The Study On Iron-biofortified Cowpeas During Germination And Its Antioxidant Activity

In this thesis,0.0～2.0 mmol/L FeSO4 solution was used to biofortified 8 varieties cowpeas during germination and the eight cowpeas varieties are as bellow:HaijiangNo1,HaijiangNo2,HaixiuNo7,3 Lard nuts,Lobular high yield king,High yield No4,901 Long bean,Small five leaf.The content of Fe,Mn,Cu,Zn in the iron-biofortified cowpea was measured by ICP-MS.After beening biofortified by different concentration of FeSO4 solution,the effctiveness of different concentration of FeSO4 solution on the content of Fe in cowpeas was discussed,also the changes of the content of Mn,Cu,Zn in cowpeas were compared.The changes about content of the total polyphenols and the total flavonoids in iron-biofortified cowpeas were measured by UV spectrophotometer.The DPPH scavenging capacity and the total antioxidant capacity were measured.In addition,the bioavailability of total polyphenols and total flavonoids in cowpeas were determined by in vitro simulated digestion,and the change of DPPH scavenging capacity and total antioxidant capacity after in vitro simulated digestion were discussed.And the main results are as follows:(1)The content of iron in the cowpeas increased rapidly after beening biofortified by different concentration of FeSO4 solution.When the FeSO4 solution concentration was 0.0 mmol/L,the content of iron in the biofortified cowpeas has a varying degrees of leakage.The content of iron in biofortified cowpeas increased greatly,and the content of iron in Haijiangyihao,Haijiangerhao,Haixiuqihao,Sandazhuyouroudoujiao,Xiaoyegaochanwang,Gaochansihao,901Changdoujiao,Xiaowuye were separately 1.39～3.18,3.54～4.87,1.97～4.35,1.88～7.69,1.57～5.31,1.93～7.88,1.91～7.12,1.62～5.37 times higher than cowpeas seed.In summary,Guaranteeing the normal germination of cowpeas,FeSO4 solution in adequete concentration(0.0～2.0 mmol/L)was positive for the iron content in cowpeas,and the iron-biofortified cowpea could be ued as a dietary source of iron for human.(2)After beening biofortified by 0.0～2.0 mmol/L FeSO4 solution,the content of Mn,Cu,Zn have a little leaky when the FeSO4 solution concentration was 0.0 mmol/L.The leakage of Mn,Cu,Fe separately are 0.05%,12.92%,0.22%-5.16%,0.00%-20.06%than in cowpeas seed.When the FeSO4 solution content was higher than 0.4 mmol/L,the content of Mn,Cu,Zn in the iron-biofortified cowpea separately increased 58%～134%,63%～75%,50%～130%.The concentration during 0.4 and 1.2 mmol/L of FeSO4 solution has positive effect on the content of Mn,Cu,Zn in cowpeas,on the other hand,higher concentration of FeSO4 solution has negtive effect on the content of Mn,Cu,Zn in cowpeas.(3)The content of total polyphenols were increased generally in contrast the content of total flavonoids decreased.As the same,cowpeas’ DPPH scavenging capacity was strengthen and the total antioxidant capacity was declined.The value of total antioxidant capacity is higher than the value of DPPH scavenging capacity means the bioactive of plant substances in cowpeas have different free radical scavenging capacity.In all,the 0.0～1.2 mmol/L FeSO4 solution has positive effect on the content of total polyphenols and total flavonoids in cowpeas,also the DPPH scavengign capacity and total andioxidant capacity were enhanced after iron biofoftification.(4)The content of total polyphenols were 2.58～4.51、2.78～4.46 mg GAE/g DW after in viro simulated stomach digestion and in vitro simulated intestinal digestion.After in viro simulated stomach digestion the content of total flavonoids in 3 Lard nuts,Lobular high yield king and Small five leaf grow a little,on the other hand the content of total flavonoids in other 5 varieties cowpea declined,but the content of total flavonoids increased after in vitro simulated intestinal digestion.The biggest value of DPPH scavenging capacity were respectivly during 366.13~479.24,274.32～471.00μg VC/g DW after in viro simulated stomach digestion and in vitro simulated intestinal digestion.And the biggest value of total antioxidant capacity respectivly were during 3490.99～758.99,408.74～736.75 μg VC/g DW after in viro simulated stomach digestion and in vitro simulated intestinal digestion.In summary,iron-biofortified cowpeas are beneficial to increase the bioaccessibility of total polyphenols and strengthen the total anxioxidant activity.The total flavonoids were released more when in vitro simulated intestinal digestion.