Physiochemical cleansing properties of soapnut

This has been a gradual upward trend attributable to several factors, including a desire for sustainability, increased media coverage of the potential health side effects of some ingredients, and the demand for manufacturers to lower their environmental footprint. Natural soapnut extract meets the requirements of a surfactant while providing many additional benefits. Natural surfactants are carbohydratebased. They are plant-derived and use renewable resources, are readily biodegradable and do not add to the Earth’s CO2 burden. One example is Vivimed’s Nisarg Soapnut Extract, a very mild, biodegradable and skin friendly surfactant. Synthetic surfactants can be produced from oleo chemicals such as palm oil and are often called natural, while those derived from petrochemicals are synthetic. These types of surfactants can be harsh in their concentrated form giving rise to skin and scalp irritation. The type of surfactants formulators use has changed over time. For example traditional Ayurvedic treatments involve all natural surfactants. As time has progressed formulators have moved more towards synthetic surfactants, however today’s consumer is more aware of the irritating potential and environmental impact of synthetic materials and are more readily considering products which use natural surfactants derived from plants. Figure 1 shows how the surfactant trend has progressed from natural to synthetic and is now shifting back towards naturally derived products. Soapnut extract is commonly known as ritha and contains saponins which are responsible for its foaming properties. Soapnut saponins are extracted from the fruit of Sapindus mukurossi, belonging to family Sapindaceae. Saponins are a large family of structurally-related compounds of steroid or triterpenoid aglycone (sapogenin) linked to one or more oligosaccharide moieties by glycosidic linkage. The carbohydrate moiety consists of pentoses, hexoses, or uronic acids. The presence of both polar (sugar) and nonpolar (steroid or triterpene) groups provide saponins with strong surface-active properties. Their physiochemical and biological properties feature structural diversity which has led to a number of traditional and industrial applications. Many saponins exhibit distinct foaming properties. They can be added to shampoos, liquid detergents, toothpastes and beverages as emulsifiers and longlasting foaming agents. Formulators are often faced with the challenge of mimicking the aesthetics and performance characteristics of synthetic ingredients with natural alternatives. Customers desire a specific colour and feel from a product that is sometimes difficult to achieve with plant-derived ingredients. Aqueous extraction is commonly used to produce soapnut extract, however this type of extraction process results in a brown powder which can significantly affect the colour of finished formulations. Vivimed has developed a unique extraction process which removes the high level of dark coloured species without reducing the level of water soluble saponins. The resulting soapnut powder has a much lower residual colour than aqueous extracted material, and this is shown in Figure 2. Vivimed Labs investigated the performance characteristics of soapnut extract in comparison to commonly used synthetic surfactants, sodium lauryl sulfate (SLS) and sodium laureth sulfate (SLES). Parameters evaluated were pH, foam height, foam stability, mildness, detergency and volunteer performance comparisons.

pH

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. Alkaline surfactants induce a greater loss of protein from the skin surface leading to skin roughness, erythema, stinging sensations and pruritus than with water or acidic surfactants. The pH of skin is 4.5-5.5 which is weakly acidic. Table 1 shows the pH of soapnut extract lies with the natural pH range of the skin thus avoiding irritation and dryness caused by alkaline surfactants, making it a milder surfactant to incorporate in cleansing formulations.