| Xinjiang Jun jujube is rich in nutrition and high yield,but its intensive and deep processing is limited,which is not conducive to the value-added and sustainable development of Jun jujube industry.For this reason,the bioactive cyclic adenosine monophosphate（c AMP）in Jun jujube was extracted by deep eutectic solvent（DES）,purified by macroporous resin,and its stability was studied.The details are as follows:1.Ultrasound-assisted extraction of c AMP from Jun jujube by choline chloride base DES.（1）With choline chloride as hydrogen bond acceptor,ultrasonic assisted technology was used to screen hydrogen bond donors suitable for c AMP and construct DES.Through single factor experiment and response surface optimization experiment,the optimal extraction conditions of c AMP were determined.Choline chloride and glycerin were used as extraction agent,and the mole ratio of the two was 1:3,the water content of DES system was 44%,the solid-liquid ratio of Jun jujube powder to DES was 1:35 g/m L,the ultrasonic time was45 min,the ultrasonic temperature was 45℃,and the extraction amount of c AMP was（284.15±0.06）μg/g.（2）For c AMP crude extract,the macroporous adsorption resin was used to separate and purify it.Through static/dynamic adsorption and desorption experiments,H103 was determined to be the macroporous resin suitable for c AMP.The optimal conditions for c AMP static adsorption were as follows:solid-liquid ratio1:50,temperature 25℃,shaking table 1140 min;The optimal conditions for static desorption were 50%ethanol solution,25℃,shaking table 50 min;The purity of c AMP under these conditions was about 75%.The optimal conditions of c AMP dynamic adsorption were as follows:loading flow rate 2 m L/min,loading concentration 45μg/m L,loading volume 36 m L;The optimal conditions for dynamic desorption were as follows:the elution flow rate was 4 m L/min,the eluent was 40%ethanol,and the elution volume was 52 m L;The purity of c AMP under these conditions was about 84%.The adsorption isotherm of c AMP for H103macroporous resin was more consistent with Temkin-Pyzhev thermodynamic model equation.The adsorption kinetics study showed that the quasi-first-order kinetic model could better predict the adsorption kinetics of H103 macroporous resin.2.Ultrasound-assisted extraction of c AMP from Jun jujube by betaine base DES.（1）With betaine as hydrogen bond acceptor,ultrasonic assisted technology was used to screen hydrogen bond donors suitable for c AMP and construct deep eutectic solvent system.Through single factor experiment and response surface optimization experiment,the optimal extraction conditions of c AMP were determined.Betaine-ethylene glycol was used as extraction agent,and the molar ratio of the two was 1:3,the water content of DES system was 42%,the solid-liquid ratio of Jun jujube powder to DES was 1:50 g/m L,the ultrasonic time was 56 min,the ultrasonic temperature was 49℃,and the extraction amount of c AMP was（319.36±0.03）μg/g.（2）For c AMP crude extract,the macroporous adsorption resin was used to separate and purify it.Through static/dynamic adsorption and desorption experiments,H103 was determined to be the macroporous resin suitable for c AMP.The optimal conditions for c AMP static adsorption were as follows:solid-liquid ratio1:50,temperature 35℃,shaking table 1440min;The optimal static desorption conditions were 50%ethanol solution,35℃,160 min shaker;The purity of c AMP under these conditions was about 80%.The optimal conditions of c AMP dynamic adsorption were as follows:loading flow rate 1 m L/min,loading concentration45μg/m L,and loading volume 26 m L;The optimal conditions for dynamic desorption were as follows:the elution flow rate was 4 m L/min,the eluent was 40%ethanol,and the elution volume was 100 m L;The purity of c AMP under these conditions was about 71%.The adsorption isotherm of H103 macroporous resin for c AMP was more consistent with Langmuir thermodynamic model equation.The adsorption kinetics study showed that the diffusion kinetics model could better predict the adsorption kinetics of H103 macroporous resin.3.Study on stability of c AMP.The effects of sterilization method,light,storage temperature,p H,metal ions and additives on c AMP stability were investigated.The results showed that illumination,Mg2+,Al3+,xylitol and D-isoascorbate had little effect on c AMP stability.With the extension of time,the higher concentration of Ca2+,vitamin C,aspartame and maltodextrin led to the greater c AMP loss rate;High temperature and high pressure sterilization reduced c AMP content by about 7%;The lower the storage temperature is,the more stable c AMP is;The stability of c AMP was the best at p H2 or p H12.0.008%potassium sorbate solution can maintain the stability of c AMP for a long time. |
