Stearic acid, also known as Octadecanoic Acid is a common fatty acid. It has a safer profile in comparison to the other saturated or unsaturated fatty acids. Here, you will find the uses of stearic acid, its good and bad side effects, safe level of intake and dosage details.
What is stearic acid?
Stearic acid is a saturated fatty acid that is found in both plant and animal fats. It is an essential component of soap, and it is also used in the manufacture of candles, crayons and cosmetics.
Stearic acid has a chemical formula of CH(CH(CH)COH. The name comes from the Greek word for tallow (stear) because it was originally isolated from animal fat.
Stearic acid is one of the most common saturated fatty acids in nature. The only other naturally occurring saturated fatty acid with comparable abundance is lauric acid (C12). Stearic acid can be found in beef tallow, palm oil, coconut oil, cocoa butter and shea butter. It is also present in glycerol esters of stearic and palmitic acids in many cosmetic products such as soaps, creams and lotions.
Stearic acid formula
Stearic acid is a saturated fatty acid with an 18-carbon chain and a carboxyl group at one end. It is a solid at room temperature, but melts slightly above room temperature. It is insoluble in water, but soluble in ethanol and diethyl ether. Stearic acid is found in many foods like milk products such as cheese, butter, ice cream, yogurt and cream.
The chemical formula of stearic acid is C₁₇H₃₅CO₂H.
Stearic acid structure
Stearic acid is a white solid that has a melting point of 75 degrees Celsius and a boiling point of 250 degrees Celsius. It has a density of 0.957 g/cm3 at 20 degrees Celsius.
The structure of stearic acid is made up of 18 carbon atoms arranged in four separate chains of three carbon atoms each. The chains are connected by a methylene bridge between the first two carbons of each chain; these bridges form a ring around the molecule, which makes it more stable than if there were only isolated chains.
Freezing point of stearic acid
The freezing point of stearic acid is -75.0 °C (168.1 K, -103.6 °F).
The freezing point of a substance is the temperature at which it changes from a liquid to a solid. At the freezing point, there is no more thermal energy left to melt the solid form of the substance.
Foods rich in stearic acid?
Stearic acid is a saturated fatty acid found in animal fats and vegetable oils, such as cottonseed oil, peanut oil, and coconut oil.
Foods rich in stearic acid include:
- Grain-based desserts
- Regular cheese
- Sausage, franks, bacon, and ribs
- Chicken, beef, pork, lamb
- Cottage cheese
- Egg yolks
- Milk (skim)
- Pizza
- Candy
- Pasta
- Butter
- Nuts/seeds
- Potato/corn/other chips
- Quickbreads, crackers
- Soups
- Cocoa butter
What is stearic acid made of?
The main components of commercial stearic acid are stearic acid and palmitic acid, although pure stearic acid is also available. Depending on the purity or grade of stearic acid, their assays differ.
According to the USP definition, its USP-NF grades can be classified into three types based on their stearic acid content:
- Type 50: stearic acid (40.0%–60.0%), stearic acid + palmitic acids: NLT 90.0%.
- Type 70: stearic acid (60.0%–80.0%), stearic acid + palmitic acids: NLT 90.0%.
- Type 95: stearic acid (NLT 90.0%), stearic acid + palmitic acids: NLT 96.0%.
How is stearic acid made?
Stearic acid is made by reacting stearin, a white solid obtained from tallow (animal fat), with diluted sulfuric acid.
Stearin is made by saponification of fats under controlled conditions. The resulting soap is neutralized with sodium hydroxide and then converted to stearin by hydrogenation.
Saponification is the process of converting fats into soap. It can be done in two ways:
- Hydrogenation – hydrogen gas is bubbled through the stearin solution, which causes the stearin molecules to split into smaller molecules called fatty acids. These are more soluble in water than the original fat molecules were before saponification took place.
- Hydrolysis – sodium hydroxide solution is added to the oil (saponification takes place). This produces soap and glycerol, which can be separated out later by distillation.
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Vegetable oils, as well as animal fats & oils, are commonly found in the following sources.
Animal fats & oils
- Mutton tallow
- Beef tallow
- Lard
- Butter
Vegetable oils
- Palm oil
- Soybean oil
- Coconut oil
- Olive oil
- Corn oil
Stearic acid derived from animal fats (up to 30%) is usually higher than stearic acid derived from vegetable oils (typically <5%). The majority of commercial vegetable stearic acid is produced from palm oil.
Hydrogenation is the physical or chemical process of converting liquid vegetable oils to solid or semi-solid fats. After hydrogenation, unsaturated double bonds in fatty acids become saturated bonds.
