Green & Clean

There are now plenty of surfactants and emulsifiers available that comply with at least one of the three main certification bodies, the emphasis being on Ecocert, which appears to be the most universally accepted

-

There are now plenty of surfactants and emulsifiers available that comply with at least one of the three main certification bodies, the emphasis being on Ecocert, which appears to be the most universally accepted

?From suppliers’ literature and hype in the media it would appear that all users of cosmetics and toiletries are looking for products made from organically grown ingredients purchased under Fair Trade agreements. In fact the natural cosmetic market only accounts for 2% of total cosmetic sales, but worldwide that makes $180bn so the market share is definitely worthwhile. And it’s growing.

Unfortunately consumers are not entirely sure just what is green, organic or sustainable so many of them look for a certification statement or logo. In Europe this means the French Ecocert, the Germany-based BDIH or the British Soil Association. As might be expected, even the certification bodies are not in close harmony over their aims and rules for compliance.

The stated objectives of Ecocert are:

_ To define a quality level superior to the one defined by the French and European legislation on cosmetic products, which will safeguard a real enhanced value of the natural substances used, a real practice of respecting the environment throughout the production process and a real respect of the consumer

_ To establish a link between certain cosmetic products and Organic Agriculture in promoting the use of Organic Agriculture plant products

_ To establish a link between certain cosmetic products and respect of the environment

Ecocert defines natural as any plant, animal or mineral product coming directly from agricultural production, from harvest or physical extraction processes. It also allows certain chemical processes that include hydrolysis, esterification and saponification but not ethoxylation or chlorination. Unlike some certification bodies it also allows hydrogenation and biotechnological fermentation provided the latter does not involve genetically modified organisms. Alkyl sulphates are permitted, water is regarded as a non-certified organic ingredient and wild harvesting and ingredients of marine origin are also permitted.

The Ecocert standard limits use of ingredients such as synthetic oils and other petroleum derivatives and is very restrictive on the preservatives that can be incorporated into the product and its constituent ingredients. It also bans the use of synthetic colours, antioxidants, perfumes and silicones and any ingredients that can be obtained by natural processes.

Alkyl polyglucosides, also known as alkyl polyglycosides or APGs, have established themselves as the natural surfactants of choice for applications as diverse as emulsifiers for skin care and foaming agents for shampoos and personal cleansing products. They are produced by linking two plant-based raw materials: fatty alcohol from coconut or palm kernel oil and glucose derived from native, unmodified, corn starch. They are anionic in character and their properties are modified by using fatty alcohols of different carbon chain lengths to modify their HLB values.

The Plantacare range of APGs from Cognis and marketed by Kemcare are described as made from entirely renewable vegetable feedstock; they contain neither ethylene oxide nor other petrochemicals. They are preservative-free and do not contain any genetically modified materials. They do not contain nitrogen and cannot contribute to nitrosamine formation. They are mild in use and completely biodegradable [NB: This description is given in full as it defines what can be considered natural in the field of surfactant chemistry]. The three Plantacare products are decyl glucoside, coco-glucoside and lauryl glucoside.

Other Ecocertified surfactants from Cognis include Plantapon LGC-Sorb and Plantapon SF. Plantapon LGC-Sorb is a mix of lauryl glucose carboxylate with lauryl glucoside. Its anionic character ensures better foaming properties than the APGs alone and it is recommended as the primary surfactant in personal washing products and for use in combination with sodium cocoampho-acetate and cocamidopropyl betaine for shampoos. Plantapon SF [INCI: Sodium cocoamphoacetate, glycerin, lauryl glucoside, sodium cocoyl glutamate and sodium lauryl glucose carboxylate] is a mild surfactant mixture that has good foaming properties and is suggested as the surfactant of choice for natural shampoos, shower gels and bath foams.

One reason that Ecocert has risen to prominence among natural certification bodies is that it allows the use of a wider range of materials, enabling product efficacy to be achieved without departing from its guidelines. This includes allowing alkyl sulfates including sodium lauryl sulfate and sodium coco-sulfate, sulfosuccinates, cocoamphoacetates, glutamates, lactylates and guar hydroxypropyltrimonium chloride to be used provided their feedstock comply with the requirements of natural origin. Various betaines have Ecocert approval but instead of the ubiquitous cocamidopropyl betaine, formulators may like to try olivamidopropyl betaine, available from Soliance as Tensolive.

