Gamma irradiation at 2 kgy to preserve wild edible mushrooms: effects on chemical parameters
Conference Paper
Overview
Overview
abstract
In spite of the immense popularity of mushrooms in the Northeast of Portugal, one of the European
regions with higher wild edible mushrooms diversity, alternative technologies to increase mushrooms
shelf-life are scarce. Treatment by irradiation emerges as a possible preservation technique,
destroying microorganisms or insects that could be present in food and, sometimes, improving
functional properties, with the least effects on sensory and nutritive quality (1). It has been
successfully tested in several foods such as fruits, vegetables, meat, fish, aromatic and medicinal
plants, being regulated by the European Union (EU) through the Directive (EC) No 1999/2/EC (2). In
different countries (Croatia, Hungary, Poland, United Kingdom, Mexico) the recommended dose for
extending the shelf life of fresh mushrooms is 1-3 kGy (3). Therefore, the aim of the present work
was to validate the use of gamma irradiation at 2 kGy to maintain chemical parameters of wild
mushrooms. The fruiting bodies of Boletus pinophilus Pilát & Dermek and Clitocybe subconnexa
Murrill were collected in Trás-os-Montes (Northeast of Portugal) in November 2012 and 2013,
respectively. The irradiation of these samples was carried out in experimental equipment with four
60Co sources. The estimated doses, dose rates and dose uniformity ratios (Dmax/Dmin) were:
2.09±0.16 kGy, 1.56 kGy/h, 1.18 for B. pinicola; and 1.95±0.22 kGy, 1.95 kGy/h, 1.33 and for C.
subconnexa. The proximate composition was evaluated by official procedures, 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. Some of the analyzed chemical
parameters (especially sugars and fatty acids) showed significant changes after irradiation treatment,
particularly in B. pinophillus, probably due to its higher water content. Nevertheless, the obtained
differences did not seem to be sufficient to change the organoleptic characteristics of these
mushrooms. The detected chemical changes might be considered as acceptable, when considering the
high advantages of gamma irradiation at decontamination and/or disinfestation level.
