José Pinela

Antioxidant activity, ascorbic acid, phenolic compounds and sugars of wild and commercial Tuberaria lignosa samples: effects of drying and oral preparation methods.

The antioxidant activity and phytochemical composition (ascorbic acid, free sugars and phenolic compounds) of decoctions and infusions of wild and commercial samples of Tuberaria lignosa (Sweet) Samp. Aerial parts were evaluated and compared. Among wild samples, the effects of the drying method (freeze or shade-drying) on those parameters were studied. Infusion of the freeze-dried wild sample gave the highest levels of sugars, while infusion of shade-dried wild sample and decoction of the freeze-dried sample presented higher ascorbic acid and phenolic compounds content (including ellagitannins and flavonoids) than the other samples. The last two samples also revealed higher antioxidant activity, in some cases even higher than Trolox. Decoctions gave lower amounts of disaccharides than infusions, which seemed to be hydrolysed, increasing the content of monosaccharides. Commercial samples showed the lowest content in phenolic compounds, mainly in ellagitannins and flavonoids, and also the lowest antioxidant activity. This work gives scientific evidence to the traditional medicinal uses of wild Tuberaria lignosa, highlighting the interest of its decoctions and infusions as a source of bioactive compounds and functional beverages.

Influence of the drying method in the antioxidant potential and chemical composition of four shrubby flowering plants from the tribe Genisteae (Fabaceae).

Flowers from several common Mediterranean shrubs, such as those from the Cytisus genus and Genista genus (tribe Genisteae/Fabaceae) have long been used for medicinal purposes and seasoning in the northeastern Portuguese region. Despite, the shade-drying traditionally used to process these plants, freeze-drying is claimed to better preserve the quality of medicinal plants. Herein, the effects of drying process in the antioxidants composition and properties of Cytisus multiflorus, Cytisus scoparius, Cytisus striatus and Pterospartum tridentatum were evaluated. Freeze-dried P. tridentatum revealed the highest antioxidant properties (EC(50) values ≤ 0.15 mg/ml). Freeze-drying benefits were confirmed showing, the samples submitted to this process, higher antioxidant activity and higher concentrations of hydrophilic (phenolics, ascorbic acid and sugars) and lipophilic (tocopherols, chlorophylls and lycopene) compounds. This process could be applied in scale-up treatments of the studied plants for cosmetic or pharmaceutical applications.

Nonthermal physical technologies to decontaminate and extend the shelf-life of fruits and vegetables: Trends aiming at quality and safety

ABSTRACT Minimally processed fruits and vegetables are one of the major growing sectors in food industry. This growing demand for healthy and convenient foods with fresh-like properties is accompanied by concerns surrounding efficacy of the available sanitizing methods to appropriately deal with food-borne diseases. In fact, chemical sanitizers do not provide an efficient microbial reduction, besides being perceived negatively by the consumers, dangerous for human health, and harmful to the environment, and the conventional thermal treatments may negatively affect physical, nutritional, or bioactive properties of these perishable foods. For these reasons, the industry is investigating alternative nonthermal physical technologies, namely innovative packaging systems, ionizing and ultraviolet radiation, pulsed light, high-power ultrasound, cold plasma, high hydrostatic pressure, and dense phase carbon dioxide, as well as possible combinations between them or with other preservation factors (hurdles). This review discusses the potential of these novel or emerging technologies for decontamination and shelf-life extension of fresh and minimally processed fruits and vegetables. Advantages, limitations, and challenges related to its use in this sector are also highlighted.

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.

Combined effects of gamma-irradiation and preparation method on antioxidant activity and phenolic composition of Tuberaria lignosa

In this study, the effect of different doses of gamma-irradiation (0, 1, 5 and 10 kGy) on colour, antioxidant activity and phenolic compounds of shade- and freeze-dried samples of Tuberaria lignosa were evaluated and compared. The last two parameters were assessed using decoctions and infusions in order to investigate the influence of the preparation method as well. In general, gamma-irradiation has no influence on colour parameter; changes caused by this technology were only identifiable on the lipid peroxidation inhibition capacity of the shade-dried samples and also on a few phenolic compounds. Differences among preparation method were significant for all assayed parameters, with decoctions being preferable over infusions, as indicated by the higher antioxidant activity and levels of phenolic compounds. Overall, the gamma-irradiation treatment (up to 10 kGy) did not significantly affect the analyzed parameters. Nevertheless, other studies are of interest to evaluate the preservation effectiveness of this technology.

