The Use of Particular Natural Oils in Formulations
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Tony O’Lenick – Siltech LLC, US WAXES AND BUTTERS The use of particular natural oils in formulations ABSTRACT CH2-OH O CH2-OC(O)-R Natural oils have become a common additive to personal care products. They CH-OH +3 RC-OH CH-OC(O)-R + 3 H2O fit the definition of natural, sustainable and can be organic and even organic. CH OH CH -O-C(O)-R While these classifications are 2 2 sometimes unclear in meaning, the reason we formulate with a particular oil Glycerin Fatty acid Triglyceride Water is often just as obscure. Is it marketing, or carbon distribution or aesthetics or Figure 1: The reaction. perhaps a particular benefit rendered to the oil by a particular native material The selection of a particular natural oil in triglycerides. Fats have a titer point of (antioxidants)? This article will look at a personal care application depends upon over 40.5˚C, oils have a titer point of some of these properties. what the formulator wants to achieve with below 40.5˚C. Butters have a titer below the particular formulation. The simplest 40.5˚C but above 20˚C. Oils are liquid choice is when the choice is simply a at room temperature and we now use results in a very wide melting ‘range’ for marketing choice. The product profile this word to describe any compound these compounds. For this reason, titer may say that the product should contain that is a liquid and is insoluble in water. point is generally determined on fats, oils, a particular oil like olive oil or argan oil. As a result, jojoba is referred to as an oil, waxes and butters. The aesthetics are dictated in large despite the fact it is really a liquid wax. amount by two properties, carbon number Because oils, fats, butters and waxes Triglycerides and amount of unsaturation (measured are complex mixtures of homologues of Triglycerides are the tri-esters of glycerin by iodine value). Finally, there may be a similar chemical structures, it is difficult with three equivalents of organic acid. particular reason to use an oil with an to obtain a true melting point. The term Fatty acids are defined as those acids antioxidant or other active that is natural titer is therefore used to define the having alkyl or alkylene groups being to the oil. While seaming simple, once the re-solidification point of the melted oil, C-5 and higher. The reaction is shown oil is chosen, the process by which the fat, butter or wax. The procedure is to in Figure 1. oil was prepared becomes the controlling heat the product to be tested until it is When the triglyceride is saponified to factor. We will address each of these completely liquid, then to cool it slowly by make a surfactant, such as soap, glycerin variables. stirring. This is done until the temperature is liberated. When a wax is saponified, stays constant for 30 seconds, or begins a fatty alcohol is liberated. Saponification Definitions to rise. The titer point is the highest is a general term to define the chemical The terms oils, fats, butters and waxes temperature indicated by this rise.1 reaction that breaks the ester linkage. have been misused over the years. The As the lower molecular weight fractions This makes it possible to produce very historical definition of wax has previous melt, they act as solvents to dissolve the different kinds of products using the two been given. Butters, oils and fats are all higher molecular weight products. This types of materials. Table 1: Oil composition example. Table 2: Carbon number calculation for oil example in Table 1. Component % Weight (a) (b) C16 20 Component % Weight Carbon atoms Calculation in component (a)*(b) C18 20 C18:1† 20 C16 20 16 3.2 C20 40 C18 20 18 3.6 C18:1 20 18 3.6 Total 100 C20 40 20 8.0 †Note: C18:1 is our short to indicate the presence of 1 double bond or unsatuartion. Total 100 18.4 So C18:1 would be oleic acid Therefore for the Carbon number = 18.4 March 2016 PERSONAL CARE 1 WAXES AND BUTTERS Glycerin, produced as a by-product of saponification is water soluble and fatty 40 insoluble. The fatty alcohol produced as a by- product of the saponification of a wax is 30 water insoluble and generally fatty-soluble. Triglycerides are commonly encountered as natural products. Plants use enzymatic 20 systems to make triglycerides, effectively at ambient temperatures. 