Extraction And Purification Of Flavonoids From Mung Bean Skin And Changes Of Flavinoid Characteristics Under Different Storage Conditions

Flavonoids are a type of natural products commonly found in nature,also known as flavonoids or flavonoids.Flavonoids are one of the main metabolites of mung beans,and have rich biological activity functions such as antioxidant,anti-inflammatory and hypoglycemic.The flavonoids have poor storage properties and are easily oxidized and degraded.Therefore,it is particularly important to explore the modified atmosphere storage of mung beans to reduce the loss of active ingredients.In this experiment,Ming mung beans and No.5 Lv feng mung beans were used as raw materials to prepare flavonoid extracts.Ultrasonic microwave with extraction technology was used to prepare flavonoid extracts.The AB-8 macroporous adsorption resin was used to purify the crude extracts.FTIR infrared spectroscopy and scanning electron microscopy were used to analyze the compounds before and after purification.Applied high-resolution mass spectrometry and ultra-high performance liquid chromatography to qualitative and quantitative analysis on flavonoids under various storage conditions.Finally,the antioxidant test in vitro was used to study the activity changes of flavonoids in Ming mung beans and No.5 Lv feng mung beans under different storage conditions.The specific results of this research are shown as followings.?1?Used Ultrasonic-microwave to synergistically extract the total flavonoids from mung bean skin under various storage conditions and discussed the relationship between the various factors such as ethanol concentration,solid-liquid ratio,temperature and the extraction rate of total flavonoids through a single factor experiment.The optimal technique conditions for ultrasonic-microwave with extraction were found by Method of Response Surface: the ethanol concentration was 61%,solid-liquid ratio was 31.4 m L/g,the time was 25.8 min,and with 521 W of the microwave power.Under these conditions,the extraction rate of flavone could reach up to 6.867%.?2?The optimal conditions for dynamic adsorption of AB-8 macroporous adsorption resin,which was obtained by analyzing the results of orthogonal test,were as followings: the sample concentration is 1 mg/m L-1,the optimal flow rate is 2 m L/min,the optimal p H is 5,and the optimal diameter to height ratio was 1:15 when the PH was 5.At this time,the static adsorption of the resin reached a maximum of 24.38 mg/g.And the best eluent was 95% in volume densityand the 175 m L of usage which had increase 44.03% compared to that before optimizing the purity.?3?Each component of the purified flavonoids was analyzed by high-resolution mass spectrometry.Vitexin and isovitexin were selected to study the contents of the subsequent flavonoids.Ultra performance liquid chromatography was used to further confirm and analyze the existence of two flavonoids in the skin of mung beans,which were called vitexin and isovitexin.The method of quantitative analysis on contents of flavonoid under various storage conditions was also use and the results of it was relatively stable.At the same temperature,vacuum storage of flavonoids has the best effect.Among them,the effect under normal temperature with CO₂ atmosphere is better than the condition that under N₂ mixing with CO₂ and under only with N₂ atmosphere.At low temperature 4 ?,the effect under CO₂ atmosphere is better than under N₂ and N₂ mixing with CO₂ atmosphere.Using vacuum packaging with N₂,N₂ mixing with CO₂,CO₂ can effectively isolate mung beans from external oxygen,inhibit their aerobic respiration,reduce reactions of related enzyme,and make mung beans in the states of dormant and semi-dormant.No matter whether it is stored at normal temperature or at a low temperature of 4 °C,vacuum packaging has the best effect in preservation for the active ingredients of flavonoid.?4?By comparing the antioxidant test in vitro of hydroxyl free radical,DPPH scavenging ability,lipid peroxidation and NO₂-scavenging ability,the antioxidant ability of flavonoids purified from No.5 Lv feng mung beans is higher than that in Ming mung beans.This is because No.5 Lv feng mung beans have higher contents of flavonoid than that in Ming mung beans.Under different storage conditions,the abilities to remove are as followings: vacuum> carbon dioxide> nitrogen plus carbon dioxide> nitrogen.Low temperature is better than normal temperature and the activity of flavonoid is similar under the storage conditions with nitrogen and with nitrogen mixing with carbon dioxide.Therefore,the methods of obtaining contents and the changing rules of activity in flavonoid,analyzing the flavonoids in mung beans under various storage conditions have provided a new idea for the refined storage of mung bean and the research on the structure and components of in mung beans.