This study is concerned with the optimization of the manufacturing process of a hot water extract containing antioxidant activity from Lycium barbarum, traditionally known to have various physiological activities. For the establishment of the optimization process, the central composite design of response surface methodology(RSM) was used. Thirteen extraction processes were performed by encoding the independent variables, extraction temperature (65.9oC–94.1oC) and extraction time (2.59 hr–5.41 hr). As a result of the experiment, the optimal manufacturing conditions for the extract were 340.0 mg/100 g of GAE at an extraction temperature of 94.1oC and an extraction time of 5 hr. The maximum yield of flavonoids was 22.44 mg/100 g of HES at an extraction temperature of 94.1oC and an extraction time of 4 hr. The conditions for producing the extract with the maximum antioxidant capacity (DPPH 92.12%) were 90oC and 4.5 hr extraction time. Therefore, the optimal manufacturing process conditions for extracts containing total phenol content, flavonoid content, and DPPH radical scavenging activity, which are dependent variables, were extraction temperature of 90-95oC and extraction time of 4 hr, which were not significantly different from the actual values. Therefore, Lycium barbarum extract rich in total phenol and flavonoid content related to antioxidant function is expected to be used as a functional food and cosmetic material.

1. Introduction
2. Materials and methods
    2.1. Reagents and materials
    2.2. Preparation of Lycium barbarumextraction
    2.3. Surface response methodology
    2.4. Analysis of total phenolic compoundcontent
    2.5. Analysis of total flavonoid content
    2.6. DPPH radical scavenging activity
3. Results and discussion
    3.1. Extraction experimental results ofresponse surface methodolgy
    3.2. Validation of response surfacemethodology and the optimization oftotal phenol extraction
    3.3. The effect of extraction time andtemperature on total phenolcompound extraction
    3.4. The effect of extraction time andtemperature on total flavonoidsextraction
    3.4. The effect of extraction time andtemperature on DPPH radicalscavenging activity
4. Conclusion
References

• Ho-Jong You(Department of Naturopathy, Joongbu University) Corresponding author