Reducing sugars produce brown colors that are desirable and important in some foods. Non-enzymatic browning (NEB) is one of the most important chemical reactions responsible for quality and color changes during the processing or prolonged storage of citrus fruit products. NEB of foods on heating or on storage is usually due to a chemical reaction between reducing sugars and a free amino acid or a free amino group of an amino acid that is part of a protein chain. This reaction is called the Maillard reaction. When aldoses or ketoses are heated in solution with amines, a variety of reactions follow, producing numerous compounds, such as flavors, aromas, and dark-colored polymeric materials. The flavors, aromas, and colors may be either desirable or undesirable. They may be produced by frying, roasting, baking, or storage. First, the reducing sugar reacts reversibly with the amine to produce a glycosylamine. This undergoes a reaction called the Amadori rearrangement, andit continues, especially at pH 5 or lower, to give an intermediate that dehydrates.Eventually a furan derivative is formed; that from a hexose is 5-hydroxymethyl-2-furaldehyde (HMF). Under less acidic conditions, the reactive cyclic compounds(HMF and others) polymerize to a dark-colored, insoluble material. NEB may lead to some quality losses by altering the final product an unfavorable appearance and even result in reduced food safety due to new formed compounds such as 5-hydroxymethylfurfural (HMF). Since NEB has a significant influence on the product quality and safety, monitoring the extent of such reaction can be a valuable tool for assessing the product quality and safety during processing and prolonged storage.