What is a Preservative?
noun: preservative; plural noun: preservative
- a substance used to preserve foodstuffs, wood, or other materials against decay.
acting to preserve something."the preservative effects of freezing"The preceding was just the first result when I simply Googled the question. Here are just a few more that came up.
From this website, http://dictionary.reference.com/browse/preservative:
2.a chemical substance used to preserve foods or other organic materials from decomposition or fermentation.
3.tending to preserve.source: World English Dictionary -Collins
—n 1. something that preserves or tends to preserve, esp a chemical added to foods to inhibit decomposition —adj 2. tending or intended to preservesource: American Heritage Medical Dictionaryn.
A substance added to food products or to organic solutions to prevent decomposition due to chemical change or bacterial action.All of these I've copied and pasted from just a single dictionary website alone, and i could go on like this, but that'd be pointless of this post. Or would it? Here's one more website, chock full of definitions of what a preservative is. Oh, wait! Can't exclude good ol' Wikipedia, right?Now these are all fine and dandy, until you talk to another soap maker or a cosmetic formulator. Apparently, in the cosmetic industry, preservatives are ONLY antimicrobial, that is, the ones that prevent contamination by bacteria, viruses, fungi and yeast. And yet, when I search, "what is a cosmetic preservative?", I don't get the same kinds of results. What I do get are several websites that give their own interpretation of preservatives in relation to cosmetics. Some will say that ONLY antimicrobials are preservatives. Some say that preservatives include antimicrobials and antioxidants. Some will go as far to say that certain natural ingredients can be used for their antimicrobial properties as preservatives. The discussion of preservatives can become very heated in many groups, with each having their own opinion based on whatever information they have. In today's post, I'm going to do my best to provide the most accurate information possible, based on my own research of course. I encourage you to take the time to do your own reading as well, and come to your own conclusions. The information is out there, it just takes asking the right questions to find it.To summarize the definitions I provided above, a preservative is something that prevents the degradation, or decomposition, or a product. If decomposition has not occurred, the product in question is considered preserved. Decomposition in cosmetics can occur via microbial growth, as noted above, or by chemical change, also known as rancidification. We all have a pretty solid idea about microbial growth in cosmetics, and the preservatives that go along with that. But what about this chemical change, aka, rancidification? Well, as the definition in the link stated, rancidification ( totally a mouth full) is related to the breakdown of fats, usually via oxidation decomposition, though can also be attributed to microbial and hydrolytic activity. We, once again, also already have an idea of how water and microbes play a role. But what about oxidative decomposition, or simply put, oxidation?
Oxidative rancidity (oxidation) occurs when the double bonds of a fatty acid react chemically with oxygen. Thus, making the fats spoil, or go rancid. In a lot of cosmetics, some form of fatty acid chain is used to create the ingredients used, like in conditioners and detergents, and in some products, raw oils are used, such as olive and coconut oils. So, without delving too deep into the chemistry of oxidation in fats, what is used to prevent this type of decomposition? Antioxidants! And what does an antioxidant do? Quite simply put, it inhibits the oxidation of other molecules by protecting them from damage by free radicals that form when oxidative breakdown occurs. So when we talk about antioxidants, exactly what, in the material sense, are we talking about? Examples of antioxidants are Vitamin E (Tocopherols), Ascorbic Acid, Rosemary Oleoresin Extract (ROE), Rosemary Essential Oil, Grapefruit Seed Extract (GSE), the more commonly known or butylated hydroxyanisole (BHA) and
butylated hydroxytoluene (BHT). These are just examples, there are plenty more out there. And they are all used to prevent oxidation in a product, be it food or cosmetic. In the food and medical industry, and technically, by definition, antioxidants are a type of preservative. But according to the cosmetic/soapmaking world, they are not? Only antimicrobials are considered preservatives. I don't want to be redundant, but, judging by all that I've read, an antioxidant is a preservative, since it prevents decomposition of a product. I just can't understand why in the cosmetic industry things are redefined. Oddly enough, throughout the book, Scientific Soapmaking by Dr. Kevin Dunn, antioxidants are also very much referred to as preservatives. So, again, I don't understand this type of confusion. By the way, I recommend this book for anyone who wants to take a more scientific approach to the soap making craft. It literally is a chemistry book for soap making, and not meant for the faint of heart. I'm having a hard time with it, so I'll have to read over it again. But anyways...Other types of preservation methods can be non chemical as well. There's mechanical: the boiling or smoking, generally of food. And of course the use of an autoclave, which is basically a very expensive pressure cooker. As a former dental assistant and technician, I'm very familiar with autoclaves, so that's the easiest comparison I can come up with to give you an idea of what they do. But then, there are some very unlikely preservation methods that seem to be forgotten, or even scoffed at, and considered "more natural" even. The use of sugar or salt has been