ARCHIVED - Irradiation of Mangoes: Summary of Submission Process
October 29, 2002
Table of Contents
A. Summary of Situation
(a) The Requests
Two submissions for the irradiation of mangoes were received: one for the use of irradiation as a disinfestation treatment (I) and the other for shelf life extension (II).
(b) Divisions of the Food Directorate Responsible for Evaluating these Submissions
Chemical Health Hazard Assessment Division, Bureau of Chemical Safety (Coordinating Division; also evaluates toxicological safety, chemical safety and dosimetry portions of submissions)
Evaluation Division, Bureau of Microbial Hazards (evaluates efficacy and microbial safety aspects)
Nutrition Evaluation Division, Bureau of Nutritional Sciences (evaluates nutritional effects)
B. Evaluation Summary
(a) Purpose, Source of Radiation and (Absorbed) Dose
i. The specific purpose of irradiation in the first submission is disinfestation, specifically, to control fruit flies.1 The proposed source of irradiation is Cobalt-60. The minimum dose for this treatment is 0.15 kGy and the maximum dose is 0.30 to 0.45 kGy, depending upon the type of irradiator employed (pallet or carrier, respectively).2
Another purpose of the irradiation is to control the mango seed weevil, in which case the minimum dose is 0.30 kGy and the maximum doses 0.60 and 0.90, respectively (see Footnote #2). For commercial disinfestation, therefore, the range proposed by the petitioner is 0.15 kGy to 1.0 kGy. The petitioner is requested in this instance that Canadian regulations be harmonized with those of the United States, since "it is primarily to protect their agricultural interests that fumigation is done."3 The petitioner claims that, in essence, the principle of such harmonization has already been recognized by Canada through the signing of the North American
Plant Protection Paper on Irradiation as a Phytosanitary Certification Procedure.
ii. The second submission is based on a request to be allowed "to extend the shelf life of mangoes permitting the import and marketing of good quality mangoes from tropical countries for the enjoyment of Canadian consumers." The source of irradiation is Cobalt-60. The dose range requested is 0.25 kGy to 1.5 kGy in order to accommodate mangoes of various varieties and different types of irradiators (i.e. having different dose uniformity ratios).
i. Staff microbiologists consider that the minimum efficacious absorbed dose proposed for disinfestation is consistent with information published in the scientific literature and that there is a general absence of adverse consequences at this dose level. As a result, there were no microbiological concerns with respect to the petition for disinfestation of mangoes.
ii. With regard to shelf-life extension, the dose required depends on the variety, harvest location and weather conditions. Evaluators noted that there was neither information that would justify the dose level selected for each variety of fruit, nor evidence that the level of irradiation applied is both necessary and effective in achieving the stated goals of shelf-life extension. Nonetheless, under the best of circumstances, it appears that a modest shelf-life extension of 6-7 days can be obtained. In practice, the extension probably would be less, given the added stress of international transport and other factors such as variety, growth and harvesting conditions, etc. Thus, there are potential factors that could mitigate against the full extension noted being realized in every instance.
Two references were cited by the petitioner as being sources for standard dosimetry practices for regular commercial practice:
- Codex Alimentarius Commission. 1984. Codex General Standard for Irradiated Foods and Recommended Code of Practice for the Operation of Radiation Facilities used for the Treatment of Foods.4
- International Consultative Group on Food Irradiation. 1988. Provisional Guideline for the Irradiation of Bananas, Papayas and Mangoes for the Extension of Shelf- Life. ICGFI Document No. 1988-05-19. As with another of the petitioner's submissions, the petitioner prepared a detailed report of a mango irradiation efficacy study undertaken in Thailand.
The first stage involved dose mapping to determine dose distribution, the ultimate goal of which is to determine the locations of maximum and minimum dose. The dosimetry was performed on a carrier of actual product,5 the carrier being preceded and followed by a carrier of dummy product. A sufficient number of dosimeter positions (163) were employed to determine the absorbed dose distribution. A summary of results of the dosimetry is shown in the following table:
The measured minimum absorbed dose using ceric-cerous and GammaChrome YR dosimeters for the dose-mapping run was 0.49 kGy. The maximum absorbed dose was 0.82 kGy and the dose uniformity ratio was therefore calculated to be 1.67.
Mango efficacy Run #1 was performed on March 29, 1990. The product filled four carriers which were preceded and followed by a carrier filled with dummy product. GammaChrome YR dosimeters (52) were placed in the previously determined positions of maximum and minimum absorbed dose.
