As part of the diploma thesis, we first determined the most optimal formulation of hair shampoo with whey. As primary surfactants (PAS), we tested sodium lauryl sulfate (SLS) and sodium laureth sulfate (SLES) as a less irritating alternative. In the first step, we determined their most optimal concentration. In the second step, we added a thickener (sodium chloride), and studied the most optimal ratio between the secondary PAS (cocamidopropylbetaine and cocamide diethanolamine (cocamide DEA)). Our goal was to add the minimal concentration of DEA, since its use is limited. In the end, we added liquid whey to the shampoos, where we wanted to add the highest concentration possible, as it has beneficial effects both on the skin and on the formulation itself. The most optimal shampoos with and without whey (as a control) were then evaluated with stability tests, in which viscosity (rotation, amplitude and frequency sweep), pH and organoleptic properties were determined. The shampoos were stored at room temperature and in a thermostatic chamber (40 ␃) for 6 weeks. We evaluated them at time 0, after 1 week, 2 weeks, 4 weeks and 6 weeks. We have found out that shampoos are stable, although no preservatives were added. The viscosity did not change over time, nor did the organoleptic characteristics. There was a slight increase in pH (0.5 units), which can be assessed as insignificant and we can conclude that shampoos are also chemically stable. Whey shampoos had a characteristic whey smell and a slight yellowish color, which could be covered with fragrances and dyes.
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