Food Irradiation

Anthony Trinh
March 7, 2018

Submitted as coursework for PH241, Stanford University, Winter 2018

Overview

Fig. 1: A portable, trailer-mounted food irradiation, loaded and tested at Brookhaven National Laboratory. (Source: Wikimedia Commons)

Roughly between one-fourth to one-third of the world's food supply is lost as a result of spoilage. [1] Furthermore, pathogenic bacterial contamination from foodstuffs, such as E. Coli. and Salmonella represent a significant public health concern, especially in developing countries. In order to alleviate this crisis, food irradiation, or the process of exposing food either to electromagnetic radiation or to high-energy particles, has emerged as a potential solution to constrain the emergence of an outbreak of foodborne pathogens.

The Technology

Food irradiation is a relatively simple process. Ionizing radiation converts an atom or molecule into an ion by adding or removing charged particles, such as electrons or other ions. [2] This ultimately results in the breakdown the DNA within pathogens, such as E. Coli. [2] Most irradiated food is processed by gamma irradiation; however, the usage of electron beams and X-ray is becoming more popular as well. [3]

Food irradiation doses are measured in kiloGray (kGy). [3] One unit of kGy indicates that the target sample receives 1000 Joules per kilogram of sample mass. [3] At high doses, irradiation can cause some loss of vitamins, but there is less vitamin degradation in comparison to microwaving or cooking. [4] Table 1 lists dosages and corresponding applications.

Effectiveness

The quality of the food product remains intact during the food irradiation process. Generally, most food micronutrients, such as water-soluble and fat-soluble vitamins, and macronutrients, such as carbohydrates, proteins, and lipids, are not modified by 10 kGy-range ionizing dose with regard to their nutrient content. [2] High reductions of bacteria are anticipated in seafood and fresh meat, albeit at a higher dosage of ionizing radiation. A dosage of 2 to 4 kGy has also been shown to inactivate food-borne pathogens including Salmonella and E. coli in a variety of ready-to-eat food products. [2]

Dosage Amount	Application	Products
Low (up to 1 kGy)	Inhibition of sprouting, insect and parasite disinfestation, delay ripening	Cereals, fresh fruit, dried foods, fresh fruit, vegetables
Medium (1-10 kGy)	Extend shelf-life, halt spoilage, kill pathogens	Fish, seafood, poultry, meat
High (10-50 kGy)	Industrial sterilization, decontamination	Meat, poultry, seafood, prepared foods

Table 1: Food Irradiation Application [4]

Constraints

While irradiation reduces the risk of infection and spoilage, it also cause chemical reactions that alter the food and therefore alters the chemical makeup, nutritional content, and the sensory qualities of the food. [5] However, contrary to popular belief, it requires high doses of radiation treatment to negatively alter the product's nutritional content and it's impact on quality is minimal. The greatest constraint to this technology is the consumer perception of it. In a recent study, 46% of interviewees expressed a belief that irradiated food meant the same as radioactive food. [6] However, a large amount of independent research has confirmed irradiation to be safe. [7] Due to the perception and the increased cost of irradiated foods, there is not much of a demand for the irradiation of foods for human consumption. In order for the technology to gain more mass appeal, the marketing approach for food irradiation must emphasize the safety of the product.

© Anthony Trinh. The author warrants that the work is the author's own and that Stanford University provided no input other than typesetting and referencing guidelines. The author grants permission to copy, distribute and display this work in unaltered form, with attribution to the author, for noncommercial purposes only. All other rights, including commercial rights, are reserved to the author.

References

[1] B. E. B. Moseley, "Irradiation of Food," Food Control 1, 205 (1990).

[2] H. A. Mostafavi et al., "The Potential of Food Irradiation: Benefits and Limitations," in Trends in Vital Food and Control Engineering, ed. by A. H. A. Eissa (InTech, 2012).

[3] R. A. Molins, Ed., Food Irradiation: Principles and Applications (Wiley-Interscience, 2001).

[4] R. Lutter, "Food Irradiation - The Neglected Solution to Food-Borne Illness," Science 286, 2275 (1999).

[5] A. Martin, "Spinach and Peanuts, With a Dash of Radiation," New York Times, 1 Feb 09.

[6] M. P. Junqueira-Gonalves et al., "Perception and View of Consumers on Food Irradiation and the Radura Symbol," Radiat. Phys. Chem. 80, 119 (2011).

[7] J. F. Diehl, Safety of Irradiated Foods (CRC Press, 1995).