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Casimir C. Akoh
Christopher J. Doona
Florence Feeherry
Jung Hoon Han
David McDade
Ruth M. Patrick
Syed S.H. Rizvi
Fereidoon Shahidi
Christopher H. Sommers
Yael Vodovotz
Karen Nachay
Malcolm C. Bourne
Dietrich Knorr
Theodore P. Labuza
Thomas J. Montville
S. Suzanne Nielsen
Martin R. Okos
Michael W. Pariza
Barbara J. Petersen
David S. Reid
Sam Saguy
Herbert Stone
Kenneth R. Swartzel
Edited by
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 History
Copyright © 2007 Blackwell Publishing Institute of Food Technologists Series, Packaging for Nonthermal Processing of Food 1e, 9780813819440
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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–dc23
LC record available at https://lccn.loc.gov/2017048968
Cover Design: Wiley
Cover Image: © panom/Gettyimages
Naerin Baek
Pulmuone Foods USA
Fullerton, California
USA
Allan B. Bailey
Office of Food Additive Safety
Center for Food Safety and Applied Nutrition
U.S. Food and Drug Administration
College Park, Maryland
USA
Mary Margaret Barth
Department of Nutrition and Health Care management
Appalachian State University
Boone, North Carolina
USA
Kanishka Bhunia
Biological Systems Engineering
Washington State University
Pullman, Washington
USA
Brian C. Bowker
U.S. National Poultry Research Center
USDA‐ARS
Athens, Georgia
Neal D. Fortin
Michigan State University
Institute for Food Laws and Regulations
East Lansing, Michigan
USA
Angela Fraser
Department of Food, Nutrition, and Packaging Sciences
Clemson University
Clemson, South Carolina
USA
Jung H. Han
Pulmuone Foods USA
Fullerton, California
USA
Richard A. Holley
Department of Food Science
University of Manitoba
Winnipeg, Canada
Tony Z. Jin
Eastern Regional Research Center
Agricultural Research Service
U.S. Department of Agriculture
USA
Vanee Komolprasert
Office of Food Additive Safety
Center for Food Safety and Applied Nutrition
U.S. Food and Drug Administration
College Park, Maryland
USA
Ghadeer F. Mehyar
Department of Nutrition and Food Technology
The University of Jordan
Amman, Jordan
Chulkyoon Mok
Department of Food Science and Biotechnology
Gachon University
Seongnam, Korea
Melvin A. Pascall
Department of Food Science and Technology
Ohio State University
Columbus, Ohio
USA
Pradeep Puligundla
Department of Food Science and Biotechnology
Gachon University
Seongnam, Korea
Shyam Sablani
Biological Systems Engineering
Washington State University
Pullman, Washington
USA
Juming Tang
Biological Systems Engineering
Washington State University
Pullman, Washington
USA
Hongchao Zhang
Biological Systems Engineering
Washington State University
Pullman, Washington
USA
Jianhao Zhang
College of Food Science and Technology
Nanjing Agricultural University
Nanjing, China
Lu Zhang
Department of Food Science and Technology
Ohio State University
Columbus, Ohio
USA
Hong Zhuang
U.S. National Poultry Research Center
USDA‐ARS
Athens, Georgia
Naerin Baek1, Jung H. Han1, and Melvin A. Pascall2
1 Pulmuone Foods USA, Fullerton, California, USA
2 Department 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.
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).
