A comprehensive review of the many new developments in the growing food processing and packaging field Revised and updated for the first time in a decade, this book discusses packaging implications for recent nonthermal processing technologies and mild food preservation such as high pressure processing, irradiation, pulsed electric fields, microwave sterilization, and other hurdle technologies. It reviews typical nonthermal processes, the characteristics of food products after nonthermal treatments, and packaging parameters to preserve the quality and enhance the safety of the products. In addition, the critical role played by packaging materials during the development of a new nonthermal processed product, and how the package is used to make the product attractive to consumers, is discussed. Packaging for Nonthermal Processing of Food, Second Edition provides up to date assessments of consumer attitudes to nonthermal processes and novel packaging (both in the U.S. and Europe). It offers a brand new chapter covering smart packaging, including thermal, microbial, chemical, and light sensing biosensors, radio frequency identification systems, and self-heating and cooling packaging. There is also a new chapter providing an overview of packaging laws and regulations in the United States and Europe. * Covers the packaging types required for all major nonthermal technologies, including high pressure processing, pulsed electric field, irradiation, ohmic heating, and others * Features a brand new chapter on smart packaging, including biosensors (thermal-, microbial-, chemical- and light-sensing), radio frequency identification systems, and self-heating and cooling packaging * Additional chapters look at the current regulatory scene in the U.S. and Europe, as well as consumer attitudes to these novel technologies * Editors and contributors bring a valuable mix of industry and research experience Packaging for Nonthermal Processing of Food, Second Edition offers many benefits to the food industry by providing practical information on the relationship between new processes and packaging materials, to academia as a source of fundamental knowledge about packaging science, and to regulatory agencies as an avenue for acquiring a deeper understanding of the packaging requirements for new processes.
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List of Contributors
1 Packaging for nonthermal processing of food: Introduction
FACTORS TO BE CONSIDERED DURING NONTHERMAL PROCESSING
PACKAGING FOR NONTHERMAL PROCESSING
CONSUMER PREFERENCE OF PACKAGING DESIGN AND REGULATION OF NONTHERMAL PROCESSING
2 Active packaging and nonthermal processing
ACTIVE PACKAGING SYSTEMS
CONSIDERATIONS FOR COMBINING AP WITH NTP
3 Antimicrobial packaging in combination with nonthermal processing
COMBINATION OF PEFS WITH ANTIMICROBIAL COATED BOTTLE
COMBINATION OF HPP WITH ANTIMICROBIAL FILM AND COATING
COMBINATION OF PULSED LIGHT (PL) WITH ANTIMICROBIAL COATING
COMBINATION OF GAMMA IRRADIATION WITH ANTIMICROBIAL FILM
COMBINATION ULTRAVIOLET (UV) WITH ANTIMICROBIAL COATING
COMBINATION OF OZONATED WATER WASHING WITH ANTIMICROBIAL COATING
4 Atmosphere packaging for nonthermal processing of food: High CO
package for fresh meat and produce
PACKAGE FOR RAW MEAT PRODUCTS
PACKAGE FOR FRESH PRODUCE PRODUCTS
5 The use of biological agents in processing
COMMON BIOLOGICAL AGENTS USED IN FOOD PROCESSING
6 Packaging for high‐pressure processing, irradiation, and pulsed electric field
INTRODUCTION TO PACKAGING FOR HPP
HOW HPP IMPACTS THE FOOD AND THE PACKAGING
INTRODUCTION TO FOOD IRRADIATION
HOW IRRADIATION IMPACTS THE FOOD AND THE PACKAGING
THE TYPES OF PACKAGING THAT ARE SUITABLE FOR HPP, IRRADIATION, AND PEF
FACTORS THAT MUST BE CONSIDERED WHEN APPLYING HPP TO PACKAGING
THE TYPES OF PACKAGING THAT ARE SUITABLE FOR IRRADIATION
THE TYPES OF PACKAGING THAT ARE SUITABLE FOR PEF
7 Packaging for new and emerging food processing technology
PACKAGING REQUIREMENTS FOR FOODS PROCESSED BY PEF
COLD OR NONTHERMAL PLASMA TECHNOLOGY
PULSED LIGHT (PL) TECHNOLOGY
8 Packaging for foods treated by ionizing radiation: An update
FDA APPROVAL PROCESSES FOR PACKAGING TREATED WITH IONIZING RADIATION
APPROVED PACKAGING MATERIALS FOR TREATMENT WITH IONIZING RADIATION
EFFECTS OF IONIZING RADIATION ON PACKAGING AND FORMATION OF RADIOLYSIS PRODUCTS (RPs)
UPDATED REVIEW OF RPs FROM POLYMER ADJUVANTS
MODELING EXPOSURE FOR PREPACKAGED FOODS TREATED WITH IONIZING RADIATION
9 Packaging technology for microwave sterilization
PACKAGING FOR MW STERILIZATION
CURRENT DEVELOPMENT IN HIGH‐BARRIER POLYMERIC PACKAGING
INTERACTION BETWEEN MW STERILIZATION AND POLYMERIC PACKAGING
INTERACTION BETWEEN PACKAGING AND STERILIZED FOOD
SUMMARY AND FUTURE DEVELOPMENT
10 The influence of package design on consumer purchase intent
TRENDS DRIVING FOOD PACKAGING
CONSUMER DECISION MAKING AND PURCHASE INTENT
RESEARCH ON CONSUMER PACKAGING PREFERENCES
BUILDING AN EVIDENCE BASE FOR PACKAGING DESIGN
11 Safety regulation of food packaging and food contact material in the European Union and the United States
THE REGULATION OF FOOD CONTACT MATERIALS IN THE EUROPEAN UNION
THE REGULATION OF FOOD CONTACT MATERIALS IN THE UNITED STATES
12 The forecast for intelligent packaging in the near future and the influence of nonthermal technologies on its performance
CHROMISM AND FOOD PACKAGING
INTELLIGENT PACKAGING, SENSORS, AND NONTHERMAL TECHNOLOGIES
QUICK RESPONSE AND BARCODES
RADIO FREQUENCY IDENTIFICATION DEVICES
NANOPARTICLES AND INTELLIGENT PACKAGING
CONCERNS ABOUT INTELLIGENT PACKAGING
End User License Agreement
Table 1.1 List of process consideration, benefits, and shortcoming of alternative nonthermal processing methods (reprinted from Neetoo and Chen, 2014, pp. 145–147).
Table 1.2 Packaging materials and adjuvants approved for irradiation by the U.S. Food and Drug Administration (FDA).
Table 3.1 Survival of
on vacuum‐packaged RTE turkey after treatments.
Table 4.1 Recommended high CO
package for raw meat products in retail (modified from Dansensor, 2016, Farber, 1991, Parry, 1993, and Scetar
Table 4.2 CO
limits for horticultural crops and fresh‐cut products (modified from Watkins, 2000).
