As it seems with every extract, papaya is a good anti-oxidant, and contains Vitamins A, B, and C. It is high in carotenoids, in the form lycopene, of which means it may help protect against UVB damage as well as acting as a very good anti-oxidant. It also contains carpaine, an alkaloid that can have some cardiovascular effects when eaten. (As we aren't eating this extract, it's not really relevant for this discussion but I like the word "alkaloid".)
The main feature of papaya is the papain, a protease enzyme, which acts like a keratolytic (exfoliant) so powerful it can clean wounds of dead tissue and help skin shed quickly so we can see the new cells underneath. It is used as a freckle or age spot treatment, and can help reduce the look of hyptertrophic scars (the red raised lumps on our skin). It is used as an anti-itch ingredient in some creams in Australia, although there has been some concern raised in the States about the safety of using high levels of papain in over the counter medical products. (They use it at much higher than the 0.5% maximum amount recommended for us formulator types).
Papain is very good at breaking down proteins, which is why it is recommended for use for very oily skin cleansers. The main protein in dirt on our skin surface is keratin, followed by sweat protein. Papain breaks up the protein and cleans it away.
Papain can penetrate the stratum corneum, which means it can be a penetration enhancer for other active ingredients.
If this all sounds very interesting but you feel you can't use it if you don't have oily skin, don't fear! There is a theory that dry skin can be caused by ultra-violet irritation, and papain may help with this. It can be an irritant (as well as an anti-inflammatory and soothing ingredient for those who can tolerate it), so try it first before adding it to everything you make.
It is, however, a little touchy about temperature and pH. The greatest activity is at pH 6, with less going on at pH 5 or 7. It is most effective when added at 30˚C to 45˚C (in the cool down phase) after dissolving it in warm water (less than 45˚C).
Because papain is such an effective keratolytic and exfoliant, do not use it with another exfoliating ingredient or extract, like salicylic acid, strawberries, or white willow bark extract. This could lead to really irritated skin, which kinda defeats the purpose!
So how can we use this product? I know I can't tolerate it in a leave on product, so I reserve the awesome power of papaya for toners and cleansers, things that will be washed off. I have tried it in a mask a few times, and I swear my skin felt softer afterwards and definitely looked exfoliated! (If you aren't sure how your skin will tolerate this, try the rinse off product first.)
It does not play well with gels - it breaks down the gel so it gets all liquidy - but it does play well with emulsified creations, surfactant mixes, and toners. Try it at 0.5%, dissolved in water no more than 45˚C before adding it to the cool down phase of your products.
If you want to try making a moisturizing scrub, make up your favourite moisturizer recipe. Add papaya at 0.5% in the cool down phase (dissolve in hot water first). When it has cooled completely and you're ready to bottle it, remove up to 100 grams, then add up to 50% exfoliants - jojoba beads, clay beads, loofah, salt, sugar, and so on - and put it in jar. Try using this is as an exfoliating scrub, then rinse off and enjoy the moisturizing loveliness that is papaya extract.
Join me tomorrow for fun with St. John's wort and orchid extract!
*Thanks to Scorpio for this great quote! Ever see a guy say good-bye to a shoe? Watch "You Only Move Twice" (season 8, the Simpsons) to enjoy this character!