Iodine Testing : Examples

Rice

Above is cooked basmati rice. Below is the reaction after adding several drops of iodine. 

Glutinous Rice Flour

Above is glutinous rice flour mixed with water. Below is the same after adding several drops of iodine tincture. 

The mixture actually turns a brown colour and not the inky blue black colour that normal rice will turn (amylose). This brown colour is not actually the colour of iodine, rather this is the colour of amylopectin reacting with iodine. Glutinous rice is very unusual for a grain in that it contains no amylose at all, and instead stores carbohydrates as amylopectin. 

Curry Powder

Here is some curry powder above mixed with water only. Below is the reaction when mixed with two drops of iodine. 

The reaction was mild, not an inky blue black reaction, and so I'm not worried about it. This looks like it has some amylopectin (safe) and no significant amylose (unsafe).