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Monday, January 2, 2017

The pH of Skin

The surface of human skin has a naturally acidic pH in the range from 4-6, probably averaging 4.7. This acidic nature of skin is called the acid mantle and is vital for the proper functioning of skin. The low pH helps to protect the skin from bacterial infection, protects the barrier function of skin and helps the skin enzymes function properly. If the pH varies greatly, skin problems arise which may include infection, dehydration, dermatitis, roughness, acne, irritation, and noticeable flaking.

For a refresher, the pH refers to the concentration of hydrogen ion. It is a logarithmic scale that goes from 1-14 with 7 being neutral, less than 7 acidic and higher than 7 alkaline (basic). The pH of a solution can be measured with a pH meter, pH of skin is more difficult to measure and requires more specialized equipment. Read more here.

 What can affect the skin's pH?
The most common thing that we do that can change the pH of the skin is cleansing the face with soap or other cleansers that have a high pH. Healthy skin can come back to its normal pH after a few hours, but not all skin can tolerate that challenge. Face toners are often used after cleansing to restore the skin pH back to acidic. Toners should always have an acidic pH for that reason. I like to use herbaldistillates/hydrosols for a toner.  Modern face cleansers though are typically not soap and are buffered to be an acidic pH. Soap however has a basic pH of about 10 which cannot be changed, that may work great on most of your body, but if you have problems with skin on the face, do not use soap there. You can find a good face cleanser here that is pH balanced to skin.

People have often asked me about cleaning their face with baking soda. This is a big no no because baking soda has a high pH between 9-10 (similar to soap) and is sure to disrupt the pH balance of skin due to its alkalinity. Even plain tap water can affect skin pH. Theoretically, tap water should be pH 7, but it is typically closer to pH 8 because of impurities.

Age also affects skin pH, increasing as we age. For this reason it is important that products for mature skin have a pH from 4-5. Skin moisture, sweat, sebum, anatomic site, and genetic predisposition also affect skin pH.

The skin's pH is maintained by secretions from the glands of the skin; both eccrine and sebaceous secretions.

Understanding the anatomy and function of skin can help you be a better formulator. If you would like to learn more, download our ebook “The Nature of Skin.”

Wednesday, November 2, 2016

What is Fractionated Coconut Oil?

Fractionated coconut oil (FCO) is often used in aromatherapy and cosmetics because it is a very light, odorless oil. Massage therapists like FCO because it leaves less of a stain on clothing and sheets than other oils. It is also used in cosmetics because it gives a lighter feel to a product as well as a glide. FCO is a very stable oil in that it will not go rancid quickly giving it a longer shelf life than other oils. FCO is also used in cooking and is said to not contribute to a rise in cholesterol. 

Photo credit: Peter Davis/AusAID, CC BY 2.0,

But how does it compare to other Coconut oils? Besides FCO you can readily find coconut oils referred to as 72 degree and 92 degree.

Coconut oil 72 degrees means that it is oil pressed from the copra (meat) of the coconut and melts between 72-78 degrees Fahrenheit. Most of this is then refined and deodorized and labeled RBD, but unrefined coconut oil is also available. Virgin coconut oil is typically made from the milk rather than the copra.

Coconut oil 92 degrees melts at about 92 degrees Fahrenheit. It is similar to the 72 degree coconut oil but has been hydrogenated (hydrogen added across a double bond) so the melting point increases. It is possible to get coconut oil of higher melting point but these are less commercially available.

Fractionated coconut oil refers to only the medium chain fatty acids of coconut oil. Fatty acids which make up triglycerides, come in different lengths most fall between 4 carbons to 28 carbons. Short chain fatty acids are defined as less than 6 carbons, medium chain fatty acids defined as 6-12 carbons, long chain as 13-21 carbons and greater than 21 carbons are very long chain fatty acids.

This is how the fatty acid profile of regular coconut oil breaks down:
Long chain, saturated fatty acids:
Myristic acid (C14) 19%, palmitic acid (C16) 8%, stearic acid (C18) 3%

Long chain unsaturated fatty acids:
Oleic acid (C18:1) 5%, linoleic acid (C18:2) 2%

Medium chain saturated fatty acids:
Caprylic (C8) 8%, Capric (C10) 7%, lauric acid (C12) 48%

Fractionated coconut oil refers to just two of the medium chain fatty acids; caprylic and capric fatty acid. The INCI (International Nomenclature for Cosmetic Ingredients) for FCO is Caprylic/Capric Triglyceride. The lauric acid with 12 carbons is borderline long chain and not extracted into the FCO or also called MCT for Medium Chain Triglycerides. 

