关键词: 响应面法, 防晒因子（SPF）值, 酪氨酸酶抑制, 成本核算, 协同效应

Abstract:

Objective: To achieve the large-scale and high-value utilization of olive pomace by-products, this study aims to develop an efficient and low-cost scaled-up extraction process for polyphenols. The extraction kinetics, economic feasibility, photoprotective properties such as UV absorption and tyrosinase inhibition activity of the polyphenol extracts were systematically evaluated, thus providing a theoretical basis and technical support for the high-value industrial application of olive pomace in cosmetics. Method: Total polyphenols were extracted from olive pomace by heated reflux extraction method with ethanol as the solvent. The extraction process parameters (extraction time, temperature, solid-liquid ratio, ethanol volume fraction) were optimized by single factor test and Box-Behnken response surface method. Further scale-up extraction experiments were conducted under optimized process conditions. The multiple models such as the Fick's diffusion, pseudo-first-order, and pseudo-second-order kinetic models were used to fit the scale-up extraction process, which revealed the release mechanisms of total polyphenols and eight monomeric polyphenols, such as hydroxytyrosol and tyrosol, from olive pomace. Lifecycle costing analysis method was used to calculate the levelized cost of production of large-scale production. The sun protection factor (SPF) value and tyrosinase-inhibition of the olive polyphenol extracts were determined, and the synergistic effects of binary combinations of its monomeric polyphenols in the polyphenol extract were investigated. Result: The optimum extraction conditions for polyphenols from olive pomace were established as follows: 70% ethanol, a solid-liquid ratio of 1∶25 g·mL^?1, extraction temperature of 98 °C, and extraction time of 77 min. Under these optimized conditions, the actual polyphenol yield was 5.67 mg·g^?1, showing a minor relative error of only 2.4% compared to the predicted value (5.81 mg·g^?1). The regression model demonstrated an excellent fit (R²>0.9, P<0.000 1). Kinetic analysis revealed distinct extraction patterns for different polyphenols. The Fick diffusion model best described the extraction of tyrosol and syringic acid (R²>0.97). The extraction process for rutin and luteolin was most accurately fitted by the first-order kinetic model (R²>0.97), while the second-order kinetic model was able to accurately reflect the extraction patterns of hydroxytyrosol, chlorogenic acid, caffeic acid, oleuropein, and total polyphenols (R²>0.92). The results of cost-effectiveness analysis showed that by reducing the solvent volume and ethanol concentration such as solid-liquid ratio to 1∶10 and the ethanol concentration to 10% of the extraction system, the unit production cost was greatly reduced from 330 yuan·kg^?1 to 92 yuan·kg^?1, whereas the polyphenol extraction yield was kept at 4.21 mg·g^?1. The functional evaluation revealed that the polyphenol extract obtained under the optimal process (1.0 mg·mL^?1) exhibited significant sun protection behavior (SPF of 15.21) and tyrosinase-inhibition (72.14%). After cost-effective optimization, the SPF value decreased marginally by 7.2% (14.12), whereas the tyrosinase-inhibition rate remained at a high level (61.11%), comparable to that of the positive control. Furthermore, Luteolin was identified as the key contributor to the photoprotective synergy, as demonstrated by its combination with oleuropein at a 5∶1 ratio (SPF 11.95, SE 10.39), whereas the combination of ferulic acid and hydroxytyrosol at a 4:3 ratio had the strongest synergistic effect on tyrosinase-inhibition (inhibition rate 72.95%, SE 1.79). Conclusion: This study has successfully established an efficient and low-cost extraction process of polyphenols from olive pomace, which has significant potential for industrial application and market competitiveness. The polyphenol extracts from olive pomace have significant sunscreen and whitening efficacy, showing a considerable potential for development and application in the field of polyphenol-based cosmetics.

Key words: response surface method, sun protection factor (SPF) value, tyrosinase inhibition, cost accounting, synergistic effect