Biurea

Abstract: The response of biurea to high pressures is investigated by in situ Raman spectroscopy and angle-dispersive X-ray diffraction (ADXRD) in a diamond anvil cell up to ∼5 GPa. Raman scattering measurements indicate a phase transition occurring over the pressure range of 0.6–1.5 GPa. Phase transition is confirmed by changes in the ADXRD spectra with symmetry transformation from C2/c to a possible space group P2/n. Upon total release of pressure, the diffraction spectrum returns to its initial state, which implies that the transition observed is reversible. We discuss variations in the Raman spectra, including splitting of modes, appearance of new modes, and abrupt changes in the slope of the frequency shift curves at several pressures. We propose that the phase transition observed in this study is attributed to rearrangement of the hydrogen-bonded networks.

Abstract: Azodicarbonamide, an approved food additive, is commonly used as a flour additive and dough conditioner in the United States and Canada A number of researchers have clearly established a link between the use of azodicarbonamide and semicarbazide contamination in commercial bread products However, all of these studies have primarily focused on the final baked product and have not extensively investigated the processing and conditions that affect the final semicarbazide levels In this study, a previously developed method for measuring free semicarbazide in bread was applied to dough samples during the mixing and kneading process Additionally, flour and bread samples were spiked with biurea or azodicarbonamide to help elucidate semicarbazide formation pathways The results showed that semicarbazide was not formed as a byproduct of azodicarbonamide decomposition to biurea, which occurs upon the addition of water Indeed, semicarbazide was not detected after room temperature or elevated temperature dough maturation, but only after baking It was concluded that although azodicarbonamide is the initial starting material, semicarbazide formation in bread occurs through a stable intermediate, biurea