From the field to the table: ionizing radiation as a feasible postharvest treatment for fresh and dried plant foods

Food irradiation is a treatment that involves subjecting in-bulk or packaged food to a controlled dose of ionizing radiation, with a clearly defined goal. It has been used for disinfestation and sanitization of food commodities and to retard postharvest ripening and senescence processes, being a sustainable alternative to chemical agents 1 . Doses up to 10 kGy are approved by several international authorities for not offering negative effects to food from a nutrition and toxicology point of view 2 . However, the adoption of this technology for food applications has been a slow process due to some misunderstandings by the consumer who often chooses non-irradiated foods. In this study, the effects of the ionizing radiation treatment on physical, chemical and bioactive properties of dried herbs and its suitability for preserving quality attributes of fresh vegetables during cold storage were evaluated. The studied herbs, perennial spotted rockrose (Tuberaria lignosa (Sweet) Samp.) and common mallow (Malva neglecta Wallr.) were freeze-dried and then irradiated up to 10 kGy in a Cobalt-60 chamber. The selected vegetables, watercress (Nasturtium officinale R. Br.) and buckler sorrel (Rumex induratus Boiss. Reut.) were rinsed in tap water, packaged in polyethylene bags, submitted to irradiation doses up to 6 kGy and then were stored at 4 C for a period of up to 12 days. Physical, chemical and bioactive parameters of irradiated and non-irradiated samples were evaluated using different methodologies the colour was measured with a colorimeter, individual chemical compounds were analyzed by chromatographic techniques, antioxidant properties were evaluated using in vitro assays based on different reaction mechanisms, and other quality analyses were performed following official methods of analysis. The irradiation treatment did not significantly affect the colour of the perennial spotted rockrose samples, or its phenolic composition and antioxidant activity 3 . Medium doses preserved the colour of common mallow and a low dose did not induce any adverse effect in the organic acids profile. The green colour of the irradiated vegetables was maintained during cold storage but the treatment had pros and cons in other quality attributes. The 2 kGy dose preserved free sugars and favoured polyunsaturated fatty acids (PUFA) while the 5 kGy dose favoured tocopherols and preserved the antioxidant properties in watercress samples. The 6 kGy dose was a suitable option for preserving PUFA and the ��-6 ��-3 fatty acids ratio in buckler sorrel samples. This comprehensive experimental work allowed selecting appropriate processing doses for the studied plant foods in order to preserve its quality attributes and edibility.

Use of inert gas-enriched atmospheres and post-packaging irradiation in shelf-life extension of watercress

Watercress (Nasturtium officinale R. Br.) is a semi-aquatic plant of the Brassicaceae family highly appreciated in the Mediterranean cuisine. It features sharp, peppery and slightly tangy taste and contains health-promoting phytochemicals. Its consumption as a fresh-cut product has increased in recent years, as well as the global market of minimally processed vegetables. This demand is driven by the growing interest in the role of food in promoting the human health and wellbeing and to meet consumer needs for fresh-like and more convenient foods. Due to the reduced shelf-life of this plant, the suitability of inert gas-enriched atmospheres and ionizing irradiation for preserving visual, nutritional and functional quality attributes during cold storage was studied. Watercress samples were gathered in the Northeast region of Portugal, rinsed in tap water and a portion was immediately analyzed (non-stored control). The remaining fresh material was packaged in polyethylene bags under N2- and Ar-enriched atmospheres, conventional atmosphere (air) and vacuum (no atmosphere). Samples under conventional atmosphere were irradiated at 1, 2 and 5 kGy of gamma-rays (predicted doses) in a 60Co experimental chamber. A non-irradiated control followed all the experiment. Then, all packaged samples were stored at 4 ��C for 7 days. The studied quality parameters included the colour that was measured with a Konica Minolta colorimeter, and total soluble solids and pH determined in squeezed juice. The proximate composition (moisture, proteins, fat, ash, carbohydrates and energy) was evaluated using the AOA C procedures. Organic acids, free sugars, fatty acids and tocopherols were analyzed by chromatographic techniques. Samples were also evaluated for its DPPH��� scavenging activity, reducing power, and lipid peroxidation inhibition capacity trough the inhibition of the ��-carotene bleaching and thiobarbituric acid reactive substances (TBAR S) formation. Differences among treatments were analyzed using the one-way analysis of variance (ANO VA) and a linear discriminant analysis (LDA ) was used to evaluate the effects on the overall postharvest quality. After evaluating the effect on the individual quality parameters, the LDA revealed that the Ar-enriched atmosphere and the irradiation at 2 kGy were suitable processing choices for preserving the integrity of the non-stored control samples during cold storage. Thus, these non-thermal treatments were highlighted for shelf-life extension of fresh-cut watercress.

