Measurement of internal shrinkage distribution in spaghetti during drying by X-ray μCT

With the addition of aluminum particles, shrinkage of spaghetti strands during drying was studied using X-ray microtomography (μCT). Images of spaghetti dried under a prescribed drying program were taken six times during a drying period of nearly 6 h. Spaghetti initially shrank in both radial and axial directions, but expanded a little later. Radially, shrinkage was initially torsional and non-central in direction, before becoming linear, and centrally- directed. The shrinkage rate was higher radially than axially. The annular distribution of the internal shrinkage was analyzed showing that radially, the periphery shrank more in the early period of drying and less in the later period. In contrast, in the axial direction, spaghetti shrank more near the center and less on the periphery. This shrinkage distribution during drying implies that residual stresses must arise and are important in explaining cracking. This study also shows that X-ray μCT is an effective technique in tracing food shrinkage during drying, especially distributions occurring internally.