Comparative effects of gamma and electron beam irradiation on the antioxidant potential of Portuguese chestnuts (Castanea sativa Mill.)

CIMO/Escola Superior Agrária, Instituto Politécnico de Bragança, Apartado 1172, 5301-855 Bragança, Portugal.
Food and chemical toxicology: an international journal published for the British Industrial Biological Research Association (Impact Factor: 2.61). 07/2012; 50(10):3452-5. DOI: 10.1016/j.fct.2012.07.041
Source: PubMed

ABSTRACT Chestnuts (Castanea sativa Mill.) are widely consumed all over the world, and have been recently studied for their antioxidant potential. The present study reports the effect of e-beam and gamma radiation (doses of 0, 0.5, 1 and 3kGy) on the antioxidant potential of Portuguese chestnuts. Irradiation might be an alternative preservation method, since Methyl Bromide, a widely used fumigant, was banished by the European Union in 2010 due to its toxicity. The antioxidant activity was evaluated through 2,2-diphenyl-1-pycrylhydrazyl (DPPH) free radical scavenging activity assay, reducing power by the Ferricyanide/Prussian blue assay, and lipid peroxidation inhibition by β-carotene/linoleate and thiobarbituric acid reactive substances (TBARS) assays. The analysis of total phenolics and flavonoids was performed by spectrophotometric assays. Irradiated samples preserved total phenolics content (but not flavonoids) and revealed higher antioxidant activity (lower EC(50) values) than the control samples. The most indicated doses to maintain antioxidants content, and to increase antioxidant activity were 1 and 3kGy for electron beam and gamma radiation, respectively.

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    ABSTRACT: Since 2010, methyl bromide, a widely used fumigant was banned from the European Union under the Montreal Protocol guidelines, due to its deleterious effects on health and risk to the environment. Since then, many alternatives for chestnut conservation have been studied (hot water dip treatment being the most common), among them, electron beam irradiation has been proposed as being a safe, clean and cheap alternative. Herein, the effects of this radiation at different doses up to 6 kGy and over storage up to 60 days in the amounts and profile of nutritionally important organic acids were evaluated. Chestnuts contained important organic acids with quinic and citric acids as main compounds. Storage time, which is traditionally well accepted by consumers, caused a slight decrease on quinic (13 to 9 mg/g), ascorbic (1.2 to 0.8 mg/g), malic (5 to 4 mg/g), fumaric (0.4 to 0.3 mg/g) and total organic (33 to 26 mg/g) acids content. Otherwise, irradiation dose did not cause appreciable changes, either individually or in total (28 to 27 mg/g) organic acid contents. Electron beam irradiation might constitute a valuable alternative for chestnut conservation.
    Food and chemical toxicology: an international journal published for the British Industrial Biological Research Association 01/2013; 55. DOI:10.1016/j.fct.2013.01.031 · 2.61 Impact Factor
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    ABSTRACT: Background: Gamma radiation has been widely used as a post-harvest food preservation process for many years. Irradiation can affect the content of phytochemicals. During processing of almonds, large amounts of by-products such as hull and shell are produced. This study evaluates the effect of gamma radiation on phytochemical content and antioxidant activity of none stored (H1) and stored (H2) almond hull. Methods: Both almond hull samples were irradiated with 0, 2, 6 and 10 kGy gamma rays. Total phenolic content (TPC), total flavonoid content (TFC) and bioactivity of the treated samples extracts were investigated by various In vitro colorimetric methods. Results: Irradiation dose of 10 kGy slightly decreased the TPC and TFC values but maintained FRAP value in H1 extracts. The TPC of H2 was increased (p<0.05) at the dose of 10 kGy, while the TFC and FRAP values were constant. 2 kGy dose of gamma irradiation slightly increased the antiradical activity of H1 and H2, but the other doses significantly reduced antiradical activity of extracts. Conclusion: Results showed that gamma irradiation can change the antioxidant content and activity of almond hull.
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    ABSTRACT: Chestnuts are widely consumed around the world, especially in China, which is the major producer. Portugal is the fifth biggest producer, reaching an income of 17 M €, with particular relevance for Trás-os-Montes region, which is responsible for 81 % of Portuguese production. During postharvest storage, a number of pests tend to attack chestnuts, contributing to high economic losses. Since 2010, the most effective postharvest treatment, i.e., fumigation with methyl bromide, was banned in the European Union, urging producers to seek effective and reasonable alternatives. One alternative could be irradiation with gamma rays or electron beam, which is used in food commodities, legally regulated and allows outstanding results. Our research group has tested both irradiation types in chestnuts and studied the nutritional, antioxidant, and other chemical parameters, obtaining promising results. Herein, we extended these studies to selected cultivars from Portugal and Italy in order to validate this technique as a viable alternative to fumigation. The selected irradiation dose (1 kGy) was chosen following previous results where it proved to be effective without causing remarkable changes in chemical or antioxidant profiles. To obtain a global knowledge about how each cultivar reacts to irradiation, principal component analysis was performed using all the measured parameters. Despite the detected differences among cultivars, which differentiated particularly Palummina and Cota, it was verified that irradiation did not cause changes in chemical and antioxidant parameters that could enable defining distinctive features among irradiated and non-irradiated chestnuts. Hence, the results herein reported might be seen as a new step toward the completion of irradiation as feasible conservation technology, independently of chestnuts origin.
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Márcio Carocho