what is achromatic point wrt salivary amylase

f we add salivary amylase to any solution ( eg:iodine solution) the colour of solution changes to blue.THE TIME TAKEN BY THE SALIVARY AMYLASE TO CHANGE ITS(iodine solution) COLOUR TO BLUE IS CALLED ACROMATIC POINT OF SALIVARY AMYLASE. 
ie, the time upto which the solution is colourless and after that it gains blue colour.