Potential for damage to fruits

In industrially produced fruit mixtures, fruit pieces are the most valuable components. For this reason, the preservation of integrity is a decisive quality criterion. However, the processing exposes the fruits to damaging stresses due to mechanical impact during the transport. These influences occur in the form of shear and expansion stresses caused by collisions with parts of the apparatus or other particles as well as by hydrodynamic forces. These stresses are especially significant in pipe fittings and their periphery, since strong currents, the formation of spatial velocity gradients and sometimes unsteady flow conditions occur there. From a technical point of view, a fast as possible transport with a homogeneous suspension state is desired to achieve quick and uniform processing of fruit mixtures. However, experience and current literature show that fast transport is accompanied by a higher disintegration potential, especially for the flow through pipe fittings.
For this reason, it is necessary to clarify how the continuous and the disperse phase are affected under conditions relevant to the application. It is particularly interesting to know which types and intensities of stress occur and cause damage. Furthermore, the determination of the spatial and temporal dependence of these flow-induced stresses is relevant. Besides, the flow-mechanical causes of spatial inhomogeneities and the dependence of particle damage on the regime of the suspension flow must be determined. Additionally, the main influencing parameters for particle phase damage and existing interactions between them are also of interest.

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