Cooling rate and temperature gradient strongly influences pathogen internalization in tomatoes and probably in all produce

Freshly harvested fruits and vegetables (produce) are chilled to extend their shelf life but the chilling process increases opportunities for contamination by pathogenic bacteria carried by water through openings such as stem scars. Using tomato as a representative system, a 3D porous medium transport model is developed. The model simulates the transport of water vapor, liquid water, bacteria, and energy in light of convection?diffusion processes driven by pressure gradients from condensation inside as well as by water concentration gradients between the cooling water and that in the tomato. Results show that increasing the rate of cooling (i.e., creating a higher temperature difference) increases the rate of infiltration due to higher-pressure gradients. A higher temperature differential drives bacteria further into the tomato. A less hydrated tomato will incur deeper and more extensive infiltration. Size, permeability, and diffusivity play a less significant role. The novel mechanistic understanding our study provides should aid in designing safer hydrocooling processes.SourcesMechanistic understanding of temperature-driven water and bacterial infiltration during hydrocooling of fresh produceAlexander Warning (a), Ashim K. Datta (a), Jerry A. Bartz (b)??? a Department of Biological and Environmental Engineering, Cornell University, 175 Riley-Robb, Ithaca, NY 14853-5701, USA??? b Plant Pathology Department, University of Florida, Gainesville, FL 32611-0690, USAPostharvest Biology and Technology, Volume 118, August 2016, Pages 159?174 Picture by colourbox.com