Process | Process considerations | Benefits | Shortcomings | Examples of applications |
High hydrostatic pressure | Processing time | Enhances product safety | Equipment is cost‐prohibitive | Fruit products |
Treatment temperature | Extends shelf life of product | Phenomenon of “tailing” during microbial inactivation | Yogurts | |
Pressure level | Desirable textural changes possible | Changes in sensory quality possible | Smoothies | |
Product acidity | Production of “novel” products | Not suitable for foods with air spaces | Condiments | |
Water activity | Minimal effect on flavor, nutrients and pigment compounds | Not suitable for dry foods | Salad dressings | |
Physiological age of target organisms | Minimal textural loss in high‐moisture foods | Refrigeration needed for low‐acid foods | Meats and vegetables | |
Product composition | Can eliminate spores when combined with high temperature | Elevated temperatures and pressures required for spore inactivation | Sauces | |
Vessel size | In‐container and bulk processing possible | High‐value commodities such as seafood | ||
Packaging material integrity | Potential for reduction or elimination of chemical preservatives | |||
Processing aids | 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 | Fruit juices |
Chamber design | Relatively short processing time | Postprocess recontamination possible | Milk | |
Electrodes design | Suitable for pumpable foods | Less effective against enzymes and spores | Whole liquid egg | |
Pulse width | Minimal impact on nutrients, flavor or pigment compounds | Adverse electrolytic reactions could occur | Soups | |
Treatment time | No evidence of toxicity | Not currently energy efficient | Heat‐sensitive foods | |
Temperature | Restricted to foods with low electrical conductivity | |||
Microbial species | Not suitable for product that contain bubbles | |||
Microbial load | Scaling up of process difficult | |||
Physiological age of organisms | ||||
Product acidity | ||||
Product conductivity | ||||
Presence of antimicrobials | ||||
Ultraviolet light/pulsed UV light | Transmissivity of product | Short processing time | Shadowing effect possible with complex surfaces | Bread |
Geometric configuration of reactor | Minimal collateral effects on foods | Has low penetration power | Cakes | |
Power | Low energy input | Ineffective against spores | Pizza | |
Wavelength | Suitable for high‐and low‐moisture foods | Possible adverse sensory effects at high dosages | Fresh produce | |
Physical arrangement of source | Amenable for postpackage processing | Possible adverse chemical effects | Meats | |
Product shape/size | Medium cost | Reduced efficacy with high microbial load | Seafood | |
Product flow profile | Possible resistance in some microbes | Cheeses | ||
Radiation path length | Reliability of equipment to be established | Food packages | ||
Combination with other hurdles | ||||
Ultrasound | Amplitude of ultrasonic waves | Ultrasound effective against vegetative cells | Has little effect on its own | Any food that is heated |
Exposure time | TS and MTS effective against vegetative cells and spores | Challenges with scaling up | ||
Microbial species | Reduced process times | Free radicals could damage product quality | ||
Volume of food | Amenable to batch and continuous processing | Can induce undesirable textural changes | ||
Product composition | Little adaptation required for existing processing plant | Can be damaging to eyes | ||
Treatment temperature | Possible modification of food structure and texture | Can cause burns and skin cancer | ||
Energy efficient | 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 | ||||
Ionizing radiation | Absorbed dose | Long history of use | High capital cost | Fresh produce |
Water activity | High penetration power | Localized risks from radiation | Herbs and spices | |
Freezing | Suitable for sterilization (food and packages) | Hazardous operation | Packaging materials | |
Prevailing oxygen | Suitable for postpackage processing | Poor consumer acceptance | Meat and fish | |
Microbial load | Suitable for nonmicrobiological applications (e.g. sprout inhibition) | Changes of flavor due to oxidation | ||
Microbial species | Packaged and frozen foods can be treated | Loss of nutritional value | ||
Product composition | Low operating costs | Development of radiation‐resistant mutants | ||
State of food | Can be scaled up | Microbial toxins could be present | ||
Food thickness | Low and medium dose has minimal effect on product quality | Outgrowth of pathogens | ||
Particle size | Suitable for low‐and high‐moisture foods | |||
Combination with other hurdles | Diverse applications |
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 |
0.5 | Kraft paper to contain only flour |
7.2 | Polystyrene foam tray |
10 | Nitrocellulose‐coated cellophane; Glassine paper; |
Wax‐coated paperboard; | |
Polyolefin film;a | |
Polystyrene film;a | |
Rubber hydrochloride film;a | |
Vinylidene chloride‐vinyl chloride copolymer film;a 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 | |
30 | Ethylene‐vinyl acetate copolymers |
60 | Vegetable parchments; Polyethylene film;a Polyethylene terephthalate film;a Nylon 6 film;a Vinyl chloride‐vinyl acetate copolymer film;a |
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.