Degradation of compounds present in cork boiling water by gamma radiation

Cork boiling water is an aqueous and complex dark liquor with high concentration of phenolic compounds such as phenolic acids and tannins [1, 2], which are considered biorecalcitrants [2]. Ionizing radiation has been widely studied as an alternative technology for the degradation of organic contaminants without the addition of any other (e.g.: Fenton technologies). The aim of this work was to identify the compounds present in cork boiling water and further evaluate the resulting stable degradation products after gamma irradiation. The irradiation experiments of standard solutions were carried out at room temperature using a Co-60 experimental equipment. The applied absorbed doses were 20 and 50 kGy at a dose rate of 1.5 kGy/h, determined by routine dosimeters [3]. The identification of radiolytic products was carried out by HPLC-DAD-ESI/MS. The phenolic compounds were identified by comparing their retention times and UV���vis and mass spectra with those obtained from standard compounds, when available, as well as by comparing the obtained information with available data reported in the literature. Concerning the obtained results and the literature review, the main cork wastewater components are: quinic, gallic, protocatechuic, vanillic, syringic and ellagic acids. Based on this, we used protocatechuic, vanillic and syringic acids as model compounds to study their degradation by gamma radiation in order to identify the corresponding radiolytic products. Standard aqueous solutions were irradiated and the derivatives of each model compound are represented in figure 1. The obtained results seem to demonstrate that the derivatives of the parent compounds could also be phenolic acids, since it was observed the loss of 44 u (CO2) from the [M-H]- ions. Gallic and protocatechuic acids are identified as derivatives of vanillic and syringic acids, and gallic acid as a protocatechuic acid derivative. Compound 5 ([M-H]- at m/z 169) was tentatively identified as 2,4,6-trihydroxybenzoic acid, since its fragmentation pattern (m/z 151, 125 and 107) is similar to that previously reported in literature [4]. The structure of compound 7 was proposed based on the molecular ion and its fragmentation and compound 6 remains unknown.

Effects of gamma radiation in mycotoxin descontamination of Aloysia citrodora Pal��u

The interest and demand for aromatic and medicinal plants have been growing due to their combined organoleptic and bioactive properties. However, in general these plants suffer natural contamination by fungi and associated toxins during growth as also in harvesting, storage and drying processes, which represents a threat to public health. The rigorous standards required by the industrial sector in terms of good quality of raw materials demand efficient decontamination procedures (1-3). Gamma radiation is assumed as an accredited methodology for the decontamination of medicinal and aromatic plants, with numerous advantages not only to the product itself but also to the consumer and the environment (4). In this study, efficient methods for detecting aflatoxins (AFB" AFB2, AFG1 and AFG2) and ocratoxin A (OTA), were optimized and validated, and afterwards, applied to spiked samples of Aloysia citrodora Pahiu submitted to gamma radiation treatment at different doses (I , 5 and I 0 kGy ), to evaluate the effectiveness of irradiation as a decontamination technique for dry plants. Mycotoxin levels were determined by reversed-phase high-performance liquid chromatography (HPLC) with fluorescence detection, after immunoaffinity column (lAC) cleanup. All the applied gamma radiation doses conducted to a degradation of the studied mycotoxins. In relation to the control sample (0 kGy), the reduction rates in the irradiated samples ranged from 4.9 and 5.2% in OTA, 5.3 and 9.6% in AFBt. 12.3 and 13.5 in AFB2, 16.4 and 23.6 in AFG1 and, finally, 52.6 and 62.7% in AFG2. The gamma radiation dose of 5 kGy stood out as the best decontamination dose for AFB1 and AFG1, which are the most significant aflatoxins naturally found in food commodities. For OTA, AFG2 and AFB2 there was no significant difference in decontamination between doses. In conclusion, the extraction and analysis methods proved to be suitable for detection of aflatoxins and ocratoxin A in A. citrodora. Gamma radiation seems to be an effective technique for reducing aflatoxins G in A. citrodora, and eventually oth~r medicinal and aromatic plants. On the other hand, aflatoxins B and OTA are less affected by this treatment.

The impact of gamma irradiation on the cytotoxic properties and phenolic composition of Thymus vulgaris L. and Menta x piperita L.

