Irradiation for Quality Improvement, Microbial Safety and Phytosanitation of Fresh Produce

Rivka Barkai-Golan, Peter A. Follett

• Publisher: Academic Press
• Year: 2017
• Print ISBN: 9780128110256
• eBook ISBN: 9780128110263
• Topic: Medicine
• Subtopic: Medical Microbiology & Parasitology

Irradiation for Quality Improvement, Microbial Safety and Phytosanitation of Fresh Produce presents the last six and a half decades of scientific information on the topic. This book emphasizes proven advantages of ionizing irradiation over the commonly used postharvest treatments for improving postharvest life of fresh fruits and vegetables to enhance their microbial safety.This reference is intended for a wide range of scientists, researchers, and students in the fields of plant diseases and postharvest diseases of fruits and vegetables. It is a means for disease control to promote food safety and quality for the food industry and can be used in food safety and agriculture courses.- Discusses pathogen resistance to common chemical synthetic compounds- Presents up-to-date research and benefits of phytosanitary irradiation- Includes comprehensive research for alternative treatments for postharvest disease control- Provides the non-residual feature of ionizing radiation as a physical means for disease control to produce chemical free foods

Chapter 1

Irradiation for Quality Improvement and Microbial Safety of Fresh Produce

Abstract

The first chapter focuses on the purposes of applying ionizing radiation to fruits and vegetables. These include the extension of their useful shelf life by inactivating postharvest pathogens or/and by delaying ripening and senescence, and inhibiting sprouting of tubers, bulbs, and roots of subterranean vegetables. Most important purposes are the improvement of microbial safety associated with human pathogenic bacteria contaminating the fresh produce and providing relevant data on wholesomeness and safety of irradiated food. Chemical and nutritional changes occurring after irradiation should be provided.

Keywords

Clearances; Dose terminology; Microbial safety; Radiation purposes; Radiation sources; Wholesomeness

Overview

With the development of pathogen resistance to some of the common chemical synthetic compounds and with the increased wish to receive fresh products free of chemical residues leading to public risk, research for alternative substances or treatments has been increased. These included the use of natural chemical compounds, the introduction of “generally recognized as safe” compounds, the use of biocontrol agents, the development of genetically engineered crops, the modulation of the natural host defense substances (Terry and Joyce, 2004; Charles et al., 2008) and the increased interest in physical control methods, such as cold storage, heating, modified or controlled atmosphere storage, hypobaric pressure, and ionizing radiation. The nonresidual feature of ionizing radiation as a physical means for postharvest disease control has been regarded as an important advantage in treating fresh fruits and vegetables.

Studies aimed at evaluating the possibilities of using ionizing radiation for extending the useful life of fresh fruits and vegetables via suppressing postharvest diseases and retarding physiological deterioration have been conducted since the 1950s. These studies were accompanied by investigations on the possible use of ionizing radiation as a means for extending the storage life of tuber, bulb, and root crops by sprout inhibition.

With the increased interest in minimally processed or fresh-cut fruits and vegetables, enhanced efforts were dedicated to evaluating the ability of ionizing radiation to enhance microbial safety by eliminating human pathogenic microorganisms that frequently contaminate the fresh-cut produce.

Studies on irradiation effects on fresh fruits and vegetables and later on minimally processed fruits and vegetables for improving their keeping quality aspects have been discussed along the years in a great number of reviews such as those by Sommer and Fortlage (1966), Dennison and Ahmed (1975), Brodrick and Thomas (1978), Thomas (1983, 1984, 1985, 1986a,b, 1986), Thayer (1990), Barkai-Golan (1992, 2001), Molins (2001), Groth (2007), Arvanitoyannis et al. (2009), Arvanitoyannis (2010), Niemira and Fan (2009), Cia et al. (2010), Fan (2010, 2012a,b, 2013b), Niemira (2013) and Fan and Sommers (2013a,b). A great number of other reviews have been focused on special aspects of fresh fruits and vegetables irradiation.

Early studies have already shown that the possible application of ionizing radiation for decay control may be limited by the susceptibility of the host plant tissue to irradiation, as expressed by radiation-induced damage and adverse changes in nutritional contents, color, texture, flavor, or aroma. Thus, the use of ionizing irradiation as a means for decay control will depend on the balance between pathogen sensitivity to irradiation and host resistance to its application.

To reduce the radiation dose effective for decay control and postharvest life extension, the possibility of using combined treatments of radiation with other physical treatments, mild chemical applications, or other accepted postharvest treatments has been developed.