Table 4.3 Results of the triangle tests comparing taste of 0 or 30% CO
to 75% CO
for different fresh‐cut produce after storage at 7 °C.
Table 6.1 Food types and radiation dosage approved by the U.S. FDA within the United States.
Table 6.2 Packaging materials and adjuvants approved for irradiation by the U.S. FDA.
Table 8.1 AO and RP residual levels, concentration in food and dietary concentrations (DC) for monolayer and multilayers.
Table 8.2 Residual AO and RP levels to be used for migration modeling.
Table 8.3 Modeled migration and dietary concentration values for AOs and RPs.
Table 9.1 Density of common glass, metal, and polymers for sterilized‐food packages.
Table 9.2 Effect of MATS and other thermally processing on the barrier properties of several EVOH‐ and PET‐based multilayer packaging films.
Table 9.3 Shelf life prediction of MATS‐processed model food in three polymer pouches * (MFA, MFB, and MFC) and a foil pouch (MF0) using Δ
=12 as the end point.
Table 10.1 Summary of food packaging research studies.
Figure 1.1 Increasing of HPP, irradiation, and pulsed electric field researches from 2001 to 2016 (https://www.ifis.org/fsta).
Figure 3.1 Survival of total aerobic bacteria (a) and molds and yeasts (b) in pomegranate juice processed at bench‐scale PEF system. UT: untreated; UT + AB: untreated and packaged in antimicrobial bottle; PEF: PEF proccessed; PEF + AB: PEF procecssed and packaged in antimicrobial bottle.
Figure 3.2 Total phenolics (a) and antioxidant (b) compounds of pomegranate juices after treatments and stored at 4 °C for seven days.
Figure 3.3 Growth of
on vacuum‐packed cooked chicken treated with HPP, active packaging (AP), and a combination of HPP and active packaging (HPP/AP) during storage at 4 °C (a) and 8 °C (b).
populations in green bean samples after treatments. Nontreatment (control), coating application alone (coating) and in combination with HHP (coating + HHP). Applied HHP treatments (a) were: 200 MPa for five minutes (HP1), 300 MPa for five minutes (HP2), and 400 MPa for five minutes (HP3).
populations in green bean samples after treatments. Nontreatment (control), coating application alone (coating) and in combination with PL (coating + PL). Applied PL treatments were: 3 x 10
per side (PL1), 6 x 10
per side (PL2), and 1.2 x10
per side (PL3).
Figure 3.6 Effect of coating treatment in combination with gamma irradiation on populations of
on green beans samples during storage at 4 °C.
Figure 3.7 Effect of UV‐C treatment at different doses (2 kJ/m
, 4 kJ/m
, 8 kJ/m
, and 10 kJ/m
) and UV‐C treatment (8 kJ/m
) in combination with coating treatment on
population on broccoli florets. Coating treatment is applied before UV‐C treatment (coating + UVC) and after UV‐C treatment (UVC + coating).
Figure 3.8 Effect of coating treatment in combination with UV‐C on populations of
on green bean samples during storage at 4 °C.
Figure 3.9 Survival of natural psychrotrophs and
on shrimp after treatments. OW: ozone water washing; CC: chitosan coating; OW + CC: ozone water washing followed by chitosan coating.
Figure 3.10 Effect of combined treatment of ozonated water (7 ppm for 2.5 minutes) and coating treatment on the population of
on broccoli florets.
Figure 3.11 Effect of coating treatment in combination with ozonated water washing on populations of
on green bean samples during storage at 4 °C.
Figure 3.12 Survival of natural psychotrophs on shrimp after treatments. NT: no treatment; CF: cryogenic freezing treatment; OW: ozone water treatment; CC: chitosan‐coating treatment; OW + CC + CF: ozone water treatment followed by coating treatment and cryogenic freezing.
Figure 3.13 Change in the populations of total aerobic bacteria of “Goha” strawberries during storage at 4 °C.
Figure 3.14 Microbial survival on ginseng roots after treatments and during storage at 4 °C. A: total bacteria; B: molds and yeasts. SW: sanitizer washing; UV: UV light treatment; CT: chitosan coating; SW/UV/CT: sanitizer washing followed by UV treatment and coating.
Figure 4.1 Effects of high CO
packages on headspace gas composition, shelf life, and microbial growth on fresh‐cut pineapple during storage at 7 °C.
Figure 4.2 Effect of permeability (oxygen transmission rate [OTR] per oz of products in package) of microperforated films on CO
contents in headspace in high CO
fresh‐cut produce packages.
Figure 4.3 Shelf life evaluations of texture and aroma attributes of fresh‐cut cantaloupe packed in high CO
(30%) atmosphere packages (score <5 means that the product is unacceptable; the fresh‐cut cantaloupe batch was processed on the different date by following the same processing method and using different raw materials).
Figure 4.4 Microbial colony formed on fresh‐cut cantaloupe in high CO
Figure 4.5 Microflora on fresh‐cut cantaloupe packed in high CO
atmosphere packages during storage.
Figure 4.6 Relationship between microbial populations and overall product acceptance in fresh‐cut cantaloupe during storage at 2 °C. Test: Cantaloupe was processed under an ideal condition; control: Cantaloupe was processed under a simulated commercial condition. Both samples were packed under high CO
atmosphere. (a) sensory consumer test results; (b) total plate counts; (c) LAB counts.
Figure 4.7 Relationship between microbial populations and overall product acceptance in fresh‐cut cantaloupe during storage at 7 °C. Test: Cantaloupe was processed under an ideal condition; control: Cantaloupe was processed under a simulated commercial condition. Both samples were packed under high CO
atmosphere. (a) sensory consumer test results; (b) total plate counts; (c) LAB counts.
Figure 4.8 Effect of initial microflora on shelf life of fresh‐cut cantaloupe packed under high CO
atmosphere. (a) LAB counts; (b) sensory consumer test results.
Figure 5.1 The chemical structure of nisin (C
Figure 5.2 The repeating polymeric unit of polylysine.
Figure 5.3 Chemical structure of natamycin.
Figure 6.1 A pilot size batch HPP unit.
Figure 6.2 The Radura that is printed on the labels of irradiated packaged foods.
Figure 6.3 A nuclear reactor containing cobalt‐60 stored under water.
Figure 6.4 The sample holder for products that are to be irradiated.
Figure 6.5 An illustration of polymerization by an addition reaction.
Figure 6.6 Illustrations of polymerization by condensation reactions.
Figure 6.7 An illustration of the induction sealing of a bottle.
Figure 9.1 Second generation of 915‐MHz MATS system at Washington State University.
Figure 9.2 Typical structure of commercially available high barrier retort grade polymeric films containing EVOH (a) and PET‐silicon oxide coating (b) as functional barrier layers.
