66 TEXTURES
temperature. For tribological testing the waxes were melted onto a filter paper substrate. The wax samples were also incorporated into a basic emulsion at 5% w/w and the lubricating properties of each formulation analysed over a range of sliding speeds. Testing was performed on a rheometer (DHR2, TA Instruments) fitted with a flat plate measuring system. For the wax-in- emulsion comparisons the emulsion sample was coated onto a latex sheet. The results are summarised in Figure 1, Figure 2, and Table 1. A sensory analysis was conducted by 20 volunteers comparing waxes in 3% O/W emulsions against placebo. The placebo cream contained 3 % more MCT oil instead of wax. The specific parameters (viscosity, whitening, skin feel, richness, skin absorption, lubricity, and cushion effect) were rated on a score of 1 (not distinct characteristic) to 5 (distinct). The web charts show (Figure 4, 6, 7, 9) the difference of the score of the verum in relation to the placebo which is set to zero. Additionally, the viscosity of waxes in 3% O/W emulsions (identical formulations as used in the sensory analysis) was measured with a Brookfield Viscometer DV2T and summarised in Figure 3.
Tea wax Tea wax (INCI: Camellia Sinensis Leaf Wax) is a soft and medium-low melting wax with a dark-olive colour. It is derived from Camellia sinensis, which is a species of evergreen shrub whose leaves and leaf buds are used to produce tea. Camellia sinensis is native to East Asia, the Indian subcontinent, and Southeast Asia, but it is today cultivated across the world in tropical and subtropical regions. The crude wax covers the leaves, protecting them against mold, parasites, and loss of moisture. For decaffeinated tea, the leaves are treated with CO2
extraction to
reduce the caffeine content. As this extraction step also removes the wax from the leaves, tea wax is a side product of decaffeinated tea.
Rheology studies showed that tea wax,
60.000 50.000 40.000 30.000 20.000 10.000 0
Placebo Tea wax Berry wax Beeswax Rice bran wax Figure 3: Viscosity of O/W emulsions with 3 % waxes as measured by viscometer.
similar to beeswax, has a lower rigidity and slightly reduces the friction/dullness of a 5% wax cream. Tea wax also softens at skin temperature (32°C). However, the wax on itself is significantly less dull than beeswax. The similarities to beeswax can be attributed to the high amount of hydrocarbons (approx. 10%), which is comparable to beeswax, and leads to a soft texture. The sensorial analysis (Fig 4) showed a
perceived impact on viscosity of the formulation, which interestingly does not match up with the instrumental viscosity measurement. Furthermore tea wax improves skin absorption, lubricity, richness, and skin feel, leading to an overall improvement in sensorial properties. It makes emulsions more substantial, and its impact was perceived as similar to that of an emollient. While having no big influence on
hardness, tea wax increases the creaminess and perceived denseness of a finished formulation. It provides good oil-binding capacity with very polar and non-polar emollients. Remarkably, tea wax works excellently with paraffin oil.
Sunflower seed wax Sunflower seed wax (INCI: Helianthus Annuus viscosity lubricity whitening n Placebo n Tea wax
Seed Cera) is a pale wax with a high melting point of approximately 78°C, high hardness and an outstanding oil binding capacity. It is a side product of the manufacturing process of the edible oil obtained by milling unhulled seeds. After separation from the oil, degumming and winterisation, the crude wax is carefully refined. Sunflower seed wax contains mainly long chained wax esters of C16–C24 fatty acids and C26–C32 alcohols while being free of glycerol- and other polyalcohol esters. It also contains a minor amount of free fatty alcohols and hydrocarbons.
Sunflower seed wax showed the highest rigidity in the rheology studies and did not soften on skin contact. This is in line with its ability to create very hard and stable oleogels (anhydrous oil and wax pastes). While the observed dullness of the pure wax is similar to tea wax, it raises the friction of 5% wax creams, which is attributed to an increase in viscosity. Used in anhydrous formulations, e.g. stick
skin absorption skin feel richness Figure 4: Sensory profile of an O/W emulsion with 3% tea wax. PERSONAL CARE ASIA PACIFIC cushion effect
preparations, sunflower seed wax leads to very stable formulations, considerably improving viscosity and providing long-lasting shine, while having a very elegant skin-feel. The ability to create very strong oleogels can be explained by looking at its crystal structure. Various studies3, 4, 5, 6 found that sunflower wax has the tendency to form thin platelet crystals, piled upon each other, forming larger needle-like structures. This crystal morphology leads to the creation of a dense and sturdy network, which can effectively immobilise oil between its numerous thin platelet-like crystals, resulting in a strong and stable oil binding capacity. The morphology of sunflower wax is mainly attributed to the presence of long chain wax esters.4, 6 In aqueous formulations like O/W emulsions sunflower wax stabilises the oil phase and improves consistency and lubricity. However, it is often not able to generate a stable and complete network in emulsions, mainly because its crystals do not form co-crystals with other crystalline materials, such as emulsifiers and waxes. Depending on the other ingredients, the incomplete wax matrix can cause instabilities.
November 2019
Hydrolyzed sunflower wax
Viscosity (mPas)
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