Investigation and modelling of natural convection and conduction heat exchange: study on food systems with modified starch by means of computational fluid dynamics

Abstract

This study is focused on the effects of starch gelatinisation on heat exchange in food systems containing four modified starch concentrations (0, 2, 6 and 10%). Viscosity profiles of samples were experimentally measured: the effect of gelatinisation was evident, particularly at 6% and 10%, where the viscosity increased from 0.010 to 70 Pa s and to 1507 Pa s, respectively. The heat exchange rate showed a decrease with the increasing of starch concentration, and the effects were observed until 6%. Four Computational Fluid Dynamics (CFD) models were also developed, experimentally validated (RMSE < 1.5°C) and used to study the heat exchange. Velocity profiles showed that the convective flows slowed down from 2.5 to 0 mms À1 after the gelatinisation. Finally, the effects on the slowest heating/cooling zone (SHZ/SCZ) location in the CFD models were studied: at 0% and 2%, the SHZ settled 15 and 80 mm from the bottom of jars in heating and cooling phase, respectively. At 6% and 10%, before the starch gelatinisation phase, the SHZ was located in a similar position of the 0% and 2% while when the gelatinisation occurred the SHZ slightly moved towards the geometric centre (50 mm) as for an only-conductive product. CFD of heat exchange in starch food systems M. Cordioli et al. 855 CFD of heat exchange in starch food systems M. Cordioli et al. CFD of heat exchange in starch food systems M. Cordioli et al. CFD of heat exchange in starch food systems M. Cordioli et al. CFD of heat exchange in starch food systems M. Cordioli et al. CFD of heat exchange in starch food systems M. Cordioli et al.

CFD simulation and experimental validation of in‐container thermal processing in Fesenjan stew

“…Earlier researches conducted on sterilization of solid foods such as canned tuna, purees, thick syrups, and concentrates were assumed to be through conduction heat transfer only, and similar to this study, SHZ was located at the geometric center of the container (Cordioli et al, 2016;Rinaldi et al, 2018;Varma & Kannan, 2006). In studies conducted by Vatankhah et al (2015), Vatankhah et al (2016), they found out that SHZ locations in Haleem and apple puree were packaged in semirigid aluminum containers, remained fixed at the geometric center of the container (Vatankhah et al, 2015(Vatankhah et al, , 2016.…”

Assessment of the volume and material container influence on juice cooling process

“…As reported in the open literature, the position of the slowest cooling zone is usually located at 75 % to 80 % of the container height. However, by increasing the fluid viscosity, the slowest cooling zone tends to be near the geometric center [15,16]. Looking at the literature result and considering the viscosity for the lower shear rate values reported in Fig.…”

Application of computational fluid dynamics simulations in food industry

“…In addition, Cordioli et al, (2016) raised a very interesting topic on heat transfer by conduction. Their study was used to analyze the effect of gelatinization of modified starch on heat transfer in food systems [73].…”