Which color result indicates a positive reaction for amylase in a presumptive test?

In a presumptive test for amylase, a positive result is generally indicated by the development of a specific color change that validates the presence of the enzyme. In this case, a purple color result signifies that amylase is present in the sample being tested. This is due to the way the test is designed to react with amylase, which breaks down starch into simpler sugars and interacts with the reagents in the test to produce this characteristic color change.

Other colors listed, such as brown, yellow, and orange, do not indicate a positive reaction for amylase in these tests. Each of those colors typically corresponds to either a negative reaction or the presence of another substance or enzyme that does not positively confirm amylase. Thus, recognizing the purple result is essential for correctly interpreting the test and confirming the presence of amylase.