Figure 9.3 Organic barrier coating to provide better barrier properties after cross‐linking during thermal processing.
Figure 9.4 Changes in oxygen transmission rate (OTR) and the dielectric loss tangent (ɛ''/ɛ') of an EVOH‐based film (Nylon/EVOH/CPP) after MATS and during storage.
Figure 10.1 A model of consumer responses to packaging form.
Figure 11.1 FCM symbol.
Figure 12.1 Capsules made with edible casings.
Figure 12.2 Photograph of a heat‐induced color‐changing polymeric material used to make smart cup lids.
Figure 12.3 Photographs of a pressure‐induced color‐changing plastic material inserted inside bottle caps: A – bottle not sealed, B – bottle sealed.
Figure 12.4 (a) Compression shear‐assembly of polymer opal. (b‐c) Optical images under natural lightning. (b) Undoped and (c) doped with carbon nanoparticles (Pursiainen
Figure 12.5 Photograph of an intelligent package.
Figure 12.6 A barcode.
Figure 12.7 A QR code.
Figure 12.8 A RFID tag.
Figure 12.9 The optimum orientation of nanoplates within the matrix of a polymer. The red line is the torturous part of a gas diffusing through the film.
Figure 12.10 Photographs show plastic bottles washed up by the sea in South America.
Table of Contents
The IFT Press series reflects the mission of the Institute of Food Technologists—to advance the science of food contributing to healthier people everywhere. Developed in partnership with Wiley‐Blackwell, IFT Press books serve as leading‐edge handbooks for industrial application and reference and as essential texts for academic programs. Crafted through rigorous peer review and meticulous research, IFT Press publications represent the latest, most significant resources available to food scientists and related agriculture professionals worldwide. Founded in 1939, the Institute of Food Technologists is a nonprofit scientific society with 22,000 individual members working in food science, food technology, and related professions in industry, academia, and government. IFT serves as a conduit for multidisciplinary science thought leadership, championing the use of sound science across the food value chain through knowledge sharing, education, and advocacy.
Casimir C. AkohChristopher J. DoonaFlorence FeeherryJung Hoon HanDavid McDadeRuth M. PatrickSyed S.H. RizviFereidoon ShahidiChristopher H. SommersYael VodovotzKaren Nachay
Malcolm C. BourneDietrich KnorrTheodore P. LabuzaThomas J. MontvilleS. Suzanne NielsenMartin R. OkosMichael W. ParizaBarbara J. PetersenDavid S. ReidSam SaguyHerbert StoneKenneth R. Swartzel
Melvin A. Pascall
Ohio State University, Columbus, OH, USA
Jung H. Han
Pulmuone Foods USA, Fullerton, CA, USA
This edition first published 2018© 2018 John Wiley & Sons Ltd
Edition HistoryCopyright © 2007 Blackwell Publishing Institute of Food Technologists Series, Packaging for Nonthermal Processing of Food 1e, 9780813819440
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The right of Melvin A. Pascall and Jung H. Han to be identified as the authors of the editorial material in this work has been asserted in accordance with law.
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Library of Congress Cataloging‐in‐Publication Data
Names: Pascall, Melvin A., 1954– editor. | Han, Jung H., editor.Title: Packaging for nonthermal processing of food / edited by Melvin A. Pascall, Ohio State University, Columbus, US, Jung H. Han, Pulmuone Foods USA, Fullerton, USA.Description: Second edition. | Hoboken, NJ, USA : Wiley, 2018. | Includes bibliographical references and index. |Identifiers: LCCN 2017048968 (print) | LCCN 2017049500 (ebook) | ISBN 9781119126867 (pdf) | ISBN 9781119126874 (epub) | ISBN 9781119126850 (cloth)Subjects: LCSH: Food–Packaging. | Food–Preservation.Classification: LCC TP374 (ebook) | LCC TP374 .P328 2018 (print) | DDC 664/.09–dc23LC record available at https://lccn.loc.gov/2017048968
Cover Design: WileyCover Image: © panom/Gettyimages
Accelerating New Food Product Design and Development
(Jacqueline H. Beckley, M. Michele Foley, Elizabeth J. Topp, J.C. Huang, and Witoon Prinyawiwatkul)
Advances in Dairy Ingredients
(Geoffrey W. Smithers and Mary Ann Augustin)
Bioactive Proteins and Peptides as Functional Foods and Nutraceuticals
(Yoshinori Mine, Eunice Li‐Chan, and Bo Jiang)
Biofilms in the Food Environment
(Hans P. Blaschek, Hua H. Wang, and Meredith E. Agle)
Calorimetry in Food Processing: Analysis and Design of Food Systems
Coffee: Emerging Health Effects and Disease Prevention
Food Carbohydrate Chemistry
(Ronald E. Wrolstad)
Food Irradiation Research and Technology
(Xuetong Fan and Christopher H. Sommers)
High Pressure Processing of Foods
(Christopher J. Doona and Florence E. Feeherry)
Hydrocolloids in Food Processing
(Thomas R. Laaman)
Improving Import Food Safety
(Wayne C. Ellefson, Lorna Zach, and Darryl Sullivan)
Innovative Food Processing Technologies: Advances in Multiphysics Simulation
(Kai Knoerzer, Pablo Juliano, Peter Roupas, and Cornelis Versteeg)
Microbial Safety of Fresh Produce
(Xuetong Fan, Brendan A. Niemira, Christopher J. Doona, Florence E. Feeherry, and Robert B. Gravani)
Microbiology and Technology of Fermented Foods
(Robert W. Hutkins)
Multivariate and Probabilistic Analyses of Sensory Science Problems
(Jean‐Francois Meullenet, Rui Xiong, and Christopher J. Findlay)
Natural Food Flavors and Colorants
Nondestructive Testing of Food Quality
(Joseph Irudayaraj and Christoph Reh)
Nondigestible Carbohydrates and Digestive Health
(Teresa M. Paeschke and William R. Aimutis)
Nonthermal Processing Technologies for Food
(Howard Q. Zhang, Gustavo V. Barbosa‐Canovas, V.M. Balasubramaniam, C. Patrick Dunne, Daniel F. Farkas, and James T.C. Yuan)
Nutraceuticals, Glycemic Health and Type 2 Diabetes
(Vijai K. Pasupuleti and James W. Anderson)
Organic Meat Production and Processing
(Steven C. Ricke, Michael G. Johnson, and Corliss A. O’Bryan)
Packaging for Nonthermal Processing of Food
(Jung H. Han)
Preharvest and Postharvest Food Safety: Contemporary Issues and Future Directions
(Ross C. Beier, Suresh D. Pillai, and Timothy D. Phillips, Editors; Richard L. Ziprin, Associate Editor)
Regulation of Functional Foods and Nutraceuticals: A Global Perspective
(Clare M. Hasler)
Sensory and Consumer Research in Food Product Design and Development, second edition
(Howard R. Moskowitz, Jacqueline H. Beckley, and Anna V.A. Resurreccion)
Sustainability in the Food Industry
(Cheryl J. Baldwin)
Thermal Processing of Foods: Control and Automation
Water Activity in Foods: Fundamentals and Applications
(Gustavo V. Barbosa‐Canovas, Anthony J. Fontana Jr., Shelly J. Schmidt, and Theodore P. Labuza)
Whey Processing, Functionality and Health Benefits
(Charles I. Onwulata and Peter J. Huth)
Naerin BaekPulmuone Foods USAFullerton, CaliforniaUSA
Allan B. BaileyOffice of Food Additive SafetyCenter for Food Safety and Applied NutritionU.S. Food and Drug AdministrationCollege Park, MarylandUSA