So how are they separated? The ‘fractionating’ is done first by hydrolyzing the triglyceride to separate it into glycerol and fatty acids. This is the same reaction a soapmaker uses to make soap. The fatty acids are then gradually heated so that the lower carbon chains melt first and the various fatty acids are ‘fractionated’ or separated.  This actual separation is done through distillation. Once this is finished the result is MCFA for medium chain fatty acids, rather than a triglyceride. The triglyceride is then reformed by esterification with glycerin/glycerol to reform the triglyceride or MCT for medium chain triglycerides, also the fractionated coconut oil. Fractionated coconut oil is commonly referred to as Mixed Chain Triglycerides (MCT). It's INCI name is

Caprylic/Capric Triglyceride which refers to the carbon chain length of the fatty acids.

These reactions that occur (hydrolysis, distillation, esterification) are generally found to be acceptable in natural products and green chemistry products. The resulting product is a triglyceride that is formed from the medium chain fatty acids; caprylic and capric acid. This FCO is lightweight and absorbs well into the skin, is odorless and has a long shelf life. It is used as a carrier oil for herbalists and aromatherapists, as a dietary supplement and as a cosmetic ingredient.

Monday, August 29, 2016

Vitamin E in Skin Care

Oils, whether they be vegetable and plant oils in a jar, or oils that make up the cell membranes of an organism are prone to oxidation and degradation. This oxidation can be stopped by antioxidants, particularly vitamin E. 

Oils are mainly triglycerides which are composed of fatty acids. These fatty acids are carbon chains that consist of either double bonds or single bonds between the carbons.  Carbon chains containing single bonds are known as saturated fatty acids while those with one or more double bonds are referred to as unsaturated. It is the unsaturated fatty acids that are more prone to oxidation and the risk of oxidation increases with the number of double bonds.

This oxidation is initiated by light, heat, metals or oxygen, so keeping oils away from these helps to slow oxidation, but it is inevitable. A free radical contains an unpaired electron which makes it highly reactive and unstable. It is looking for an electron on another molecule to steal, thus setting up a chain reaction of forming free radicals. When these oxidative products are formed from oils the breakdown products are off flavor compounds such as ketones, aldehydes, alcohols and more. They tend to have a characteristic smell known as ‘rancid’.

Your body is constantly making free radicals, and at the same time making antioxidants to stop them from causing damage. Hopefully, a nice balance exists, but not always. The oil in a bottle on your shelf or your newly made skin care product has no way to make antioxidants like your body does so it is helpful to add an antioxidant to prevent oxidation.

Vitamin E is an important oil soluble antioxidant to protect polyunsaturated fatty acids and other cell membrane components from oxidation. Vitamin E reacts with a lipid radical faster than that lipid radical can react with other lipids and so suppresses the propagation of oxidation.  It does this by transferring a hydrogen atom to a lipid free radical. Of course now the vitamin E molecule becomes a free radical but it can react with another vitamin E free radical to form a non-radical product. This terminates the chain reaction of oxidation.

Vitamin E is a family of eight different molecules; 4 tocopherols and 4 tocotrienols. Vitamin E is high in wheat germ oil, canola oil, and almond oil, but commercially, vitamin E is typically extracted from soybean oil. Buy your vitamin E from a skin care ingredient supplier, do not use capsules from the store as this is not pure vitamin E.

Bottom line is that your skin care products should contain an antioxidant such as vitamin E to prevent the breakdown of oils in your product. Many crafters are being taught that this is similar to a preservative that will prevent the growth of bacteria or fungus in a product where it is not at all similar. If you have a product that contains any form of water, you need to have a preservative to prevent growth of microbes. Vitamin E will not prevent growth of microbes, but vitamin E should be in your products that contain oil to prevent the breakdown of these oils.

To learn more about preservatives (anti-microbials) see this post on What is the Best Preservative?


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