Browsing by Author "Silva, Cristina"
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- Chemical composition, antioxidant capacity and phenolic contents of carob (Ceratonia siliqua L.) flour as related to seed presence and roasting effectsPublication . Brassesco, María; Vilas-Boas, Ana M.; Brandão, Teresa; Silva, Cristina; Pintado, ManuelaCarob is the fruit of an evergreen tree (Ceratonia siliqua L.) cultivated in the Mediterranean area, where Portugal has a high-cultivated extent with relevant production and low prices. Carob is well known for its valuable locust bean gum. However, carob pods contain various relevant nutrients, including proteins, carbohydrates and fiber, and phytochemicals such as polyphenols, which position carob flour with great potential to be used as a functional ingredient. This study aimed to evaluate the impact of different roasting processes of carob flour (with and without seeds) on its nutritional composition and antioxidant activity. Seed presence led to a higher content of macronutrients in carob flour. The roasting processing affected the total content of polyphenols (TPC), determined by Folin-Ciocalteau, since the content at 150 ºC was twice of that obtained at 80 ºC, probably due to the formation of certain Maillard reaction products (MRPs), or certain phenolics that may degrade during roasting. The antioxidant activity is correlated with TPC, increasing when the flour was roasting at 150ºC. Regarding the total fiber content, a significant increase was observed in samples processed at 150 ºC. These findings confirm the importance of understanding the impact of processing on the nutritional value and bioactive properties of carob flours, to use them efficiently as a functional food ingredient.
- Chemical composition, antioxidant capacity and phenolic contents of carob (Ceratonia siliqua L.) flour as related to seed presence and roasting effectsPublication . Brassesco, María; Vilas-Boas, Ana M.; Brandão, Teresa; Silva, Cristina; Pintado, Manuela
- Comparison of the dietary fiber content of carob (Ceratonia siliqua L.) flour as related to seed presence and roasting effectsPublication . Vilas-Boas, Ana Martins; Brassesco, María; Brandão, Teresa; Silva, Cristina; Pintado, ManuelaCarob fruit originates from the carob tree, a leguminous evergreen tree (Ceratonia siliqua L.) cultivated in the Mediterranean area, namely in Portugal, with high relevance in production and low prices. Carob pods contain various relevant nutrients that include proteins, carbohydrates and fiber, as well as phytochemicals such as polyphenols, conferring great potential for carob pods to be used as functional ingredient. This study focused on extracting, by a thermal-enzymatic process and characterizing, by HPLC, the dietary fiber (DF) content for carob powders with and without seed at different roasting temperatures. An initial nutritional evaluation on carob powders (CPs) indicated that seed presence led to higher content in macronutrients. The CPs processed at 150 ºC showed significantly higher content in neutral sugars (NS). As for the determination of DF content, results indicated that the main fiber fraction present in all samples was insoluble dietary fiber (IDF) corresponding to 98.4 % of total fiber content. The uronic acid content was significantly higher in IDF, for both roasting temperatures. The Klason lignin was higher for CPs processed at 150 ºC and represented, in all cases, 50 % of total IDF. The DF were also evaluated for antioxidant activity and phenolic content. The total phenolic content (TPC), determined by Folin-Ciocalteau, was twice on IDF as high at 150 ºC than 80 ºC, probably due to the formation of certain Maillard reaction products (MRPs), or certain phenolics that may degrade during roasting. The free phenolic content was significantly affected by the roasting temperatures and seed presence. The antioxidant activity is correlated with TPC, increasing in IDF when the flour was roasted at 150 ºC. These findings could put in the best light the utilization of DF in food industry according to the requirement of the final product and can also incline the interest of consumers towards the less utilized carob flours.
