Protecting Perishable Foods During Transport by Truck and Rail Jeffrey K. Brecht, Steven A. Sargent, Patrick E. Brecht, Jorge Saenz, and Leonard Rodowick Protecting Perishable Foods During Transport by Truck and Rail This document is a revision of USDA AMS Handbook No. 669, Protecting Perishable Foods During Transport by Truck, last revised in 1995, which is in the public domain. The authors are grateful to USDA AMS Transportation Services Division for the funds to support the revision and publication of this handbook under Cooperative Agreement No. 17-TMTSD-FL-0007. Author affiliations: Jeffrey K. Brecht, Professor, Horticultural Sciences Department, University of Florida, Gainesville, FL Steven A. Sargent, Professor, Horticultural Sciences Department, University of Florida, Gainesville, FL Patrick E. Brecht, President, PEB Commodities, Inc., Petaluma, CA Jorge Saenz, President, Wireless Data Solutions, Weston, FL Leonard Rodowick, Strategic Relations – Food Safety & OEM, Thermo King Corporation, Nixa, MO Copyright © 2019 by the University of Florida. All rights reserved. DOI: http://www.dx.doi.org/10.9752/TS230.04-2019 This report is the proprietary work product of the University of Florida, Institute of Food and Agricultural Sciences. The views and opinions expressed in this report are those of the authors and do not necessarily reflect the policies and opinions of the U.S. Department of Agriculture. Mention of trade names or commercial products in this publication is solely for the purpose of providing specific information and does not imply recommendation or endorsement by the University of Florida or the U.S. Department of Agriculture. An Equal Opportunity Institution. UF/IFAS Extension, University of Florida, Institute of Food and Agricultural Sciences, Nick T. Place, dean for UF/IFAS Extension. Back to previous page iv — Protecting Perishable Foods During Transport by Truck and Rail Back to previous page Contents Preface ...................................................................................................vii I. Important Factors in Protection of Perishable Foods ..........................1 Refrigeration ...............................................................................................1 Transport Refrigeration Basics ................................................................1 Heat Transfer .......................................................................................1 Types of Heat .......................................................................................3 Refrigeration Methods ................................................................................4 Mechanical Refrigeration .........................................................................4 Cooling .................................................................................................4 Defrost .................................................................................................7 Ice ............................................................................................................7 Cryogenic Refrigerants ............................................................................8 Trailer, Railcar, and Container Design and Construction ...........................9 Insulation ..................................................................................................9 Types of Transport Equipment ...............................................................10 Refrigerated Containers .....................................................................10 Refrigerated Trailers ..........................................................................13 Multi-temperature Refrigerated Trailers .............................................14 Refrigerated Railcars .........................................................................15 Electric Powered Systems (Vehicle-Powered Systems) ....................16 Airfoils and Fuel Efficiency .....................................................................18 Transport Temperature Management .......................................................20 Airflow Management .............................................................................21 Frozen Cargo .....................................................................................21 Chilled Cargo .....................................................................................23 Refrigeration Efficiency .........................................................................24 Packaging and Unitization ........................................................................26 Benefits of Unitization ............................................................................26 Standardized Pallet Size and Construction ............................................26 Slip Sheets .............................................................................................27 Package Dimensions .............................................................................27 Package Venting ....................................................................................28 Table of Contents — v Back to previous page Package Materials .................................................................................29 Pallet Stabilization ..................................................................................30 Telematics ................................................................................................32 Cargo Space Management ......................................................................35 Temperature Management .....................................................................35 Air Temperature vs. Product Temperature .........................................35 Chilling and Freezing Injury ...................................................................36 Thawing of Frozen Foods ......................................................................39 Atmosphere Management ........................................................................42 Fresh Air Exchange ................................................................................43 Controlled and Modified Atmosphere Systems ......................................44 Humidification and Dehumidification Systems .........................................45 Sources of Humidity ...............................................................................45 Humidity Maintenance ...........................................................................46 Dehumidification ....................................................................................46 II. Preparation for Loading .......................................................................47 Product Temperatures and Tolerances .....................................................47 Adequacy of Equipment ...........................................................................49 Expert Systems ........................................................................................50 Cleaning and Sanitation ...........................................................................51 Vehicle Preparation and Maintenance .....................................................54 Precooling the Product and Equipment ....................................................55 Precooling (or Prewarming) the Vehicle .................................................55 Precooling the Product ...........................................................................57 Temperature Recording and Tracking ......................................................58 Other Types of Recorders ......................................................................61 III. Loading and Unloading Considerations ............................................61 Type of Air Delivery System .....................................................................62 Top-Air Delivery ......................................................................................62 Bottom-air Delivery ................................................................................62 Type of Packaging ....................................................................................62 Whether Frozen or Non-frozen ................................................................65 Bracing Needs ..........................................................................................65 vi — Protecting Perishable Foods During Transport by Truck and Rail Back to previous page Compatibility of Mixed Loads ...................................................................66 Whether Palletized or Unitized .................................................................68 Length of Transit Period ...........................................................................69 Loading and Unloading Checklists ...........................................................69 IV. Loading (Stowage) Patterns ...............................................................72 Loading Trailers and Railcars with Top-Air Delivery .................................72 Unitized or Pallet Loads .........................................................................72 Loading Containers with Bottom-Air Delivery ...........................................73 Unitized or Pallet Loads .........................................................................73 Hand-Stacked Loads .............................................................................74 Vented Loads ...........................................................................................77 Top-Iced