RECOVERY OF THE SUSTAINABLE USE OF TRADITIONAL FOODS THROUGH EMERGING PRESERVATION TECHNOLOGIES

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Physical hurdles to enhance watercress' quality and safety: Effects on chemical and bioactive parameters

Publication . Pinela, José; Barreira, João C.M.; Fernandes, Ângela; Cabo Verde, Sandra; Antonio, Amilcar L.; Carvalho, Ana Maria; Oliveira, Beatriz; Ferreira, Isabel C.F.R.

The hurdle concept provides a framework for combining a number of milder preservation factors (hurdles) in order to achieve an enhanced level of product safety and stability. For fresh vegetables such as watercress (Nasturtium officinale R. Br.), characterised by a reduced shelf-life, some of these hurdle have focused on the use of modified atmosphere packaging (MAP) combined with other physical or physicochemical factors (Alexandre et al., 2011; Silveira et al., 2014). Thus, in the present work, the combined effects of passive MAP, gamma irradiation and refrigerated storage on chemical and bioactive quality parameters of watercress were evaluated. Wild specimens were gathered in the Northeast region of Portugal, rinsed in tap water and a portion was immediately analysed (control). The remaining fresh material was packed under passive MAP, exposed to 1, 2 and 5 kGy of y-rays in a 6°Co chamber and stored at 4 oc for 7 days. Non-irradiated samples followed all the assays. Sugars, fatty acids, tocopherols and organic acids were analysed by chromatographic techniques. Phenolics and flavonoids were determined by spectrophotometer methods. The antioxidant activity was evaluated in hydroalcoholic extracts using four distinct in vitro assays. In general, the sucrose and organic acid levels increased in stored samples. The 5 kGy dose protected MUF A (monounsaturated fatty acids), while the 2 kGy dose was effective in favouring PUF A (polyunsaturated fatty acids). In either case, the hurdle treatment allowed obtaining watercress samples with a healthier fatty acids profile, as also verified in the increased PUF A/SF A (saturated fatty acids) ratio. Concerning tocopherols, the most relevant result was the effect achieved with the 5 kGy dose, particularly owing the contributions of a- (the major isoform) and ytocopherols. The same dose also allowed the best results in maintaining the antioxidant activity, as well as in phenolics and flavonoids. Through Linear Discriminant Analysis it was concluded that 2 kGy is the preferable hurdle to maintain the original characteristics of watercress. Nevertheless, the 5 kGy dose should also be considered when aiming to obtain a final product with healthier properties. Thus, this study highlighted the suitability of the applied hurdles to enhance watercress functionality and shelf-life.

2015Conference object

Open access

Análise cromatográfica de compostos hidrofílicos em acessos de tomate (Solanum lycopersicum L.) conservados ex-situ

Publication . Martins, Valter; Pinela, José; Barros, Lillian; Carvalho, Ana Maria; Rocha, Filomena; Barata, Ana Maria; Ferreira, Isabel C.F.R.

O Banco Português de Germoplasma Vegetal (BPGV), situado em Braga, acolhe e conserva coleções representativas de germoplasma dos mais importantes recursos agrícolas de Portugal Continental e Ilhas. A manutenção destas coleções exige que o material vegetal seja regenerado e caracterizado periodicamente. Neste sentido, este trabalho teve como objetivo fazer uma caracterização química dos acessos das variedades tradicionais de tomate (Solanum lycopersicum L.) apresentados na Tabela 1. As sementes conservadas ex-situ foram regeneradas e multiplicadas nos campos experimentais do BPGV e os frutos maduros foram analisados quanto à sua composição em açúcares livres e ácidos orgânicos. Estes compostos hidrofílicos foram determinados por cromatografia líquida de alta eficiência (HPLC) acoplada a um detetor de índice de refração ou a um detetor de fotodíodos, respetivamente [1]. Com base nesta análise foi possível verificar que o acesso 12260 tinha os maiores teores de frutose, glucose e açúcares totais, enquanto que a sacarose foi particularmente abundante no acesso 13034. Foi possível identificar os ácidos oxálico, málico, ascórbico e cítrico (o mais abundante) em todas as amostras. O acesso 13034 apresentou as maiores concentrações de ácido oxálico, ácido cítrico e ácidos orgânicos totais. O ácido málico e o ácido ascórbico foram particularmente abundantes nos acessos 12260 e 12437, respetivamente. Este trabalho destacou os acessos de tomate coração-de-boi (originários de Bragança e Guarda) como sendo ricos em açúcares e ácidos orgânicos, compostos relevantes do ponto de vista organolético e nutricional.

2017Conference object

Open access

Crocin and β-Carotene bleaching assays as analytical tools in the optimization of the extraction of hydrophilic and lipophilic antioxidants from tomato

Publication . Pinela, José; Prieto Lage, Miguel A.; Barreiro, M.F.; Carvalho, Ana Maria; Oliveira, Beatriz; Vázquez, J.A.; Ferreira, Isabel C.F.R.