Mary Margaret BarthDepartment of Nutrition and Health Care managementAppalachian State UniversityBoone, North CarolinaUSA
Kanishka BhuniaBiological Systems EngineeringWashington State UniversityPullman, WashingtonUSA
Brian C. BowkerU.S. National Poultry Research CenterUSDA‐ARSAthens, Georgia
Neal D. FortinMichigan State UniversityInstitute for Food Laws and RegulationsEast Lansing, MichiganUSA
Angela FraserDepartment of Food, Nutrition, and Packaging SciencesClemson UniversityClemson, South CarolinaUSA
Jung H. HanPulmuone Foods USAFullerton, CaliforniaUSA
Richard A. HolleyDepartment of Food ScienceUniversity of ManitobaWinnipeg, Canada
Tony Z. JinEastern Regional Research CenterAgricultural Research ServiceU.S. Department of AgricultureUSA
Vanee KomolprasertOffice of Food Additive SafetyCenter for Food Safety and Applied NutritionU.S. Food and Drug AdministrationCollege Park, MarylandUSA
Ghadeer F. MehyarDepartment of Nutrition and Food TechnologyThe University of JordanAmman, Jordan
Chulkyoon MokDepartment of Food Science and BiotechnologyGachon UniversitySeongnam, Korea
Melvin A. PascallDepartment of Food Science and TechnologyOhio State UniversityColumbus, OhioUSA
Pradeep PuligundlaDepartment of Food Science and BiotechnologyGachon UniversitySeongnam, Korea
Shyam SablaniBiological Systems EngineeringWashington State UniversityPullman, WashingtonUSA
Juming TangBiological Systems EngineeringWashington State UniversityPullman, WashingtonUSA
Hongchao ZhangBiological Systems EngineeringWashington State UniversityPullman, WashingtonUSA
Jianhao ZhangCollege of Food Science and TechnologyNanjing Agricultural UniversityNanjing, China
Lu ZhangDepartment of Food Science and TechnologyOhio State UniversityColumbus, OhioUSA
Hong ZhuangU.S. National Poultry Research CenterUSDA‐ARSAthens, Georgia
Naerin Baek1, Jung H. Han1, and Melvin A. Pascall2
1Pulmuone Foods USA, Fullerton, California, USA
2Department of Food Science and Technology, Ohio State University, Columbus, Ohio, USA
Nonthermal processing technologies are food preservation methods designed to eliminate pathogenic and food spoilage microorganisms at low temperatures, when compared with commonly used thermal processes that use more heat (Min et al., 2005). Interests in nonthermal processing technologies have grown in food industry and academic laboratories due to the benefits associated with them. These include minimal impact on nutritional compositions, freshness and flavors, and the extension of shelf life, while diminishing the risk of pathogenic and food spoilage microorganisms. These technologies deliver convenience and efficiency of energy/water utilization when compared with conventional thermal treatments. Currently, some nonthermal processing treatments are commercially available, but others are still in the developmental stages for industrial applications.
Food products to be processed by nonthermal treatments are required to have specific characteristics when compared to similar foods that are thermally processed. Specific packaging materials and systems are required for nonthermally treated foods in order to achieve and maintain the safety and quality attributes of the products. Packaging materials selected for exposure to nonthermal processing must have good resilience and gas barrier properties in order to tolerate the physical and mechanical stresses of the process environment. Examples of nonthermal processing and preservation methods include technologies such as high pressure processing (HPP), pulsed electric fields (PEF), irradiation, light treatments, microwave sterilization, and active and modified atmosphere packaging. This book discusses packaging implications for these nonthermal processing techniques, mild food preservation methods and other hurdle technologies.
Conventional thermal methods for food processing applications are stove‐top cooking, blanching, pasteurization and retorting. These are designed to inactivate microorganisms, enzymes, and other chemical reactions, as well as achieve the expected shelf life and food safety. Chemical and physical changes taking place in foods during conventional heat treatments have been well documented in the published literature. Numerous practical applications of thermal treatments in a wide range of foods have been used from early ages to current times. Additionally, natural interactions and chemical reactions occurring in thermally processed foods and packaging materials are well known. However, in order to better understand and identify the physical, chemical and mechanical interactions taking place within foods and packaging materials exposed to nonthermal treatments, more studies are needed. These will provide data that can be used by engineers and food scientists as they seek to optimize these nonthermal technologies.
Prior to writing this book, the authors reviewed information about nonthermal processing techniques such as HPP, irradiation and PEF, that were reported in the FSTA‐Food Science Technology Abstract database (https://www.ifis.org/fsta). As seen in Figure 1.1, the numbers of nonthermal processing publications have continuously increased from 2001 to 2016, especially in topics relating to HPP and irradiation. Recent studies on HPP, irradiation, and PEF technologies have extensively focused on improving the functionality, safety and fresh tasting qualities of a wide range of foods in response to consumers’ demands. These publication trends also reported on recent developments and improvements to these technologies. As a result, various foods and beverages are now commercially treated by HPP and irradiation, and are in retail trade in various markets around the world.
Figure 1.1 Increasing of HPP, irradiation, and pulsed electric field researches from 2001 to 2016 (https://www.ifis.org/fsta).
High pressure processing is a nonthermal preservation technique that uses high pressured water or another appropriate liquid to transfer the pressure to a food product, either by itself or in its primary package. Microorganisms and enzymes are inactivated by this high pressure treatment, and this helps to maintain the safety and shelf stability of the food. The high pressure process is considered nonthermal due to its ability to inactivate pathogenic and food spoilage microorganisms without causing significant changes to the fresh‐like qualities, sensory attributes or nutrients of the food. This is done without the use of heat normally generated by conventional thermal treatments such as retort processing, for example. Recent trends have shown that a growing consumer interest in HPP is due to its ability to extend the shelf life of food products without the addition of chemical preservatives. Thus, HPP provides benefits to food companies by helping them to meet the requirements for “clean label claims” for their packaged food products. The clean label claim is a recent trend driven by consumers and it relates to their concerns about too much synthetic chemicals being in processed foods.
