COMPREHENSIVE STUDY OF THE EFFECTS OF RAYS AND ELECTRON BEAM IN WILD MUSHROOMS: PHYSICO-CHEMICAL, NUTRITIONAL AND BIOACTIVE PARAMETERS

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Effects of gamma irradiation in the antimicrobial activity of wild mushroom extracts

Publication . Fernandes, Ângela; Alves, Maria José; Barreira, João C.M.; Antonio, Amilcar L.; Oliveira, Beatriz; Martins, Anabela; Ferreira, Isabel C.F.R.

The interest of mushrooms hás been increasing over time due to their potential in prevention or treatment of different diseases. Mushrooms have been reported for their anticancer, antiinflammatory, and immunosuppressive and antimicrobial properties. In particular, several authors reported the antibacterial activity of extracts prepared from different mushroom species [1]. In spite of these undeniable qualities, mushrooms are one of the most perishable products and tend to loose quality immediately after harvest. Irradiation is recognized as a safe and effective presen/ation method, being used worldwide to increase the shelf life of foods (e. g, fruits and vegetables, spices, grains, meat or seafood, aromatic and medicinal plants and spices) [2, 3]. In the present study, the antibacterial properties of methanolic extracts prepared from Boletus edulis Buli. and Hydnum repandum L. Fr., previously submitted to gamma irradiation, were assessed against clinicai isolates with different resistance profiles (two Gram negative bacteria; Escherichia coli and Proteus mirabilis, isolated from urine, and two Gram positive bactéria: MSSA- methicillin-sensitive Staphylococcus aureus, isolated from wound exudate and MRSA- methidllin-resistant Staphylococcus aureus, isolated from expectoration) from hospitalized patients in Local Health Unit of Mirandela, Northeast of Portugal. The fruiting bodies were collected in Trás-os-Mõntes (Northeast of Portugal) in November 2012. Gamma irradiation was performed in experimental equipment with four Co-60 sources at 1 and 2 kGy doses. The 1 kGy dose does not seem to be the preferable choice to treat B. edufe and H. repandum(which have a better response to the 2 kGy dose). Among the tested extracts, those obtained from B. ecfufe presented the highest activity against ali the tested bacterial. The antimicrobial activity of the mushroom extracts did not suffer significant changes that might compromise applying irradiation as a possible mushroom conservation technology. As a general conclusion, the 2 kGy should be considered as the best choice in terms of antimicrobial activity maintenance.

2015Conference object

Open access

Effects of gamma irradiation on the chemical composition and antioxidant activity of Lactarius deliciosus L. wild edible mushroom

Publication . Fernandes, Ângela; Antonio, Amilcar L.; Barreira, João C.M.; Botelho, M. Luísa; Oliveira, Beatriz; Martins, Anabela; Ferreira, Isabel C.F.R.

TThe short shelf-life of mushrooms is an obstacle to the distribution and marketing of the fresh product. There has been extensive research on finding the most appropriate technology for mushrooms preservation and a particular interest arises for wild species. Treatment by irradiation emerges as a possible conservation technique that has been tested successfully in several food products. Herein, the effects of gamma irradiation on Lactarius deliciosus (L. ex Fr.) S. F. Gray chemical composition and antioxidant activity were evaluated in samples submitted to different storage periods (0, 4 and 8 days) at 4 °C. The irradiation treatments were performed in a Co-60 experimental equipment. Nutritional value was accessed by macronutrients analysis and determination of energetic value; fatty acid, sugar and tocopherol profiles were determined by gas chromatography– flame ionization detector, high-performance liquid chromatography (HPLC) refractive index and HPLC fluorescence, respectively. The antioxidant activity was evaluated through radical scavenging activity, reducing power, lipid peroxidation inhibition and phenolics content. The obtained data show that, until 1 kGy, gamma irradiation might provide a useful alternative to ensure the quality and extend the life of mushrooms, since its effects on macronutrients, energetic value, tocopherols and antioxidant activity EC50 values were less significant than the changes caused by storage time. Moreover, the chemical and nutritional composition was similar in irradiated and non-irradiated L. deliciosus samples.

2013Journal article

Open access

Gamma irradiation preserves oleic acid in wild Hydnum repandum L.: Fr.

Publication . Fernandes, Ângela; Barreira, João C.M.; Antonio, Amilcar L.; Oliveira, Beatriz; Martins, Anabela; Ferreira, Isabel C.F.R.