Properties
| Other names | Octadecanoic acid, Mixture of stearic acid and palmitic acid |
| CAS number | 57-11-4 |
| Chemical formula | C₁₇H₃₅CO₂H |
| Molecular weight | 284.484 |
| Melting point | 69.3 °C |
| Boiling point | 361 °C |
| Acid value | 194–212 |
| Viscosity (mPa·s) | 7.79 (80°C), 6.29 (90°C) |
Appearance
It is a white gloss soft powder or flakes at room temperature, but it becomes liquid at around 70°. Pungent and oily aromas are associated with it.
Solubility
Insoluble in water (solubility 0.00034 g/100 g at 30°C, will float on water), soluble in oils & alcohols, e.g. 5.42 g/100 g in ethanol (30°C).
Why is it insoluble in water but soluble in ethanol?
Stearic acid is a saturated fatty acid that is found in many natural products, including tallow and coconut oil. Stearic acid is insoluble in water but soluble in ethanol.
Stearic acid forms a soap-like layer of molecules around itself, which makes it insoluble in water. The same thing happens with other oils such as olive oil and peanut oil. The insolubility of stearic acid in water means that it doesn’t dissolve into the watery environment around it. Water has a high surface tension and repels the oily surface of the stearic acid molecules.
Ethanol has low surface tension and thus easily breaks down the soap-like layer of molecules surrounding the stearic acid, allowing it to dissolve into solution.
How to dissolve it in water?
Stearic acid is a waxy solid used to make soaps and other personal care products. It’s also used in foods as a fat substitute. Stearic acid dissolves easily in water when heated, but if you want to dissolve stearic acid in water at room temperature, you may need to add some heat.
Stearic Acid Dissolution Method 1: Heat Water and Stearic Acid
Heat distilled water until it boils, then add the desired amount of stearic acid. The mixture will begin to boil immediately, which means that the stearic acid will begin to dissolve in the water.
Stearic Acid Dissolution Method 2: Add a Catalyst
To speed up the process of dissolving stearic acid in water, use a catalyst such as sodium hydroxide or potassium hydroxide (KOH). When added to the solution, these chemicals will catalyze a reaction between sodium ions and water molecules that results in an increase of dissolved ions within the solution. This increase of dissolved ions results in an increase of free energy within the solution that makes it easier for additional stearic acid molecules to dissolve.
Hydrophilic-Lipophilic Balance (HLB)
The HLB value of this substance is 6.5, which means it is hydrophobic and soluble in oil.
Structure
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Unlike other fatty acids, stearic acid has a carboxyl group at one end and a methyl group at the other. A total of 18 carbons are contained in the molecule structure, with the structural formula CH3(CH2)16COOH.
Types of stearic acid and their difference
According to the source, it can be divided into two types: animal-based and vegetable-based. According to the purity degree or manufacturing process, stearic acid can be divided into three types: single, double, and triple-pressed.
There are different levels of purity associated with different levels of C18 content. The common measurement of C18 (stearic acid) content is 40%-60%.
The difference between triple pressed stearic acid, double and triple pressed stearic acid, one pressed stearic acid is that in the case of triple pressed stearic acid, it is derived from animal fat or tallow, which is a form of saturated fatty acid. On the other hand, double pressed stearic acid is obtained from vegetable oils such as palm oil, coconut oil or soybean oil.
The one pressed stearic acid is obtained from natural sources such as vegetable oils or animal fats. The difference between these three types of stearic acids is that they have different melting points. This makes them suitable for different applications in cosmetics and personal care products.
The main application of one-press stearic acid is in industrial applications, including:
- as a vulcanization active agent in the rubber
- a stabilizer in plastics
- as a water repellent and brightener in paper
- as a softener, waterproofing agent in textile
Difference between cetyl alcohol and stearic acid
Cetyl alcohol is an emulsifier, meaning it helps to maintain the consistency of a final product. It is used as a thickener in many products, including hand lotions and conditioners. Stearic acid is often used as a substitute for cetyl alcohol because it has similar properties to cetyl alcohol and can be used in many of the same products.
Cetyl Alcohol vs Stearic Acid
Cetyl alcohol is a fatty alcohol that is derived from coconut or palm kernel oil. It has been used in cosmetics and personal care products for over 30 years as an emulsifier and surfactant (i.e., cleanser). Cetyl alcohol can also be found in many foods such as chewing gum, butter, margarine, cookies, cakes and candies.
Stearic acid is also derived from vegetable sources such as palm kernel oil or beef tallow but has different uses than cetyl alcohol. In fact, cetyl alcohol cannot be used as a substitute for stearic acid because they act differently when heated or mixed with water. In addition, stearic acid does not work well with some essential oils commonly used in cleaning products, such as lemon, because it is not suitable for cleaning.
