COSMETICS & PERSONAL CARE linkage . The carbohydrate moiety consists of pentoses , hexoses or uronic acids .
The presence of both polar ( sugar ) and non-polar ( steroid or triterpene ) groups provides saponins with strong surface-active properties . Their physicochemical and biological properties feature structural diversity , which has led to a number of traditional and industrial applications . Many saponins exhibit distinct foaming properties and can be added to shampoos , liquid detergents , toothpastes and beverages as emulsifiers and long-lasting foaming agents .
Soapnut in personal care
Aqueous extraction is commonly used to produce soapnut extract . However this type of extraction process results in a brown powder that can significantly affect the colour of finished formulations . By using alternative extraction techniques , it is possible to remove the high level of dark-coloured species present without reducing the level of water-soluble saponins . This will result in a soapnut powder with a much lower residual colour than aqueous extracted material .
The research team at James Robinson Speciality Ingredients has investigated the performance characteristics of soapnut extract in comparison to commonly used synthetic surfactants , sodium lauryl sulfate ( SLS ) and sodium laureth sulphate ( SLES ). The parameters used were pH , foam height , foam stability , mildness , detergency and volunteer performance comparisons .
Performance v . synthetics
When surfactants are applied on the skin , they interact with the skin ’ s structure , particularly with lipid and protein components , and may determine important skin toxicity at high concentrations .
The degree of skin damage by cleansing products depends on surfactant type , pH and product formulation . Our findings show that soapnut extract lies within the natural pH range of the skin , thus avoiding the irritation and dryness caused by alkaline surfactants , and making it a milder surfactant to incorporate in cleansing formulations .
Foam has an aesthetic utility in many detergent and personal care products . When comparing the foam height between 1 % solutions of SLS , SLES and soapnut extract , we found that the properties of soapnut are comparable to those of synthetic foaming agents .
Foam stability is an important parameter in cleansing formulations , as the rate of weakening defines the stability of the foam . Foam with R50 values higher than 50 % can be regarded as metastable . When comparing the R50 value of 1 % solutions of soapnut extract , SLS and SLES , the soapnut extract displayed a foam stability of 92 %, comparable to that of both SLS and SLES .
The degree of mildness of a surfactant-based product helps to indicate the level of potential irritation on the skin . Using the Zein solubility test method , an in vitro technique based on the solubilisation of waterinsoluble corn protein , we discovered that SLS has an irritancy potential four times greater than that of natural soapnut extract .
The primary function of a surfactant is its detergency ability . This can be calculated by measuring sebum removal from the hair . Our tests revealed that 80 % of sebum can be removed from the hair using a
1 % solution of soapnut extract . While slightly lower than the level removed by SLS and SLES , this indicates that soapnut extract is an effective detergent .
Performance comparison
We asked ten volunteers to blind-test two shampoos formulations , one containing soapnut extract and one containing SLES and to evaluate and score the formulations for colour and odour , speed of foam , amount of foam , foam stability , usage feel , after-feel and overall liking .
The subjective opinions confirmed the data produced within the laboratory and show that the performance of soapnut to be comparable to synthetic surfactants . Overall , the volunteers preferred the formulation using soapnut extract .
Our studies demonstrate how soapnut extract is a comparable natural alternative to commonly used synthetic surfactants . It is mild in its application and has been shown to perform as effectively as both SLS and SLES .
The challenge now is to incorporate natural ingredients into the products that consumers use at an affordable price . When it comes to creating a greener planet , it is key that researchers have the support to find innovative , cost-effective , practical solutions to help us shift away from the reliance on synthetic ingredients to more sustainable alternatives . ●
Jennie Teague
HAIR CARE TECHNOLOGY MANAGER
JAMES ROBINSON SPECIALITY INGREDIENTS
k + 44 1484 320500 J jennie . teague @ jrsi . com j https :// jrsi . com /
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