Numerical simulation and experimental validation of bacterial detachment using a spherical produce model in an industrial-scale flume washer

Authors: TAN, JUNZHONG - Rutgers University; Zhou, Bin; Luo, Yaguang - Sunny; KARWE, MUKUND V. - Rutgers University

Submitted to: Food Control
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/31/2021
Publication Date: 6/16/2021
Citation: Tan, J., Zhou, B., Luo, Y., Karwe, M. 2021. Numerical simulation and experimental validation of bacterial detachment using a spherical produce model in an industrial-scale flume washer. Food Control. 130:108300. https://doi.org/10.1016/j.foodcont.2021.108300.
DOI: https://doi.org/10.1016/j.foodcont.2021.108300

Interpretive Summary: Washing in flume systems is widely practiced in fresh and fresh-cut produce industry for improving product quality and safety. The effectiveness of washing is influenced significantly by system configuration and operations. Scientists at Rutgers University and USDA-ARS systematically investigated these operational parameters using computational modelling and pilot-scale experimental validation. Results indicate that increased distance between two adjacent pieces of fresh produce allowed for greater shear force applied by water flow, leading to greater reduction bacterial population from the product surface. Research findings benefit fresh-cut produce processors with their effort in improving food quality and safety.

Technical Abstract: Thorough and proper washing of fresh produce is critical for ensuring their microbiological quality and safety. Using spherical produce models (40 mm diameter), the effect of the separation distance (40 mm to 200 mm) between adjacent models placed in flow in an industrial flume washer, on bacterial detachment was investigated. The fluid flow in the flume washer was numerically simulated using COMSOL MULTIPHYSICS®, and the shear stress on the surface of the produce models was calculated. The numerical simulation indicated that varying the center-to-center distance between produce models from 40 mm to 200 mm increased the average shear stress on the produce models from 264 mPas to 469 mPas. The corresponding experimental data of the number of bacteria that survived on the surface of the produce models after 60 s of washing ranged from 8.6 × 103 CFU/cm2 to 2.7 × 102 CFU/cm2. An empirical model, which incorporated the effect of calculated shear stress on the kinectis of bacteria removal, was developed to predict the number of bacteria that survived on the surface of the produce after washing. The findings in this study are useful for fresh-cut produce processors in optimizing product loading rate without compromising food quality and safety during flume washing.