| In our studies, a liquid film cultivation experiment was carried out to examine the influence of iodide concentration uptake by mung bean as well as on the germination, growth and nutrition quality and the influence of iodine and other trace elements in cooking process. Provide the theory basic and experimental basis for developing new iodine-enriched food from iodine-enriched mung bean sprout to prevent and cure of iodine deficiency disorders. The paper main includes the following aspects of content:(1) Two iodine determination methods were developed for the plant samples in different moisture. The dry ashing-iodide ion-selective electrode method (I--ISE) was suitable for determination low moisture samples. The iodine content in laver standard was determined with this method and the result (82.00±1.68mg·kg-1) was in consistent with the reference value (79±8mg·kg-1), shows that the method is high accuracy and dry ashing sample can be determined for other4trace element contents, such as Fe, Zn, Mn and Cu. A wet reduction-I--ISE method was also developed for determination of iodine in wet samples, which is convenient, quick determination, large quality treatments, high sensitivity and less interference. So that the method can be determined the iodine content of fresh iodine-enriched mung bean sprouts.(2) Using liquid film cultivation biofortificated iodine-enriched mung bean sprouts with soaked6h by distilled water and cultivated96h by0～300mg-L-1iodide solution (KI). The germination rates, fresh weights, lengths of true leaf, epicotyl, hypocotyl and root, diameter of hypocotyl, the number of roots, iodine accumulations and trace element contents (Cu, Fe, Mn and Zn) were determinated. The results show that the growth indicators of mung beans promote weakly or not with iodide concentration below10mg·L-1, significantly promote, especially hypocotyl, with20～80mg·L-1, and significantly inhibit with above100mg·L-1. The iodine accumulations in whole mung bean sprouts from cultivated24h to96h were2.25mg·kg-1FW(1mg·L-1)～183mg·kg-1FW(300mg·L-1),1.58mg·kg-1FW(0mg·L-1)～104mg·kg-1FW(300mg·L-1),1.17mg·kg-1FW(CK)～163mg·kg-1FW(300mg·L-1) and0.70(CK)·193mg·kg-1FW(300mg·L-1), respectively, and the accumulation increased to a certain concentration and increased again with increased concentration of iodide solution at the same cultivated time, and the accumulation decreased to the lowest content then increased with increased cultivated time at the same iodide concentration. The suitable cultivated iodide solution is20～80mg·L-1, which considered about the growth indicators, iodine accumulation and elements contents. Four kinds of trace elements, Cu, Fe, Mn, Zn in mung bean sprouts, cultured by different iodide concentration solutions and times, were determined by the optimization method of dry ashing-FAAS. The result showed that the contents of the four trace elements decreased with extended of incubation time, and not increased which cultured by Hoagland nutrition solution lacking iodine. The dissolution ratios of Cu, Fe and Zn were promoted by appropriate concentration of iodide (20～80mg·L-1), and the leakage ratios of Cu, Fe and Mn were inhibited by excessive100mg·L-1iodide solution.(3) The contents of Vc and protein in iodine-enriched mung bean sprouts were determined by2,6-dichloro indophenol and coomassie brilliant blue G250. The results showed that contents of Vc and protein were significant differences between different iodide concentration at the same cultivated time. Besides cultivated48h, Vc content in sprouts declined to the lowest and then increased with increased iodide concentration. But the content of protein was significantly declined, especially iodide concentration of1～80mg·L-1,with extension of cultivated time. The result showed that low iodide concentration can promote the decomposition ratio from protein to peptide or amino acids of mung beans. The most suitable cultivated iodide solution is20～60mg·L-1, which considered all indicators (growth indictors, trace elements contents, Vc and protein contents) above.(4) A series of simulation experiments were carried out to examine the influence of cooking process, such like boiled, fried, roasted and steamed, on the content of iodine. And examine the loss of trace elements in boiled process. The results showed that the iodine retentions were significant difference between different cooking process. The iodine retention of iodine-enriched mung bean sprout declined with increased boiled time and reached a balance after boiled more than10min. The maximum retention rate of iodine was66.5%. The content of iodine in iodine-enriched mung bean sprouts approximate conformed to the formula (GI=55.49-6.13t+0.313t2-4.99×10-3t3) and suited for boiled under30min. Besides Mn, contents of Cu, Fe and Zn declined with increased of boiled time. Maximum rentention rates of five elements were66.5%(I),50.0%(Cu),45.9%(Zn),38.1%(Fe) and almost no dissolution (Mn). After baking process, the iodine content of iodine-enriched mung bean sprouts was not declined with declined moisture content, and it no significant during short time baking (<15min), and significant loss of long time baking (30min). The iodine loss was decreased by fried temperature, and significantly increased between low temperature fried and raw (75.1%,150℃). The loss of iodine was increased by extensive steamed time, reached34.2%at30min steamed. A normal mung bean sprouts (not I biofortificated) boiled experiment with added KI was carried out to examine the difference in the way of supplemental iodine through compared with the result of boiled iodine-enriched mung bean sprouts. The result showed that the contents of iodine in normal mung bean sprouts were not significantly improved before and after boiled about0to30min. Although low iodine retention of iodine-enriched mung bean sprouts during boiled, the iodine content (lowest, boiled15min,18.19mg·kg-1FW) was50.8folds than it in normal sprouts, which only need8.24g to satisfy the RNI of iodine(intake150μg·d-1).So that the products of iodine-enriched mung bean sprout have ability to become the iodine intake resource of human. |
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