Rita Corporation is a US supplier from the US that has decided to adopt Ecocert principals and has just announced a number of surfactants and emulsifiers that have Ecocert approval. These are based on the well established class of acyl lactylates sold under their Pationic trade name. Acyl lactylates are a group of anionic surfactants that appear to have excellent foaming and cleansing characteristics. Their properties are largely determined by the carbon chain length of their fatty moiety as well as the cation used in their neutralisation. For example C8-C12 lactylates are good foaming agents; C10-14 lactylates are good foam boosters. Sodium caproyl lactylate is said to be an excellent foam booster and stabiliser when used in conjunction with CAPB or alkyl polyglycosides. Acyl lactylates are also suitable as emulsifiers and Rita provides a neat method for determining optimum ratios of emulsifiers for various applications that is downloadable from its website.

GLUTAMATE SURFACTANTS

Glutamate chemistry is perceived as natural-based and Ajinomoto offers four with Ecocert approval under its Amisoft trade name. Amisoft CS-22 is an anionic surfactant comprising disodium cocoyl glutamate, and sodium cocoyl glutamate said to have exceptional mildness to skin and hair, and to leave a moisturised feeling after use. Amisoft LS-11 is sodium lauroyl glutamate, recommended for personal cleansers because of its selective cleansing properties. It is said to remove squalane but not cholesterol so it cleans without destroying the skin’s natural protective barrier. The other two materials with Ecocert approval are Amisoft HS-11P [INCI: Sodium stearoyl glutamate] and Amisoft LS-11 [INCI: Sodium lauroyl glutamate].

Glutamate surfactants with Ecocert approval are also available from Schill-Seilacher of Germany under its Perlastan trade name, which also encompasses sarcosinates. In common with other glutamates and sarcosinates these amino-acid-based surfactants provide fine lather and good detergency, are very mild in use, improve moisture retention on the skin and are rapidly biodegradable. Sarcosinates have good lathering properties and a high resistance to delathering by sebum. Glutamates are non-comedogenic, tolerant to hard water and hypoallergenic.

FOAM & SUBSTANTIVITY

Sugar chemistry is behind many of the materials claiming natural credentials. Although not claiming Ecocert approval, the Poly SugaPhos series of anionic surfactants from Colonial Chemical satisfy a need for high foaming anionic surfactants that are not ethoxylated. They are based on polymerised alkyl polyglycosides with the phosphate diester structure that characterises Gemini surfactants. Colonial Poly SugaPhos 1000P is sodium hydroxypropyl phosphate decyl glucoside crosspolymer and Colonial Poly SugaPhos 1200P is sodium hydroxypropyl phosphate lauryl glucoside crosspolymer. They are said to offer formulating advantages over traditional mono-alkyl phosphate products. They foam well, are extremely mild and are stable over a wide pH range.

The Colonial Poly SugaNate Series are sulfonated surfactants based on the renewable resource of alkyl polyglycosides and are extremely mild when tested against other traditional primary personal cleansing surfactants. Also derived from polymerised alkyl polyglycosides the Poly SugaQuat materials are naturally derived and cationic in character. They provide substantivity to skin and hair, providing longer lasting benefits than can be achieved using conventional surfactant systems while reducing the irritation common with traditional quaternary compounds.

Vegetable proteins are the starting points for a number of surfactants. Enzymatic hydrolysis of cereal proteins results in a specific degradation of proteins to polypeptides with an average molecular weight of about 2000 Daltons. By condensing a protein hydrolysate with a fatty acid chloride and then neutralising with either an organic or inorganic base, products are obtained with surfactant structures containing both a hydrophilic head and a hydrophobic tail. Sinerga uses different mixtures of fatty acids and hydrolysed protein chains of different lengths to obtain anionic surfactants with detergent properties.

Potassium undecylenoyl hydrolysed soy protein is derived from undecylenic acid, which in turn comes from castor seed oil. Abietic acid comes from tall oil from coniferous trees. It is the major component of Canadian balsam and gives rise to abietoyl soy polypeptide. Both materials are suitable for use in shampoos and trials show that they reduce the oiliness of greasy hair. Also from Sinerga, Lauroat is the condensation of the protein hydrolysate derived from Avena sativa and lauric acid [INCI: Sodium lauroyl oat amino acids]. Oat-based functional materials act without damaging or denaturing the proteins of the horny layer and without having the undesired effects common to so many surfactants. Oat protein is rich in arginine, lysine and cysteine, which are known to stimulate epidermal renewal of keratinocytes.

