerol (source).

What makes glycerine such a valuable commodity in both the food and skincare industry and pharmaceutically is its chemical and physical makeup. 

Depending on its application, there are a multitude of reasons for its use, including its unique ability to act as a humectant — attracting and absorbing moisture from the air and holding on to it like a sponge.  

Glycerine is also mildly antimicrobial — it can aid in wound care in small amounts by preventing bacteria growth and infection, making it an ideal addition to topical medications and first aid creams. 

It is even used in toothpaste since it does not feed the bacteria in our mouths that would ultimately lead to tooth decay.  

In the food industry, glycerine is deemed by the FDA to be a sugar alcohol, and a replacement for higher-calorie sweeteners, being a little over half as sweet as sucrose but at a lower glycemic index.

It is used as an additive to aid in the texture of certain food products, too, especially those that are prepackaged, and it serves as a thickening agent for some low-fat foods and liqueurs.

But as a primary preservative, it is more commonly seen in natural skincare products and soaps. With a concentration of 50% or more, glycerine replaces the need for any other preservative ingredient.  

For example, when used in tinctures — a way in which to deliver essential oils or other herbal extracts — glycerol can replace alcohol as a carrier due to its preservation qualities and for those who wish to avoid alcohol-based products.  We’ll learn more about that shortly.  

But in this way, it acts as a preservative for plant leaves and food-based ingredients used in many soaps, skincare, and even wound care products. Without it, the shelf life of many of these items would be limited as the plant or food extracts and leaves would inevitably grow bacteria, mold, or fungi.  

This incredibly vast blend of properties is uncommon, and one reason its usage is so diversified — likely somewhere around 1500 known uses throughout various industries.  

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Extracting Glycerol for Use

Now that we are aware of the many benefits of glycerine and its application, the question is, how exactly do we get glycerine?  

Most often, glycerine used in everyday skincare products is sourced from a vegetable-based oil through a natural process called hydrolysis. In hydrolysis, they use high-pressure and high-temperature water to break the chemical bond, creating a separation of oils, water, and resulting glycerine (source).

Another way of obtaining glycerine is through a process called saponification, which is also how soaps are made. The process is similar to hydrolysis, but with an added chemical component of sodium or potassium hydroxide — also known as “lye” — used to create the separation, resulting in glycerine as a byproduct of the soap-making process. 

Soap-making is actually a relatively simple process and takes about 24 yo 48 hours to achieve a set mold, depending on the amount of heat applied. More heat results in a faster process, while less heat slows it down. 

This process allows for more natural, homemade soap products, as well as a wide variety of combinations of ingredients and oils that each provide different moisturizing and cleansing characteristics.  

Vegetable Glycerine in Skin Care

While glycerine can be sourced from animals and even produced synthetically, you’ll find that glycerine comes more often from plant sources, particularly for skincare and food products. When they use either palm, soy, or coconut oils, they call it vegetable glycerine.  

In this way, it is, indeed, all-natural and can be labeled as organic if produced without nonagricultural substances (source). 

Because glycerine is such a strong humectant, it is promoted as having anti-aging as well as moisturizing benefits. By bringing water from the second layer of your skin to the top layer, glycerine helps to keep the surface of your skin much more hydrated and soft, while also adding plasticity. 

In addition to retaining moisture, glycerine helps to draw oxygen into the skin. When you consider added oxygen and hydration, combined with antimicrobial properties, the benefits to a healthy, anti-aging skincare regime are vast. 

Glycerine is a preferred soap ingredient for people with sensitive skin, too. Pure glycerine soap will not dry out your skin, unlike soap that is stripped of its glycerine and replaced with harsh chemicals and fragrances that are more likely to cause dryness or breakouts.

You will also commonly find glycerine in products such as shampoos, cleansers, toners, and even face masks.

Another benefit of added glycerine is that it will not clog your pores — one of the reasons why it is a primary ingredient in acne medications. You’ll also find it in other topical remedies for surface wounds, including cuts, rashes, and even psoriasis, a skin disease that causes red, itchy patches on the skin’s surface (source).

If you are seeking natural alternatives to body care to avoid conventional products with synthetic ingredients, glycerine is a powerful natural alternative. In its liquid form, vegetable glycerine makes it easy to use and infuse into many of these cosmetic products.

What about Glycerine as a Preservative?

Many well-known brands are beginning to make preservative-free skincare products, acknowledging the premise that some preservatives can be harmful. 

They’ve also undoubtedly observed that many consumers are moving toward the use of fewer preservatives on the whole and toward more natural ingredients.

However, even natural products do require some form of preservative when water is present. Without a preservative quality, skincare products can grow harmful bacteria, preventing them from working effectively and certainly reducing shelf life from manufacturer to consumer.

Skincare products with glycerine also preserve other added food and plant ingredients, such as dried herbs and vegetables, avocado in an avocado-based face mask, or cocoa in body scrubs, shaving creams, and moisturizing lotions.  

The important factor when it comes to understanding whether or not glycerine is a preservative is in knowing the percentage of glycerol present. At high concentrations of glycerol, no other preservative is necessary, but that concentration must remain at a minimum of 50% for this to be the case.  

This is why so many natural skincare products that have a high concentration of glycerol to aid in hydration or anti-aging properties do not need additional chemical-based preservative ingredients, making it a sought-after element natural skincare.

Preserving Glycerites and Tinctures

When considering the many uses for plants and herbal extracts, whether in soap or in food products, glycerine is an increasingly common ingredient here as well. 

The way in which to apply these extracts is through the use of a tincture, often called glycerites. Tinctures are concentrations of ingredients, such as plant leaves (dried or fresh), herbs, roots, essential oils, and even berries that are soaked in alcohol, vinegar, or glycerine.  