What is stearic acid used for?
Stearates are a group of compounds that are used as emulsifiers and surfactants in food, cosmetics and pharmaceuticals. They are also used in industry for lubrication and as corrosion inhibitors. Stearic acid uses include:
Stearic acid for food
Stearates are commonly found in food products such as chocolate and chewing gum because they prevent the formation of unwanted crystals. They can also be used to improve the texture of food products such as margarine, butter or shortening by preventing separation of the oil and water phases. Stearates may be added to peanut butter to prevent it from separating into oil and solids when stored at room temperature.
Stearates are also used in baked goods such as breads, cakes and pastries to reduce sponginess and increase volume during baking by providing extra moisture retention capacity.
It may be found in the following food list:
- Bakery
- Dairy
- Sauces, seasonings, snacks
- Desserts & ice cream
- Cocoa products
- Chewing gum
- Vitamins & dietary supplements
Stearates
Stearates are salts or esters of stearic acid. They are also called stearates or stearic salts. Stearic anhydride is the main stearate used industrially. It may be prepared by treating stearic acid with concentrated sulfuric acid or by dehydrating ethyl oleate with sulphur at 200–250 °C (392–482 °F).
Emulsifiers
Furthermore, stearic acid is used as an emulsifier to produce the following products:
- DATEM
- Mono and Diglycerides
- Glycerol monostearate
- Sorbitan monostearate
- Sodium stearoyl lactylate
- Calcium stearoyl lactylate
- Polysorbates (20, 40, 60, 80)
- Sorbitan tristearate
- Sucrose esters of fatty acids
Coating agent
Stearic acid is used as a coating agent for tablets, capsules and films because it dissolves well in water and alcohols but not in fat-based systems like lipids or phospholipids. A 10% solution of stearic acid in water forms an emulsion which can be applied to tablets by spraying them with aqueous solution of the powder before drying under vacuum.
Stearic acid for cosmetics
Stearates are used as emulsifiers in cosmetic creams and lotions to prevent separation of oils from water due to their amphipathic nature: they are more soluble in water than oil but more soluble in oil than water. This property allows them to stabilize emulsions formed by two immiscible liquids like oil-in-water or water-in-oil emulsions where one component is insoluble in the other.
Is stearic acid an emulsifier?
There is no simple “yes” or “no” answer to this question. The product does not function as an emulsifier, although it can stabilize and thicken an emulsion.
Although sodium stearate is an emulsifier if used in combination with sodium hydroxide (or in alkaline conditions), it produces sodium stearate which works as an emulsifier and helps oil and water phases mix.
Stearic acid for skin
Stearic acid is used in skin care products because it acts as an emollient that softens the skin, improves its texture and reduces fine lines and wrinkles. It may also be used to help treat psoriasis, eczema and acne. Some studies have shown that stearic acid may act as an antioxidant to protect against free radical damage to the skin.
Stearic acid for pharmaceuticals
Stearic acid is also used in pharmaceuticals as a thickening agent, emulsifier or solubilizer in ointments, creams and suppositories (rectal meds). It can be used for treating dry eye syndrome, conjunctivitis (pink eye), corneal abrasions and irritation from contact lenses.
Stearic acid for wax
Stearic acid is often used as an ingredient in waxes used for candles and lipsticks. It can also be used to make soap or as part of the process of making certain types of plastic containers.
Stearic acid for soap
Stearic acid is used in many soaps because it produces a hard bar of soap that cleans well but doesn’t leave behind any residue on the skin. Stearic acid may also be added to detergents for its cleaning power.
Stearic acid for rubber
Stearic acid has been used as an additive in rubber products since the early 19th century. For example, it was added to rubber tyres during World War II to make them more durable.
Stearic acid for plastics
Stearic acid can be used as a plasticizer for PVC (polyvinyl chloride) plastics, increasing their flexibility and durability. It is also used in making polyester resins more rigid and stable in high temperature applications such as automotive exhaust systems and electrical components like cables and wires.
What are the benefits of stearic acid?
Stearic acid benefits including:
1. Inhibit tumour development
Stearic acid helps to inhibit tumour development. This is because it has an anti-inflammatory effect on the body, which can reduce the risk of cancer.
2. Benefits breast cancer
Stearic acid may also be beneficial for those who suffer from breast cancer, as it can help to prevent metastasis, meaning that the cancer cannot spread throughout the body. The anti-inflammatory effect of stearic acid also helps to reduce pain and swelling caused by the disease.
3. Decrease Cardiovascular Risks
Stearic acid may also lower cardiovascular risks, as it lowers LDL cholesterol levels (the bad type) and raises HDL cholesterol levels (the good type). It also lowers triglyceride levels in both healthy individuals and those with high blood pressure or diabetes mellitus type 2.