10 INCI nomenclature of Number triglycerides INCI names require the genus and species of the plants or insects that produce a given wax, oil, butter or fat and all products 0 which are derived from the various oils, Below 16 16-17 17-18 Over 18 Carbon number fats, butters and waxes. This is due, in part, to the European Union’s use of the Figure 2: Carbon number of common triglycerides. Latin names for ingredient listings. This information is very helpful to the formulator predominant species is not very 16 to 18. Today there is a growing trend in understanding the source of the fatty enlightening to the formulator as to the toward using materials with carbon portion of the surfactant. source of the raw material. numbers of 22 or more for conditioning. It is also quite interesting that nature Since few oils offer these high carbon Classification has provided many triglycerides that have numbers, manufacturers often fractionate In order to simplify the information, we very similar carbon numbers. In fact, methyl esters to pure compounds or, have divided the raw materials that we of 38 triglycerides presented here, 31 alternatively, they hydrogenate unsaturated discuss into two groups: those derived from have carbon numbers between 17 and 18. oils to make saturated compounds having animal sources and those derived from This also explains why the other important high carbon numbers. plant sources. Within each of these groups variable, unsaturation, is critical in In general, double bonds lower the one finds additional classes depending choosing an oil for a specific application titer point of the triglyceride, resulting upon the carbon distribution of the raw (Figs. 2 & 3). in a triglyceride that stays liquid at lower material. It is very interesting that there are only temperatures. Conjugated double bonds three triglycerides having a carbon number (i.e. those with only one carbon between Carbon number below 16. Since this is a key number for two double bonds (-C=C-C=C-), are very In addition to classifying products by their detergents, it becomes clear why coconut effective in depressing titer point, but can sources (animal or plant) and by their oil is so important to the surfactant present problems with rancidity, a process chemistry (triglyceride or ester), we have industry. There has been a growing by which the double bond is oxidised and classified them within these groups by demand for products based upon oils ultimately broken. This releases many carbon number and unsaturation level. having a carbon number over 18 (for different molecules, many of which have Carbon number is the value obtained by example behenic derivatives). In order to objectionable odors. Rancidity can be multiplying the percentage of a component get these products, one must choose a mitigated at times with the addition of in a product by the number of carbon different class of oils. The selection of the antioxidants, prior to the start of the atoms in the component, then adding up oil is a major variable, which normally rancidity process. all the components. eludes the formulator, being made more Finally, upon additional processing, For example, if an oil had the commonly by the derivative manufacturer. many oils, fats, butters and waxes lose composition shown in Table 1, the carbon Oil selection is assuredly one important their identity as oils and become known by number calculation would be as seen in factor in formulating cosmetic products. Table 2. There are several types of oils that have Effect of carbon number 5 8 very similar carbon numbers; consequently, One major factor that affects the 5 we have classified them further by functionality of both the oil itself and any unsaturation. One can expect derivatives potential derivative is the number of carbon from oils having very similar carbon atoms in the chain. Other factors include numbers and levels of unsaturation to the number and location of double bonds have very similar, often identical functional and the presence of additional functional properties. In this instance, the choice of groups. which of the many oils to use depends Generally, as one evaluates the tactile n Below 16 n 16-17 upon the economics of the oil and the properties of an oil on the skin, the lower n 17-18 formulator’s desire to name the oil for label the molecular weight is, the less oily the n Over 18 and marketing purposes. As will become feel of the compound will be. Conversely, clear, there are many different fats, oils, the higher the molecular weight is, the waxes and butters, which when derivatised, more greasy the feel will be. In surfactant 82 result in compounds of strikingly similar preparation, detergent products and high- carbon distributions, while having their foaming products generally peak between a source oil, wax, fat or butter being quite carbon number of 12 and 14. Conditioners Figure 3: Carbon number percentage shown different. Thus, naming the material by the and softeners have a carbon number of in common triglycerides. 2 PERSONAL CARE March 2016 WAXES AND BUTTERS the fatty names of the predominant species Table 3: Carbon number and iodine value for common triglycerides.