The carrier — either alcohol or glycerine in food and herbal extracts — pulls out the active ingredient constituents in the plants or herbs that have been added. Tinctures look a lot like medicine droppers in a small vial, similar to what you would use to give an infant Tylenol or vitamins.  And, the use for tinctures varies widely.  

More often, tinctures use alcohol as a carrier or necessary solvent. And while this is perfectly fine, many people wish to avoid the use of alcohol — especially for children or those with sensitivities to the ingredient — and prefer an alternative option, such as glycerine.  

A glycerite tincture is essentially one that uses glycerine as a base in which to carry and, yes, even preserve those extracts, essential oils, or food and plant ingredients.  

One of the benefits of glycerites and tinctures is that the options are endless, whether you are using them to flavor food with dried or fresh fruit and vegetables, as a dilution for essential oils, or to concentrate herbal ingredients.  

Because of its sweet taste, not only does glycerine help to act as a preservative, it can also be used in flavoring oils and extracts, adding depth to anything from baked goods to fresh, homemade iced tea.

When it comes to preservation using glycerine, how much you need varies, and it depends, too, on what and how much of any particular ingredient you have used.  

If you think about the shelf life of an alcohol-based tincture, generally anywhere from three years to five years or more, you may wonder how they can possibly last that long without adding additional preservatives, especially if there are food or plant ingredients added (source). 

But alcohol is already a strong preservative. With glycerine, however, the jury is still out on just how well it acts as a preservative and for how long. And this is where it can get tricky. 

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Determining the Correct Ratios for Glycerite Preservation

Glycerites do not last as long as alcohol-based tinctures, and the length of time depends on the combination of ingredients. Remember, we said that a glycerine solution, to be effective as a preservative, must contain at least 50% glycerine. 

You can use less, but the preservation qualities are dramatically reduced as you go under that seemingly golden number — perhaps only up to six months but, in some cases, anywhere from 14 to 24 months with an added preservative such as benzyl alcohol.

Still, if you are trying to avoid added preservatives, you’ll want to stick to a ratio of 1:1 or a minimum of 50% glycerine.  

Herbalists and those who make all-natural glycerites and herbal extracts recommend erring on the safe side with a minimum of 60% glycerine or more. 

And even that is tough because — when you are adding fruits, vegetables, or plant ingredients — it is impossible to know the exact sugar and water content in order to obtain an exact ratio of water to glycerine.  

What you can do, however, is find the average water and sugar content for a particular ingredient or additive, and do some math to determine the exact ratio.  

But if you hate math as much as many of us do, to avoid bacteria growth, start with 50% as a minimum for all glycerites if you choose to avoid adding any additional preservative. 

If the ingredients you are using have a high water content, or if the herbs you choose are already fresh and moist, you can use 100% glycerine and simply muddle the herbs in the solution well. 

Then, be sure to label your glycerite tincture with the date it was made, or read the labels carefully for those you purchase to avoid use past the expiration date.  

Another tip often shared amongst those using glycerine as a stand-alone preservative is to minimize the shelf life that we talked about a bit ago. Reduce it down to six months, maximum, especially with the use of food ingredients such as cucumber or fruit. 

If you are using dried herbs or plants, you may be able to push it a bit longer, but there’s really no conclusive evidence just yet as to exactly how long. And be sure to store your tinctures in a cool, dark place to avoid earlier spoilage or bacterial growth. 

As with all things, it’s better to err on the side of caution when it comes to proper preservation and glycerites.  

Using Glycerine for Plant Preservation

Glycerine is commonly used to preserve plant material, too. It’s actually called “glycerining,” despite it being an odd-sounding verb form. Using a combination of glycerine and water will keep plants soft and supple, preserving decorative bouquets much longer than without — up to a few years, even.

If you think about one of glycerine’s main characteristics — its ability to attract and hold onto moisture — it makes perfect sense that glycerine is the ideal remedy for keeping plants from turning dry and brittle.  

Adding a humectant, such as glycerine, prevents the plant’s cellulose — the primary substance in the walls of plant cells — from drying out (source). In this case, while other preservatives can be used because of glycerine’s natural ability to retain moisture, it is the most effective method of preservation.  

For example, you’ll often find flower petals in fresh, homemade soaps. One of the reasons the flowers stay beautiful is because of the preservation qualities of glycerol. 

In essence, the glycerine replaces the water in the plant tissue, maintaining moisture and acting as a lubricant, not only for your skin but also for plant leaves and stems (source).

Are there Drawbacks to Using Glycerine-Based Products?

To answer whether or not there are any disadvantages to glycerine-based products is primarily subjective. It depends on the way in which you are using it, as well as whether or not you may personally have a negative reaction or sensitivity.

The FDA (Food and Drug Administration) has placed no restrictions on its use and has deemed it safe to consume. However, as with all natural ingredients, there is a risk of reaction.

In rare instances, those with sensitivities to vegetable-based glycerine have had mild allergic reactions, not so much from the glycerol itself, but from the source — palm, coconut, or soy-based oils. 

You can also have a reaction specifically to the glycerine, most commonly occurring as redness or itchiness to the skin. 

If this occurs, of course, you’ll want to stop using the product immediately.  But, in general, there are few, if any, disadvantages to its use, whether for skincare, as part of wound care, as a sweetener in foods, or as a preservative in glycerites.  

Final Thoughts

It is safe to say that glycerine has an array of uses and added benefits, alongside being a naturally-occurring preservative.  

From foods to cosmetics to pharmaceuticals, glycerine can keep your skin healthy, heal minor wounds and burns, and be added to many of your favorite dishes as a subtly sweet alternative to sugar.

In a time when many are looking for a more natural way to stay healthy, glycerine is somewhat of a miracle ingredient for many of the products we use and consume daily.

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