Mango efficacy Run #2 was performed on May 17, 1990. A total of 31 GammaChrome YR dosimeters were used this time.
The minimum dose, maximum dose and dose uniformity ratio averaged over all carriers for Run #1 was 0.49 kGy, 0.77 kGy and 1.58, respectively.
The minimum dose, maximum dose and dose uniformity ratio averaged over all carriers for Run #2 was 0.48 kGy, 0.75 kGy and 1.56, respectively.
The dosimetry work undertaken in Canada petitioner and in Thailand was considered to be acceptable.
(d) Alteration of Chemical. Physical and Microbiological Characteristics
The petitioner provided a literature review entitled Chemical Aspects of Irradiated Mangoes, undertaken by a consultant. The review was accompanied by a binder of photocopies of all of the references cited in its text.
With regard to physical alterations, the main one noted is that higher doses than those required to delay ripening (i.e. extend shelf-life) can result in scalding (surface browning or brown spots) of the mango peel (skin). Optimal doses are variety-dependent and, from Table 2 of the consultant's review, seem to vary from 0.25 - 0.75 kGy for shelf life extension (reports examined encompass 12 varieties). Based on work undertaken on Haden, Keitt and Tommy Atkins varieties, physical defects seem to be minimal up to a total overall average absorbed dose of 0.60 kGy (maximum of approximately 1.0 kGy, assuming a dose uniformity ratio of 1.2). This work, undertaken by two separate research groups, examined percentage scald, the "scald index," as well as two other physical defects known as "flesh darkening" and "hollow pockets." While the petitioner has requested a maximum dose of 1.5 kGy in the present submission, the possibility of observing such defects may in fact limit to 1.0 kGy or less the maximum dose that can be applied. It is to be noted that the maximum dose observed in the two runs undertaken in the feasibility study presented as part of this submission was about 0.75 kGy.
Concerning organoleptic aspects, in studies that examined the quality of irradiated mangoes compared with controls at the same stage of ripeness, within the dose ranges typically mentioned in this submission, the results are unremarkable. Irradiation does not seem to adversely affect the organoleptic qualities of mangoes. Organoleptic studies undertaken to evaluate the acceptability of mangoes irradiated under different atmospheres suggest that nitrogen be used, rather than air or carbon dioxide (air was superior, though, to carbon dioxide).
A comprehensive study on composition of mangoes (and other sub-tropical fruits) before and after gamma-irradiation was published in 1979 by Marguerite Beyers et al.9 Essentially these authors concluded that cultivar differences, seasonal variations, method of analysis and the analyst concerned have a greater influence on the results reported for analysis of mangoes than does irradiation. Analyzing four varieties of mangoes (Kent, Zill, Haden, Peach), while there were significant differences (P=0.01) between the water content of irradiated and non-irradiated Kent mangoes (80.11% vs 81.85%, respectively), and the acidity of treated and untreated Zill (0.46% and 0.47%, respectively) and Peach (0.46% and 0.41%, respectively) mangoes, no significant differences could be found in the concentrations of any of the other components (fat, ash, protein, starch, sugar, carotene, ascorbic acid, riboflavin, niacin, thiamin, calcium, phosphorus, iron, sodium and potassium) of the four mango cultivars studied. The authors concluded that changes wrought by (-irradiation are not significant and, insofar as no significantly detrimental changes were observed in any of the radiosensitive vitamins, the nutritional value of the fruits is not affected.
A second paper in this series was also published in 1979 by C. Newton Blakesley et al.10 This paper deals with volatile components, lipids and amino acids of mangoes and other subtropical fruits before and after gamma-irradiation. Mangoes were irradiated at 0.75 kGy. Fruit pulp was extracted with dichlorodifluoromethane (Freon 12). Volatiles were analyzed by gas liquid phase chromatography (GLPC) using capillary columns and a flame-ionization detector. Three replicate extractions of both the irradiated and control samples were prepared and 4-6 replicate chromatograms were run on each extract. Composite chromatograms of each sample were then constructed and 137 peaks were noted. The overall profiles of irradiated and non-irradiated mangoes are similar. In undertaking a peak-by-peak analysis of variance, the petitioner found no significant differences in the profiles. With the exception of linolenic acid (29.3%11 for the nonirradiated vs 26.7% for the irradiated), there was no significant difference in fatty acid composition between irradiated and non-irradiated mangoes at the same degree of ripeness.12 With the exception of arginine when determined as total amino acids, no significant differences between the free and total hydrolyzed amino acid compositions of mango were detected after (-irradiation. Although the levels of free arginine were reported to be higher in the non-irradiated mango compared with the irradiated mango, the total arginine levels in the control and test groups were comparable. Tryptophan was not able to be determined.