Emulsifiers are also surfactants and natural ones were in relative short supply until recently. Subject to suitable origin and standards of purity the available ones were glyceryl stearate and its self-emulsifying version, the non-ionic sorbitan esters but unfortunately not their ethoxylated counterparts, lecithins and alkyl sulfates. To these can be added any of the surfactants already mentioned of which the APGs are particularly useful, sugar esters, citro/lactoglycerides and, for w/o emulsions, polyglyceryl-3 diisostearate.

Lecithins are natural emulsifiers with a long history of cosmetic use. Emulmetik lecithins from Lucas Meyer are natural lecithins and phospholipids with various phosphatidylcholine contents to give a range of emulsifiers with liquid crystal forming possibilities. Their emulsifying properties are improved by combining them with fatty acids and fatty alcohols. An advantage of lecithin-based emulsions is their compatibility with human skin lipids and their silky soft after-feel. Also from Lucas Meyer is Amisol Soft, a blend of phospholipids, phytosterols and vegetable lipids that forms o/w emulsions that are said to soothe skin irritations, be anti-inflammatory and to provide a natural protective barrier. For the preparation of fluid emulsions Lucas Meyer recommends Heliofeel, an o/w emulsifier based on sunflower phospholipids [INCI: Glyceryl stearate citrate, polyglyceryl-3-stearate, hydrogenated lecithin].

Sugar esters are made by combining sucrose with a fatty acid via an esterification reaction and they are used in the food, pharmaceutical and cosmetic industries. They are predominantly used as emulsifiers, although they do have other unique properties, such as forming stable oily gels that emulsify on contact with water. They are extremely mild and have a long history of safe use. Sucrose laurate is suitable for use in organically certified products and Alfa Chemicals provides a number of materials incorporating this as its Sucragels.

Sucragel AOF is based on sucrose laurate with sweet almond oil and is recommended for use with vegetable oils to obtain clear oily gels. It can also be used to make milks, lotions and creams by adding an oil phase followed by a water phase. Sucragel CF is based on sucrose laurate with caprylic/capric triglycerides and can be used with most esters and non-polar oils to obtain crystal clear gels and can also be used to make milks, lotions and creams.

Sisterna also supplies sucrose-based emulsifiers that have Ecocert approval. They are non-ionic in character and by varying the degree of esterification of the sucrose molecule it is possible to obtain emulsifiers with HLB values ranging from 1 for the higher esterified esters up to 15 for the low esterified esters. Sisterna literature describes some interesting properties of the different esters. For example, at 5% Sisterna sucrose esters with mono-ester contents of 30% and higher give soft, water-dispersible gels, which are easy to use and give immediate foam. Foam volume is low, but skin-defatting is strongly reduced and the irritancy of anionic detergents is minimised. At 1.5% Sisterna sucrose esters provide controlled detergency while at the same time imparting mildness, a pleasant after-feel and good foaming properties. In this type of formulation sucrose esters are outstanding rheological modifiers. By increasing their level of use from 1% to 5%, flowing characteristics of formulations change considerably from fluid, easily pourable gels to viscous but easily dispersible ones.

Sasol is in the process of gaining Ecocert approval for its Imwitor emulsifiers that include polyglucoside esters, alkyl lactylates and citro/lactoglycerides such as glyceryl stearate citrate, glyceryl citrate/lactate/linoleate/oleate and glyceryl cocoate/citrate/lactate. Sasol also has a number of w/o emulsifiers including diisostearoyl polyglyceryl-3 dimer dilinoleate, polyglyceryl-2 dipolyhydroxystearate and isostearyl diglyceryl succinate. The Imwitor w/o emulsifiers are extremely mild and may be used for hot or cold processing. The citro/lactoglycerides are oil soluble and water dispersible and form stable o/w emulsions at pH 3 to 7. They enable a wide range of viscosities to be obtained and form liposomes in-situ providing some interesting formulation possibilities.

