Impact of natural deep eutectic solvents-based microalgae extracts on the stability and properties of skincare products
Podium 67
Presented by: Emilie Munnier
Introduction
Natural deep eutectic solvents (NaDES), as novel non-volatile green solvents have gained a positive momentum for cosmetic ingredients preparation from biomasses and are candidates to replace conventional solvents. The main interest of NaDES lies in their renewability and biodegradability. These green ionic liquid are prepared by mixing vegetal cellular constituent and metabolites such as sugars, polyols, aminoacids or organic acids. Their specific hydrogen-bond network confers high dissolution power combined with stabilizing ability, which make NaDES perfect media for sustainable valorization of vegetal biomasses. Their composition makes the resulting extracts truly biocompatible and then the solvent removal step in extraction processes becomes superfluous. In addition, NaDES can show intrinsic properties, like skin penetration enhancement, which is in favour of their conservation in the finished product.
In the present work, the potential impact of the introduction of this new type sustainable extracts in model cosmetic skincare products was explored, in terms of stability, rheology and sensory properties. Typical situations will be illustrated through examples of Arthrospira platensis microalgal extracts.
Methods
NaDES were prepared by mixing appropriate ratio of hydrogen bonding donors and acceptors. The mixture was heated at maximum 80°C and stirred until a homogenous liquid was obtained. Extraction studies and sensory analysis permitted to select adequate NaDES which were introduced in skincare gels and cream based on ingredients of natural origins (n=3). Resulting cosmetic formulations were characterized one day after preparation then after a stay of 30 days in an oven under accelerated aging conditions (40°C, 75% humidity, obscurity). For each stable sample, organoleptic characters, including colorimetry (CR 400 Chromameter, Konica Minolta), pH, viscosity (Brookfield DV1 Prime, low shearing rate) were measured. Rheology analyses were performed on the most interesting samples (rotational and oscillatory, Kinexus+ rheometer, Netzsch). Triangular tests were performed on a large naïve panel (n = 30) to establish if NaDES-containing products were sensorially different from control products. Sensory profiles were then performed by a small panel of experts (n=4).
Results and discussion
Twenty hydrophobic or hydrophilic NaDES compliant to European cosmetic regulation were eventually selected for formulation. Sensory analysis led to the exclusion of some of them, which showed pronounced inappropriate odours. NaDES were included in model products at concentrations from 1% to 10% wt/wt, depending on their polarity and the type of product. The impact on the pH of the product was significant for only 2 NaDES, containing specific amino-acids. The accelerated aging stability studies indicated that if cosmetic gels show a great stability, creaming was observed for some emulsions containing high concentrations of hydrophobic NaDES. Viscosity measurements and rheological studies showed that some NaDES can have a significant impact on the product consistency and that this impact is not necessarily directly proportional to their concentration. Sensory analysis showed that if hydrophobic NaDES in the oil phase have a low impact on the properties of the cream, the inclusion of specific hydrophilic NaDES in the aqueous phase or in cosmetics gels can have a positive impact on the sensory properties, like for example the reduction of the stickiness.
Conclusion
Various NaDES were incorporated in cosmetic formulation chassis to evaluate their impact on the stability, the physico-chemical and sensory properties. This study indicates that if some NaDES do not show appropriate formulability, several families of NaDES could be used to prepare vegetal extracts that can be introduced up to 2.5% in the oil phase of creams, or up to 10% in gels or water phase of emulsions. Moreover, the introduction of specific NaDES improved the properties of the model formulations. The results of this study are definitely in favour of the development of the exploration of NaDES as sustainable cosmetic ingredients.