Two types of irradiation techniques are currently used in food processing. These include ionizing and nonionizing radiations. Ionizing radiation works by using high energy to remove electrons from atoms and it produces ionization as a result. Examples of these include x‐rays, alpha and beta particles, and gamma rays. Ionization can be initiated by radioactive elements such as uranium, radium, tritium, carbon‐14, and polonium, or by high voltage generators that produce x‐rays. Currently, beta particles and gamma rays obtained from cobalt‐60 and cesium‐137 are used for industrial food irradiation applications. Ionization radiation is utilized to inactivate detrimental microorganisms and reduce the rate of spoilage in selected foods. Conversely, nonionizing radiation has a much lower energy level than ionizing radiation. However, nonionizing radiation that is used to treat food, causes atoms within the molecules to vibrate. This vibration produces heat which raises the temperature of the food. Microwave and infrared heating are examples of these. Food irradiation is associated with nonthermal processing due to its ability to inactivate microorganisms, kill insects, and other types of infestation, by using significantly lower temperatures when compared with conventional heat treatments.
Pulsed electric field is a processing technique which uses a high voltage pulse to treat a substrate positioned between two electrodes. Only pumpable liquid or semi‐liquid foods which can flow between the two electrodes can be treated by this technique. During the treatment, harmful microorganisms can be inactivated by the application of micro to millisecond pulses of high voltages to the product that is pumped in the gap between the electrodes. In batch applications, a static treatment can be employed by exposure of the product to the pulsed electric field in a chamber designed with two electrodes. The PEF treatment, due to its extremely short processing time and insignificant increase in temperature, sustains freshness, sensory and nutritional qualities much better than commonly used industrial conventional heat processes such as retorting or microwave cooking.
In general, due to its relatively mild preservation methodology, nonthermally processed foods provide better nutritional and organoleptic characteristics when compared with similar conventionally heated products. Nonthermal processing techniques are also capable of producing safe and extended shelf life foods by inactivating enzymes, and killing pathogenic and spoilage microorganisms.
Bacilllus stearothermophilus is currently used as a microorganism indicator to estimate standard thermal treatment parameters. Other spore forming microorganisms are also used to validate other suitable thermal processes and food applications with extreme pH, water activity, and/or solute concentrations. To assist with these validation studies, food engineers have developed and used standardized data tables showing the values for D (time) and Z (temperature) for the reduction of standard microorganisms. The effectiveness of the thermal treatment on the organisms is determined by the F‐value. However, the resistances of standard microorganisms to nonthermal treatments are different when compared with their responses to conventional thermal techniques. This makes the validation of nonthermal techniques a more challenging feat. Hence this is the reason why more research on nonthermal techniques is needed. In some cases, nonthermal processing can be a replacement for conventional heat treatments, at least, partially, by combining the nonthermal process with heat and or chemical treatments, and other hurdle technologies, depending on nature of the food. However, a better understanding of the effects of nonthermal techniques on chemical and physical changes and of microbiological inactivation in processed products is still needed in order to bridge the gaps between research achievements and industrial applications. Table 1.1 summarizes the process considerations, benefits, and shortcomings of nonthermal processing methods relevant to food products (Neetoo and Chen, 2014).
Table 1.1 List of process consideration, benefits, and shortcoming of alternative nonthermal processing methods (reprinted from Neetoo and Chen, 2014, pp. 145–147).
Examples of applications
High hydrostatic pressure
Enhances product safety
Equipment is cost‐prohibitive
Extends shelf life of product
Phenomenon of “tailing” during microbial inactivation
Desirable textural changes possible
Changes in sensory quality possible
Production of “novel” products
Not suitable for foods with air spaces
Minimal effect on flavor, nutrients and pigment compounds
Not suitable for dry foods
Physiological age of target organisms
Minimal textural loss in high‐moisture foods
Refrigeration needed for low‐acid foods
Meats and vegetables
Can eliminate spores when combined with high temperature
Elevated temperatures and pressures required for spore inactivation
In‐container and bulk processing possible
High‐value commodities such as seafood
Packaging material integrity
Potential for reduction or elimination of chemical preservatives
Positive consumer appeal
No evidence of toxicity of HHP alone
Pulsed electric field
Electric field intensity
Effective against vegetative bacteria
Not suitable for non‐liquid foods
Relatively short processing time
Postprocess recontamination possible
Suitable for pumpable foods
Less effective against enzymes and spores
Whole liquid egg
Minimal impact on nutrients, flavor or pigment compounds
Adverse electrolytic reactions could occur
No evidence of toxicity
Not currently energy efficient
Restricted to foods with low electrical conductivity
Not suitable for product that contain bubbles
Scaling up of process difficult
Physiological age of organisms
Presence of antimicrobials
Ultraviolet light/pulsed UV light
Transmissivity of product
Short processing time
Shadowing effect possible with complex surfaces
Geometric configuration of reactor
Minimal collateral effects on foods
Has low penetration power
Low energy input
Ineffective against spores
Suitable for high‐and low‐moisture foods
Possible adverse sensory effects at high dosages
Physical arrangement of source
Amenable for postpackage processing
Possible adverse chemical effects
Reduced efficacy with high microbial load
Product flow profile
Possible resistance in some microbes
Radiation path length
Reliability of equipment to be established
Combination with other hurdles
Amplitude of ultrasonic waves
Ultrasound effective against vegetative cells
Has little effect on its own
Any food that is heated
TS and MTS effective against vegetative cells and spores
Challenges with scaling up
Reduced process times
Free radicals could damage product quality
Volume of food
Amenable to batch and continuous processing
Can induce undesirable textural changes
Little adaptation required for existing processing plant
Can be damaging to eyes
Possible modification of food structure and texture
Can cause burns and skin cancer
Depth of penetration affected by solids and air in product
Several equipment options
Potential problems with scaling up of plant
Effect on enzyme activity
Can be combined with other unit operations
Long history of use
High capital cost
High penetration power
Localized risks from radiation
Herbs and spices
Suitable for sterilization (food and packages)
Suitable for postpackage processing
Poor consumer acceptance
Meat and fish
Suitable for nonmicrobiological applications (e.g. sprout inhibition)
Changes of flavor due to oxidation
Packaged and frozen foods can be treated
Loss of nutritional value
Low operating costs
Development of radiation‐resistant mutants
State of food
Can be scaled up
Microbial toxins could be present
Low and medium dose has minimal effect on product quality
Outgrowth of pathogens
Suitable for low‐and high‐moisture foods
Combination with other hurdles
The main goal of food packaging is the storage, preservation and protection of the product for an extended period of time. The objective is to ensure the quality and safety of the product for convenient consumption when desired by the consumer. Besides these primary functions, other required functions are the effective marketing and distribution of the product, in addition to consumer matters such as obtaining information about the commodity, efficient and convenient handling, dispensing, and sales promotion. The significance of these packaging functions can shift from one aspect to another according to the needs of society and the lifestyle of consumers, plus the emergence of new technologies.
