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.

Chestnuts are a widely consumed fruit around the world, being Portugal the fourth biggest producer in Europe. Storage of these nuts is an important step during processing, and the most widely used fumigant was banned in the European Union under the Montreal protocol due to its toxicity. Recently, radiation has been introduced as a cheap and clean conservation method. Previous studies of our research group proved that gamma radiation had no negative effect on the nutritional value of chestnuts; in fact, storage time had a much bigger influence on the chestnut quality. In the present study, we report the effect of a less ionizing radiation, electron beam, with doses of 0, 0.5, 1, 3 and 6 kGy in the nutritional value of chestnuts (ash, energy, fatty acids, sugars and tocopherols), previously stored at 4 ºC during 0, 30 and 60 days. The storage time seemed to reduce fat and energetic values but reported a tendency for higher values of dry matter. Regarding fatty acids, there was a higher detected quantity of C20:2 in non-irradiated samples, and four fatty acids were only detected in trace quantities (C6:0; C8:0; C10:0 and C12:0). γ-tocopherol decreased during storage time but did not alter its quantity for all the radiation doses (as like α-,β-and δ-tocopherol); in fact these compounds were present in higher concentration in the irradiated samples. Sucrose and total sugars were lower in non-irradiated samples and raffinose was only detected in irradiated samples. Electron beam irradiation seems to be a suitable methodology, since the effects on chemical and nutritional composition are very low, while storage time seems to be quite important in chestnut deterioration.

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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 3 kGy) 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 kGy and 3 kGy for electron beam and gamma radiation, respectively.