- Dos riscos à criminalidadePublication . Esteves, Alexandra; Cunha, Manuel Antunes da; Sá, Vítor J.; Panyik, Emese; Ponte, Filomena; Monteiro, Daniela; Silva, Cristina; Fernandes, Sílvia
- Freeze and freeze drying applied as preservation processes of melon peelPublication . Sabinova, Aida; Miller, Fátima; Fundo, Joana Freitas; Chalova, Vesela I.; Silva, Cristina; Brandão, Teresa R. S.
- Freeze-drying processes applied to melon rinds to attain a value-added food ingredientPublication . Brandão, Teresa; Sroy, Sengly; Fundo, Joana; Silva, Cristina; Miller, FátimaAim: Several studies pointed out melon rinds as rich sources of bioactive compounds with relevant antioxidant activity. Being considered a non-edible part with no economic value, fruit industries discharge large amounts of these residues to the environment. If these wastes are conveniently processed and transformed, novel food ingredients with potential health benefits may arise.The objective was to transform melon rinds by freeze-drying to attain dried small bits that can be used as additives to enrich diverse food matrixes. An ozone pre-treatment was applied seeking decontamination and retention of quality characteristics. The impact of these processes was assessed in bioactive compounds (vitamin C, total phenolics and chlorophylls), antioxidant activity, and melon peel microflora (mesophylls, yeasts and moulds) during 7 weeks of storage of the dried materials at room temperature. Method: Melon rinds (Cucumis melo L. var. reticulatus) were cut in small cubes. Before freeze-drying (-50 °C, 1.5-2 bar, 80-90 h) and storage (7 weeks in the dark at room temperature), part of the samples was exposed to a gaseous ozone pre-treatment (15 °C, 152±71 ppm, 30 min). Vitamin C, total phenolics, chlorophylls and antioxidant activity were analysed by HPLC and spectrophotometric methods in raw peel and throughout storage. Mesophylls, yeasts and moulds were also enumerated. Results: Vitamin C, total phenolics, chlorophylls, and antioxidant activity decreased during storage in both non-ozonized and ozonized dried samples. However, pre-ozonized samples retained better the bioactive compounds analyzed throughout the storage: almost 85% of total phenolics and chlorophylls were preserved, and 66% of vitamin C. In terms of microflora inactivation, the effects of ozone and freeze-drying were not significant. However, a decrease of ~1 log-cycle was observed at the end of storage for the groups of microorganisms considered. Studies with undesirable target microorganisms are required to attain a safe product. Conclusion: Freeze-drying with an ozone pre-treatment can be considered a potential process to transform melon peel into an edible form. When the small cubes of melon rinds were freeze-dried, they became lighter and softer. They can be incorporated into different products (e.g., cakes, breads, yogurts), enriching their nutritional profile and creating a value-added food ingredient.
- Microwave and ultrasound pre-treatments for ‘Rocha’ Pear: impact on drying kinetics and selected quality attributesPublication . Onal, Begum; Adiletta, Giuseppina; Di Matteo, Marisa; Russo, Paola; Ramos, Inês Nunes; Silva, CristinaRocha’pear (Pyruscommunis L.) is the main cultivar produced in Portugal, and is classified as protected designation of origin (PDO).This pear fruit is characterized by its own typical and specific properties, such as pleasant flavor, crispness and also sweetness.Pears are rich in polyphenols with strong antioxidant activity,offering health promoting benefits. In order to extend its shelf life and increase availability along the year, drying processes are widely applied as a good alternative method for fruits preservation. Drying is used to improve food stability, decrease moisture content and microbial activity, and minimize physico-chemical changes during storage. However, drying process conditions (i.e. air temperature, time, and velocity) usually may lead to food quality degradation in terms of physico-chemical and nutritional attributes. In this context, drying combined with pre-treatments have been proposed in order to reduce the drying impact on products quality. The objective of this work was to evaluate the use of microwave and ultrasound pre-treatments on ‘Rocha’ pear drying kinetics and quality attributes (water activity, color, shrinkage, total phenolics, antioxidant activity, and texture and rehydration behavior of dried slabs).Three different samples were compared: a) Control, b) Microwave Pre-treatment (1540 MW, 4 min) (MW), and c) Ultrasound Pre-treatment (35 kHz, 10 min, 25°C) (US). Drying experiments were conducted on pear slabs (thickness and diameter of 6 and 38 mm, respectively) in a tray dryer with an air temperature of 60°C and a fixed velocity of 0.75 m/s. Pear samples pre-treated with MW had shorter drying time than control and ultrasound treated ones.Pear samples pre-treated with US showed the lowest colour changes and shrinkage, higher total phenolics and antioxidant activity, the highest rehydration capacity, and similar drying time to the control. This study contributes with information for the development of new drying pre-treatment conditions of ‘Rocha” pear fruits, as an alternative to traditional drying in an industrial context.