For nonthermally treated foods, the nature of the packaging and its design should be carefully selected in order to ensure the success of the specific technology. In addition to these, consideration must be given to the process parameters and mechanisms, the microbial growth kinetics, and the mechanical and physical properties of the packaging materials and systems. Food products treated by HPP are usually prepackaged within individual flexible or semi‐rigid packaging materials, or could be packaged in bulk after the treatment. The prepackaged processing method is essential during batch HPP treatments. In this process, the packaging and the material, of which it is made, will be exposed to the same HPP as the food, and must be designed with the ability to survive the pressure treatment. This means that the package must be designed to survive the water‐mediated high hydrostatic pressures which typically range from 30‐600 MPa, but could be as high as 800 MPa. Since the application of pressure will result in volume changes according to the laws of physics, the reversible response of the whole package to the compression/decompression process during HPP is crucial to the successful commercialization of this non‐thermal processing technology. Plastics are the best choice of material for HPP food packaging because they are flexible and most have excellent water‐resistant properties.
The microbicidal purpose of radiating food will be lost if the safety and the shelf life of the treated product is not maintained after the irradiation process. This is facilitated by packaging the food prior to the irradiation process. This ensures that the food remains sterile during transportation, storage and handling prior to consumption. Irradiation applied to prepackaged foods will also expose the packaging material to the radiation treatment. This means that the selection of the packaging material must be of such that minimal changes to the molecular structure are caused by the irradiation. Severe changes to the chemical or morphological composition of the material could accelerate an unsafe release of chemical additives from the package to the food. As a result, the United States Food and Drug Administration (FDA) has published a list of approved packaging materials, additives and the irradiation doses for food processing operations.
Since PEF treated products are not prepackaged before exposure to the electric field, the packaging material does not come in contact with the electrical energy. However, at the end of the PEF process, the product must be aseptically packaged for extended shelf life. To accomplish this, the packaging material must be sterilized by dry heat, steam, ultra violet light, chemicals, and/or a combination of these methods. Not only must the material survive these sterilization methods, any residual sterilant must be removed from the package prior to filling it with the PEF treated food. The packaging material must also be compatible with the product and not allow the migration of undesirable substances, odors, and flavors to the foods, in addition to maintaining its safety and quality.
An aesthetically appealing package influences consumers’ purchasing decisions, and it serves as a strategic marketing tool. A good comprehension of consumer preferences for package design is important for the marketing success of the product. However, package design must not compromise the proper material selection because this could impact the safety and quality of the nonthermal product. Nonthermal processing operations, packaging methods, and materials in contact with the food must be used in accordance with permitted governmental regulations. As an example, the Radura logo is required on the labels of most irradiated packaged foods. Also, a list of packaging materials and the dosages approved for food irritation in the United States are shown in Table 1.2 (FDA, 2015).
Table 1.2 Packaging materials and adjuvants approved for irradiation by the U.S. Food and Drug Administration (FDA).
Maximum Radiation Dose (kGy)
Types of Packaging Materials and Adjuvants Approved for Irradiation
Kraft paper to contain only flour
Polystyrene foam tray
Nitrocellulose‐coated cellophane; Glassine paper;
Rubber hydrochloride film;
Vinylidene chloride‐vinyl chloride copolymer film;
Vinylidene chloride copolymer‐coated cellophane; Nylon 11; Optional adjuvants for polyolefin films plus optional vinylidene chloride copolymer coating; PET film plus optional adjuvants, vinylidene chloride copolymer and polyethylene coatings
Ethylene‐vinyl acetate copolymers
Vegetable parchments; Polyethylene film;
Polyethylene terephthalate film;
Nylon 6 film;
Vinyl chloride‐vinyl acetate copolymer film;
a Plus limited optional adjuvants
In summary, the packaging of a nonthermally processed food is subject to a combination of the nature of the corresponding nonthermal technology, the response of the packaging material to the nonthermal process, regulatory guidelines, consumer acceptance, and the economic analysis of the nonthermal method for the specific food product. Therefore, business studies relating to nonthermal processing and packaging methods should be both technical and socio‐economical.
FDA. 2015. U.S. regulatory requirements for irradiating foods.
(accessed September 16, 2016).
Min, S., Zhang, Q.H., and Han, J.H. 2005. Packaging for non‐thermal food processing. In:
Innovations in Food Packaging
, J. H. Han (Ed.) Elsevier Academic Press. pp. 482–500.
Neetoo, H. and Chen, H. 2014. Alternative food processing technologies. In:
Food Processing: Principles and Applications
, Second Edition. S. Clark
(Eds.) John Wiley & Sons, Ltd. pp. 137–169.
Ghadeer F. Mehyar1 and Richard A. Holley2
1Department of Nutrition and Food Technology, The University of Jordan, Amman, Jordan
2Department of Food Science, University of Manitoba, Winnipeg, Canada
The function of conventional food packaging is primarily to be a passive barrier that protects the contents from external environmental impacts such as water, water vapor, gases, light, odors, microorganisms, insects, dust, shock, vibration, and compression, so that the safety and quality of the contents is preserved from the time of packaging to final consumption. The packaging also serves as a way to communicate to the consumer through the label content and it provides information on issues such as the manufacturer, product, measurements, handling instructions, nutritional content, warnings, and closure applications (Robertson, 2012). The addition of active ingredient(s) to the package and its interaction with the content to keep or improve its properties during post‐packaging storage and transportation converts the passive package into an active package. An active package (AP) is defined as one that performs desirable functions other than providing a passive barrier to the packaged food. The incorporated components are designed to release or absorb substances into or from the food or the surrounding environment with the intent of extending the shelf life of the product (Johansson, 2013). AP involves interactions between the food, the packaging materials and the gaseous atmosphere (ShivalkarYadav, Prabha, and Renuka, 2015). Materials or substances used in AP should be subjected to approval by the U.S. Food and Drug Administration (FDA) pursuant to Section 409(h)(6) of the Federal Food Drug and Cosmetic Act, for food contact substances. Systems with which AP are operated can be classified as scavenging/absorbing, emitting/releasing, or other systems.