In the consultant's review, it is indicated that studies on the radiolysis of aqueous solutions of sugars are relevant to understanding radiation effects on fruits. Of the products produced in such studies , hydrogen peroxide, ",$-carbonyls and malondialdehyde are potentially toxic. The toxicity of hydrogen peroxide has been shown to be due to the production of hydroxyl radicals. In high sugar solutions, however, these are scavenged by sugars to form ",$-carbonyls (in air-free solutions). While these are toxic in in vitro studies, they are not in vivo and are reported to show a low toxicity to mammals. Malondialdehyde is formed in oxygenated systems at alkaline pH and its yield decreases with decreasing pH. For these reasons, these compounds are not considered to be problematic.
The consultant has commented and presented references on sugars (i.e. total content) and starches, pectins (de-esterification), and the effects of irradiation on acidity and pH. These references have been noted but are not really related to an assessment of safety.
A paper by Aboul-Enein et al.13 is worthy of some comment, since it examines volatiles in greater detail than the papers on the subject mentioned above. These workers irradiated, at doses of 0, 0.25, 0.50, 1.0 and 2.0 kGy, several lots of Ewais variety of mangoes at the mature green stage. At different periods of storage, the vapour over the homogenate was directly subjected to GLPC analysis. GLPC separation of mango volatiles revealed the occurrence of 20 compounds, of which 16 were identified. In the unirradiated controls, most of these volatiles were lost during ripening. This was not so in the irradiated samples. The majority of the compounds noted in the unripe fruit persisted in the ripe fruit. Cis-ocimene, myrcene and limonene, the main volatiles in mangoes, all increased during ripening of the unirradiated controls. Generally, irradiation at the mature stage at 1.0 kGy resulted in lower amounts of these volatiles, both in the mature stage and at the ripened stage. Perhaps this is an indicator, or rather, a confirmation that irradiation delays the ripening process. It is of interest to note that 12 of the 16 identified compounds, including myrcene and limonene, are flavouring materials recognized by the Council of Europe14, and one (cis-ocimene) is a component of a well-known spice, basil (in itself, recognized as a flavour by the Council of Europe).
The consultant provided data on Vitamin C and carotenoids (Vitamin A). Mention was also made of riboflavin, thiamin and niacin. These same data were duplicated in a separate Nutrition Review provided by the consultant. The data were assessed from a nutritional viewpoint, rather than a chemical one, by staff nutritionists.
It is considered that the data provided on the chemical and physical characteristics of irradiated mangoes are adequate. Data on microbiological characteristics are not relevant in this submission. The disinfestation aspects of this submission, examined by staff microbiologists, are addressed in Section (b) above. The nutrition aspects were evaluated by staff nutritionists and are dealt with in Section (e) below.
With regard to specific packaging materials that may be used on foods offered for sale in Canada, letters of opinion are offered upon request to packaging material manufacturers upon submission of appropriate technical data, including extraction data. The same voluntary procedure is followed in the case of materials intended to package foods to be irradiated. In all cases, the letters of opinion consider the requirements of Section B.23.001 of the Regulations which states that "No person shall sell any food in a package that may yield to its contents any substance that may be injurious to the health of a consumer of the food."
(f) Nutritional Aspects
The petitioner submitted two items with respect to the nutritional aspects of gamma- irradiation of mangoes. These were a literature review by the petitioner's consultant entitled Nutritional Aspects of Irradiated Mangoes: A Review with copies of its references, and an efficacy study entitled, A feasibility study of the effect of gamma-irradiation on mangoes from Thailand (Nahng Glahng Wahn variety), Final Version, March 1992.
The latter report was based on a study conducted in Canada and Thailand, involving three organizations.15 Separate earlier reports for results from Canada and Thailand were also submitted, but they do not provide any additional information. The literature review and the feasibility study have been reviewed.
