is a cationic peptide derived from natural sources, primarily produced by fermentation of Streptomyces albulus. It has gained popularity as a natural preservative due to its broad-spectrum antimicrobial activity and safety profile. However, the stability of ε-polylysine hydrochloride under various storage conditions is crucial for its efficacy and commercial viability.
Factors Influencing Stability:
Several factors can influence the stability of ε-polylysine hydrochloride during storage, including temperature, humidity, light exposure, pH, and interactions with other ingredients or packaging materials. Understanding these factors is essential for maintaining its stability and effectiveness.
Storage at Refrigeration Temperature:
Refrigeration temperature (2-8°C) is commonly employed for preserving food ingredients. Studies have shown that storing ε-polylysine hydrochloride under refrigeration conditions helps maintain its stability and functionality over an extended period. Low temperature inhibits degradation and microbial growth, thereby preserving the antimicrobial properties of ε-polylysine hydrochloride.
Storage at Ambient Temperature:
Storage at ambient temperature (typically around 25°C) is common in many food storage conditions. However, ε-polylysine hydrochloride may be susceptible to degradation and loss of activity when exposed to higher temperatures for extended periods. Studies have shown that the stability of ε-polylysine hydrochloride decreases significantly at ambient temperature compared to refrigeration.
Impact of Humidity and Light Exposure:
Humidity and light exposure can also affect the stability of ε-polylysine hydrochloride. High humidity can cause clumping or hygroscopicity, leading to reduced functionality. Additionally, exposure to light, particularly ultraviolet (UV) light, can induce degradation and loss of antimicrobial activity. Therefore, storing ε-polylysine hydrochloride in a dry and light-protected environment is recommended.
pH and Ingredient Interactions:
The pH of the storage environment and interactions with other ingredients or packaging materials can influence the stability of ε-polylysine hydrochloride. It is generally stable within a broad pH range (3-9), but extreme pH conditions may affect its stability and antimicrobial activity. Additionally, interactions with certain ingredients or packaging materials, such as metal ions or oxygen, can lead to degradation and reduced effectiveness.
Recommendations for Optimizing Storage:
To optimize the stability of ε-polylysine hydrochloride during storage, several recommendations should be followed. These include:
Storing ε-polylysine hydrochloride in airtight containers or packaging to minimize exposure to oxygen and moisture.
Avoiding direct light exposure by storing it in opaque or light-protected containers.
Maintaining a cool and dry storage environment to minimize temperature and humidity fluctuations.
Regularly monitoring the pH of the storage environment to ensure it remains within the recommended range.
Quality Control and Shelf Life Determination:
Regular quality control tests should be conducted to assess the stability and antimicrobial activity of ε-polylysine hydrochloride during storage. These tests may include measuring antimicrobial efficacy against target microorganisms, monitoring degradation or impurities, and evaluating physical and chemical properties. The shelf life of ε-polylysine hydrochloride can be determined based on these quality control tests and specific storage conditions.