Scavenging systems (also called also non‐migrating) absorb gases such as oxygen, ethylene, moisture, carbon dioxide, or flavors from the headspace of the package. Emitting systems (called also migrating) emit/release carbon dioxide, ethanol, antioxidants, antimicrobial agents, flavors, and other types of preservatives. Examples of other systems involve temperature controllers such as isolating materials and self‐heating or self‐cooling containers and compensating films that have the ability to change their gas permeability to match or exceed changes in the respiration rates of fresh produce in response to ambient temperature (ShivalkarYadav, Prabha, and Renuka, 2015; Hosseinnejad, 2014; Restuccia et al., 2010). The active components in these systems can be added directly to the packaging material or they can be included as a separate unit inside the package. Examples of these include sachets, cards, adhesive labels, or packaging films immobilizing the active components (Prasad and Kochhar, 2014; Rooney, 2005). A specific AP is designed for a particular food product based on its predetermined predominant deterioration mechanism(s) (Mehyar and Han, 2011). Therefore, it is important to understand the mechanism of deterioration in term of the initiation factors, the effect of the surrounding environment, and the food composition.
Nonthermal processing (NTP) is defined as using nonthermal technologies to extend the shelf life of the food by inhibiting or killing microorganisms with minimal impact on the nutritional and sensory properties of the food (Morris, Brady, and Wicker, 2007). The major advantage of nonthermal (NT) technology is that they preserve the physiochemical characteristics of the food. Examples of this include changes in nutrients such as ascorbic acid or phenolic compounds content, texture, flavor profile, color, and so on, whereas thermal processing causes irreversible loss of quality properties (Barba et al., 2012). Furthermore, NTP is environmentally friendly because it acts at ambient or sub‐thermal temperatures, and does not contribute in global warming, it minimizes waste water, increases water and energy savings, and results in minimal impact to the quality of foods, thus retaining “fresh‐like” characteristics. The electricity savings of pulsed electrical field (PEF) can be up to 18‐20% based on the assumed electricity consumption compared to existing thermal technologies (Pereira and Vicente, 2010). Some authors considered AP among NTP because both techniques are based on the same principle of delaying possible food deterioration through inactivation of causative agents without the application of heat (Morris, Brady, and Wicker, 2007).
Due to the diversity in mechanisms of inactivation for the NTP, no standard target microorganism or biochemical reaction is suggested as an efficiency index for this process. This could also change the type and requirements for a suitable AP that is to be used for efficient preservation of a nonthermally processed foods. A case study is suggested to determine the suitable combinations of NTP and AP for a particular food product before a commercial application is produced (Akbarian et al., 2014). Another consideration is that the addition of an active component to the packaging should not affect the package properties and the subsequent performance of the NTP in prepackaged foods. For example, incorporating antioxidants or antimicrobial agents in the packaging materials should not affect the mechanical properties of the package if this product to be treated with high hydrostatic pressure or should not affect transparency of the package if the product to be treated by pulsed UV/white light emission process. As another example, if the NTP is to be used in foods before packaging, it should be taken into consideration that structural changes in the food may affect the performance of the AP if the production of free radicals by the ionized radiation occurs and these affect the oxygen scavenging mechanisms (Moseley, 1989; López‐Rubio et al., 2007).
The presence of dissolved or gaseous oxygen in a food has a high detrimental effect by causing the oxidation of oils, fats, flavors, vitamins, and pigments (in plants and animal muscles) as well as the growth of molds and aerobic bacteria. These reactions decrease the shelf life of the food by causing rancidity, off odor, loss of flavors, and nutritional value as well as discoloration and an unacceptable microbial growth. The levels of residual oxygen that can be achieved by regular (MAP) technologies are too high for maintaining the desired quality and shelf life of packaged food. The use of oxygen scavenging packing systems could be used to help reduce the levels of residual oxygen dissolved or present in the headspace much lower (<0.01%) than those achievable by the MAP (0.3‐3%) (Realini and Marcos, 2014). However, some conditions must be fulfilled for oxygen scavenging systems to work properly. The packaging containers or films should be of high oxygen barrier or as a passive monolithic composite, offering a delay in the oxygen transport, caused by the high tortuosity of the material for oxygen diffusion. Otherwise, the scavenger will rapidly become saturated and lose its ability to trap oxygen (Brody et al., 2008). Another consideration is that in flexible packaging, the heat sealing should be successful, so that no air leaks can occur through the seals after closing the package. Other factors that may affect choosing the appropriate type of oxygen scavenger are initial headspace oxygen level, the package surface area, biochemical reactions in the packaged food, and storage temperature (Solis and Rodgers, 2001; Benson and Payne, 2012).
The following shows the reaction for oxygen scavenger mechanisms of action:
Oxidation of iron or iron salts that react with water (provided by the food) to produce stable iron oxide
In the food industry, this scavenger is available within laminates containing ferrous oxygen or it could be incorporated into the resin that is thermoformed into trays or bottles (ShivalkarYadav, Prabha, and Renuka, 2015; Prasad and Kochhar, 2014).
The oxidation of nonmetallic oxygen scavengers such as ascorbic acid, ascorbate salts, and catechol. Most of these reactions are slow but can be accelerated by light or a transition metal that works as a catalyst (e.g., copper) (Cruz, Camilloto, and Pires, 2012). Celox® (used in lined crowns, aluminum ROPP, plastic caps) and Darex® (an oxygen scavenger master batch) of W.R. Grace and Co. (USA) are commercial applications on ascorbate based oxygen scavengers.
The oxidation of photosensitive dye impregnated onto polymeric films. When the film is irradiated by UV light, the dye activates the oxygen to its singlet state, making the oxygen removal reaction much faster (Cruz, Camilloto, and Pires, 2012). Cryovac® OS Films are UV light–activated oxygen scavenging films developed by Cryovac Food Packaging, Sealed Air Corporation (USA) and composed of an oxygen scavenger layer extruded into a multilayer film. Since OS films are colorless, they do not alter the look of the package. However, they inhibit the growth of molds and aerobic microorganisms. ZerO2®is another example of a UV light–activated oxygen scavenging polymer developed by CSIRO (Division of Food Science, Australia) in collaboration with Visy Pak Food Packaging (Visy Industries, Australia). It is incorporated into a layer in a multilayer package structure and can be used in common packaging materials as polyethylene terephthalate (PET). The active ingredient is a nonmetallic and it is activated by UV light once it is incorporated into packaging material (Day, 2008). Chevron Phillips Chemical Company (USA) developed an oxygen scavenger resin (OSP®) consisting of an oxidizable polymer contains a catalyst that would chemically bind oxygen without the production of undesirable by products. The resin is supplied with an ultraviolet initiator to trigger the oxygen scavenging directly after packaging the product (Solis and Rodgers, 2001). FreshMax® (by Multisorb Technologies, NY, USA), a self‐adhesive oxygen absorber, is attached inside the package in a flat, flexible format with an ultrathin low‐profile design, making them seemingly invisible. It is shown that it can reduce oxygen in packaged sliced ham to approximately 0.1% in 36–48 h and to less 0.01% shortly after that (Benson and Payne, 2012).