SOLUBILISING CHALLENGES

Solubilising essential oils without the use of ethoxylated materials constitutes a particular challenge. A lipoaminoacid obtained by acylation of fatty acids from coconut with proline gives Natisol [INCI: Cocoyl proline], produced by Sinerga and with Ecocert certification is in progress. For correct use it is suggested that it is mixed with the essential oil and then small increments of water are added while stirring until complete solubilisation is achieved. Occasional additions of sodium chloride could increase its solubilising capacity. Sinerga also markets two natural fragrances that have antimicrobial properties that may be of interest if formulating natural products. Also for solubilising essential oils, Natpure Sol from LCW is a mixture of sucrose esters with glycerine and sorbitol.

Through IMCD the French company Soliance supplies a number of Ecocertified materials amongst which are Xyliance [INCI: Cetearyl wheat straw glycerides and cetearyl alcohol], Joazirine [INCI: Zizyphus joazerio bark extract] and Tensolive [INCI: Olivamidopropyl betaine]. Xyliance is the result of combining xylose from wheat straw with cetearyl alcohol from vegetable oil. It has an HLB of 10.5, it forms liquid crystals and provides very stable o/w emulsions when used at 2% - 5% with polar and non-polar oils that are not affected by product pH. Zizyphus joazerio is a tree native to Brazil and the bark contains a large amount of natural foaming saponins with a high cleansing power and is traditionally used for shampoos, soaps and toothpaste.

From Symrise we have the intriguingly named Soap Nut Tree that produces small orange coloured drupes (a fruit in which an outer fleshy part surrounds a shell of hardened endocarp with a seed inside) 1cm - 2cm in diameter. These are wild harvested and are used locally for washing hair and clothes and for polishing jewellery. Symrise offers a 100% natural extract containing a minimum of 35% natural saponins as Neo Extrapone Soap Nutshell [INCI: Sapindus mukurossi peel extract], which is recommended for personal cleansing products including shower gels and shampoos. Another natural foaming material is Quillaia saponaria extract from Paroxite. It is 93% active and organically certified by USDA, is gentle enough to be left on the skin to leave a silky soft feel and is also an o/w emulsifier and pigment disperser.

A?GOOD STORY

For marketing purposes a story behind the plant helps sell the ingredient and a good story is attached to Amaranth from Arch Personal Care. Typical Amaranth plants are bushy, growing five to seven feet tall, with broad leaves and displaying a bright, showy flower head of small, red or magenta clover-like flowers. Amaranth was a staple food in the diets of pre-Colombian Aztecs, who believed it had supernatural powers and therefore incorporated it into their religious ceremonies. In Mexico and India it is used to make a confection and Peruvians use fermented amaranth seed to make beer. In the Cusco area the flowers are used to treat toothache and fevers and as a food colourant for maize and quinoa. In Nepal, amaranth seeds are eaten as gruel or milled into flour to make chapattis. In Ecuador, the flowers are boiled then the coloured boiling water is added to rum to create a drink claimed to purify the blood.

To obtain the surfactant, Amaranth powder is dispersed in water and enzymatically hydrolysed to produce a colloidal solution. Further filtration removes the insoluble components resulting in a clear, aqueous solution, high in hydrolysed amaranth proteins. Amaranth S is prepared by taking the resultant hydrolysed proteins and reacting them with naturally derived acylated fatty acids from coconuts. The reactive fatty acid group is covalently bonded to the protein chain as a result of this reaction. Alkaline base may be used to neutralise the carboxylic acid group, which produces the soluble foaming polypeptide, Amaranth S.

Amaranth S is non-ionic in nature, stable over a wide pH range and highly compatible with other ingredients. It provides excellent foam, foam density and stability even in the presence of salt. It is extremely mild and biodegradable. The presence of the protein base enhances substantivity to skin and hair, leaving behind an elegant, conditioned feel after rinsing.

Natural surfactants and emulsifiers are used as a part of natural cosmetics. Many cosmetics suppliers are now active in providing emollients, oils, fats and waxes, botanical extracts and active additives in order that the entire product can meet with Ecocert or similar approval. Evonik, Croda, A&E Connock, Adina, Cognis, Zschimmer & Schwarz, Soliance, Paroxite, S. Black, Univar, Rahn, Gattefossé and Chemlink each have a number of certified cosmetic ingredients and no doubt there are many others and will be many more.

Featured Companies

Rahn (more information, website)
Univar Solutions (more information, website)

See also