Gamma radiation preserves chemical and bioactive properties of Boletus edulis wild mushrooms
Conference Paper
Overview
Overview
abstract
Boletus edulis Bull: Fr. is an edible mushroom quite appreciated for its organoleptic and nutritional
properties. However, the seasonality and perishability cause some difficulties in its distribution and
marketing in fresh form; losses associated with this type of food during marketing can reach 40% [1].
Irradiation is recognized as a safe and effective method for food preservation, being used worldwide to
increase shelf life of fresh and dehydrated products (e.g. fruits, vegetables and spices) [2]. In particular,
gamma irradiation has already been applied to cultivated mushrooms (especially Agaricus, Lentinula
and Pleurotus Genus) and proved to be an interesting conservation technology [3]. However, the
studies with added-value wild species are scarce. In this work, the effects of gamma irradiation on
chemical and antioxidant properties of wild B. edulis, were evaluated. Fruiting bodies were obtained in
Trás-os-Montes, in the Northeast of Portugal, in November 2012. The irradiation was performed in
experimental equipment with 60Co sources at 1 and 2 kGy. All the results were compared with nonirradiated
samples (control). Macronutrients and energy value were determined following official
procedures of food analysis; fatty acids were analyzed by gas-chromatography coupled to flame
ionization detection (GC-FID), while sugars and tocopherols were determined by high performance
liquid chromatography (HPLC) coupled to refraction index (RI) and fluorescence detectors,
respectively. Antioxidant activity was evaluated in the methanolic extracts by in vitro assays measuring
DPPH (1,1-diphenyl-2-picrylhydrazyl) radical scavenging activity, reducing power, inhibition of β-
carotene bleaching and inhibition of lipid peroxidation using thiobarbituric acid reactive substances
(TBARS) assay. Total phenolics were also determined by the Folin-Ciocalteu assay. The nutritional
profiles were not affected in high extension. Fatty acids and sugars were slightly affected, decreasing
with the increasing doses. The performed assays for antioxidant activity, indicate that irradiated
samples tended to have lower scavenging activity and reducing power, but higher lipid peroxidation
inhibition. Despite the detected differences in individual compounds, the results of nutritional
parameters, the most relevant in terms of mushroom acceptability by consumers, were less affected,
indicating an interesting potential of gamma-irradiation to be used as an effective conservation
technology for the studied mushrooms.
