Science Behind the Mystery White Rice which turns red after cooking
Science Behind the Mystery White Rice which turns red after cooking
1. Retro-gradation of amylose (2-30%) part of rice starch is the basic understanding in this case.
2. During retrogradation (polymerization of glucose units of amylose) chain length with 14 glucose units starts giving light red color in the presence of iodine.
3. The intensity of red color increases gradually with the increase in chain length upto 38 glucose units (the maximum intensity of red color after which the color changes to purple and deep blue {reference-http://www.jbc.org/content/236/4/969.full.pdf}).
4. In this case, the so called mystery rice, the above reaction take place after approximately 8 -10hrs in the presence of iodine which is introduced by addition of the iodized salt.
5. In this case, the above reaction was supported by the fact that the red color was clearly noticed at(or)above room temperature.
6. The salt used in this case will be having high concentration of Iodine.
7. The rice used in this case might be having high amylose (20-30%) content.
7. This complex is not known to cause any harm or hazards.
8. Hence, the mystery unlocked.
Note: The bacteria Serratia marcescens, which produces red -orange pigment may also cause red color of the glucose rich food (pigment prodigiosin). But the bacterial growth is not homogeneous, but in this case the color relatively rapidly spreads on exposure to light.
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