Is stearic acid safe to eat?
Yes, as a food additive, it almost has no side effects.
FDA
According to the FDA, stearic acid is generally recognized as safe (GRAS) as a direct human food ingredient. Foods can use it as a flavoring agent and adjuvant with no limitations other than current acceptable manufacturing practices. A fatty acid that can be used directly in food as a lubricant, binder, defoaming agent, and as a component in the manufacture of other food-grade additives. A wide variety of fatty acids are found in the body, such as palmitic acid, oleic acid, myristic acid, lauric acid, capric acid, and caprylic acid.
EFSA
E570 represents the E number for stearic acid, a fatty acid that is approved by the European Food Safety Authority for use as a food additive.
A 2017 safety re-evaluation by the EFSA concluded that fatty acids (E 570) pose no safety risk at the reported uses and levels.
Fatty acids (E 570) are These additives are in Group I of QS-authorized food additives, which means they can be used in a wide variety of foods without specific quantity restrictions. Furthermore, it is used as a glazing agent for fruit and as a carrier of nutrients, except for those containing unsaturated fatty acids.
Other Authorities
It has been approved as a flavoring agent by the JECFA with no safety concerns at current dosage levels. With the code number 570, it is also approved in Australia and New Zealand.
What are the side effects of stearic acid?
Stearic acid is a saturated fatty acid that can be found in butter, beef tallow, and coconut oil.
The side effects of stearic acid are minimal. Stearic acid is generally considered to be safe for consumption at moderate doses, although it may cause mild gastrointestinal upset in some people.
The severity of these side effects depends on the amount consumed. It’s important to keep in mind that stearic acid is also found naturally in many foods, so it’s unlikely that you’ll consume enough to cause any serious problems.
Stearic acid side effects including:
Gastrointestinal Upset
Stearic acid can cause gastrointestinal distress when taken at higher doses. Symptoms include nausea, stomach pain and diarrhea. These symptoms will likely subside once you stop taking stearic acid supplements or other products containing stearic acid.
Blood Sugar Balance
In addition to its role as an antioxidant, stearic acid may help improve blood sugar balance by increasing insulin sensitivity and decreasing blood sugar levels after meals. This effect has been demonstrated in animals with diabetes; however, there is currently no evidence from human studies demonstrating this effect.
Where to buy stearic acid?
You can find stearic acid at many beauty supply stores or online retailers like Amazon.com or eBay.
Frequently asked questions
Is stearic acid natural?
No, stearic acid is a fatty acid found in animal and vegetable fats. It is widely used in food products, such as margarine, shortening, and chocolate. Stearic acid is also used in soaps and cosmetics.
Stearic acid can be made from plant oils or animal fat. It is usually combined with other ingredients to form a solid compound before it is added to foods or other products.
Is stearic acid halal?
Yes, stearic acid is halal. Stearic acid is a fatty acid that is found in animal fats and vegetable oils. It is used in many cosmetic products as an emulsifier or to help bind the ingredients together.
Is stearic acid kosher?
Yes, stearic acid is kosher. It is considered a food additive and is used in a variety of foods, including baked goods. It may be derived from animal products (such as tallow), but it can also be obtained from plant sources (such as palm oil). Stearic acid has been declared kosher by the Orthodox Union and the National Kosher Supervision Association.
Is stearic acid gluten free?
Yes, stearic acid is gluten free.
Stearic acid is a fatty acid that is derived from stearin, a byproduct of vegetable fats. It’s used in foods as an emulsifier and thickener, as well as in cosmetics and toiletries.
Is stearic acid vegan?
Yes, stearic acid is vegan. Stearic acid is a fatty acid found in animal products. It’s also found in plants, from which it can be extracted. Chemical composition includes: CH3(CH2)16COOH.
Stearic acid is a white solid that can be used as an emulsifier and thickening agent for food and cosmetic products.
Is stearic acid good for skin?
Yes, stearic acid is a fatty acid that is naturally found in the skin. It’s also commonly used in cosmetics and other personal care products, though, which means it can be a great natural ingredient for your skin.
Stearic acid has been shown to help reduce inflammation and irritation when applied topically. It’s also an excellent emollient—it helps to soften and smooth dry skin, which makes it a great way to treat dryness or flaking on your face.
Conclusion
You can buy stearic acid online in small quantities. There are not many side effects. The stearic acid is mostly used as a hardener in creams and lotions or in toothpaste or soap. The most popular brand is the E570 which originates from tallow, lard or palm oil. Most of them have also an expiration date and some guarantee that the stearic acid has no heavy metals and other harmful chemicals in it.
