Avril asks: 'What do protein treatments really do for your hair, in particular eggs? What is it in ApHogee 2 step protein treatment that makes the hair so hard, and how do we benefit from it?'
Kelly asks: 'I thought natural hair was undamaged, do we really need to use protein conditioners?'
Jan asks: 'Can I add amino acids to my hair conditioner to make a protein conditioner?'
Let me start by describing proteins. Proteins are made up from single units known as amino acids(see the diagram below). These amino acids (approximately 20 different types) are arranged joined together through peptide bonds. For simplicity I have drawn just 4. The order and number of amino acids that make up a protein is determined genetically (DNA is wonderful!!). Each protein is made up several hundred to a few thousand amino acids. Again for simplicity I have drawn just a few amino acids.
So why is hydrolysed protein the correct size?
This is because to be useful, the protein has to adsorb (yep with a D) to hair. Adsorb means the protein sticks to and forms temporary bonds with the hair. Very large protein simply can't form these bonds reliably. Amino acids on the other hand tend to be very soluble in water so you can expect that you will remove majority of whatever you put on once you rinse your hair. With damaged hair, very small hydrolysed protein (known as peptide fragments) can also be absorbed - yes this can penetrate through to the cortex and be deposited in the hair shaft (Journal of Cosmetic Science, pg69-87, 1993).
Just before moving on, let me just say that even hydrolysed protein has an ideal size for use:
For collagen hydrosylates for example, this is a molecular weight of 2000 (Book reference - Conditioning agents for hair and skin By Randy Schueller, Perry Romanowski).
For wheat hydrosylates this is around 5000-10000 ( Book reference -Principles of Polymer Science and Technology in Cosmetics and Personal Care By Errol Desmond Goddard, James V. Gruber).
The problem is that I have not seen a single protein conditioner actually state the molecular weight. The protein part of eggs (egg white/egg albumin) has a molecular weight of approximately 33000- 40000 (The Journal of Biological Chemistry, pg 189-193, 1939). I can't find a reference for hydrolysed egg albumin size but I would strongly suspect that this molecular weight is too large to be beneficial.
In part 2 tomorrow, I will describe (with diagrams!) exactly how protein can help hair and attempt to answer the question on aphogee (hint - think about egg white and heat)!!