The nutrients which mangoes contain in significant amounts are sugars, vitamin A (as beta-carotene) and vitamin C. While there is a fairly large number of studies conducted to test effects of irradiation on mango nutrient composition, most of these studies have limitations that make them unreliable. This includes the feasibility study conducted by the petitioners. The only study that was of good quality was the one by Marguerite Beyers et al. (1979), mentioned in section (d). The results of this study along with the general direction of results found in other studies indicated that changes in carotene and vitamin C levels due to irradiation at the doses to be employed for this commodity are smaller than the normal variation of these nutrients in mangoes as influenced by cultivar, season, method of analysis, and change of analyst and, therefore, not nutritionally significant. In addition, although the commercial availability of mangoes appears to have increased in the past few years, it remains a food that is not eaten in Canada as a staple. While the preservation of nutritional quality of foods should be an aim of all food handling and processing, in the case of mangoes, any impact of irradiation on Vitamins A (betacarotene) and C available in the food supply would be of very limited nutritional consequence. With regard to sugar, numerous studies have demonstrated that macronutrients in foods (lipids, proteins and carbohydrates) are not significantly affected by irradiation.
(g) Toxicological Studies
In undertaking a safety assessment of irradiated mangoes, staff toxicologists considered the following studies that were provided with the submission:
- The effects of low-dose gamma-irradiation on the wholesomeness of mangoes (Mangifera indica) as determined by short-term feeding studies using rats (Horton, G.M.J., 1976. Brit. J. Nutr. 35:67-75. Faculty of Veterinary Science, University of Pretoria)
- Toxicological studies on rats fed diet containing 15% irradiated Kent mangoes: 90-day study (WARF Institute, Inc., Madison, Wisconsin, USA. Study Nr. T-701, January 16, 1978)
- Toxicology studies on rats fed a diet containing 15% irradiated Kent mangoes. Two-year feeding study (Raltech Scientific Services (formerly, WARF Institute, Inc.), Madison, Wisconsin, study No. T-604, June 1, 1980)
- Toxicology studies on rats fed a diet containing 15% irradiated Kent mangoes. Reproduction studies" (Raltech Scientific Services (formerly WARF Institute, Inc.), Madison, Wisconsin. Study No. T-605, January 17, 1978)
- Toxicology studies on rats fed a diet containing 15% irradiated Kent mangoes, Teratology study (Raltech Scientific, Inc. (formerly, WARF Institute, Inc.) Madison, Wisconsin, USA. Study No. T-605, January 17, 1978)
- In vivo mutagenicity study in Chinese hamsters fed irradiated mangoes" (Institute of Biochemistry, Federal Research Center for Nutrition, Karlsruhe, Germany. Technical Report Series IFIP-R64, November, 1982)
- Dominant lethal studies in rats fed a diet containing 15% irradiated Kent mangoes" (Raltech Scientific Services, Madison, Wisconsin, USA. Study No. and date not identified)
The following constitutes excerpts from the toxicological review comprising the overall comments and recommendations of staff toxicologists:
Each study presented in this report (unpublished or published in scientific journals) was conducted prior to the introduction of good laboratory practices (GLP). With the exception of the teratology study, in which individual and summary data for maternal body weights during gestation were not provided, the studies were designed, performed and reported adequately. Maternal body weight data in teratology studies are important in the interpretation of the results only if adverse developmental effects are observed (potential maternal mediation). In this particular study, no developmental adverse effects were reported.
Results from sub-chronic (28- and 90-day) and chronic (2 year) studies in rats showed that consumption of a diet containing 15% irradiated (0.75-0.8 kGy) mangoes for extended periods of time, including in utero exposure, had no adverse effects on the investigated parameters such as general health, mortality, food consumption, body weight gain, hematology, clinical chemistry, urinalysis and organ weights. Necropsy and microscopic examinations of major organ and tissue samples revealed no increase in the incidence of either non-neoplastic or neoplastic lesions.
Continuous consumption of a diet containing 15% irradiated (0.80 kGy) mangoes for either one or two consecutive generations (each generation producing one-three litters) had no adverse effect on the general health, reproductive performance and pre- and post-natal development in rats.
There were no dominant lethal mutations, as determined by pre- or post-implantation losses, in rats when male rats were exposed to the diet containing 15% irradiated (0.8 kGy) mangoes in utero and throughout the sexual maturation period (up to 12 weeks of age) prior to mating.
