In situ investigation of cellular water transport and morphological changes during vacuum cooling of steamed breads

Abstract

Dynamic investigation of the effects of vacuum cooling on cellular water transport and structural changes of steamed bread was carried out using transverse relaxation times (T2) and proton density-weighted images in a nuclear magnetic resonance (NMR)/magnetic resonance imaging (MRI) analyser, respectively. Initially, both steamed bread at room temperature of 25 °C and freshly steamed bread at 85 °C had three peaks of T21, T22, and T23, respectively representing the tightly bound water, loosely bound water, and free water, while an additional peak T24, was observed in freshly steamed bread at 85 °C. After vacuum cooling, freshly steamed bread at 85 °C had a higher mass loss of 10.29% due to its high initial temperature, and both samples were clearly discriminated with PCA of 88.2%, indicating that the initial food condition affected the vacuum cooling process. Lastly, the NMR/MRI technique and correlations were accurate (R2> 0.98), thus suitable for model validation at microscale and macroscale.