Acknowledgments :
Conseil régional Centre val de Loire : PIERIC project funding in the frame of the ARD CVL Cosmetoscience research program (n° 2020 00141275)
References :
Wils, L., Hilali, S., Boudesocque-Delaye, L., Biomass Valorization Using Natural Deep Eutectic Solvents: What’s New in France? Molecules 2021, DOI: 10.3390/molecules26216556
Hilali, S., Wils, L., Chevalley, A. et al. Glycerol-based NaDES as green solvents for ultrasound-assisted extraction of phycocyanin from Arthrospira platensis—RSM optimization and ANN modelling. Biomass Conv. Bioref. (2022). https://doi.org/10.1007/s13399-021-02263-6
Natural deep eutectic solvents (NaDES), as novel non-volatile green solvents have gained a positive momentum for cosmetic ingredients preparation from biomasses and are candidates to replace conventional solvents. The main interest of NaDES lies in their renewability and biodegradability. These green ionic liquid are prepared by mixing vegetal cellular constituent and metabolites such as sugars, polyols, aminoacids or organic acids. Their specific hydrogen-bond network confers high dissolution power combined with stabilizing ability, which make NaDES perfect media for sustainable valorization of vegetal biomasses. Their composition makes the resulting extracts truly biocompatible and then the solvent removal step in extraction processes becomes superfluous. In addition, NaDES can show intrinsic properties, like skin penetration enhancement, which is in favour of their conservation in the finished product.
In the present work, the potential impact of the introduction of this new type sustainable extracts in model cosmetic skincare products was explored, in terms of stability, rheology and sensory properties. Typical situations will be illustrated through examples of Arthrospira platensis microalgal extracts.
Methods
NaDES were prepared by mixing appropriate ratio of hydrogen bonding donors and acceptors. The mixture was heated at maximum 80°C and stirred until a homogenous liquid was obtained. Extraction studies and sensory analysis permitted to select adequate NaDES which were introduced in skincare gels and cream based on ingredients of natural origins (n=3). Resulting cosmetic formulations were characterized one day after preparation then after a stay of 30 days in an oven under accelerated aging conditions (40°C, 75% humidity, obscurity). For each stable sample, organoleptic characters, including colorimetry (CR 400 Chromameter, Konica Minolta), pH, viscosity (Brookfield DV1 Prime, low shearing rate) were measured. Rheology analyses were performed on the most interesting samples (rotational and oscillatory, Kinexus+ rheometer, Netzsch). Triangular tests were performed on a large naïve panel (n = 30) to establish if NaDES-containing products were sensorially different from control products. Sensory profiles were then performed by a small panel of experts (n=4).
Results and discussion
Twenty hydrophobic or hydrophilic NaDES compliant to European cosmetic regulation were eventually selected for formulation. Sensory analysis led to the exclusion of some of them, which showed pronounced inappropriate odours. NaDES were included in model products at concentrations from 1% to 10% wt/wt, depending on their polarity and the type of product. The impact on the pH of the product was significant for only 2 NaDES, containing specific amino-acids. The accelerated aging stability studies indicated that if cosmetic gels show a great stability, creaming was observed for some emulsions containing high concentrations of hydrophobic NaDES. Viscosity measurements and rheological studies showed that some NaDES can have a significant impact on the product consistency and that this impact is not necessarily directly proportional to their concentration. Sensory analysis showed that if hydrophobic NaDES in the oil phase have a low impact on the properties of the cream, the inclusion of specific hydrophilic NaDES in the aqueous phase or in cosmetics gels can have a positive impact on the sensory properties, like for example the reduction of the stickiness.
Conclusion
Various NaDES were incorporated in cosmetic formulation chassis to evaluate their impact on the stability, the physico-chemical and sensory properties. This study indicates that if some NaDES do not show appropriate formulability, several families of NaDES could be used to prepare vegetal extracts that can be introduced up to 2.5% in the oil phase of creams, or up to 10% in gels or water phase of emulsions. Moreover, the introduction of specific NaDES improved the properties of the model formulations. The results of this study are definitely in favour of the development of the exploration of NaDES as sustainable cosmetic ingredients.
Acknowledgments :
Conseil régional Centre val de Loire : PIERIC project funding in the frame of the ARD CVL Cosmetoscience research program (n° 2020 00141275)
References :
Wils, L., Hilali, S., Boudesocque-Delaye, L., Biomass Valorization Using Natural Deep Eutectic Solvents: What’s New in France? Molecules 2021, DOI: 10.3390/molecules26216556
Hilali, S., Wils, L., Chevalley, A. et al. Glycerol-based NaDES as green solvents for ultrasound-assisted extraction of phycocyanin from Arthrospira platensis—RSM optimization and ANN modelling. Biomass Conv. Bioref. (2022). https://doi.org/10.1007/s13399-021-02263-6