No chromosomal aberrations, as determined by the micronucleus induction test and sister chromatid exchange test, were noted in the bone marrow of Chinese hamsters fed a diet comprising 50% irradiated (0.8 kGy) mangoes for 4 days prior to the tests.
One of the major aspects concerning the potential toxicity of irradiated foods is the possibility of the formation of potentially toxic substances (radiolytic products). Studies have shown that chemical changes occurring in food during irradiation are similar in foods of similar composition (water, carbohydrates, proteins, lipids), if irradiated under similar conditions (dose, temperature, oxygen concentration, etc.). On the basis of the general principles of radiation chemistry, it is possible that information obtained from toxicity studies from one irradiated food type could be extrapolated to another food item of similar composition irradiated under the same conditions (Taub et al., 1976. J. Food Sci., 41:942; Basson, 1983, in Recent Advances in Food Irradiation, (Elias and Cohen, eds.), Elsevier Biomedical, The Netherlands; Elias, 1989. Food Technol., 43:81; Diehl, 1990. Safety of Irradiated Foods, Marcel Dekker, Inc. N.Y.; Giddings, 1992, in "Food Safety Assessment" (Finley et al., eds.), American Chem. Soc.).
Fruit, in general, consists predominantly of water and carbohydrates and, therefore, during irradiation, they would likely undergo similar radiation-induced chemical changes. Since the irradiation of fruit is performed at relatively low doses, normally in the range of 0.5 to 2.0 kGy, the magnitude of these changes will be small, compared with the changes induced during other food preservation methods, for example heating (Thomas and Beyers, 1979. J. Agric. Food Chem., 27:157-163). Compositional similarities have been reported between mangoes and strawberries, both before and after irradiation (Basson et al., 1979. Food Chem., 4:131-142; Blakesley et al., 1979. J. Agric. Food Chem., 27:42-48). Results from a number of toxicity studies with laboratory animals (mice, rats, dogs) have shown that strawberries irradiated at doses up to 3.0 kGy and fed in diets at levels up to 35% for short (90 days) or prolonged (2 years) periods were neither toxic nor carcinogenic. Reproductive performance in chickens was also not affected and short term mutagenicity tests were negative. In addition, controlled studies with human volunteers who were fed for 15 days a variety of irradiated foods, including strawberries, revealed no deleterious effects on the health of the subjects (Joint FAO/IAEA/WHO Expert Committee on the Wholesomeness of Irradiated Food. 1977. Report No. 604).
It should be noted that the petitioner has requested clearance for mangoes irradiated at doses of 0.15-1.5 kGy, while the doses applied in the submitted studies did not exceed 0.8 kGy. In spite of this anomaly, the above quoted data and the internationally accepted safe food irradiation dose up to 10 kGy (WHO, Wholesomeness of Irradiated Food, 1981, Technical Report Series 659) suggests that consumption of mangoes irradiated at the doses as proposed will not result in a health hazard to the consumer.
C. Proposed Amendment
A new item proposed for addition to the Table in Division 26 is as follows:
Permitted source of ionizing radiation
Purpose of treatment
Permitted Absorbed Dose
|5||Mangoes||Cobalt-60||To control insect infestation during storage and to extend durable life||0.25 - 1.5 kGy|
Consultation was undertaken with the Toxicological Evaluation Section of this Division; the Evaluation Division, Bureau of Microbial Sciences; and the Nutrition Evaluation Division, Bureau of Nutritional Sciences, as noted above.
Secondly, the Pest Management Regulatory Agency was requested to comment on data supplied regarding the effect of radiation on pesticide residues. The extent of decomposition of a pesticide depends primarily on its structure. It is likely that some pesticide degradation products will have structures similar to or identical to those formed through normal decomposition or metabolic pathways. In any event, from data available on experiments conducted in solution, expected residues in irradiated food commodities are estimated to be 30,000 times lower than that of the pesticide itself.
A major Canadian horticultural association was requested to comment on this proposal. It deferred comment to its retail marketing association. The latter organization stated that retailers have no objection to the sale of irradiated mangoes.
Officers of the Dairy, Fruit and Vegetable Division of the Food Production and Inspection Branch of Agriculture and Agri-Food Canada expressed no objection to Health Canada proceeding to amend its regulations to allow irradiated mangoes to be offered for sale in Canada.
