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Effects of gamma irradiation on physical parameters of Lactarius deliciosus wild edible mushroom
Publication . Fernandes, Ângela; Antonio, Amilcar L.; Oliveira, Beatriz; Martins, Anabela; Ferreira, Isabel C.F.R.
Studies evaluating the effects of ionizing radiation in mushrooms are mostly available in cultivated species [1], being scarce reports on wild species, considered add-value foods. In the present work, the effects of gamma radiation dose (0, 0.5 and 1 kGy; at a dose rate of 2.3 kGy/h using a gamma camera with 60Co sources) and storage time (0 to 8 days at 5 ºC) on the physical parameters (colour, cap diameter and weight) of the wild edible mushroom Lactarius deliciosus were evaluated. The results were submitted to an analysis of variance (ANOVA) with Type III sums of squares, performed using the GLM (General Linear Model) procedure of the SPSS software, and a hierarchical cluster analysis (HCA) was used as an unsupervised learning method [2].
It was observed a slight decrease in redness (a; Hunter’s colour) with irradiation dose and a slight decrease in the cap diameter with storage time. Regarding the weight loss profiles along the 8 days of storage, the results were very similar for irradiated and non-irradiated samples. Despite the particular tendencies previously described, the results obtained for the assayed parameters seemed to indicate that neither irradiation nor cold storage, exerted significant influence. The interaction among the two factors (Irradiation dose×Storage time) was only significant (p<0.05) for L (lightness) parameter. The HCA indicated high similarity among the assayed samples; nevertheless, the well defined evolution that some Hunter’s colour parameters showed with irradiation dose should not be neglected.
Overall, this study demonstrated that up to 1 kGy, gamma irradiation and cold storage did not affect significantly the assayed physical properties, and can be considered an alternative storage methodology for mushrooms in dose values considered.
Combined effects of electron-beam irradiation and storage time on the chemical and antioxidant parameters of wild Macrolepiota procera dried samples
Publication . Fernandes, Ângela; Barreira, João C.M.; Antonio, Amilcar L.; Oliveira, Beatriz; Martins, Anabela; Ferreira, Isabel C.F.R.
Mushrooms are very perishable foods due to their
high susceptibility to moisture loss, changes in color and texture,
or microbiological spoilage. Drying is considered as the
most appropriate method to prevent these alterations, but it has
some limitations, such as shrinkage, enzymatic and nonenzymatic
browning reactions, and oxidation of lipids and
vitamins. According to previous studies, irradiation might effectively
attenuate the undesirable changes caused by drying
process, ensuring also higher shelf-life of mushrooms and their
decontamination. Electron-beam irradiation presents some
technological advantages, since it allows higher dose rates
and the possibility to be used in most foods/or thin products
in a short period. Herein, the combined effects of electron-beam
irradiation (0, 0.5, 1 and 6 kGy) and storage time (0, 6 and
12 months) were evaluated by measuring changes in nutritional
parameters, namely, free sugars, tocopherols, fatty acids and
antioxidant activity. As indicated by linear discriminant analysis,
storage time had a higher effect on all the evaluated parameters,
except fatty acids, which suffer significant changes with
both factors. Overall, the obtained results indicate that electronbeam
irradiation might be considered as a suitable technique,
allowing long-lasting conservation periods while reducing
changes induced by drying treatment.
Gamma irradiation at 2 kgy to preserve wild edible mushrooms: effects on chemical parameters
Publication . Fernandes, Ângela; Pinela, José; Antonio, Amilcar L.; Barreira, João C.M.; Oliveira, Beatriz; Martins, Anabela; Ferreira, Isabel C.F.R.
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.
Effects of gamma radiation on physical and chemical parameters of wild Lactarius deliciosus L.
Publication . Fernandes, Ângela; Antonio, Amilcar L.; Oliveira, Beatriz; Martins, Anabela; Ferreira, Isabel C.F.R.
The short shelf life of mushrooms is a barrier to their distribution and, therefore, there
has been extensive research to find technologies that ensure the preservation of
mushrooms, maintaining their organoleptic properties. Irradiation is an alternative that
has already been successfully applied in various food products1. There are several
studies in the literature assessing the effects of the application of ionizing radiation in
cultivated mushrooms in particular Agaricus bisporus, Lentinus edodes and Pleurotus
ostreatus, as reviewed recently by our research group.2 However, there are almost no
studies on wild species, which are generally highly valued commercially. Herein, the
effects of gamma radiation on physical and chemical properties of wild Lactarius
deliciosus L. were evaluated. Irradiation was performed in an experimental equipment
with 60Co sources (at the doses 0.5 and 1 kGy) and analyzes were performed throughout
the period of storage at 4 °C (0, 4 and 8 days). All results were compared with nonirradiated
samples (control). The physical properties determined were mass, color and
diameter of the cap3; the chemical properties evaluated included nutritional profile, and
fatty acids, tocopherols, mono and oligosaccharides by chromatographic techniques4.
The irradiated samples showed similar properties to the control. Up to 1 kGy, gamma
irradiation may be an alternative to ensure the quality and prolong the shelf life of
mushrooms, since the effects on the tested parameters were less significant than that
caused by the storage time.
Antioxidant activity of decoctions of Centaurea paniculata L. and Helichrysum stoechas L. Moench
Publication . Barroso, Marisa; Fernandes, Ângela; Carvalho, Ana Maria; Ferreira, Isabel C.F.R.
Ethnobotanical surveys conducted in Northeastern Portugal have documented the use of
Decoctions prepared with flowering aerial parts of Centaurea paniculata L. (starthistles,
knapweeds; port. escalabiosa) for inflammation and Helichrysum stoechas (L.) Moench (shrubby
everlasting; port. douradinha) for the respiratory system and to reduce fever [1], from the
Asteraceae botanical family. Although antioxidant properties of those plants have been
investigated [2-4], there are no reports on its most used form, the decoction. Therefore, in the
present work, decoctions of inflorescences and leafy flowering stems of the two mentioned
species were prepared and submitted to evaluation of antioxidant potential. Four different in vitro
assays were performed: scavenging effects on DPPH (2,2-diphenyl-1-picrylhydrazyl) radicals,
reducing power (measured in Folin Ciocalteu and ferricyanide Prussian blue assays), inhibition of
13-carotene bleaching and inhibition of lipid peroxidation in brain cell homogenates by TBARS
(thiobarbituric acid reactive substances) assay.
Thedecoction of H. stoechas revealed higher antioxidant activity (lower EC50 values) than C.
paniculata in all the tested assays. Data obtained could provide scientific evidence for some folk
uses in the treatment of diseases related to the production of reactive species and oxidative stress, but further experiments are required to explore the mechanisms of action.
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Funding agency
Fundação para a Ciência e a Tecnologia
Funding programme
SFRH
Funding Award Number
SFRH/BD/76019/2011