Which kind of rosemary extract should you seek? The goodness of rosemary is offered to us in many different ways - deodorized, bleached, hexane, methane, or acetone extracted.
For the best levels of carnosic acid, choose hexane extracted. For the best levels of carnosol, acetone extracted is your choice. And for the best levels of ursolic acid, hexane extracted or bleached are your best choices.
Having said this, all the versions offer good levels of each ingredient (except methane extracted or bleached, either of which will offer trace amounts of carnosic acid), although if you're choosing rosemary solely as an anti-oxidant, the hexane and acetone extracted version are better than BHT and BHA at free radical scavenging, while the methane extracted and bleached are about the same as BHT or BHA. In the end, the extracts you find at our suppliers' sites and stores will work well if you want great anti-oxidants and the other features of rosemary.
Rosemary works better as an anti-oxidant in ingredients with some fat in them - anhydrous bars or whipped butters, lotions, conditioners - but you can still include them in things like body washes and shampoos for low levels of anti-oxidants and all the other great features.
And there are some studies showing that a little Vitamin C added to anything containing rosemary extract can boost the anti-oxidizing capabilities of both, making it an incredible addition to a product! Vitamin C is a water soluble anti-oxidant; rosemary can be used in both water and oil based products, but is better in oil based products. This is a perfect combination for oil and water lotions, toners that contain a little bit of oil somewhere, conditioners, and anything containing at least a little oil and a little water. (Apparently the ideal ratio is 500 mg/kg Vitamin C to 200 mg/kg rosemary. So for a 100 gram batch of lotion you'd want 50 mg Vitamin E and 20 mg rosemary - 0.05% Vitamin C and 0.02% rosemary extract.)
As a note, rosemary can be an irritant to some people, so make sure you test it on your skin before using (if you're in doubt) and put a little note on your label if you're sharing your products with friends.
POWDERED ROSEMARY EXTRACT
A lot of rosemary's awesome polyphenols are sensitive to the heat, so you will want to include any rosemary extract in the cool down phase of your creation. With the powdered extract, use 0.5% to 1% in the cool down phase. Mix it with a little hot water and add it when it has completely dissolved. If you use this in a toner or facial cleanser, it might turn your creation a little green or brown, depending on the level of bleaching (if bleached).
LIQUID ROSEMARY EXTRACT
You can get a liquid extract of rosemary that isn't the essential oil or rosemary oil extract (rosemary oleoresin or ROE). It is soluble in water and should be used at the rate suggested by the supplier. Again, add it to the cool down phase of your creation.
Rosemary hydrosol is not the same as liquid rosemary extract. It contains the goodness of rosemary, but you'll want to use it in higher quantities. At least 10% to replace the water phase of your creation will give you some of the goodness of the rosemary, but not so much of the anti-oxidant features. You can add this to the heated or cool down phase of your creation.
CO2 EXTRACTS OF ROSEMARY
You can get CO2 extracts of rosemary that are oil soluble, so you can add it to your anhydrous creations this way. Check your supplier's suggested usage rates as everyone is different. This is a great way to get rosemary into an anhydrous creation, and you can use it in emulsified creations as well. As usual, add to the cool down phase.
OIL BASED ROSEMARY EXTRACTS
ROE is generally used as an anti-oxidant and not for the other features of rosemary, but you can use it in place of the extract. It is oil soluble and should be used as suggested by the supplier. You can add this to anhydrous creations without worries about it not emulsifying!
ROSEMARY ESSENTIAL OIL
I'm not getting into this now - look for posts in the future. Just know you can get a rosemary essential oil, and you can use this at 0.5% to 1% in your creations for the great anti-oxidant and other benefits.
As usual, check the safety information on using rosemary essential oil in your products if you are using it on pregnant or nursing women. (Normally I forget to include this, but Mich has me trained well!!!) The essential oil is reported to have stimulating benefits, so you might want to re-consider using this ingredient in anything you might use at night!
Join me tomorrow for fun formulating with rosemary!