Finally, the Plant Protection Division (PPD), Plant Health Directorate of Agriculture and Agri-Food Canada, which deals with quarantine matters, was also consulted and indicated that, while it regulates the importation of specific fruits and some vegetables, particularly rootcrops, to prevent the introduction of pests harmful to Canada, it does not regulate the importation of citrus and tropical fruits including mangoes. While, at the time, the PPD had yet to establish a formal position on the use of irradiation to eradicate pests on plant commodities, officers in that Division consider that if irradiation were registered for use as a safe treatment for use in controlling pests on such commodities, the Division would recommend its use in cases where the regulated pest could be effectively controlled.
E. Interdisciplinary Impact
The Bureau of Chemical Safety recently commented on a document on irradiation for quarantine purposes prepared by the Plant Protection and Quarantine, Animal and Plant Health Inspection Service, U.S. Department of Agriculture (USDA) entitled The Application of Irradiation to Phytosanitary Problems, Position Discussion, Document III, July, 1995. The Bureau of Chemical Safety was cognizant that, in future, this document might be used as a reference for developing a North American Plant Protection Organization (NAPPO) standard on irradiation. It was in light of this Bureau being requested to comment on this document, that the Forestry and Horticultural Crops Unit, Operations Section, Plant Protection Division, Animal and Plant Health Directorate, Food Production and Inspection Branch, Agriculture and Agri-Food Canada (AAFC) was requested to address certain questions in connection with this specific submission (see Section immediately above).
1 The intimation is that, in this application, but not in the mango seed weevil one mentioned next, irradiation will replace methyl bromide. The petitioner admits that the proportion of mangoes now entering Canada treated with methyl bromide is unknown. Mangoes shipped to Canada are not required to undergo a quarantine treatment because they do not harbour insects that would harm Canadian agricultural commodities.
2 The dose uniformity ratio for a pallet irradiator is about 3 and for a carrier-type irradiator, about 2.
3 The United States regulations (21 CFR 179.26) specify a maximum dose of 1 kGy.
4 While the Recommended Code of Practice makes reference to dosimetry, there are few details on how the dosimetry should be undertaken. This is not a critical deficiency in the submission; adequate guidelines and methodology have been published by the American Society for Testing Materials, namely, ASTM Designation E 1204-87 (Standard Practice for Application of Dosimetry in the Characterization and Operation of a Gamma Irradiation Facility for Food Processing; 1987), ASTM Designation E 1261-88 (Standard Guide for Selection and Application of Dosimetry Systems for Radiation Processing of Food; 1988), ASTM Designation E 1431-91 (Standard Practice for Dosimetry and Bremsstralung Irradiation Facilities for Food Processing; 1991). These latter publications were cited in another of the petitioner's irradiation submissions.
5 Each box of mangoes in the carrier was 30 cm x 50 cm x 10 cm. The carriers held 52 boxes each. The total weight of mangoes in a carrier was 234 kg. The product density was 0.30 g/cm3.
6 DUR = dose uniformity ratio
7 On account of their stability over a long period of time, used by the petitioner as the reference transfer standard dosimeter for absorbed dose measurements in the kGy range.
8 Used to obtain independent dose measurements.
9 Marguerite Beyers, Austin C. Thomas, and Adrian Van Tonder. 1979. (- Irradiation of Subtropical Fruits. 1. Compositional Tables of Mango, Papaya, Strawberry, and Litchi Fruits at the Edible-Ripe Stage. J. Agric. Food Chem., 27(1): 37-42.
10 C. Newton Blakesley, Johan G. Loots, Lourens M. du Plessis, and Gerrit de Bruyn. 1979. (-Irradiation of Subtropical Fruits. 2. Volatile Components, Lipids, and Amino Acids of Mango, Papaya, and Strawberry Pulp. J. Agric. Fd. Chem., 27(1): 42-48.
11 Based on the weight of the fat.
12 Having three double bonds and consequently quite prone to oxidation, linolenic acid might be expected to be susceptible in an irradiated system.
13 A.M. Aboul-Enein, H.M. Salem and M.M. Zaharan. 1983. Effect of Gamma Irradiation on Mango Volatiles during Ripening. Chem. Mikrobiol. Technol. Lebensm. 8: 60-63.
14 Council of Europe. Chemically-defined flavouring substances, (Strasbourg: Council of Europe Publishing, 2000).
15 The organizations were: The Canadian Irradiation Centre, the Thai Irradiation Centre and the Research Centre in Sciences Applied to Food (CRESALA) (Laval, Québec)
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