The first part of the book brings together the variety of approaches aimed at using ionizing radiation as an alternative physical means for improving the shelf life of harvested products, including studies in various countries over the last six decades. The studies involved are aimed mainly at four directions: (1) the extension of postharvest life or shelf life directly by inactivating postharvest pathogens alone or combined with other known postharvest control means; (2) the extension of postharvest life by delaying the ripening and senescence processes, which may indirectly lead also to decay suppression in harvested fruits and vegetables; (3) the improvement or enhancement of microbial safety associated with human pathogens in minimally processed or fresh-cut fruits, vegetables, and mushrooms, a subject that gained increased interest during the last decades; (4) postharvest life extension of subterranean vegetables via sprout inhibition of tubers, bulbs, and roots.

An important advantage of ionizing radiation over chemical application is its ability to penetrate deeply into the host tissues without leaving residues. Thus, in contrast to chemicals, gamma radiation enables the control of not only surface- or wound-infecting microorganisms but also pathogens implanted within the host either as latent or as active infections. Therefore, ionizing radiation may also be considered as a therapeutic means for postharvest diseases.

The data given in part 1 of the book include, along with up-to-date information on irradiation effects on the fresh produce, also early studies because some basic or pioneer studies associated with the ability of irradiation to extend the useful shelf life of fresh fruits and vegetables by inhibition of pathological and physiological changes and enhancement of their safety and wholesomeness have been carried out in earlier investigations.

Radiation Purposes—Safety and Wholesomeness of Fresh Produce

The aim of food irradiation, similar to that of other food technologies, such as freezing and high-temperature or chemical treatments, is to maintain its quality, enhance its safety, and prolong its shelf life by eliminating microbial development and food-borne illness caused by contaminating human pathogenic microorganisms. Regarding fruits and vegetables, irradiation may act as postharvest fungicidal or fungistatic means against spoilage microorganisms and will replace chemical treatments without leaving residues in the vegetal tissues intended for consumption. Irradiation is capable of inhibiting the accumulation of human pathogenic bacteria that frequently contaminate the surface of fresh and fresh-cut fruits and vegetables and are responsible for serious outbreaks. Irradiation may also extend postharvest life by retarding the physiological activity of fresh fruits and vegetables, mainly those associated with the ripening and senescence processes, and by inhibiting sprout inhibition of potato tubers or onion and garlic bulbs during postharvest stages.

Safety and wholesomeness are basic factors for applying irradiation. Extensive research on food exposed to ionizing irradiation from different sources provided evidence that ingestion of irradiated food is safe (WHO, 1988; CAST, 1996; IAEA, 2006; EFSA, 2011). The process of irradiation includes the passage of the food items through the radiation field without having contact with radioactive substances (O’Beirne, 1989; Crawford and Ruff, 1996; Grolichova et al., 2004). Wholesomeness implies satisfactory nutritional quality and microbiological safety for consumers. Regarding wholesomeness of irradiated food, early studies have already indicated that the nutrient breakdown is considerably reduced after irradiation than after other established processes, such as heating and canning (Brodrick et al., 1985). To assess the biological safety of irradiation and provide relevant data on the wholesomeness of irradiated food, investigation of biochemical changes occurring in food exposed to irradiation has been included in many laboratories in various countries.

The new terminology of wholesomeness means “safety for consumption” in the widest possible sense. It includes the radiological, toxicological, and microbiological safety and the nutritional adequacy and the sensory quality of the irradiated product (Ehlermann, 2005).

Radiation Sources and Dose Terminology

Sources of ionizing radiation aimed at suppressing or inactivating pathogenic microorganisms of fruits and vegetables and those contaminating the ...

Table of contents

• Cover image
• Title page
• Table of Contents
• Copyright
• Preface
• Acknowledgments
• Chapter 1. Irradiation for Quality Improvement and Microbial Safety of Fresh Produce
• Chapter 2. Ionizing Radiation for Shelf Life Extension
• Chapter 3. Postirradiation Changes in Fruits and Vegetables
• Chapter 4. Irradiation Effects on Mycotoxin Accumulation
• Chapter 5. Sprout Inhibition of Tubers, Bulbs, and Roots by Ionizing Radiation
• Chapter 6. Irradiation for Quality Improvement of Individual Fruits
• Chapter 7. Irradiation for Quality Improvement of Individual Vegetables Including Mushrooms
• Chapter 8. Safety of Fresh and Fresh-Cut Fruits and Vegetables Following Irradiation
• Chapter 9. Benefits of Fruit and Vegetable Irradiation, Labeling and Detection of Irradiated Food, Consumer Attitude, and Future Research
• Chapter 10. Phytosanitary Irradiation of Fresh Horticultural Commodities for Market Access
• Chapter 11. Phytosanitary Irradiation: Generic Treatments
• Chapter 12. Phytosanitary Irradiation: Combination Treatments
• Chapter 13. Current Issues in Phytosanitary Irradiation
• Appendix
• References
• Index