Non-destructive characterisation and quantification of the effect of conventional oven and forced convection continuous tumble (FCCT) roasting on the three-dimensional microstructure of whole wheat kernels using X-ray micro-computed tomography (μCT). (October 2016)

• Record Type: Journal Article
• Authors: Schoeman, Letitia; du Plessis, Anton; Manley, Marena
• Is Part Of: Journal of food engineering. Volume 187(2016:Oct.)
• Page Start: 1
• Page End: 13
• Publication Date: 2016-10
• Subjects: Microstructure -- X-ray micro-computed tomography -- Image analysis -- Roasting -- Porosity; Food industry and trade -- Periodicals; Food -- Analysis -- Periodicals; Aliments -- Industrie et commerce -- Périodiques; Aliments -- Analyse -- Périodiques; Aliments -- Recherche -- Périodiques; 664.005
• DOI: 10.1016/j.jfoodeng.2016.04.015
• Languages: English
• ISSNs: 0260-8774

Abstract

Abstract: Food microstructure influences the characteristics of end products. X-ray micro-computed tomography (μCT) enables investigating internal structure of food products non-destructively. High-resolution X-ray μCT, in combination with image analysis, was used to visualise and quantify the impact of conventional oven and forced convection continuous tumble (FCCT) roasting (180 °C for 140 s) on the microstructure of whole wheat kernels. After image acquisition, two-dimensional (2D) cross-sectional images were reconstructed into three-dimensional (3D) volumes. Quantitative parameters, i.e. volume, porosity, expansion ratio (ER) and relative density, were calculated. Oven roasting was associated with a significantly ( P < 0.05) larger increase in kernel volume (4.47%) than FCCT roasting (1.57%). Porosity was higher in the oven-roasted samples (10.33 ± 4.63%), indicating a more destructive impact on the internal structure (FCCT = 8.29 ± 2.29%). Roasting introduced cavities and cracks within the wheat kernels, resulting in a decrease in whole kernel density (oven = 2.76%; FCCT = 0.55%), however the material density remained unaffected during FCCT roasting. Highlights: Roasted wheat can be characterised using X-ray micro-computed tomography (μCT). X-ray μCT enables non-destructive measurements of different regions-of-interests (ROIs). The structural changes during roasting depend on the method used. Oven roasting results in a larger increase in porosity and decrease in material density.