Since natural-origin, sustainable ingredients are preferred by modern consumers, novel emulsifiers and emollients keep entering the market. This study hypothesizes that a combination of in silico, instrumental tools and simplified sensory studies could be used to efficiently characterize emulsions in a shorter timeframe. A total of 22 rather simple o/w emulsions were prepared by a time/energy-saving emulsification process. A natural mixed emulsifier (Lauryl Glucoside/Myristyl Glucoside/Polyglyceryl-6 Laurate) and two emollients (both with INCI name C15–19 Alkane) were used. The performed D-optimal experimental design within the response surface method (RSM) significantly narrowed down the number of samples about to enter the stage of texture, friction and sensory studies to the samples comprising 30% of a respective Emogreen emollient and 2% or 3% of the emulsifier. The sample comprising 2% emulsifier/30% Emogreen^® L15 showed significantly higher firmness (42.12 mN) when compared to the one with 2% emulsifier/30% Emogreen^® L19 (33.62 mN), which was somewhat unexpected considering the emollients’ inherent viscosity values (4.5 mPa·s for L15 and 9 mPa·s for L19). The sample with 2% emulsifier/30% Emogreen^® L19 managed to maintain the lowest friction, while the one with 3% emulsifier/30% Emogreen^® L19 released its full lubricating potential in the second part of the measurement (30–60 s). The obtained results revealed the strengths and weaknesses of each formulation, narrowing down their possible applications in the early development stage.

Bioactive peptides are promising cosmetic active ingredients that can improve skin health and appearance. They exhibit a broad spectrum of activity, including anti-aging, antioxidant, antimicrobial, and anti-inflammatory effects. The aim of this study was to develop a safe, stable, and efficacious environmentally friendly (“green”) emulsion using a milk protein hydrolysate as a model active ingredient. Potential emulsions were formulated with biodegradable emollients, stabilized with naturally derived mixed emulsifier, and prepared by cold process. They were evaluated for rheological behavior (continuous rotation and oscillation tests), physical stability (dynamic mechanical thermal analysis—DMTA test), and texture profiles, as well as cytotoxic, antioxidant, and antimicrobial effects. Rheological characterization revealed shear-thinning flow behavior with yield point from continuous rotation tests and predominantly elastic character from oscillation (amplitude and frequency sweep) tests, with small structural change detected in the DMTA test. These results implied satisfactory rheological properties and good stability. Texture analysis revealed acceptable spreadability and substantivity of the emulsions. The protein hydrolysate showed antioxidant activity. The developed emulsions showed low antibacterial activity against selected microorganisms, but this was due to the action of preservatives, not peptides. All potential emulsions showed a desirable safety profile. The results obtained provide the basis for the next stage of formulation development, i.e., in vivo efficacy tests.

Bioactive peptides are promising cosmetic active ingredients that can improve skin health and appearance. They exhibit a broad spectrum of activity, including anti–ageing, antioxidant, antimicrobial and anti–inflammatory. The aim of this study was to develop a safe, stable and efficacious environmentaly friendly ("green") emulsion using milk protein hydrolysate as a model active ingredient. Potential emulsions were formulated with biodegradable emollients, stabilised with a naturally-derived mixed emulsifier and prepared by cold process. They were evaluated for rheological behavior (continuous rotation and oscillation tests), physical stability (dynamic mechanical thermal analysis - DMTA test) and texture profiles, as well as for cytotoxic, antioxidant and antimicrobial effects. Rheological characterization revealed shear-thinning flow behaviour with yield point from continuous rotation tests and predominantly elastic character from oscillation (amplitude and frequency sweep) tests, with small structural change detected in the DMTA test. These results implied satisfactory rheological properties and good stability. Texture analysis revealed acceptable spreadability and substantivity of the emulsions. The protein hydrolysate showed antioxidant activity. The developed emulsions showed low antibacterial activity against selected microorganisms, but this was due to the action of preservatives, not peptides. All potential emulsions showed desirable safety profile. The results obtained provide the basis for the next stage of formulation development, i.e. in vivo efficacy tests.