Amylase is an enzyme that breaks down starches to simpler sugars. Only living organisms can produce amylase. Animals produce only alpha-amylase. Plants, bacteria, and fungi produce both beta- and alpha- amylases. Like all proteins, the presence of amylase in food depends on if it is permanently denatured by high enough temperatures or extremes in pH. Interestingly, amylases can be classified into high/intermediate/low thermostability groups, depending on whether they become inactivated at a certain temperature. Taking this into consideration, saliva would definitely have alpha-amylase. Bread and biscuits may have alpha or beta amylase (depending on baking temperatures/pH, if amylase was added at all, and if it comes from a grain). Of the rest of your list, banana, corn, milk, and sweet potato would have amylase. Honey (not listed) would also have it. Tomato seems to amylase activity as well. For ketchup, it seems to be an added ingredient to speed processing.