Oleic acid is an essential fatty acid, omega 9, which participates in the metabolism and plays a key role in the synthesis of hormones. Studies have demonstrated that monounsaturated fatty acids help in lowering the leveis of LDL (low-density lipoprotein), increasing the leveis of HDL (high-density lipoprotein), suppressed appetite and short-term food intake in overweight subjects [1]. Wild mushrooms are excellent to be induded in low caloric diets, presenting higher levels of unsaturated fatty adds than saturated ones [2]. Nevertheless, the high perishability is a common characteristic in mushrooms that leads to lose quality immediately after harvest. In this sense, there are continuous investigations to find an effective consenservation technology. Gamma irradiation has been applied with success in extend the post-harvest of fresh mushrooms [3]. In the present work, the effects of gamma irradiation (1 and 2 kGy) in fresh samples of wild Hydnum repandum L.: Fr. were assessed, regarding the content and profile of fatty acids. The fruiting bodies were collected in Trás-os-Montes (Northeast of Portugal) in November 2012. The irradiation was performed in experimental equipment with four Co-60 sources and fatty acids were analyzed by gas-chromatography coupled to flame ionization detection (GC-FID). The most abundant fatty acids in H. repandum were palmitic acid (C16:0), oleic acid (C18:1) and linoleic acid (C18:2). The 1 kGy dose maximized the amount of oleic acid (40. 9%), avoiding the oxidation observed in non-irradiated or irradiate at 2 kGy samples. These results indicate an interesting potential of gamma irradiation to be used as an effective conservation technology.

2015Conference object

Open access

Effects of different processing technologies on chemical and antioxidant parameters of Macrolepiota procera wild mushroom

Publication . Fernandes, Ângela; Barros, Lillian; Barreira, João C.M.; Antonio, Amilcar L.; Oliveira, Beatriz; Martins, Anabela; Ferreira, Isabel C.F.R.

Mushrooms are very perishable foods, demanding for processing technologies that retain chemical and nutritional characteristics of fresh forms. In this work, the influence of freezing, drying and gamma irradiation on chemical parameters and antioxidant potential of Macrolepiota procera was assessed through one-way ANOVA complemented with principal component analysis. Proximate composition was evaluated by AOAC procedures, while fatty acids, tocopherols and free sugars were determined using chromatographic techniques. Antioxidant activity was measured using in vitro assays. M. procera samples have low energetic values, with moisture and carbohydrates as major nutrients. Linoleic, palmitic and oleic acids were the major fatty acids; δ-tocopherol was the prevalent isoform in fresh, frozen and irradiated samples, while β-tocopherol predominated in dried samples. Trehalose was the most abundant sugar in fresh and irradiated samples, whereas mannitol predominated in frozen and dried samples. Dried samples gave higher DPPH scavenging activity and β-carotene bleaching inhibition; freeze and irradiated samples showed higher reducing power and TBARS formation inhibition, respectively. Overall, freezing and drying caused significant differences in chemical parameters. On the other hand, gamma irradiation revealed the highest capacity to retain chemical profile of fresh samples, which highlights its potential to be explored and validated as an alternative conservation methodology.

2013Journal article

Open access

Influência da radiação gama nas propriedades físicas de Lactarius deliciosus

Publication . Fernandes, Ângela; Antonio, Amilcar L.; Oliveira, Beatriz; Martins, Anabela; Ferreira, Isabel C.F.R.

Este estudo descreve o efeito da radiação gama e do tempo de armazenamento nas propriedades físicas (cor, diâmetro do chapéu e massa) de amostras do cogumelo silvestre Lactarius deliciosus L. Gray, comumente consumido na região de Trás-os-Montes, Nordeste de Portugal. As doses aplicadas foram 0,5 e 1 kGy a um débito de dose de 2,3 kGy/h, usando uma câmara de radiação gama com fonte de 60Co. Após tratamento, as amostras foram armazenadas sob refrigeração (4 a 5 ºC) e analisadas diariamente durante 8 dias. Em simultâneo, foram processadas amostras não sujeitas a qualquer tratamento (controlo). Nas medições de cor, registaram-se os valores de L, a, b, da escala de Hunter, tendo-se observado uma diminuição do parâmetro “a” com a dose de radiação, e uma diminuição do diâmetro do chapéu com o tempo de armazenamento. Em relação à perda de massa ao longo dos 8 dias de armazenamento, os resultados foram muito semelhantes para as amostras irradiadas e não irradiadas. Os resultados obtidos parecem indicar que, até à dose máxima testada (1 kGy), a irradiação gama e o armazenamento a frio não afetam as propriedades físicas analisadas.

2012Conference paper

Open access