The key difference between enzymatic and nonenzymatic browning is that the enzymatic browning involves enzymes such as polyphenol oxidase and catechol oxidase whereas the nonenzymatic browning does not involve any enzymatic activity.
The terms enzymatic and nonenzymatic browning is very important in describing the food browning. They differ according to their mechanism of action. Food browning is the process of turning a food such as fruits and vegetables into a brown color due to the chemical reactions that take place in that food. This has many implications for the food industry, especially regarding the cost.
CONTENTS
1. Overview and Key Difference
2. What is Enzymatic Browning
3. What is Nonenzymatic Browning
4. Side by Side Comparison – Enzymatic vs Nonenzymatic Browning in Tabular Form
5. Summary
What is Enzymatic Browning?
Enzymatic browning is the process of food turning brown due to an enzyme-catalyzed chemical reaction that takes place in that food. We can see this in fruits, vegetables and seafood as well. It affects the taste, color and the value of the food. These reactions involve enzymes such as polyphenol oxidase and catechol oxidase. These enzymes create melanin and benzoquinone from natural phenols. Another name for this process is “oxidation of food”. This process requires the exposure to oxygen.
Figure 01: Enzymatic Browning
Enzymatic browning initiates with the oxidation of phenols by phenol oxidase into quinones. These quinones are strong electrophiles which cause high susceptibility to nucleophilic attacks from other proteins. These quinones can polymerize via a series of reactions. Eventually, it results in brown colored pigments on the surface food. Therefore, if we need to inhibit this process, we have to focus on hindering the polyphenol oxidase activity. However, sometimes this browning has positive effects as well. For example, it develops the color and flavor in coffee, cocoa beans and tea.
What is Nonenzymatic Browning?
Nonenzymatic browning is the process of food turning brown due to a chemical reaction that is not catalyzed by an enzyme. It also produces brown pigments in food. There are two main types of this reaction as caramelization and Mallard reaction.
Figure 02: Nonenzymatic Browning
Caramelization involves the pyrolysis of sugar. Therefore, this process is useful in cooking to get a nutty flavor and brown color. In this process, volatile chemicals release producing the characteristic caramel flavor. In Mallard reaction, a chemical reaction takes place between the amine group of free amino acid and the carbonyl group of reducing sugar. Further, this reaction occurs with the addition of heat. The sugar reacts with the amino acid producing a variety of odors and flavors. Hence, this reaction is responsible for the production of flavor after we cook food. Moreover, this reaction is important in producing artificial flavors for processed food. The type of amino acid that involves the reaction determines the flavor of the end product.
What is the Difference Between Enzymatic and Nonenzymatic Browning?
Enzymatic browning is the process of food turning brown due to an enzyme-catalyzed chemical reaction that takes place in that food. It involves enzymes such as polyphenol oxidase and catechol oxidase. Moreover, it initiates with the oxidation of phenols by phenoloxidase into quinones that are then polymerized to give brown colored pigments. Nonenzymatic browning is the process of food turning brown due to a chemical reaction that is not catalyzed by an enzyme. It does not involve any enzymatic activity. In addition to that, it involves a chemical reaction between the amine group of free amino acid and the carbonyl group of reducing sugar. The below infographic presents the difference between enzymatic and nonenzymatic browning in tabular form.
Summary – Enzymatic vs Nonenzymatic Browning
Food browning is a very important process we discuss in the food industry. There are two main ways in which it can occur; they are enzymatic and nonenzymatic browning. The key difference between enzymatic and nonenzymatic browning is that the enzymatic browning involves enzymes such as polyphenol oxidase and catechol oxidase whereas the nonenzymatic browning does not involve any enzymatic activity.
Reference:
1. “Food Browning.” Wikipedia, Wikimedia Foundation, 9 July 2018. Available here
Image Courtesy:
1.”Barangan banana Indonesia”By Midori – Own work, (CC BY-SA 3.0) via Commons Wikimedia
2.”Brioche” (CC BY-SA 3.0) via Commons Wikimedia