Food Structure


Milk protein concentrate powder has found a wide application as a food ingredient. We investigated the effects of ionizing ')'-radiation at doses ranging from 2 to 20 kGy on electron spin resonance and thermoluminescence intensities in samples of milk protein concentrate powder with varying protein contents (36-73 %wt), containing addltional Fe++ ions (12-910 ppm) and stored under different conditions.

Electron spin resonance and thermoluminescence intensities increased unambiguously with absorbed -ydose. Added Fe++ ions showed a quenching effect as measured by both methods. Storage conditions affected strongly the decay of electron spin resonance signal intensity . Lineshape analysis of thermoluminescence curves indicated the existence of two trap levels of different depths which reflected two different recombination processes.

Fe++ ions bound to states corresponding to trap levels of shallow depth, thus inactivating their effect. Electron spin resonance and thermoluminescence methods were equally suitable for the detection of the degree of irradiation but their applicability depended on storage conditions. A close correlation was found between these two methods (r = 0.973).

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