Characterization of gamma radiation damages on major food components using vibrational spectroscopy

This study aims to characterize gamma irradiation damages in the 0.2 to 10.00 kGy range on major food components: proteins, carbohydrates, and fats, employing rapid yet structurally sensitive and discriminative vibrational spectroscopic tools.; The most remarkable gamma irradiation-activated damages on carbohydrates were determined to be the random rupture of glycosidic linkages in polysaccharides due to direct effect of ionizing energy as monitored in the 900–950 cm−1 region (C-O-C stretch) of irradiated starches. Abstraction of hydrogen atoms from C-H bonds of irradiated carbohydrates due to direct and indirect gamma radiation damage was apparent from the C-H stretch mode in the 2800–3000 cm−1 region.; Utilizing the spectral regions associated with irradiation damages, several multivariate statistical models were developed to discriminate irradiated carbohydrates. A canonical variate analysis (CVA) was used to discriminate high dose irradiated carbohydrates (5–17 kGy) with hundred percent success. The classification ability of CVA decreased for carbohydrates irradiated at low dose rate (0.2–0.5 kGy).; Thermodynamically irreversible gamma irradiation modifications in the secondary structure of myoglobin were characterized using Fourier transform infrared spectroscopy (FTIR). The amide I vibrations in the 1600–1700 cm−1 region expressed significant spectral variations due to irradiation. The amide I region was used to predict changes in secondary structure of myoglobin. In this study, it was shown that native secondary structure of myoglobin was severely destructed. Irradiation of myoglobin even at low doses (0.2 and 0.5 kGy) resulted in the formation of beta sheet type of structure that was absent in native myoglobin and an increase in turn structures.; On fats and oils, direct and indirect effect of gamma irradiation brings about changes in the total degree of unsaturation (number of C=C) and ester linkages of fats and acceleration of lipid peroxidation leading to rancidity in irradiated food. Conformational changes following gamma irradiation of adipose tissues were characterized by 2D correlation map of the spectral responses in the C=O (1746 cm−1) and C=C (1654 cm−1 ) stretch regions. Changes in spectral variations corresponding the C=O and C=C stretching characterize breakage of ester bonding in the triglyceride group of the adipose tissue and shifting of the spatial distribution of hydrogen atoms bound to the C=C group. In addition, damages to C–H bending (1453 cm−1) were also elucidated by 2D correlation spectroscopy. (Abstract shortened by UMI.)...