Irradiation has been increasingly recognized as an effective decontamination technique, also ensuring the chemical and organoleptic quality of medicinal and aromatic plants 1 . The use of medicinal plants in the prevention and or treatment of several diseases has revealed satisfactory results as anti-inflammatory, antimutagenic, anti-cancer and antioxidant agents 2 . The aim of the present study was to evaluate the effects of gamma irradiation on the cytotoxic properties and phenolic composition of Thymus vulgaris L. and Menta x piperita L. (methanolic extracts). Phenolic compounds were analyzed by HPLC-DAD-ESI MS, while the cytotoxicity of the samples was assessed in MCF-7 (breast adenocarcinoma), NCI-H460 (non-small cell lung cancer), HeLa (cervical carcinoma), HepG2 (hepatocellular carcinoma) cell lines, as also in non-tumor cells (PLP2). Thirteen and fourteen phenolic compounds were detected in T. vulgaris and M. piperita, respectively, but none of them was affected by the irradiation up to a dose of 10 kGy. However, despite there were no changes in the cytotoxic properties of irradiated peppermint samples in tumor cell lines, the thyme samples irradiated with 10 kGy showed higher cytotoxicity in comparison with the samples submitted to other doses (2 and 5 kGy). This highlights that 10 kGy can be a suitable dose to ensure the sanitary treatment, without modifying the bioactive composition and properties of these aromatic plants.

Para l�� do azul: radia����es ionizantes para preservar alimentos

A radia����o vis��vel representa apenas uma parte do espectro de radia����o electromagn��tica com o qual temos interac����o permanente. As radia����es com maior energia, para al��m do azul, como os UV, raios-X ou radia����o gama t��m diferentes usos tecnol��gicos. Estas radia����es s��o consideradas ionizantes podendo ser utilizadas na preserva����o de alimentos, permitindo a inibi����o da germina����o, a elimina����o de insectos ou microrganismos patog��nicos. O conhecimento destas aplica����es tem mais de um s��culo e o seu uso industrial meio s��culo. Propomo-nos apresentar o estado-de-arte relativo ao uso desta tecnologia em Portugal em alimentos, apresentando estudos recentes e perspectivas futuras.

A F��sica aplicada �� qualidade alimentar: identifica����o de metais por ���pixe��� em castanhas

A concentra����o na castanha de minerais como o c��lcio, pot��ssio, o magn��sio e outros tem sido estudada tradicionalmente por absor����o at��mica ou por espectrofotometria de UV-VIS [1-2]. Neste trabalho foi estudada a composi����o elementar de duas variedades (Longal e Judia) de castanha europeia (Castanea sativa Mill.) com a t��cnica PIXE (Proton Induced X-ray Emission). Os resultados preliminares mostram que a composi����o difere de acordo com a variedade, nos elementos maiorit��rios e nos minorit��rios. Este estudo �� parte de um projecto mais amplo, que visa avaliar o efeito do processamento p��s-colheita de alimentos com feixe de electr��es e raios-X.

Aplica����o das f��rmulas CIELAB e CIEDE2000 na avalia����o da cor de folhas vegetais irradiadas por uma fonte de Cobalto-60

A cor dos alimentos est�� directamente associada �� sua aceita����o pelo consumidor. A procura de m��todos de processamento seguros e eficazes destaca a radia����o ionizante, j�� que permite a desinfec����o do alimento e a extens��o do seu tempo de prateleira [1]. O espa��o de cor CIELAB �� comummente utilizado para avaliar diferen��as de cor (��E*) entre dois objectos. No entanto, a f��rmula CIEDE2000 permite atenuar varia����es entre valores calculados e percepcionados [2]. O impacto da radia����o ionizante na cor de um vegetal folhoso foi avaliado durante o tempo de armazenamento e os resultados discutidos utilizando ambas as f��rmulas de ��E*.

Valoriza����o de produtos de montanha pela utiliza����o de tecnologias de processamento n��o convencionais

