FRCFT, School of Biosystems Engineering, University College Dublin, National University of Ireland, Agriculture and Food Science Centre, Belfield, Dublin 4, Ireland.
FRCFT, School of Biosystems Engineering, University College Dublin, National University of Ireland, Agriculture and Food Science Centre, Belfield, Dublin 4, Ireland.
Ultrason Sonochem. 2014 Jul;21(4):1461-9. doi: 10.1016/j.ultsonch.2014.01.029. Epub 2014 Feb 21.
The effects of acoustic energy density (6.8-47.4 W/L) and temperature (20-50 °C) on the extraction yields of total phenolics and tartaric esters during ultrasound-assisted extraction from grape marc were investigated in this study. The ultrasound treatment was performed in a 25-kHz ultrasound bath system and the 50% aqueous ethanol was used as the solvent. The initial extraction rate and final extraction yield increased with the increase of acoustic energy density and temperature. The two site kinetic model was used to simulate the kinetics of extraction process and the diffusion model based on the Fick's second law was employed to determine the effective diffusion coefficient of phenolics in grape marc. Both models gave satisfactory quality of data fit. The diffusion process was divided into one fast stage and one slow stage and the diffusion coefficients in both stages were calculated. Within the current experimental range, the diffusion coefficients of total phenolics and tartaric esters for both diffusion stages increased with acoustic energy density. Meanwhile, the rise of temperature also resulted in the increase of diffusion coefficients of phenolics except the diffusion coefficient of total phenolics in the fast stage, the value of which being the highest at 40 °C. Moreover, an empirical equation was suggested to correlate the effective diffusion coefficient of phenolics in grape marc with acoustic energy density and temperature. In addition, the performance comparison of ultrasound-assisted extraction and convention methods demonstrates that ultrasound is an effective and promising technology to extract bioactive substances from grape marc.
本研究考察了声能密度（6.8-47.4 W/L）和温度（20-50°C）对超声辅助提取葡萄渣中总酚和酒石酸酯提取率的影响。超声处理在 25 kHz 超声浴系统中进行，50%的乙醇水溶液用作溶剂。初始提取率和最终提取产率随声能密度和温度的升高而增加。采用双位动力学模型模拟提取过程动力学，采用基于菲克第二定律的扩散模型确定葡萄渣中酚类物质的有效扩散系数。两种模型都给出了令人满意的数据拟合质量。扩散过程分为快速阶段和缓慢阶段，计算了两个阶段的扩散系数。在当前实验范围内，总酚和酒石酸酯的扩散系数随声能密度的增加而增加。同时，温度的升高也导致除快速阶段的总酚扩散系数外，酚类物质的扩散系数增加，其值在 40°C 时最高。此外，还提出了一个经验方程来关联葡萄渣中酚类物质的有效扩散系数与声能密度和温度的关系。此外，超声辅助提取与常规方法的性能比较表明，超声是从葡萄渣中提取生物活性物质的一种有效且有前途的技术。
