Elsevier

Food Control

Volume 20, Issue 5, May 2009, Pages 526-528
Food Control

Short Communication
The RADURA-terminology and food irradiation

https://doi.org/10.1016/j.foodcont.2008.07.023Get rights and content

Abstract

The meaning of the international RADURA-logo and the terminology behind it is not clearly understood, the historical background of the RADURA-idea is no longer present in the actual interpretation by many people in the field of food irradiation. The history of this terminology is narrated here, in order that this heritage is not lost by time passing.

Introduction

The word RADURA is derived from radurization, composed from radiation and ‘durus’ (Latin for hard, lasting etc.). Radicidation is derived from radiation and ‘caedere’ (Latin for fell, cut, kill). Radappertization (resembling the terminology of ‘pasteurization’ derived from Pasteur) is derived from radiation and the name of Appert,1 a French scientist/engineer who invented sterilized food for the troops of Napoleon in Egypt.

The proposal for a new terminology was intended to replace the then terminology of radiation sterilization and radiation pasteurization, which were not technically correct and to find a more descriptive wording (Goresline et al., 1964). The identical argument is valid against other proposed terminology as ‘cold pasteurization’. There has been no attempt to invent a similar, new radiation-specific terminology also for other applications such as ripening delay, sprout inhibition, insect disinfestation. The three proposed terms radappertization, radurization, radicidation cover different classes of beneficial applications of processing food by ionizing radiation for microbial objectives (Diehl, 1995):

  • Radappertization: The application to foods of a dose of ionizing radiation sufficient to reduce the number and/or activity of viable microorganisms to such an extent that very few, if any, are detectable in the treated food by any recognized method (viruses being excepted). No microbial spoilage or toxicity should become detectable in a food so treated, no matter how long or under what conditions it is stored, provided the package remains undamaged. The required dose is usually in the range of 25–45 kGy.

  • Radicidation: The application to foods of a dose of ionizing radiation sufficient to reduce the number of viable specific non-spore-forming pathogenic bacteria to such a level that none are detectable when the treated food is examined by any recognized method. The required dose is in the range of 2–8 kGy. The term may also be applied to the destruction of parasites such as tapeworm and trichina in meat, in which case the required dose is in the range of 0.1–1 kGy. When the process is used specifically for destroying enteropathogenic and enterotoxinogenic organisms belonging to the genus Salmonella, it is referred to as Salmonella radicidation.

  • Radurization: The application to foods of a dose of ionizing radiation sufficient to enhance its keeping quality by causing a substantial decrease in numbers of viable specific spoilage microorganisms. The required dose is in the range of 0.4–10 kGy.

It should be noted that those three processes all are combination applications like their classical counter-parts: packaging is indispensable to avoid re-contamination by microorganisms. Radappertization, additionally, requires a (mild) heat treatment for enzyme inactivation which is a constituent part of the heat-variant.

The inventors of the symbol RADURA came from the Pilot Plant for Food Irradiation, Wageningen, the Netherlands, which was the nucleus for the later Gammaster (today Isotron). And the leading head was R.M. Ulmann, the then director, who already in 1972 introduced this symbol to the international community (Ulmann, 1972). The term ‘RADURA’ clearly relates to radurization.

Ulmann provided the interpretation of this symbol (Fig. 1): denoting food – as an agricultural product – i.e. a plant (dot and two leaves) in a closed package (the circle) – irradiated from top by penetrating ionizing rays (the breaks in the upper part of the circle) in order to preserve its quality.

From the beginning in the 1960s, the symbol RADURA was always used as a symbol of quality exceptionally for food processed by ionizing radiation. The Dutch pilot plant used the logo as an identification of their irradiated products and as a promotion tool for a high quality product with extended shelf life. In supermarkets in the Netherlands where irradiated mushrooms (one of the first products on the market) were on sale the logo was dominantly displayed and buyers received a leaflet with information about the process and the advantages of the treated products. In clearances for other products granted by the Dutch authorities at later dates, application of the logo on the product or a clearly visible logo near treated bulk product was even demanded.