a common method of preservation for the centuries, and is still used this day by folks who do any type of homesteading or quite simply, at home canning and long term food storage. But how do these relate to cosmetics? Well, many of us like to make sugar and salt scrubs right? Salt and sugar both draw out water and tie it up within itself, making the water unavailable for any chemical reactions to occur. High concentrations of salt interfere with the growth of microbes, while sugar may also encourage the growth of healthy microbes that prevent the harmful type from growing. High concentrations of sugar also exert osmotic pressure that will draw water out of bacteria, preventing them from growing as well. You can find very simple to understand, solid confirmation of this here, here and here. So, aside from the essential or carrier oils used in scrubs, they are made of nothing but salt or sugar. The concern comes in when wet fingers dip into the jars. The preceding pretty much explains what will happen in that case, especially considering it's such a low concentration of water. Plus, why would you put your wet fingers in your scrub or salt jar? I mean, think about it for a minute. I could go on and on about this, and share arguments on both sides. Some sources say to use a preservative in scrubs "just in case", as in the end user and how they use and keep the product, ie getting water drops in them from the shower, leaving the cap off, etc. From my understanding, most scrubs commerically sold don't have preservatives in them either. On that note, I'd say take into consideration the type of packaging you use for your scrubs. Do they absolutely have to be in jars, or can you use some type of bottle or tube? You could also leave a disclaimer, or instructions about product use and care, like most commercial packaging does anyhow. It's up to the end user to read instructions, in my opinion. And and, preservatives need to be mixed in with ALL ingredients in the scrub for it to be effective. Even if you used a liquid commercial Preservative and mixed it in your oils you use in your scrubs, it's still not mixed with the sugar or salt itself, and could more likely render it ineffective. Another thought: it's a known fact that certain chemical preservatives can cause contact dermatitis in wash off and especially leave on products that are meant to go on the skin's surface. Using a scrub debrides the skin of dead cells, and can possibly cause micro tears as well. When we design our scrubs, we add skin loving ingredients that fresh skin will soak up and benefit from. Why would you want to also include an ingredient that could cause irritation on nice, fresh skin, especially if it's known to cause irritation on the very surface of skin alone? And lastly, some formulator feel scrubs need a chemical preservative in a anhydrous scrub because of the potential for moisture, and dirty hands, to contaminate it, despite many reputable resources(science) saying sugar and salt are preservatives in their own right, making scrubs self preserving. So why don't soapers say the same thing for bar soap? If I were to ask any random soaper if bar soap needed a preservative, they'd be quick to say no: because it is anhydrous and it's pH is too high to support microbes. In that, they are repeating science. Look at some of the soaps made. Highly superfatted, made with food mixed in and dried fruit and botanicals on top. Left in showers, next to sinks. Left in the wettest, germiest places in the house ,where if you don't close your toilet lid, it's been proven fecal matter can spray several feet into the air from the toilet. This is my personal opinion, but if we're going to talk preservatives in an anhydrous scrubs for the reasons in mentioned, and ignore scientific fact there, then we need to talk about preservatives for soap as well. But I can guarantee, NO soap maker is going to consider that.Other well known ingredients in soap making and cosmetics are alcohol, which is self explanatory, honey and glycerin. Honey, like sugar and salt, has been used to preserve foods for centuries. Here's an interesting tidbit on using honey to preserve milk. Glycerin( glycerol), is a product of sugar and alcohol (simply put) and is used in food and medicine, especially vaccines, as a method of preservation. There has been some debate as to the amounts needed for an effective preservation with glycerin, but accoridng to the FDA (United States), it seems that if the glycerin content is between 10 to 50%, it is considered self preserved. Sodium lactate, very common for not only making hot process soap fluid for pouring in the mold, but also creating a harder bar, is also a preserative in many food items, most notibly meats, and in some cosmetics. A few sources I've found will say it's great in combination with other preservative systems, in that they piggy back each other."But soap isn't cosmetic, and what does this all mean?", you ask? Aaahhh, see here's the catch 22: liquid soap is water based. And according to many cosmetic formulators, anything that is water based MUST have a preservative. But what many formulators fail to realize is that soap, be it in bar or liquid form, is self preserving in it's own right. Bar soaps more so for their minimal water content. But with liquid soap, that luxury obvious isn't ours, so we need to look as other reasons. First of, is it's pH. Harmful microbes thrive best in slightly acidic to slightly alkaline environments, a pH range between 6 and 8. They are called neutrophiles and prefer that "neutral" pH environment. Now there are some microbes that thrive in acidic (acidophiles) and alkaline (alkaliphiles) environments, but the ones we are most concerned with are the neutrophiles. Keep in mind, microbes are everywhere, and nothing is sterile, not even with the best of preservatives. So don't freak out. So aside from