Low-pH Skin Care Composition for HCA Solubility and Stability
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Solution Overview
Problem
Hydroxycinnamic acids (HCAs) exhibit poor solubility and stability in conventional aqueous skin care compositions, particularly at low-pH levels, leading to undesirable crystal formation, oxidation, and reduced efficacy.
Innovation Solution
Formulating a low-pH skin care composition with a combination of polar emollients and co-solvents having a Hansen solubility parameter distance of less than 15 from HCA, along with optional ingredients like vitamin B3 compounds and sensory improving agents, to enhance solubility and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If hydroxycinnamic acid is used in conventional aqueous skin care compositions at neutral pH, then the composition provides antioxidant benefits, but the HCA oxidizes or degrades causing undesirable color changes, odors and reduced efficacy
Solution Approach 1:
The patent applies parameter changes by adjusting the pH of the composition to pH 5.0 or less. This pH adjustment stabilizes the hydroxycinnamic acid, preventing oxidation and degradation that would otherwise cause color changes, odors, and reduced efficacy. The low-pH environment maintains HCA integrity while still providing antioxidant benefits.
2Reliability
If the composition is formulated at lower pH to stabilize HCA, then HCA stability improves, but HCA solubility decreases leading to crystal formation
Solution Approach 1:
The patent uses an intermediary approach by incorporating specific solubilizing agents into the low-pH composition. These agents mediate between the low-pH environment (which stabilizes HCA) and the solubility requirement. The solubilizing agents enable HCA to remain dissolved and stable simultaneously in the pH 5.0 or less environment, preventing crystal formation while maintaining stability.
3Stability of the object's composition
If HCA is added to the oil phase to increase solubility, then HCA solubility improves, but the sensory profile of the composition is adversely affected due to introduction of oils and additional emulsifiers
Solution Approach 1:
The patent employs water-soluble solubilizing agents instead of oil-phase incorporation. These agents allow HCA to remain soluble in the aqueous phase without requiring additional oils or emulsifiers that would degrade the sensory profile. The approach uses minimal, targeted ingredients to achieve solubility while preserving the desired sensory characteristics of the composition.
4Stability of the object's composition
If encapsulation is used to increase HCA solubility, then HCA solubility improves, but the amount of hydroxycinnamic acid in the composition is reduced due to encapsulate loading limits
Solution Approach 1:
The patent uses parameter changes in the form of chemical solubilizing agents rather than physical encapsulation. This approach allows higher concentrations of hydroxycinnamic acid to be achieved directly in the aqueous phase by modifying the chemical environment (pH and solubilizing agents) rather than being constrained by the loading capacity of encapsulation vehicles. The result is higher effective HCA concentration without the limitations of encapsulation technology.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The composition achieves stable and effective delivery of HCAs without crystal formation, maintaining sensory appeal and efficacy, suitable for improving skin appearance and health.
Implementation Method 1
from about 1.5% to less than 20% of a co-solvent with a Hansen solubility parameter distance of less than 15 from the—hydroxycinnamic acid (HCA)
Implementation Method 2
when HCA is used at neutral pH (e.g., pH 5.0-8.0), which is common for skin care compositions, the HCA may oxidize or degrade, causing undesirable color changes, odors and/or reduced efficacy of the product
Data Source
AI summary
Low-pH, aqueous skin care composition, comprising: a) about 0.1% to about 10% of a hydroxycinnamic acid (HCA); b) about 0.1% to about 10% of a polar emollient; c) from about 1.5% to less than 20% of a co-solvent with a Hansen solubility parameter distance of less than 15 from the—hydroxycinnamic acid (HCA); and d) water, wherein the pH of the composition is about 5.0 or less, and wherein the composition meets at least one of the following conditions (i)-(iii): (i) the composition further contains from about 0.1% to about 10% of a vitamin B3 compound; (ii) the weight ratio between HCA and the polar emollient is from about 1:1 to about 1:10; and (iii) the composition further contains from about 0.1% to about 5% of a sensory improving ingredient selected from the group consisting of: sugar alcohols, sugar-based emulsifiers, modified sugar derivatives, and mixtures thereof.