Browning chemical changes during

M. Buglione and J. Lozano, Nonenzymatic browning and chemical changes during grape juice storage, J. Food Sci., 2002, 67, 1538-1543. 

The brown color observed in Figure 14.19(b) indicates the formation of Br2( g). If this were the complete reaction, bromide ion would not be a catalyst because it xmdeigoes chemical change during the reaction. However, hydrogen peroxide also reacts with the Bt2(cu]) generated in Equation 14.30 ... 

The induction period, followed by a sharp increase in rate is, however, the most characteristic feature of autocatalysis in closed vessels. One manifestation of this behaviour is the clock reaction . An experimental system which is a typical chemical clock and which also exhibits cubic autocataiysis is the iodate-arsenite reaction. In the presence of excess iodate, the system which is initially colourless eventually undergoes a sudden colour change to brown (or blue in the presence of starch). The potential of an iodide-sensitive electrode shows a barely perceptible change during most of the induction period, but then rises rapidly, reaching a peak at the point of colour change. 

Thanh NTK, Stevenson G, Obatomi DK et al. (2001) Urinary lipid change during the development of chemically induced renal papillary necrosis. A study using mefenamic acid and N-phenylantranihc acid. Biomarkers 6 417-427 Weingand K, Brown G, Hall R et al. (1996) Harmonization of animal clinical pathology testing in toxicity and safety studies. Fund Appl Toxicol 29 198-201... 

All nutrients (except water) may undergo either chemical or physical changes during processing that render them inactive or less bioavailable. This occurs for macro- as well as micronutrients. During browning, the amino acid lysine can react with carbohydrates to lower the biological value of protein. 

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