- Microwave and ultrasound pre-treatments for drying of the “Rocha” Pear: impact on phytochemical parameters, color changes and drying kineticsPublication . Onal, Begum; Adiletta, Giuseppina; Matteo, Marisa Di; Russo, Paola; Ramos, Inês Nunes; Silva, CristinaThe objective of this research was to evaluate the effect of drying temperature and innovative pre-treatments (i.e., microwave and ultrasound) on “Rocha” pear drying behavior and quality characteristics, such as color, total phenolic content and antioxidant activity. Experiments were carried out with pear slabs subjected to microwaves (2450 MHz, 539 W, 4 min, microwave oven) and ultrasounds (35 kHz, 10 min, in an ultrasonic bath) as well as control samples. The drying process was conducted in a tray dryer at three different temperatures (50, 55 and 60 °C) and a fixed air velocity of 0.75 m/s. Microwave technology resulted in a higher quality deterioration in dried pear samples compared to those of controls and ultrasound pre-treated samples. The combined application of ultrasound pre-treatment and the higher drying temperature of 60 °C was characterized by the lowest color changes (ΔE = 3.86 ± 0.23) and higher preservation of nutritional parameters (total phenolic content, TPC = 345.60 ± 8.99; and antioxidant activity, EC50 = 8.80 ± 0.34). The drying characteristics of pear fruits were also analyzed by taking into account empirical models, with the Page model presenting the best prediction of the drying behavior. In conclusion, ultrasound application is a promising technology to obtain healthy/nutritious dried “Rocha” pear snacks as dietary sources for consumers.
- Preservation processes applied to kiwi peel as strategies to add value to fruit wastesPublication . Striglio, Federica; Miller, Fátima A.; Fundo, Joana Freitas; Silva, Cristina; Brandão, Teresa R.S.
- Prior experimental learning (APEL): a way to short-cut the University studies in technical degrees?Publication . Rosa, Marco Dalla; Costa, Rui; Silva, CristinaThis paper presents the activity carried out inside a work package (WP7) of the ISEKI_Food 3 Academic Network project (2008-2011) dedicated to the facilitation and promotion of Life Long Learning in higher education. In fact, recognition of prior learning is an essential tool to foster lifelong learning within the European Higher Education Area. Professionals could be more attracted to go back higher education if their competences would be adequately recognised as credits in the programmes they want to study and complete. Within the aims of the cited work package, recognition or accreditation of learning performed in non academic environment (“prior learning”) by means of the network partners was investigated. Owing to the presentation of the aim and objective of the topic, we present the results of a questionnaire set-up to be filled on-line by ISEKI_Food partners, in order to collect information around the consideration of prior experiences and /or learning activity, certificated when possible, are recognized by University to obtain ECTS in order to facilitate the student’s curriculum. Maximum of credits to be recognized, disciplines more frequently subjected to this procedure of recognition, type of agreement between university and other institutions (secondary schools, training agencies, etc,), prior experience/learning, are all items covered by the survey. Many of the partners participating in the survey and/or attending the meetings where the prior experiential learning was explained showed interest in reporting their own experience whose results are changing from country to country.