Originally, the logo was used exclusively by the Pilot Plant for Food Irradiation, Wageningen, the Netherlands, owning the copyright. The use of the logo was also permitted to everybody else adhering to the same rules of quality. The symbol was also widely used by Atomic Energy of South Africa, including the labelling by the term ‘radurized’ instead of irradiated, the word ‘radurized’ appearing in the lower part of the unbroken circle. This use of ‘radurized’ included even sterile ready-prepared meals for outdoor enthusiasts. And it was the then president of Gammaster, Jan Leemhorst, who untiringly propagated the use of this logo internationally. By his intervention, it was also included in the Codex Alimentarius standards on irradiated food as an option to label irradiated food (Anon, 2005).

Following the later interpretation by some food and process engineers, the symbol may also be read the following way:

  • -

    The central dot is the radiation source.

  • -

    The two circle segments (‘leaves’) are the biological shield to protect the workers and the environment.

  • -

    The outer ring is the transport system, the lower half of it is shielded from radiation by the biological shield, the upper broken half symbolizes the rays hitting the target goods on the transport system.

This later explanation more generally covers the range of radiation processing applications to food, no longer exclusively restricted to a fresher agricultural produce. And it resembles more closely the physical arrangement of the goods, the radiation source and the transport system in a radioisotope irradiation facility.

Following this historical development of the RADURA-terminology, the allegations from opponents to food irradiation this RADURA-logo would be ‘too positive’ by showing a green, growing plant is without substance. Some proposals by opponents to replace it by the international warning symbol for radiation hazards or for biological risks would be clearly misleading the consumer as irradiated food does neither present a radiological nor a biological hazard.

The use of the RADURA-logo is voluntary according to the Codex Alimentarius standard (Anon, 2005). However, a few countries (namely the USA) make its use compulsory; a few countries allow the optional use; others, in particular the European Union, do not provide for the use of this international logo. In the Codex standard the symbol is in green with all elements filled; some countries allow for different designs and even varying colours.

Until today the terminology of radappertization, radurization and radicidation has not found wide recognition and nearly no practical use. Its use would have the advantage of clearly informing the consumer that ionizing radiation was involved in processing the particular product. One of the early proposals for naming radiation pasteurization was cold pasteurization, for the reason that processing by ionizing radiation even at higher doses does not increase the temperature of the treated food by a significant amount (Crawford and Ruff, 1990, Loaharanu, 1996, Read, 1999). However, in radiation pasteurization the term ‘pasteurization’ is not technically correct as the elimination of microorganisms differs fundamentally from heat pasteurization; and, hence, cold pasteurization is not correct for the same reason. Other proposals for a more ‘neutral’ terminology as ‘picowaved’ resembling the wavelength of gamma-rays from radioisotopes (Brynjolfsson, 1988, Goebel, 1985) or ‘electronically pasteurized’ (Benjamin and Eckland, 1946, Hannan, 1953, Huber, 1948, Pillai et al., 2006) could rather be seen as an attempt to hide the nature of the treatment. Furthermore, additionally to the wrong use of ‘pasteurized’, the adjective ‘electronically’ is misleading, as ‘electronics’ are not involved, and the treatment by high-energy electrons is effective by the ionization induced. There are only two national terminologies which create the correct imagination for the consumer: in French ‘ionized’ and in Dutch ‘doorstraalt’ (radiated through).

Section snippets

Conclusions

The RADURA-logo and the terminology of radappertization, radicidation and radurization are explained; the heritage is recalled of a number of people, of great names and eminent scientists and businessmen in the field of food irradiation which need to be preserved in the memories of the radiation processing community. This paper intends to serve this sole purpose.

Acknowledgement

This summary and review includes contributions by Henry Delincée, Harry Farrar, Ives Henon, and Jan Leemhorst.

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