When using l-alanyl-l-cystine in cosmetics, the following precautions should be taken:
I. Raw Material Quality Control
Purity Requirements: Ensure that the l-alanyl-l-cystine raw material used has a high purity, and the impurity content should comply with relevant standards. High-purity raw materials can ensure the effectiveness of l-alanyl-l-cystine in cosmetics and reduce adverse reactions that may be caused by impurities.
Reliable Source: Select a regular raw material supplier and require the provision of quality certification documents and relevant inspection reports of the raw materials to ensure the stability and safety of the raw material quality.
II. Compatibility Taboos
Avoid Contact with Oxidants: The sulfhydryl group (-SH) in l-alanyl-l-cystine has reducibility and is easily oxidized by oxidants, thus losing its activity. Therefore, in the formulation design, it should be avoided to use it together with strong oxidants such as peroxides, like hydrogen peroxide and benzoyl peroxide.
Pay Attention to the Interaction with Metal Ions: Certain metal ions, such as copper ions (Cu²⁺), iron ions (Fe³⁺), etc., may undergo complexation reactions with l-alanyl-l-cystine, affecting its stability and efficacy. Therefore, it is necessary to avoid the presence of a large amount of such metal ions in the formulation, or add appropriate metal ion chelating agents to prevent the occurrence of complexation reactions.
III. Control of Addition Amount
Balance between Efficacy and Safety: The addition amount of l-alanyl-l-cystine in cosmetics needs to be reasonably adjusted according to the specific product type and efficacy requirements. Generally speaking, an addition amount between 0.1% and 2% is more common. If the addition amount is too low, the expected efficacy, such as moisturizing and antioxidant effects, may not be achieved; while if the addition amount is too high, it may cause adverse reactions such as skin allergies and increase the irritation of the product.
IV. pH Value Range
Suitable pH Environment: The stability and existing form of l-alanyl-l-cystine will vary under different pH values. Usually, it has better stability and activity in a weakly acidic to neutral environment with a pH value of 5-7. Therefore, when formulating cosmetics, it is necessary to control the pH value of the product within this range by adding appropriate acid-base regulators to ensure that the efficacy of l-alanyl-l-cystine can be fully exerted.
V. Production Process
Temperature Control: During the production process of cosmetics, it is necessary to avoid high-temperature treatment of the formulation containing l-alanyl-l-cystine, because high temperatures may cause it to decompose or denature, affecting its efficacy. It is generally recommended to control the production temperature below 40°C, especially when adding it in the final stage, more attention should be paid to the control of the temperature.
Stirring Speed and Time: When adding l-alanyl-l-cystine to the cosmetic matrix, the stirring speed and time should be controlled well. Excessive stirring may cause damage to its molecular structure and affect the product quality. Usually, a gentle stirring method is adopted, and the stirring time depends on the specific formulation and equipment conditions, generally about 10-30 minutes, to ensure that it is evenly dispersed in the product.
VI. Product Stability
Accelerated Stability Test: In the product development stage, it is necessary to conduct an accelerated stability test on cosmetics containing l-alanyl-l-cystine. By placing the product under conditions such as high temperature and high humidity, observe the changes in its appearance, smell, pH value, microbial indicators, etc. within a certain period of time to evaluate the stability of the product during the shelf life. If problems such as delamination, discoloration, peculiar smell, pH value fluctuation, or excessive microbial content are found in the product, the formulation or production process needs to be adjusted in a timely manner.
Selection of Packaging Materials: l-alanyl-l-cystine is quite sensitive to light, oxygen, and moisture, and is easily deteriorated by external environmental factors. Therefore, appropriate packaging materials should be selected, such as plastic bottles, glass bottles, or aluminum tubes with good barrier properties, and sealed packaging should be used to prevent the product from contacting air, light, and moisture, and to extend the product's shelf life.
VII. Safety Assessment
Toxicological Testing: Before applying l-alanyl-l-cystine to cosmetics, comprehensive toxicological tests need to be carried out, including acute toxicity, skin irritation, eye irritation, sensitization, and other tests. These tests should be carried out in accordance with relevant international and domestic standards to ensure that the product has no obvious toxic and side effects and irritation to the human skin and eyes.
Human Trial Evaluation: Before the product is launched on the market, it is advisable to conduct a human trial evaluation of a certain scale. Select volunteers with different skin types, ages, and genders, and let them use cosmetics containing l-alanyl-l-cystine for a period of time. Observe and record their usage feelings and skin reactions, such as whether there are uncomfortable symptoms such as redness, itching, and dryness. According to the trial results, further optimize the product formulation and usage instructions to ensure the safety and applicability of the product.