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.

Postharvest changes in the phenolic profile of watercress induced by post-packaging irradiation and modified atmosphere packaging

The effects of γ-ray irradiation and modified atmosphere packaging (MAP) on watercress (Nasturtium officinale R. Br.) phenolic compounds were evaluated after 7-day storage at 4 °C. Irradiation doses of 1, 2 and 5 kGy were tested, as well as vacuum-packaging and MAP enriched with 100% N2 and Ar. A non-irradiated, air-packaged control was included in all experiments. p-Coumaric acid was the most abundant compound in fresh watercress, followed by quercetin-3-O-sophoroside and isorhamnetin-O-hydroxyferuloylhexoside-O-hexoside. Four kaempferol glycoside derivatives were identified for the first time in this species. In general, flavonoids predominated over phenolic acids. Samples stored under vacuum and irradiated at 2 kGy revealed lower phenolic levels. Ar-enriched MAP and control conditions preserved the initial phenolic content. The 5 kGy dose also maintained concentrations of flavonoids and total phenolic compounds, but increased the phenolic acids content. Additionally, flavonoids were found strongly correlated to DPPH scavenging activity and β-carotene bleaching inhibition capacity.

Wild edible plants: Nutritional and toxicological characteristics, retrieval strategies and importance for today's society

Wild edible plants (WEPs) are part of the cultural and genetic heritage of different regions of the world. In times of famine and scarcity, these sources of nutrients and health-promoting compounds have received high importance mainly in rural and suburban areas. Although currently underutilized, WEPs are still consumed traditionally by different communities and are gaining relevance in todays society. However, these foods lack recognition as significant contributors to the human diet in developed areas. This review describes the nutritional value of WEPs from the North-eastern region of Portugal and points out those containing potentially toxic compounds. Several retrieval strategies are presented with the aim of promoting the (re)use, production, commercialization and conservation of WEPs (wild harvested plants and crop wild relatives), and their importance for social, economic and agro-ecological development is highlighted.

Stability of total folates/vitamin B9 in irradiated watercress and buckler sorrel during refrigerated storage

The suitability of post-packaging gamma radiation treatment for preserving total folates or vitamin B9 in watercress (Nasturtium officinale R. Br.) and buckler sorrel (Rumex induratus Boiss. & Reut.) during storage at 4 °C was evaluated. Comparable amounts of total folates were found in fresh, non-stored samples of both species. In watercress, the irradiation treatment of up to 5 kGy reduced the loss of total folates caused by 7 days of storage. In turn, the 12-day storage period did not affect the total folate content of buckler sorrel (while the 2 kGy dose decreased the initial levels), evidencing that packaging and refrigeration are enough for preservation. These results suggest that the suitability of post-packaging irradiation for preserving total folates may depend not only on the applied dose but also on the plant matrix under analysis. In addition, new data useful to complete food composition tables or databases is provided.

Optimization of heat- and ultrasound-assisted extraction of anthocyanins from Hibiscus sabdariffa calyces for natural food colorants

Heat- and ultrasound-assisted extraction methods were applied to recover anthocyanins from Hibiscus sabdariffa calyces. The extraction variables, time (t), ethanol proportion (S), and temperature (T) or ultrasonic power (P), were combined in a 5-level experimental design and analysed by response surface methodology for process optimization. The delphinidin-3-O-sambubioside (C1) and cyanidin-3-O-sambubioside (C2) levels were monitored by LC-DAD-ESI/MSn and used as response criteria. The developed models were successfully fitted to the experimental data and used to determine optimal extraction conditions. UAE was the most efficient method yielding 51.76 mg C1 + C2/g R under optimal conditions (t = 26.1 min, P = 296.6 W and S = 39.1% ethanol, v/v). The dose-response effects of the solid/liquid ratio on the extraction rate were also determined. The anthocyanin levels herein reported are higher than those found in the literature, which support the potential use of H. sabdariffa as a sustainable source of natural colorants with application in different industrial sectors.