The effect of extrusion pretreatment ultrasound-assisted extraction on chlorogenic acid from sweet potato stems and leaves

The study aimed to investigate the effect of extrusion on the yield of chlorogenic acid and the extrudate's physicochemical property from sweet potato stems and leaves and enhance the rational utilization of resources. Chlorogenic acid was obtained in an ultrasonic bath and a single-screw extruder following Box-Benhnken design and orthogonal array design. A desirable value (yield of CGA of 1.529%) was procured at low temperature (70 degrees C), low moisture content (21%), and intermediate screw speed (120 rpm), and ultrasonic bath condition was the volume fraction of ethanol solution of 40%, the solution/solid ratio of 40 ml/g, time of 50 min, temperature of 50 degrees C, and the IC(50)values of crude extract of chlorogenic acids was 0.168 mg/ml. The results suggested that sweet potato stems and leaves had the potential to become a new source of chlorogenic acids and was applied to functional food industry. Practical applications The effects of extrusion technique on the extraction of chlorogenic acid from sweet potato leaves and stems were studied. Sweet potato leaves and stems were discarded in the fields, whereas it is rich in bioactive substances. The cost can be reduced by utilization of extrusion technique on it. This paper can put forward some suggestions for food industry and environmental protection.