Tuesday, April 12, 2011
An aside: Shelf lives of our products (part 1)
Will commented in this post...I use liquid germall plus in my own concoctions and haven't noticed anything go bad, but I typically use a batch of lotion within a month, so that's probably not surprising. On the other hand, I've purchased products (gasp!) and haven't used them within a couple of years, and they "seem" to be still good. I'm sure I'm not the only guy that does this sort of thing. I think many lotions are purposely made with mineral oil and such so that rancidity is less of a concern. Anyhow, knowing something may sit for a long time, here's my question -- is a single preservative like germall plus truly sufficient or would adding in a second preservative really be best? If yes, what would you recommend? Yes, I am a little bit of a germ-a-phobe.
We're all germ-a-phobes around here when it comes to lotion making, Will! It's the safest way to think!
To answer your question, a good broad spectrum preservative will last the life of your lotion, long after your oils have gone off. Most have shelf lives of two years. You can combine preservatives to create a broader spectrum preservative - for instance, adding something like one of the organic acids (which tend to be good fungal killers) with Optiphen - or you could do something like add liquid Germall Plus at 0.25% (range 0.1% to 0.5%) with 0.5% Germaben II (range 0.5% to 1.0%) to cover all your bases if you have something especially hard to preserve. I use liquid Germall Plus at the maximum 0.5%, and I've found my oils will go rancid long before I have any preserving problems, so it's not like someone's going to use it! (Believe me, if you've ever smelled rancid products, you won't accidentally use them!).
Will's question leads me to another thought...I addressed the idea of figuring out the shelf life of your products in this post, but I thought it was a good idea to re-visit it and think more about the ingredients we could use to extend the shelf life of any product.
One of the reasons we see mineral oil and petroleum in so many products is thanks to its shelf life. Both can last for years before going rancid, whereas most of our oils have a 6 month to one year shelf life. And shelf life is another reason we see a lot of our natural oils coming in at tiny percentages when they are used in a commercial product.
When we're working with natural oils we will have a year or so maximum for our products. We can add all kinds of things to extend the life span, but we're not going much over a year. For butters, most have a two year life span, but that's irrelevant if you're pairing them up with short lived oils.
Want to know the shelf life of your favourite oils? Please check out these posts on oils (under the emollients tag in the links to pages section) or the charts for more information. (If you click on the link for all the posts, you'll see charts for exotic oils and butters as well!)
Join me tomorrow as we take a look at the shelf life of a few recipes then think about how to extend them!