Evaluation of physicochemical properties of day and night cream for oily and combination skin

Mastna in mešana koža potrebuje za razliko od suhe kože manj sestavin, ki jo varujejo pred izsuševanjem, potrebuje pa več sestavin za njeno pravilno uravnavanje (regulacija izločanja sebuma). Za učinkovito nego vsakega tipa kože je pomembna uporaba dnevne in nočne kreme. Cilj diplomske naloge je razvoj in vrednotenje dnevnih in nočnih krem za mastno in mešano kožo, pri čemer želimo izdelati kremo z ustrezno stabilnostjo in boljšo razmaznostjo, kot jo imajo kreme proizvajalca Naravna kozmetika Meze, ki so že na trgu. Na osnovi prvotnih formulacij dnevne in nočne kreme, ki sta že na trgu, smo za posamezni tip kreme (dnevna, nočna) ohranjali delež hidrofilne in lipofilne faze, spreminjali pa smo vrsto olja in emulgatorje. Izdelali smo sedem vzorcev krem (vključno s prvotnima formulacijama dnevne in nočne kreme) in jih testirali z vidika stabilnosti, da bi preverili njihovo obstojnost, saj kreme uvrščamo med fizikalno nestabilne emulzijske sisteme. Fizikalno stabilnost smo vrednotili z neizotermnimi testi staranja (temperaturno ciklanje). Pred izvedbo cikličnih testov stabilnosti smo vzorcem pomerili reološke lastnosti – viskoznost in jih izpostavili preliminarnim testom centrifugiranja. pH vrednosti krem, ki smo jih določili pred izvedbo stabilnostnih testov, med njimi in po njih so ostale v sprejemljivem pH območju med 4 in 6,5. Prav tako ni prišlo do organoleptično zaznavnih sprememb pri nobeni formulaciji. Viskoznost spremenjenih formulacij dnevnih in nočnih krem se je v primerjavi s prvotnimi formulacijami nekoliko povečala, z izjemo formulacije dnevne kreme D3, pri kateri smo zamenjali emulgator. Rezultati testa razmaznosti, ki smo jih določali z optimizirano metodo dveh vzporednih plošč, so pokazali da zamenjave sestavin v formulacijah dnevnih krem niso povzročile sprememb v njihovi razmaznosti. Formulaciji nočnih krem, pri katerih smo zamenjali vrsto olja (N2 = mandljevo olje namesto konopljinega, N3 = šipkovo olje namesto jojobinega) pa sta izkazali boljšo razmaznost v primerjevi s prvotno formulacijo.S tem je bil dosežen tudi naš cilj izdelati kremo z boljšo razmaznostjo, primerljivo viskoznostjo in ustrezno stabilnostjo.As opposed to dry skin, oily and combination skin requires less ingredients that protect it from drying out. It does, however, need more ingredients for skin control (regulation of sebum secretion). For efficient care of all skin types the use of both day and night creams is essential. The main aim of the present diploma thesis is the development and evaluation of day and night creams for oily and combination skin whereby we want to produce cream with adequate stability and better spreadability than the creams of brand Natural cosmetics Meze that are already on the market. Based on the initial recipes of day and night creams that are already on the market, the ratio between water and oil phases per cream type (day, night) was kept, whereas the oils and emulsifiers were changed. We made seven samples of cream (including the original formulations of day and night cream) and tested them from the point of stability in order to verify their persistance, because creams are classified as physicaly unstable emulsion systems. The physical stability was evaluated with non – isothermal aging test (temperature cycling). Before performing the cyclic stability tests the rheological properties of the samples were tested, i.e. viscosity, and the samples were subjected to preliminary tests with the use of a centrifuge. The pH values of creams, which were determined before, during and after carrying out the stability tests were within the acceptable range between 4 and 6,5. No organoleptic changes were detected in any of the formulations. The viscosity of modified formulations of day and night creams increased slightly compared to the original formulations, with the exception of day cream D3 in which emulsifier was replaced. The results of spreadability test which we determined by use of an optimised method of two parellel plates, showed that the replacement of ingredients did not show the changes in their spredability. The formulations of night creams in which oil was replaced (N2 = almond oil instead of hemp oil, N3 = rose hip oil instead of jojoba oil) showed better spredability than the original formulation of night cream.With this results we achieved our goal to produce cream with better spredability, comparable viscosity and adequate stability