Biofortification Of Soybean With Iron And Zinc During Germination

Soybean is rich in nutrients and is the most important sourse of iron and zinc in human.However,conventional processing leads to a dramatic plunge in content of iron and zinc in soybean.During the germination of soybean,the content of antinutritional factors(ANFs)such as phytic acid which interferes with the absorption of micronutrients decreased and the bioavailability of iron and zinc increased.Biofortification with a appropriate concentrations of solution containing iron and zinc could promote the accumulation of iron and zinc.It is particularly necessary and urgent to study the effect of added iron and zinc on soybean and explore the interaction between iron and zinc during biofortification.In this paper,appropriate type of soybeans were chosen with appropriate gradient concentration of Fe2+ and Zn2+.The content and existence form of soybean micronutrients before and after biofortification were measured and compared.The bioaccessibility of iron and zinc in soybeans biofortificated in three types of solutions was determined by in vitro digest and dialysis method.The antioxidant activity of soybeans biofortificated in different concentrations of solution were also evaluated.All the results are as follows:1.Soybeans were soaked and germinated in ultrapure water,manganese content was reduced by 81.94%,copper content increased by 5.18%,iron and zinc increased by 59.23%and 59.23%respectively,ferritin levels decreased 10.37%,the DPPH radical scavenging increased by 10.23%.2.There was no significant difference(p>0.05)on the moisture of soybeans soaked in three types of solutions consist of iron,zinc,iron and zinc.After the iron biofortification,the content of iron in soybean increased by 74.13%～203.74%.After the zinc biofortification,the content of zinc in soybean increased by 66.77%～1029.10%.Concentration factor of sprouted soybean seeds gradually reduced with the increasing concentration of solutions,indicating that high levels of solution reduced the enrichment ability of soybeans.Biofortification in solution composed of iron and zinc was studied,finding that added iron has an negative effect on the zinc uptake,which reduced zinc content by 19.22%-57.78%comparing to soybeans biofortificated in iron alone.The addition of zinc promoted the iron uptake and increased the iron content by 6.70%～81.27%.It shows that the biofortification of iron and zinc has an interaction during germination and affects mineral uptake in soybeans.3.There was no significant difference(p>0.05)in the content of copper during germination,but there was significant difference(p<0.05)in the content of manganese.The enhancement of manganese content in soybean in iron biofortification ranged from 8.56%to 42.77%.Iron and zinc biofortification and zinc biofortification could promote the leakage of manganese from soybeans.4.There was a significant difference(p<0.05)among the effect of three types of solutions on the ferritin content in soybeans.Iron biofortification and iron and zinc biofortification induced a overexpression of soybean ferritin.When ferritin content reached the maximum,it was 101.63 and 234.57 ng/mg,respectively.Zinc biofortification inhibited the accumulation of ferritin in soybean,in this case,ferritin content was lower than that of non-germinated soybean seeds.5.The antioxidant capacity of the methanol extracts was studied in the form of DPPH radical scavenging,which indicating that the DPPH radical scavenging of methanol extract of germinated soybean was higher than that of soybeans after biofortification in three types of solutions,up to the summit by 71.36%.Germination had no significant effects(p>0.05)on the antioxidant capacity of soybeans,and showed a rule that lower concentration showed a promotion action,higher concentration showed a severe inhibition action.It was speculated that when soybean was germinated in solutions involving toxic metals,such as iron and zinc,oxidative stress occurs in plant cells,resulting in a large amount of reactive oxygen species and free radicals,then the antioxidant activity declined.6.In vitro digest and dialysis method was used to evaluate the bioaccessibility of iron and zinc in samples.The bioaccessibility of iron and zinc in non-germinated soybean seeds were 14.63%and 15.56%,respectively.The effects on bioaccessibility presented large significant difference(p<0.05)among three types of solutions.Soybean biofortificated in solution including iron or zinc presented the bioaccessibility of minerals up to 62.33%(iron),56.25%(zinc).Iron biofortification led to a decrease in the bioaccessibility of zinc,with the deeper extent in increasing concentrations of the solutions.Zinc biofortification had no significant effect(p<0.05)on the bioaccessibility of iron.It showed that iron and zinc biofortification made antagonism between the two minerals in the process of absorption in vivo.