Tomato (Lycopersicon esculentum Mill.) is the second most important vegetable crop worldwide and a rich source of hydrophilic (H) and lipophilic (L) antioxidants. The H fraction is constituted mainly by ascorbic acid and soluble phenolic compounds, while the L fraction contains carotenoids (mostly lycopene), tocopherols, sterols and lipophilic phenolics [1,2]. To obtain these antioxidants it is necessary to follow appropriate extraction methods and processing conditions. In this regard, this study aimed at determining the optimal extraction conditions for H and L antioxidants from a tomato surplus. A 5-level full factorial design with 4 factors (extraction time (I, 0-20 min), temperature (T, 60-180 •c), ethanol percentage (Et, 0-100%) and solid/liquid ratio (S/L, 5-45 g!L)) was implemented and the response surface methodology used for analysis. Extractions were carried out in a Biotage Initiator Microwave apparatus. The concentration-time response methods of crocin and P-carotene bleaching were applied (using 96-well microplates), since they are suitable in vitro assays to evaluate the antioxidant activity of H and L matrices, respectively [3]. Measurements were carried out at intervals of 3, 5 and 10 min (initiation, propagation and asymptotic phases), during a time frame of 200 min. The parameters Pm (maximum protected substrate) and V m (amount of protected substrate per g of extract) and the so called IC50 were used to quantify the response. The optimum extraction conditions were as follows: r~2.25 min, 7'=149.2 •c, Et=99.1 %and SIL=l5.0 giL for H antioxidants; and t=l5.4 min, 7'=60.0 •c, Et=33.0% and S/L~l5.0 g/L for L antioxidants. The proposed model was validated based on the high values of the adjusted coefficient of determination (R2.wi>0.91) and on the non-siguificant differences between predicted and experimental values. It was also found that the antioxidant capacity of the H fraction was much higher than the L one.

2016Conference object

Open access

Postharvest quality of fresh-cut watercress: impact of non-thermal treatments based on inert-gas and ionizing radiation

Publication . Pinela, José; Barreira, João C.M.; Barros, Lillian; Antonio, Amilcar L.; Cabo Verde, Sandra; Carvalho, Ana Maria; Oliveira, Beatriz; Ferreira, Isabel C.F.R.

Ready-to-eat vegetables are having a growing consumer acceptance for attending to contemporary requirements of convenience, safety and wholesomeness. The growth of this sector has led to the introduction of new food products and the implementation of more efficient and sustainable postharvest technologies1 In this sense, the suitability of modified atmosphere packaging (MAP) and post-packaging gamma irradiation for preserving quality parameters of fresh-cut watercress (Nasturtium officinale R. Br.) during cold storage was evaluated. Wild samples of watercress were rinsed in tap water and a portion was immediately analysed (fresh control). The remaining fresh material was packaged under nitrogen- and argon-enriched atmospheres, air (passive MAP) and vacuum. Air-packaged samples were then irradiated at doses up to 5 kGy in a cobalt-60 chamber. All packaged samples were stored at 4 oc for 7 days. The quality analyses included color, total soluble solids, pH, macronutrients, the individual profiles of sugars, organic acids, tocopherols and fatty acids, and total phenolics and flavonoids. Four in vitro assays based on different reaction mechanisms were also performed to evaluate the antioxidant capacity. After assessing the effect on the individual quality parameters, it was possible to conclude that argon-enriched atmospheres and the 2 kGy dose were suitable choices for preserving quality attributes of watercress during cold storage2 . However, samples irradiated at 5 kGy revealed chemical profiles more prone to exert positive health effects. Thereby, advantageous effects induced by modified atmospheres and ionizing radiation in the quality of fresh-cut watercress were highlighted, justifying the inclusion of this vegetable in human diets.

2015Conference object

Open access

Alimentos tradicionais e inovação: Uso de atmosferas modificadas e radiação ionizante na conservação da qualidade das azedas

Publication . Pinela, José; Barreira, João C.M.; Barros, Lillian; Cabo Verde, Sandra; Antonio, Amilcar L.; Oliveira, Beatriz; Carvalho, Ana Maria; Ferreira, Isabel C.F.R.

O crescimento do setor dos vegetais embalados prontos a comer tem levado à introdução de novos produtos e à adoção de tecnologias de conservação mais eficientes, seguras e sustentáveis. Neste sentido, este estudo teve como objetivo avaliar a eficácia de diferentes atmosferas de embalamento e de diferentes doses de radiação ionizante na conservação de azedas (Rumex induratus) armazenadas a 4°C durante 12 dias. Ambos os tratamentos tiveram efeitos positivos e negativos na qualidade das amostras. Tendo em conta a contribuição de todos os parâmetros analisados, foi possível concluir que o embalamento a vácuo foi a melhor opção para conservar a qualidade global das amostras durante o armazenamento, seguido do embalamento em atmosfera enriquecida em árgon. Este estudo destacou também o potencial das azedas na indústria dos alimentos minimamente processados.

2017Journal article

Open access