Enzymatic Degradation Mechanisms
The lipolytic enzyme lipase reacts with triglycerides to form free fatty acids in a degradation process known as hydrolytic rancidity. Lipase enzymes cleave fatty acids from triglycerides. The fatty acids have definite detectable flavors which can render the food unacceptable. Lauric acid (C12:0) has a strong soapy flavor and is readily detectable in rancid coconut and coconut oil. As little as 0.3% lauric acid will produce this effect. This hydrolysis reaction requires either high temperature, e.g., deep fat frying with water present or lipase enzyme activity. Therefore, it is not a reaction which occurs during normal food storage unless there is lipolytic enzyme activity. With the exception of lauric acid mentioned above, low levels of free fatty acids have minimal effect on the flavor of foods. Fatty acids from domestic oils (C16:0 or higher) do not affect the flavor until they reach a level of about 2% and then they impart a bitter taste. If butter is present, the short chain fatty acid released, butyric acid, have a very strong and undesirable odor and flavor at lower levels.