Distribution Of Mineral Elements And Effects Of Lead Stress On The Physicochemical Characteristics Of Mung Bean Germination In The Main Production Area Of Heilongjiang

Minerals are one of the seven essential nutrients for the human body and play an important role in building body tissues,regulating physiological functions and participating in the regulation of body fluid balance.Mineral elements cannot be synthesised in the human body and must be taken in from the diet.As a traditional bean grain and agricultural product in China,mung bean is rich in carbohydrates,proteins,vitamins and trace elements such as calcium,iron and phosphorus,and has high nutritional value,making it a very healthy natural food of medicinal and food origin.In this study,to investigate the distribution of mineral elements in mung beans in the main production areas of Heilongjiang,mung bean samples were collected from four main production areas,namely,Tai Lai County,Dumeng County,Longjiang County and Daqing City,and the contents of 52 mineral elements in mung beans were detected by inductively coupled plasma mass spectrometry(ICP-MS),through variance analysis,frequency analysis,correlation analysis and principal component analysis,the distribution characteristics of mineral elements in mung beans from different producing areas were obtained.The heavy metal lead stress,which is harmful to food safety,among 52 mineral elements was further explored on the physico-chemical characters during seed growth of mung beans.As a result,the toxic effect of heavy metal lead on mung bean germination will be clarified,which also provides theoretical basis for predicting,evaluating,preventing and controlling heavy metal pollution of mung bean.The research results are as follows:1.Using ICP-MS technique,52 mineral elements were detected in 75 mung bean samples from four regions,namely,Tai Lai County,Dumeng County,Longjiang County and Daqing City.Analysis of variance,frequency analysis,correlation analysis and principal component analysis showed that 22 mineral elements(Al,Mn,Cu,Sr,Mo,Rh,Cr,Sn,V,Se,Co,Ce,La,Nd,Y,Pr,Sm,Gd,Dy,Ir,Eu and Ho)were significantly different among the four regions(P<0.05).The mineral content of Cr,Ce,La,Nd,Y,Pr,Eu and Ho were higher in mung bean samples from Dumeng County;Al,Mn,V,Gd,Sm and Dy were higher in mung bean samples from Longjiang County;Cu,Sr,Mo,Rh,Se,Sn,Co and Ir were higher in mung bean samples from Daqing City.The mineral elements in mung bean among the four origins distributed unique characteristics.2.Statistical analysis of heavy metal elements in mung beans revealed that the heavy metal lead content in mung beans in a roadside farmland in Longjiang County was exceeded,and the effect of lead stress on the physicochemical characteristics of mung bean seeds during germination was further investigated.The results showed that the germination potential,germination rate,shoot length,root length and fresh weight of mung bean seeds were significantly inhibited with increasing lead concentration and germination days compared with the control group,and the indicators of the control group were higher than those of the lead-treated group.The results indicated that under the stress of heavy metal lead,it had toxic effect on the growth of mung bean seeds and the higher the lead concentration,the stronger the toxic effect.3.Effects of lead stress on the physicochemical characteristics of mung bean germination.During the 7 days germination of mung beans under lead stress,the soluble protein content showed a decreasing trend with the increase of germination days,the soluble protein content showed a trend of increasing and then decreasing with the increase of lead concentration at the same number of days of germination,and the soluble protein content of the lead-treated group was higher than that of the corresponding control group;the soluble sugar content showed a trend of increasing and then decreasing with the increase of germination days;the superoxide dismutase(SOD)activity showed a trend of increasing and then decreasing with the increase of germination days;the proline content,peroxidase(POD)activity and catalase(CAT)activity showed a trend of increasing and then decreasing with the increase of lead concentration and the number of days of germination.4.Effect of lead stress on phenolic and antioxidant activities of mung bean germination.During 7 days of lead-stressed mung bean germination,both total phenol and total flavonoid contents showed an increasing trend with the increase of germination days;however,total phenol and total flavonoid contents of the control group reached a maximum at the 6th day of germination and then showed a decreasing trend,while the lead-treated group continued to show an increasing trend.The scavenging ability of hydroxyl radicals increased with the increase of germination days,but the scavenging ability of hydroxyl radicals reached the maximum at 80,120 and 160 mg/L of lead at the 6th day of germination and then showed a decreasing trend;the scavenging ability of DPPH radicals showed an increasing trend with the increase of germination days and then decreased;the ABTS free radical scavenging ability increased with the increase of germination days,but the ABTS free radical scavenging ability of the control group reached the maximum on the 6th day after germination and then showed a downward trend.