Zhu Zhenzhou, Jiang Tian, He Jingren, Barba Francisco J, Cravotto Giancarlo, Koubaa Mohamed
College of Food Science and Engineering, Wuhan Polytechnic University, Wuhan 430023, China.
Nutrition and Food Science Area, Preventive Medicine and Public Health, Food Science, Toxicology and Forensic Medicine Department, Faculty of Pharmacy, Universitat de València, Avda. Vicent Andrés Estellés, s/n, 46100 Burjassot, València, Spain.
Molecules. 2016 Nov 20;21(11):1584. doi: 10.3390/molecules21111584.
This work provides an evaluation of an ultrasound-assisted, combined extraction, centrifugation and ultrafiltration process for the optimal recovery of polyphenols. A purple sweet potato (PSP) extract has been obtained using ultrasonic circulating extraction equipment at a power of 840 W, a frequency of 59 kHz and using water as solvent. Extract ultrafiltration, using polyethersulfone (PES), was carried out for the recovery of polyphenol, protein and anthocyanin. Pre-treatment, via the centrifugation of purple sweet potato extract at 2500 rpm over 6 min, led to better polyphenol recovery, with satisfactory protein removal (reused for future purposes), than PSP extract filtration without centrifugation. Results showed that anthocyanin was efficiently recovered (99%) from permeate. The exponential model fit well with the experimental ultrafiltration data and led to the calculation of the membrane's fouling coefficient. The optimization of centrifugation conditions showed that, at a centrifugation speed of 4000 rpm (1195× ) and duration of 7.74 min, the optimized polyphenol recovery and fouling coefficient were 34.5% and 29.5 m, respectively. The removal of proteins in the centrifugation process means that most of the anthocyanin content (90%) remained after filtration. No significant differences in the intensities of the HPLC-DAD-ESI-MS² peaks were found in the samples taken before and after centrifugation for the main anthocyanins; peonidin-3-feruloylsophoroside-5-glucoside, peonidin-3-caffeoyl--hydroxybenzoylsophoroside-5-glucoside, and peonidin-3-caffeoyl-feruloyl sophoroside-5-glucoside. This proves that centrifugation is an efficient method for protein removal without anthocyanin loss. This study considers this process an ultrasound-assisted extraction-centrifugation-ultrafiltration for purple sweet potato valorization in "green" technology.
本研究对一种超声辅助的提取、离心和超滤联合工艺进行了评估，以实现多酚的最佳回收。使用功率为840 W、频率为59 kHz的超声循环提取设备，以水为溶剂，获得了紫薯提取物。采用聚醚砜（PES）进行提取物超滤，以回收多酚、蛋白质和花青素。通过在2500 rpm下对紫薯提取物进行6分钟的离心预处理，与未离心的紫薯提取物过滤相比，多酚回收率更高，蛋白质去除效果令人满意（可用于后续用途）。结果表明，从渗透液中能有效回收花青素（99%）。指数模型与超滤实验数据拟合良好，并据此计算了膜的污染系数。离心条件优化结果表明，在4000 rpm（1195× ）的离心速度和7.74分钟的离心时间下，优化后的多酚回收率和污染系数分别为34.5%和29.5 m。离心过程中蛋白质的去除意味着过滤后大部分花青素含量（90%）得以保留。对于主要花青素芍药素-3-阿魏酰槐糖苷-5-葡萄糖苷、芍药素-3-咖啡酰-对羟基苯甲酰槐糖苷-5-葡萄糖苷和芍药素-3-咖啡酰-阿魏酰槐糖苷-5-葡萄糖苷，离心前后样品的HPLC-DAD-ESI-MS²峰强度没有显著差异。这证明离心是一种有效去除蛋白质且不损失花青素的方法。本研究认为该工艺是一种用于紫薯增值的“绿色”技术中的超声辅助提取-离心-超滤工艺。