pH, soap to water concentration plays a role. Also, the fact that our soap is constantly on heat to cook and dissolve paste helps kill harmful microbes, to "wipe the slate clean" essentially. If you use alcohol at any point, that helps preserve the soap. The use of chelating agents such a borax or citric acid, helps bind metals to keep the soap from oxidizing, thus helping to boost the effectiveness of any other preservative you may choose to use. So they're not just for adjusting pH folks!! Also, another not thought after factor: glycerin content. We all know that saponification creates the by-product glycerin, correct? Understandably, bar soaps will have a higher percentage than liquid due to water content. But, we also like to add extra glycerin to our liquid soaps for extra emolliency, and to boost bubbles and help with clarity. Added in the beginning, and it speeds trace. Two words for you to think about in relation to this subject: Glycerin Method. Wouldn't that fall within the 10 to 50% mark indicated by the FDA for self preservation? Food for thought there. But, most importantly in all of this, is GMP- Good Manufacturing Practices. Keeping you workspace and utensils clean and sanitary. Keeping your ingredients from being contaminated. I personally keep bottles of high percentage alcohol in the house just for soaping, so I clean the counters before I start. I'll also squirt it on my utensils and in my pots as well. Don't soap when you're sick!! You wouldn't go to work sick, so why soap while sick, knowing family and friends, or even customers, will use your products? Quite simply put, whatever preservation method, or lack of, you choose, isn't going to be worth the container it came in if your products are dirty to begin with.Should you plan on superfatting your LS, paired with a solubilizer, of course, you can always use an antioxidant preservative, along with the other methods outlined above, if you don't want to use a chemical/antimicrobial preservative.If you do choose to use an antimicrobial preservative in LS anyhow, you can't just use any one available to us formulators and soapers. Most antimicrobial preservatives have pH restrictions to consider. Otherwise, it won't be effective if used in a product outside of it's range. You need to ensure the preservative is effective above a pH 9. Not up to it, above it. This will ensure that you get the maximum effectiveness for from your ingredient. There are only 2 preservatives that I know of that are broad spectrum and within that guideline, Suttocide A, which is a formaldehyde releaser, and Optiphen MIT Plus. I've heard that Liquid Germall is also effective, despite manufacturer recommendations, but I've found nothing substantive to that nature. So it's best to follow what the manufacturer says, just to play it safe. Here's a little chart of some commonly used preservatives, with their pH restrictions listed. With pH consideration in mind, I recommend a good pH meter if deciding to invest in preservatives. As you could probably see in the chart, the Optiphen, though above 9, only goes up to a 10, whereas the Suttocide A is all the way up to a 12. This really limits your choices for antimicrobials doesn't it? But, should you choose the Optiphen, making absolutely sure you soap isn't outside of it's effective range is imperative, otherwise, you're wasting money. Even if you were to superfat your recipe at 2% to avoid the need to neutralize, that doesn't mean your pH isn't pushing limits. It just means you've neutralized any possibility of free lye and will only marginally effect pH. That's it. You can try and use strips, but I've seen all too often that folks still get the cheap strips despite recommendations against them because of their potential for inaccuracy, and being off the mark by as much as 2 points. I recommend lab grade, should you choose to get any. I personally don't use strips at all. I invested in a meter with a changeable probe. But I'll save further discussion on that for another time.So, now that I've gotten that out of the way, I'll leave you all with this:
Whether you choose to use a preservative or not is clearly up to you. No one, and i mean no one, can tell you that you HAVE to, or NEED to do anything. Any advice given should be in the tone of a recommendation. Not a borderline command. Also, keep this under your hat. Whether you use any form of preservative system additive or not, just remember that things happen. It CAN fail. Even the FDA recognizes that cosmetics/soap is not meant to be sterile, and that so long as the method used inhibits further growth of microbes, and that no harmful microbes are present. It's just not possible. Sometimes microbes can overtake a preservative system. The question is, has it happened frequently, or is it a one time fluke? For me, when my conditioner kept failing, it was because of lack of preservative. I probably also wasn't following GMP at the time, considering I was just starting out. So i caved and looked into a preservative to fit my needs. And so far I'm pleased. I'd love to get it challenge tested to know for sure that it's working but thus far, I'm not having the problems I had previously. So I'm getting somewhere. I assessed the situation of constant failures, and determined a change was needed. Now, had it been only 1 failure out of the many batches made, I wouldn't bat an eye to it more than i need to make sure everything is clean. It all breaks down to experimenting with what works for you. Do the research yourself. Ask questions. You make the final call for your products. Not those who have a biased opinion to one side of the fence or the other. I personally want to stay as unbiased as possible while providing good resources, like this. An unbiased read on preservatives to use on home made bath and body care products. So anyways, happy soaping folks. Until next time....