Os vegetais embalados prontos a comer t��m tido uma crescente aceita����o por parte do consumidor por atenderem aos requisitos contempor��neos de conveni��ncia, seguran��a e salubridade. O crescimento deste setor tem levado �� introdu����o de novos produtos e �� ado����o de tecnologias de conserva����o mais eficientes, seguras e sustent��veis [1]. O consumidor procura tamb��m alimentos com caracter��sticas organol��ticas diferenciadas das dos alimentos habitualmente consumidos diariamente. A recupera����o do uso de Rumex induratus Boiss. & Reut. (azedas) e Nasturtium officinale R. Br. (agri��o) poder�� responder a esta procura, aliando garantia de qualidade e inova����o. Visto a maioria dos tratamentos convencionais ser ineficaz em assegurar seguran��a sem comprometer a qualidade, e dada a preocupa����o em torno dos agentes qu��micos vulgarmente utilizados, a irradia����o de alimentos e o embalamento em atmosfera modificada t��m emergido como alternativas seguras e eficazes [1-4]. Neste sentido, este estudo teve como objetivo avaliar a efic��cia de diferentes atmosferas de embalamento e de diferentes doses de radia����o ionizante na conserva����o da qualidade destas esp��cies durante o armazenamento refrigerado. O uso sustent��vel de produtos vegetais para a recupera����o de biomol��culas ou produ����o de ingredientes funcionais de valor acrescentado �� uma estrat��gia ��til que pode ajudar a enfrentar os desafios societais deste s��culo. Atualmente �� originada uma grande quantidade de res��duos de tomate (Lycopersicon esculentum Mill.) fresco durante as v��rias etapas do seu ciclo produtivo, desde a cultura at�� ao armazenamento e venda [5]. Estes res��duos s��o ricos em licopeno e vitaminas, mas tamb��m em compostos fen��licos [6,7]. Estes compostos bioativos est��o envolvidos na preven����o de v��rias patologias humanas e s��o de elevada import��ncia para a ind��stria alimentar, farmac��utica e cosm��tica. Visto os m��todos convencionais utilizados para a extra����o destas biomol��culas apresentarem v��rias desvantagens, novas tecnologias mais eficientes e sustent��veis t��m vindo a ser adotadas. Neste sentido, este trabalho teve como objetivo otimizar as condi����es de extra����o assistida por tecnologia micro-ondas de antioxidantes hidrof��licos e lipof��licos e dos ��cidos fen��licos e flavonoides maiorit��rios da variedade de tomate redondo utilizando a metodologia de superf��cie de resposta (RSM).

Suitability of gamma irradiation for preserving fresh-cut watercress quality during cold storage

The suitability of gamma irradiation (1, 2 and 5kGy) for preserving quality parameters of fresh-cut watercress (Nasturtium officinale R. Br.) during storage at 4��1��C for 7d was investigated. The storage time decreased the protein content and the main carbohydrates, and increased the levels of malic and fumaric acids, sucrose and mono- and polyunsaturated fatty acids (MUFA and PUFA). The different irradiation doses did not caused any significant colour change. In general, the 2kGy dose favoured PUFA and was the most suitable to preserve the overall postharvest quality of fresh-cut watercress during cold storage. In turn, the 5kGy dose better preserved the antioxidant activity and total flavonoids and favoured MUFA, tocopherols and total phenolics, thus originating a final product with enhanced functional properties. Therefore, the suitability of gamma irradiation for preserving fresh-cut watercress quality during cold storage was demonstrated.

Definindo dificuldades de aprendizagem espec��ficas na leitura

Uma dificuldade de aprendizagem, que tem uma origem neurobiol��gica. �� caracterizada por dificuldades no correto e/ou fluente reconhecimento de palavras e por pobres capacidades de soletra����o e de descodifica����o. Geralmente, estas dificuldades refletem d��fices na componente fonol��gica da linguagem, que s��o geralmente inesperadas tendo em conta n��o s�� as capacidades cognitivas do aluno como tamb��m as pr��ticas eficazes que lhe t��m sido proporcionadas na sala de aula. Consequ��ncias secund��rias podem incluir problemas na compreens��o da leitura e reduzidas experi��ncias de leitura que podem impedir a aquisi����o de vocabul��rio e de conhecimentos pr��vios (Shaywitz & Shaywitz, 2003, p. 2).

Heavy elements in chestnuts

Chestnut fruit (CasChestnuts, Castanea sativa, heavy elements, PIXEtanea sativa Miller) are an important food resource in several countries. Portugal is the third largest European producer, with an average production of 25 thousand tons [1], being mainly produced in the North region of Tr��s-os-Montes. Earlier studies on chestnuts elemental composition were performed by atomic absorption to detect Ca, Mg, Na, K, Cu, Fe, Mn and Zn or by UV-VIS spectrophotometry to detect P [2-3]. In this work the elemental composition of two cultivars (Longal and Judia) of Castanea sativa Miller were studied by means of PIXE (Proton Induced X-ray Emission), using a broad proton beam at CTN-IST, Lisbon. Element identification (from Si to Pb) and quantification (following the method described in [4]) was done. Preliminary results show different composition according with the cultivar, not only in the major and minor elements (as it is described in the bibliography) but also in the trace elements, which includes the presence of Pb and other heavy elements. These preliminary results are part of a wider project that aims to evaluate chestnut fruits decontamination treatment with high energy electron beam and X-rays technology.