, 1989, Lee and Hsu, 1996, Tsuji et al., 1985, White, 1982 and White and Schulz, 1977). However, optical tracking techniques are limited to transparent systems and suffer a low resolution due to refraction of light. A significant amount of food is processed after packing into cans or pouches, and the solid and liquid motions cannot be tracked through optical technique. A number of models have been developed for

such systems, such as Chen and Ramaswamy, 2002, García María-Sonia et al., 2006, Miri et al., 2008, find more Abdul Ghani and Farid, 2006, Jun and Sastry, 2007 and Kannan and Sandaka, 2008. Positron Emission Particle Tracking (PEPT) was developed at the University of Birmingham for tracking a single particle accurately and non-invasively (Bakalis et al., 2006, Cox et al., 2003, Parker et al., 1993 and Yang et al., 2008a). The significant advantage of the method is that PEPT can track particles accurately through 20–30 mm of metal. The equipment used thus need not be transparent as with particle imagery velocimetry (PIV) (Duursma, Glass, Rix, & Yorquez-Ramirez, 2001) or be metal free as with magnetic resonance imaging (MRI) experiments (Reyes, Lafi, & Saloner, 1998). The technique has been recently further improved to track three particles simultaneously (Yang, Parker, Fryer, Bakalis, &

Fan, 2006). This makes it possible to track both translational and rotational motions of a particle simultaneously. Yang, Fan, Bakalis, Parker, and Fryer (2008b) presented the algorithm, and have demonstrated the use of the method for one simple case. In this study the solids behaviours CHIR99021 in a rotating can system are investigated systematically using our newly developed technique called Multiple-PEPT. The translational motion gives the solids velocity profile, whilst from the rotational motion the distribution of rotational speed is constructed. The aim of the work is to demonstrate

the method and to give data which can be incorporated into future models of food flows. Experimental methods consist of Multiple-PEPT and reconstruction Avelestat (AZD9668) of the translational and rotational motions by three tracked tracers, described as follows. The technique involves a positron camera at the University of Birmingham, radioactively labelled tracers (Fan et al., 2006a and Fan et al., 2006b), and a location algorithm used for calculating the tracer location and speed. The camera consists of two position-sensitive detectors to detect pairs of 511 keV γ-rays as shown in Fig. 1. Each detector has an active area of 500 × 400 mm2. The tracer particles are 200-micron resin beads which are labelled with radionuclide 18F. Three of the labelled resins beads were mounted to different corners of a potato cube. 18F has a short half-life of 109 min. It will decay to oxygen next morning. The nuclear dose used in the experiments is much less than the dose used in hospital for tumour diagnosis.