Postharvest quality changes in fresh-cut watercress stored under conventional and inert gas-enriched modified atmosphere packaging

The effect of modified atmosphere packaging (MAP) on the postharvest quality of fresh-cut watercress (Nasturtium officinale R. Br.) stored at 4 ºC for 7 d was studied. A portion of watercress was immediately analyzed (non-stored control) and the remaining fresh material was stored packaged under atmospheres enriched with N2, Ar, air, or vacuum. The analyzed parameters included colour, total soluble solids, pH, macronutrients, the individual profiles of sugars, organic acids, tocopherols and fatty acids, and total phenolics and flavonoids. Furthermore, four in vitro assays were performed to evaluate the antioxidant activity. After assessing the effect on individual quality parameters, it was possible to conclude that air was the less efficient atmosphere in preserving quality attributes of the non-stored control samples during cold storage. In turn, Ar-enriched MAP was the most suitable choice to preserve the overall postharvest quality. The present study also highlighted the nutritional and antioxidant properties of watercress, as well as the interest of its inclusion in human diets.

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.

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 ºC 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 β-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.

Nitrogen vs argon: what is the most effective atmosphere for shelf-life extension of buckler sorrel leaves?

Buckler sorrel (Rumex induratus Boiss. & Reut.) is an underutilized leafy vegetable with peculiar sensory properties and potential as a gourmet food. In the food industry, different packaging methods have been used for shelf-life extension, but it is important to know how the quality of minimally processed vegetable is affected by these treatments. Recently, nitrogen and argon have been used for food packaging. Nitrogen is low soluble in water and other food constituents and does not support the growth of aerobic microbes. In turn, argon is biochemically active and appears to interfere with enzymatic oxygen receptor sites. In this study, modified atmospheres enriched with nitrogen and argon were evaluated for shelf-life extension of buckler sorrel leaves. Wild samples were gathered in Bragança, Portugal, considering local consumers’ sites and criteria. Healthy and undamaged leaves were selected, rinsed in tap water, and a portion was immediately analyzed (non-stored control). The remaining fresh material was packaged in polyethylene bags under nitrogen- and argon-enriched atmospheres and a conventional control atmosphere (air). All packaged samples were stored at 4 ºC for 12 days and then analyzed. The headspace gas composition was monitored during storage. Different quality attributes were evaluated, including visual (colour), nutritional (macronutrients, individual sugars and fatty acids) and bioactive (hydrophilic and lipophilic molecules and antioxidant properties) parameters. Different statistical tools were used; the one-way analysis of variance (ANO VA) was applied for analyse the differences among treatments and a linear discriminant analysis (LDA ) was used to evaluate the effects on the overall postharvest quality. The argon-enriched atmosphere better prevent the samples yellowing. The proximate composition did not change significantly during storage. Samples in control atmosphere revealed higher protein and ash contents and lower levels of lipids. The non-stored control samples presented the higher amounts of fructose, glucose and trehalose. The storage time increased the palmitic acid levels and decreased the content in α-linolenic and linoleic acids. The γ- e δ-tocopherols were higher after the 12 days of cold storage. Probably, the synthesis of these lipophilic compounds was a plant strategy to fight against the abiotic stress induced by storage. Higher levels of total phenolics and flavonoids and increased reducing power and β-carotene bleaching inhibition capacity were also found in the stored control samples. Once again, this result may be attributed to the intrinsic plant-protection mechanisms. Overall, the argon atmosphere was more suitable for quality preservation and shelf-life extension of buckler sorrel.

Avaliação da disponibilidade de espaços verdes públicos no contexto urbano e a sua relação com a perceção dos residentes. Um estudo para a cidade de Bragança

Os espaços verdes públicos urbanos são muito importantes no contexto urbano. Influenciam de diversas formas na qualidade de vida das populações, proporcionando benefícios ambientais, sociais e econômicos. A fim de avaliar a disponibilidade destes espaços na cidade de Bragança, foram realizadas análises utilizando indicadores, com apoio dos software ArcGIS 9.3 e QGis 2.14.0-Essen, que permitiram avaliar a oferta destes espaços nas suas diferentes tipologias e categorias dimensionais. Para o efeito foram aplicados os indicadores: Percentagem de espaços verdes, Espaços verdes per capita, Distância média, Índice de Área Verde por Área de Implantação e Índice de Área Verde por Área Coberta. Posteriormente, procedeu-se à aplicação de inquéritos a fim de avaliar as perceções e atitudes de uma amostra da população de Bragança, realizando análises descritivas e estatísticas, com recurso ao software SPSS17, buscando descrever a atual relação com os espaços verdes e usando testes não paramétricos para identificar diferenças entre subgrupos da amostra, numa análise centrada em dois níveis: a escala urbana e a escala de Bairro. Procurando avaliar possíveis alterações futuras, foram testados cenários realistas, um correspondendo à introdução de espaços verdes em terrenos na posse da Autarquia e outro considerando a ampliação das áreas verdes previstas no Plano de Urbanização de Bragança de 2010. Os Resultados permitiram identificar diferenças relevantes na oferta de espaços verdes da cidade. Aplicando os indicadores foi possível verificar que existe a concentração de espaços verdes de maior dimensão na zona central da cidade, denotando um claro desequilíbrio na introdução de novos espaços em zonas de expansão urbana. Os inquéritos aplicados possibilitaram constatar que os inquiridos que possuem maior disponibilidade de espaços verdes em seu bairro de residência apresentam respostas mais satisfatórias em relação a acessibilidade e a aparência visual e paisagística dos bairros. Da análise de cenários resulta que com a implantação de novos espaços verdes, para as duas análises, ocorreria uma melhoria da oferta e distribuição dos espaços verdes na cidade permitindo um maior reequilíbrio face à concentração na zona central, melhorando a acessibilidade para toda a população.

Quality control of gamma irradiated dwarf mallow (Malva neglecta Wallr.) based on color, organic acids, total phenolics and antioxidant parameters

This study addresses the effects of gamma irradiation (1, 5 and 8 kGy) on color, organic acids, total phenolics, total flavonoids, and antioxidant activity of dwarf mallow (Malva neglecta Wallr.). Organic acids were analyzed by ultra fast liquid chromatography (UFLC) coupled to a photodiode array (PDA) detector. Total phenolics and flavonoids were measured by the Folin-Ciocalteu and aluminium chloride colorimetric methods, respectively. The antioxidant activity was evaluated based on the DPPH(•) scavenging activity, reducing power, β-carotene bleaching inhibition and thiobarbituric acid reactive substances (TBARS) formation inhibition. Analyses were performed in the non-irradiated and irradiated plant material, as well as in decoctions obtained from the same samples. The total amounts of organic acids and phenolics recorded in decocted extracts were always higher than those found in the plant material or hydromethanolic extracts, respectively. The DPPH(•) scavenging activity and reducing power were also higher in decocted extracts. The assayed irradiation doses affected differently the organic acids profile. The levels of total phenolics and flavonoids were lower in the hydromethanolic extracts prepared from samples irradiated at 1 kGy (dose that induced color changes) and in decocted extracts prepared from those irradiated at 8 kGy. The last samples also showed a lower antioxidant activity. In turn, irradiation at 5 kGy favored the amounts of total phenolics and flavonoids. Overall, this study contributes to the understanding of the effects of irradiation in indicators of dwarf mallow quality, and highlighted the decoctions for its antioxidant properties.