Li Zheng, Zeng Jijiao, Tong Zhaohui, Qi Yajing, Gu Liwei
Food Science and Human Nutrition Department, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, FL 32611, United States.
Agricultural and Biological Engineering Department, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, FL 32611, United States.
Food Chem. 2015 Dec 1;188:337-42. doi: 10.1016/j.foodchem.2015.05.021. Epub 2015 May 6.
Depolymerization of procyanidin polymers into oligomers enhances their bioavailability and bioactivity because oligomers are bioavailable. Hydrogenolysis was applied in this study to depolymerize hi-tannin sorghum bran procyanidin polymers into oligomers. The yield and composition of oligomers under different hydrogenolysis conditions was investigated. Results showed that raising temperature from 50 to 100 °C significantly increased total yield of oligomers. Higher temperatures (150 and 200 °C) produced monomers with lower yield. The highest yield of oligomers (38.8%) was obtained using 1 MPa hydrogen whereas 3 MPa hydrogen in reaction vessel decreased yield. Total yield of oligomers reached the highest at 1-3 h and then decreased with prolonged reaction time. Yield increased with palladium-on-carbon (Pd/C, a catalyst) amount from 0.5 to 3 mg and plateaued with Pd/C amount from 3 to 10 mg. The maximum yield of produced oligomers was achieved under 100 °C, 1 MPa hydrogen pressure, 1-3 h, and 3-10 mg Pd/C.
原花青素聚合物解聚为低聚物可提高其生物利用度和生物活性，因为低聚物具有生物可利用性。本研究采用氢解反应将高单宁高粱麸皮中的原花青素聚合物解聚为低聚物。研究了不同氢解条件下低聚物的产率和组成。结果表明，将温度从50℃提高到100℃可显著提高低聚物的总产量。较高温度（150℃和200℃）产生的单体产率较低。使用1MPa氢气时低聚物的产率最高（38.8%），而反应容器中3MPa氢气会降低产率。低聚物的总产量在1-3小时达到最高，然后随着反应时间延长而降低。产率随钯碳（Pd/C，一种催化剂）用量从0.5mg增加到3mg而增加，在Pd/C用量从3mg增加到10mg时趋于平稳。在100℃、1MPa氢气压力、1-3小时和3-10mg Pd/C条件下可实现所产生低聚物的最大产率。
