Thursday, April 7, 2011

Some thoughts on storing products in the fridge

As I mentioned in this post, I'm really enjoying Cooking for Geeks, a book I originally bought for Raymond, and I'm reading a lot about safety in the kitchen. Although I'm not a fan of comparing cooking to product making, there are some points we can take from it when it comes to product safety.

When we refrigerate a something at 40˚F or 4.4˚C, we can stop the bacteria from multiplying, but we don't kill them (Click here for more information as it relates to food). The key is that the bacteria growth is only retarded, not stopped. This is why food can only be kept so long in the fridge before it needs to be thrown away. (Have we all had the wonderful experience of finding a piece of last week's chicken hiding behind the milk? Ick! No, well, I guess I was just a horrible housekeeper my last year of university!) If we want that food to stay better longer, we need to put it in the freezer. (Click here for more information on this topic!)

Let's say you make an amazing water-containing product and decide to not to preserve it because it's just for you or that you'll always keep it in the fridge. Even if you're scrupulous about taking it out of the fridge, squirting out a bit, then returning it to the fridge, the bacteria will still be growing. It might be slow, but they are growing. And there will come a point where your lotion is like last week's chicken and you can't use it any more (and no, I don't know how long...)

When you remove that product from the fridge, the bacteria will start to multiply again when it gets above 4.4˚C, which isn't that hard to do considering room temperature is around 18˚C to 20˚C. (You don't need the entire product to warm. If the surface gets warm and there's bacteria there, they'll be partying while their colder brothers are still chilling.) If you're taking that amazing conditioner into the shower and back to the fridge, imagine how warm it's getting in your bathroom!

No matter how obsessively clean we are in the workshop, there's always a chance of contamination. (Does anyone use a brand new bottle of distilled water every time you make a product?) This is the reason we use our preservatives. Not only will most of them prevent contamination in the future, but they will help us kill the nasties that might have been transferred into the product as we made it. If you aren't using preservatives, you aren't able to kill the contamination that might be in the product when we put it in the fridge, and those bacteria could eventually multiply. By using a broad spectrum preservative, we can prevent this! (Make sure you're using something that actually kills the bacteria. Something like sodium benzoate is a bacteriostatic, which will retard growth, but it won't kill it.)

Yeah, I know I harp on and on about this topic, but it's a vital one. And it's not helped by the deceptive labels that don't include preservatives on the list or hide them under other ingredients or the misinformation passed around by those who make products. Besides, it's a really interesting book that has me thinking before I go to sleep! 


Sarah said...

I think we can never harp on enough about this vital step in making products. I've lost count of the times I've explained to customers and hopefully the importance is getting through. I always say 'better safe than sorry'.

Anonymous said...

I am so glad you posted this.
Many people think they can make a natural product without a preservative and use it within a month and it will be fine, and or store it in a fridge and expect it will be fine and dandy as well! NOT!

madpiano said...

And shops like Lush don't help by selling unpreserved, water-based products that should be kept in the fridge and used in a short time-period. Several of their fans have reported mould growing on the stuff and they still buy more....

Tara said...

Maybe you could do an "experiment" in one of your blogs: make products that are heated and held, with no preservatives and stored in the fridge, others that are formulated cold yet preserved with a chemical, and other variations in between. Then you could see how long it takes for visible signs of contamination to appear (although we know that not all contamination is readily visible, but we don't have lab culture media to identify this). Take some pictures and show us what you come up with. ;-)

Will said...

I've got a weird question re preserving product. (Theoretical question)

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.

Thanks as always.


Susan Barclay-Nichols said...

Hi Sarah & Anonymous. Yes, I'm obsessed with this concept - using preservatives - and I'm fascinated by all the different ways people try to justify the non-usage of them. So I'm always thinking of different ways to reach those people.

Hi madpiano! I don't get the fascination with Lush products. The shop is interesting and they have some great product ideas (I used to love their shampoo bar until I started making my own), but I don't get why people will put up with expensive products going off and justify it somehow.

Hi Tara. Although this is a great idea, there are two small problems with it. One, I don't have enough time to play in the workshop as it is and I'd hate to waste that time making a product that I can't use. Two, it would be like using an apostrophe in the wrong place. Knowing I'd done something wrong on purpose wouldn't make it less irritating and I'd know it was wrong and I would get really annoyed by it! (Yeah, I'm a bit of a perfectionist.) Besides, the people who I'm trying to reach with these posts wouldn't pay attention anyway.

Hi Will. Look for your VO5 duplication tomorrow! You can combine preservatives, but if you've chosen a good broad spectrum preservative, there's really no point. If you're trying to make a really long shelf life product, just choose your ingredients and preservatives wisely. (This is a really good idea for a post!)

chowsr said...

I hate Germall plus, though it proved beyond a shadow of a doubt lavender essential oil has better antimicrobial properties than rose or vanilla. I don't care what the uneducated populace thinks I'm using my Liqupar Optimum! Yes! Yes! Yes! I use the evil parabens! I'll send them this link too. I have lotions that have last years without rancidity or mold.
Thank you. Mad rantings from a chemist are complete. I feel better :)