Indigo carmine degradation in the presence of maltose and ethanol

Abstract

The majority of important reactions in beer are associated with the action of oxygen during malting and brewing. With respect to oxygen, beer is considered to possess a relatively strong reducing environment. The gradual reduction of oxygen gives rise to reactive oxygen species (ROS) capable of attacking beer components that are important to consumers. Indigo carmine (IC) bleaching was used to prove ROS formation formed by oxidation of beer energy sources such as maltose and ethanol. This paper examines oxygen radical oxidation of organic matter in the presence of the radical initiator potassium peroxodisulphate. A mixture of organic sources of energy such as maltose and ethanol, oxygen, radical initiator and cupric ions generates ROS formation in a broad range of concentrations even at room temperature. ROS irreversibly split blue dye IC into the colourless form and takes part in the radical transformation of organic matter, which is similar to its burning at low temperature or to radical oxidation of reducing agents. Other organic matter can suppress ROS formation and be incorporated into the radical chain of the pathway of its ‘cold burning’. Ethanol inhibited phenylalanine oxidation during its oxidative Maillard reaction. IC bleaching can serve as simple indicator of ROS generation in aerated food. Copyright © 2015 The Institute of Brewing & Distilling