Development of a new home-care detergent: experimental design in the optimization of performances and study on the safety of use through physico-chemical and toxicological data

Manual dishwashing is still used by a great portion of the households. The formulation of a new dishwashing detergent was optimized with the aim of obtaining a product which could be effective in the field of detergency, but at the same time could be safely used without the need to wear gloves. The development process involved the chemical analysis of the market leaders in the home-care detergent field and therefore the identification of the main parameters to be satisfied: dry residue>10%, as an index of the amount of surfactants in the formulation, and viscosity>800 mPa·s. On the basis of these preliminary data, a formulation hypothesis was implemented and then further tuned by an experimental design strategy. The selected factors were the percentages of the surfactants sodium lauryl sulfate, cocamidopropyl betaine, disodium capryloyl glutamate and of potassium cocoate soap. The investigated responses consisted in foam formation, as an index of the emulsifying capacity and therefore of cleaning performance; viscosity, identified as an organoleptic characteristic appreciated by the consumers; variation of the degree of skin hydration when the product is applied, as an index of safety of use; pH, due to its role in both solution equilibria and product conservation. A Central Composite Design was employed for calculating the quadratic models relating the factors to the responses and contour plots were drawn. For all the responses a target value was fixed and sweet spot plots made it possible to identify the zone where all the responses were simultaneously optimized. An optimum point was identified and the corresponding formulation was prepared, verifying the agreement between the measured and predicted responses. The suitability of the new formulation was assessed through the execution of stability tests, pH monitoring and organoleptic properties evaluation. In order to ascertain the safety of use of the new product, both a theoretical study based on Margin of Safety (MOS) and a measurement of the variation of skin hydration caused by the application of the developed formulation were carried out, confirming the good safety properties of the novel formulation.