Extraction of Phenolic and Flavonoid Compounds from Mung Bean (Vigna radiata L.) Seed Coat by Pressurized Liquid Extraction

Mung bean seed coat (MBC) is a by-product of the mung bean processing industry. It contains a large number of phenolic compounds with therapeutic anti-inflammatory, anti-diabetic and antioxidant properties. This research aimed to investigate the optimum conditions for phenolic and flavonoid extraction from MBC by pressurized liquid extraction (PLE). Response surface methodology (RSM) was used to study the effects of temperature (80-160 degrees C), pressure (1200-1800 psi) and ethanol concentration (5-95%) on total phenolic content (TPC), total flavonoid content (TFC) and 2,2 '-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) scavenging activity (ABTS). Scale-up extraction was also performed. The optimum conditions for extraction were 160 degrees C, 1300 psi and 50% ethanol. Under optimum conditions, the TPC was 55.27 +/- 1.14 mg gallic acid equivalent (GAE)/g MBC, TFC was 34.04 +/- 0.72 mg catechin equivalent (CE)/g MBC and ABTS scavenging activity was 195.05 +/- 2.29 mg trolox equivalent (TE)/g MBC. The TFC and ABTS scavenging activity of the extracts obtained at the pilot scale (10 L) was not significantly different from the laboratory scale, while TPC was significantly increased. The freeze-dried MBC extract contained vitexin and isovitexin 130.53 +/- 17.89, 21.21 +/- 3.22 mg/g extract, respectively. In conclusion, PLE was able to extract phenolics, flavonoids with ABTS scavenging activity from MBC with the prospect for future scale-up for food industry.

Automated summary

This research investigated the optimal conditions for extracting phenolic and flavonoid compounds from mung bean seed coat using pressurized liquid extraction. The study found that this method can efficiently extract compounds with therapeutic and antioxidant properties. The results showed that under the optimal conditions, the extract had high levels of phenolic and flavonoid compounds and exhibited strong antioxidant activity.