CHEMILUMINESCENCE OF CEREAL PRODUCTS II - CHEMILUMINESCENCE SPECTRA

Spectra of ultraweak chemiluminescence (CL) accompanying auto-oxidatio n and hydration of cereal products have been measured using single pho ton counting and cut-off filters. The spectra cover the 380-880 nm spe ctral range with maxims centred around 600 nm. Analytically pure air-d ried carbohydrates like agar, cellulose and nitrocellulose give emissi on too weak for spectral measurements. The emission from water pure ca rbohydrates is on average 4-12 times higher and emission spectra are s imilar to those from cereal products. The effect of free radical scave ngers, SOD and O-2(.) ((1) Delta(g))-quenchers on CL spectra indicates a contribution of radical reactions with the participation of excited carbonyls, O-2(-) and excited molecular oxygen dimoles. Moreover, pos sible mechanisms of chemi-excitation due to a cooperative H-bond forma tion during the hydration of carbohydrates and/or recombination of tra pped radicals and electron-holes are discussed. It is also postulated that the excitation energy transfer to natural sensitizers occuring in cereal products may account for non-specific broad spectra and differ ences in the intensity of CL. (C) 1998 John Wiley & Sons, Ltd.