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Rice is the staple food of the Iranian people and its pollution with heavy metals has irreparable dangers for consumers. The aim of this study is to find a way to reduce the absorption of heavy metals from rice. To study the effect of nitrogen fertilizer and parboiling process on heavy metals, a factorial experiment was conducted in a randomized complete block design with three replications. In this study, nitrogen fertilizer at three levels (N₁: 60, N₂: 80 and N₃:100 KgN /Ha) and parboiling at two levels of soaking temperature (C₁:50 and C₂:80 °C) and two levels of steaming time (T₁:10 And T₂:15 min) were applied. Induced plasma mass spectrometry (ICP-MS) was used to determine heavy metals. Increasing the soaking temperature and steaming time reduced all heavy metals, but changes in fertilizer levels had no significant effect on heavy metals. The interaction effects of the treatments showed that N₃C₁T₁ treatment had the highest percentage of weekly allowance for Cr and Ni (99% and 58%, respectively) and N₂C₁T₁ treatment had the highest percentage of weekly allowance for Mg and Cd (11% and 9.5%, respectively). Increasing the soaking temperature and steaming time minimizes the weekly intake of all heavy metals so that the N₂C₂T₂ treatment shows the lowest weekly intake of all heavy metals. In less heat and time, the remaining heavy metals cannot be ignored, so parboiling at higher temperatures and times is recommended to maintain consumer safety and health.

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One of the reasons of the bakery products poor quality and quality defection in the country is the low quality and the impropriety of wheat. Regarding the uncontrollability of so many effective factors in wheat quality. Using of improving agents in wheat flour has been highly considered. In this study, the effect of tow improving agents, ascorbic acid in three levels (20, 40, 60 ppm) and α-amylase enzyme in three levels (25, 50 and 75 ppm) over dough was investigated. Rheological tests results showed that increasing level of ascorbic acid from 20 ppm to 60 ppm is effective in dough stability time and dough developing time increment, reduction in dough softening degree, increasing elasticity, improving gluten structure and increasing the usage level of α-amylase enzyme from 25 ppm to 75 ppm is effective in the collapse of polymeric structure of starch, dough softening, stability, developing time and reduction elasticity characteristics. In simultaneous use of additives in constant amount of α-amylase enzyme, increase of ascorbic acid from 20ppm to 60ppm causes rheological individually betterness. Dough stability time, developing time and dough elasticity as well. This effect in constant amount of ascorbic acid shows a diverse relationship specially with high amount of added α-amylase (50 and 75 ppm). Generally, in addition to ascorbic acid containing treatment on its own using of α-amylase enzyme in 50 ppm level with 60 ppm ascorbic acid in improving the rheological and quality specialty of dough is suggested.