Study On Preparation Of Compound Solid Beverage Of Ziziphus Jujube And Its Activity Of Water-soluble Substance

Ziziphus jujube is a traditional Chinese medicine and food homologous plant,and its pulp and kernel have high nutritional value and medicinal value.At present,there are more and more researches on the development of ziziphus jujube food and its activity.Therefore,how to use the high-efficiency method to fully and effectively extract the active ingredients in the ziziphus jujube pulp and kernel is essential for the development of new products and the study of their activities.Ziziphus jujube food mainly had juice liquid beverage,so it is necessary to develop a nutritious,portable and preserved solid beverage that combines ziziphus jujube pulp with kernels.In this paper,three different methods,the water-soluble substances from ziziphus jujube pulp and the saponin from kernel,were optimized by single factor test and response surface test to obtain the best process conditions and the best method.The extract of ziziphus jujube pulp and kernel were freeze-dried,and the extract powder from ziziphus jujube pulp and kernel were mixed in a certain ratio and an appropriate amount of sweetener and stabilizer were added to prepare a solid beverage with the compound of ziziphus jujube.The antioxidant activities of the extract of ziziphus jujube pulp,compound of ziziphus jujube pulp and kernel was evaluated by in vitro antioxidant test and oxidative damage of HepG₂ cells.The main results are as follows:（1）The effects of three different extraction methods on the extraction rate of water-soluble substances in ziziphus jujube pulp:ultrasound-assisted enzymatic method>enzymatic hydrolysis method>ultrasonic method,the extraction rate were 74.49±1.00%,69.47±0.7%,67.05±0.52%,respectively.The best process conditions were:ultrasonic method:ultrasonic time 36.7 min,ultrasonic power 158W,ultrasonic temperature 60℃,liquid to material ratio 13:1（mL/g）;enzymatic hydrolysis method:liquid to material ratio11:1（mL/g）,amount of enzyme 2.5%,enzymatic hydrolysis time 1.6 h,enzymatic hydrolysis temperature 47°C;ultrasonic assisted enzymatic method:liquid to material ratio 13:1（mL/g）,amount of enzyme 2.1%,enzymatic hydrolysis time 1.2 h,ultrasonic time 29 min,ultrasonic power 146 W.（2）The effect of three different extraction methods on the extraction rate of saponins from ziziphus jujube kernel:ultrasound-assisted enzymatic method>enzymatic hydrolysis method>ultrasonic method,the extraction rate were 1.49±0.05%,1.37±0.03%,1.05±0.01%,respectively.The best process conditions were:ultrasonic method:liquid to material ratio 13:1（mL/g）,ultrasonic time 32 min,ultrasonic temperature 69°C,ultrasonic power 245 W;enzymatic hydrolysis method:liquid to material ratio 12:1（mL/g）,amount of enzyme 2.2%,enzymatic hydrolysis time 1.9 h,enzymatic hydrolysis temperature 50°C;ultrasound-assisted enzymatic method:liquid to material ratio 16:1（mL/g）,ultrasonic time 41 min,ultrasonic power 250 W,amount of enzyme 2.7%.（3）The compound ratio of the extract powder of ziziphus jujube pulp and ziziphus jujube kernel,the addition amount of sweetener and stabilizer as a single factor;the brewing,clarity,stability and sensory evaluation of solid beverage were used as indicators to optimize the preparation of solid beverage with the compound of ziziphus jujube,the best conditions were a compound ratio of 17:1,a sweetener of 4.3%,and a stabilizer of 2.3%.Under these conditions,after parallel test（n=3）,the actual average value was measured 80.11,which was similar to the predicted value（79.24）,which indicated that the experimental model could better reflected the relationship between each factor and the score of solid beverage.Under these conditions,the solid beverage prepared was stable in state,and has good mouthfeel and odor and color.（4）DPPH,ABTS,hydroxyl radical scavenging test and total reducing power in vitro antioxidant test proved that the extract of ziziphus jujube pulp and the compound of ziziphus jujube pulp and kernel had certain antioxidant properties.Using HepG₂ cell as a model,when the concentration of extract and compound extract of ziziphus jujube was1,2,3 mg/mL,both of them could protected the cells from oxidative damage induced by H₂O₂（2 mmol/L）,reduced the content of ROS and MDA in the cells,and increased the activity of glutathione peroxidase（GSH-PX）,and when the concentration was 2,3 mg/mL,they could significantly improved the activity of superoxide dismutase（SOD）.The result shows the extract of ziziphus jujube could enhanced the antioxidant capacity of cells,and the antioxidant activity of the compound extract of ziziphus jujube was slightly higher than the extract of ziziphus jujube pulp.