Enzymatic oxygen scavengers using glucose oxidase or ethanol oxidase. These can be incorporated into sachets, adhesive labels, or immobilized onto packaging films surfaces. These scavengers are based on natural biological components (such as enzymes or microorganism) and have advantages such as recyclability, safety, material compatibility, less environmental impact and product cost compared to chemical‐based oxygen scavengers (Hosseinnejad, 2014). Another advantage of the enzymatic oxygen scavenger is that it could be used for food products with a wide range of water activities since it does not require water to operate. The disadvantage of this scavenger is its low efficiency because catalase, a natural contaminant found in the glucose oxidase preparation, react with H
, a byproduct of oxidase enzyme action on glucose, to form H
O and O
and, therefore, decreasing the system efficiency. However, the glucose oxidase production without catalase is very expensive (Cruz, Camilloto, and Pires, 2012).
Carbon dioxide scavengers are used to control fruits/vegetables post‐harvesting respiration, prevent flavor oxidation in ground coffee and control the growth of aerobic and anaerobic microorganisms (ShivalkarYadav, Prabha, and Renuka, 2015). High levels of carbon dioxide (10‐80%) are desirable in meat and poultry products, because it creates carbonic acid that has antimicrobial properties and inhibit surface microbial growth (Hosseinnejad, 2014). Dual action oxygen scavenger/carbon dioxide emitter sachets and labeled have been used with food products highly susceptible to fats/oils oxidation and in some applications, where removal of oxygen from the package creates a partial vacuum that may result in the collapse of flexible package (e.g., nuts and coffee pouches) (Day, 2008).
Calcium oxide is converted to calcium carbonate
It can be used in combination of activated charcoal that has a very large surface area for adsorption of water.
Potassium hydroxide absorbs gaseous CO2:
There are many commercial sachets and labels that are used to scavenge or emit carbon dioxide. Agless® G (Mitsubishi Gas Chemical Co.) and FreshPax® M are dual action oxygen scavengers and carbon dioxide emitters and they are available in sachets and labels (ShivalkarYadav, Prabha, and Renuka, 2015; Hosseinnejad, 2014).
The antioxidants mechanism of action depends on their structure, polarity, and effective concentration. They act by interfering or chelating the metal catalytic or act as free radicals or oxygen scavengers (Caillet et al., 2012). Natural antioxidants (such as tocopherol, plant extract, and essential oils) or synthetic antioxidant (such as BHA and BHT) eliminate oxo, hydroxyl, and superoxide free radicals originated from oxygen by oxidation reaction. Therefore, these antioxidants break down the accelerated auto‐oxidation process by radical scavenging (Prasad and Kochhar, 2014). Incorporation of antioxidants in packaging materials is the most commonly used application form of oxygen scavengers. Ascorbic acid, ferulic acid, quercetin, and green tea extract have been successfully incorporated into ethylene vinyl alcohol (EVOH) copolymer packaging matrix to improve lipid stability of brined sardine. Films with green tea extract provided the best protection against lipid oxidation (López‐de‐Dicastillo et al., 2012).
Ethylene is a gaseous phytohormone that initiates and accelerates climacteric fruit ripening, fruit softening, and degradation of chlorophylls, and may lead, upon excessive ripening to quality deterioration of fresh and fresh‐cut fruits. Therefore, reducing ethylene in the headspace of packaged fruit is important to control fruit post‐harvesting quality deterioration by overripening. The ethylene scavenger mechanism of action is based on the use of potassium permanganate that oxidizes ethylene to carbon dioxide and water. Potassium permanganate as oxidizes ethylene changes its color from purple to brown.
For efficient scavenging of the gaseous ethylene, ethylene scavenger (KMnO4) must be adsorbed on a suitable inert carrier with a large surface area such as celite, vermiculite, silica gel, alumina pellets, activated carbon, or glass (Hosseinnejad, 2014). Because of its high toxicity, potassium permanganate cannot be used in direct contact with foods; therefore, it is replaced by palladium chloride (PdCl) loaded within charcoal that has a higher ethylene adsorption capacity than potassium permanganate and it is a safer alternative in high relative humidity conditions (ShivalkarYadav, Prabha, and Renuka, 2015).
Ethanol as vapor is an effective antimicrobial agent against the growth of molds, anaerobic bacteria and yeasts in high moisture foods due to its high water solubility. As a result, it is capable of reaching microbes on the surface and within the matrix of a product. Ethanol can be sprayed directly onto food products just prior to packaging or incorporated into the package material. It is important that the packaging material can deliver ethanol in a controlled manner to maintain headspace concentration above the minimum inhibitory concentration (MIC) of the targeted microorganisms. A practical and safer method of generating ethanol is through the use of ethanol‐emitting films and sachets that contain absorbed or encapsulated ethanol, which is allowed to control the release of the ethanol vapor (ShivalkarYadav, Prabha, and Renuka, 2015).
Humidity absorbers and regulators can be used to control the surrounding moisture as effective desiccants and humectants, respectively. Therefore, they can maintain the food quality and safety by inhibiting microbial growth and other moisture‐dependent degrading reactions. Humidity absorbers control transpiration in fresh produce, softening of dried foods, and deterioration of flavor (Mehyar and Han, 2011). In high water activity foods, excessive moisture loss may lead to dryness. Microporous sachets containing active substances are mostly used. Inorganic salts such as sodium chloride, potassium chloride, and potassium nitrate are considered both desiccants and humectants. Silica gel, activated clays and minerals, activated carbon, zeolite, calcium sulfate, and calcium oxide are the most commonly used desiccants (Brody, Strupinsky, and Kline, 2001).
Moisture‐absorbing products, including moisture‐drip absorbent pads, sheets, and blankets, consist of two layers of a microporous nonwoven plastic film, such as polyethylene or polypropylene, between which is placed a superabsorbent polymer capable to absorb up to 500 times its own weight in water (ShivalkarYadav, Prabha, and Renuka, 2015). These products are commonly placed under packaged fresh meats, fish, and poultry to absorb unsightly tissue drip exudates. Commercial examples of moisture‐absorber sheets, blankets, and trays include Toppan Sheet™ (Toppan Printing Co. Ltd, Japan), Thermarite™ (Thermarite Pty Ltd, Australia), Luquasorb™ (BASF, Germany), and Fresh‐R‐Pax™ (Maxwell Chase, Inc., Douglasville, GA, USA). Typical superabsorbent polymers include polyacrylate polymer, carboxymethyle cellulose (CMC), and starch copolymers (Day, 2008).
Moisture control technology (MCT) is an example of using humidity regulators in response to temperature. It is an innovative fiberboard box that functions as a relative humidity (RH) buffer through a super absorber paper layer in the multilayer system that is used for storage of fruits and vegetables. When temperature drops and RH rises, it absorbs moisture around the packaged food. Conversely, when the temperature rises and RH drops, it releases moisture in response to low RH, therefore maintains a relatively constant RH around the food (Rooney, 2005).
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