F. Xavier Malcata

Universidade Católica Portuguesa, Lisboa, Lisbon, Portugal

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Publications (518)912.25 Total impact

  • E. Jerónimo · F.X. Malcata
    [Show abstract] [Hide abstract] ABSTRACT: Cheese constitutes an important source of essential nutrients and health-promoting compounds in human diet, including proteins, amino acids, bioactive peptides, fatty acids, minerals, vitamins, and polyphenolic compounds. Cheese nutritional value depends on the milk characteristics and the cheesemaking conditions, determining unique and distinct nutritional properties for each cheese type. Although cheese shows some nutritional properties that are regarded as being negative to human health, such as an increase in the cardiovascular disease risk, cheese intake seems to not exert detrimental effect on cardiovascular health. Cheese has been associated with several beneficial health properties – antihypertensive, anticarcinogenic, anticariogenic, and antiosteoporotic effects.
    No preview · Article · Dec 2016
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    [Show abstract] [Hide abstract] ABSTRACT: Bovine α-lactalbumin (α-La) and lysozyme (Lys), two globular proteins with highly homologous tertiary structures and opposite isoelectric points, were used to produce bio-based supramolecular structures under various pH values (3, 7 and 11), temperatures (25, 50 and 75 ºC) and times (15, 25 and 35 min) of heating. Isothermal titration calorimetry experiments showed protein interactions and demonstrated that structures were obtained from the mixture of α-La/Lys in molar ratio of 0.546. Structures were characterized in terms of morphology by transmission electron microscopy (TEM) and dynamic light scattering (DLS), conformational structure by circular dichroism and intrinsic fluorescence spectroscopy and stability by DLS. Results have shown that protein conformational structure and intermolecular interactions are controlled by the physicochemical conditions applied. The increase of heating temperature led to a significant decrease in size and polydispersity (PDI) of α-La–Lys supramolecular structures, while the increase of heating time, particularly at temperatures above 50 ºC, promoted a significant increase in size and PDI. At pH 7 supramolecular structures were obtained at microscale – confirmed by optical microscopy – displaying also a high PDI (i.e. > 0.4). The minimum size and PDI (61±2.3 nm and 0.14±0.03, respectively) were produced at pH 11 for a heating treatment of 75 ºC for 15 min, thus suggesting that these conditions could be considered as critical for supramolecular structure formation. Its size and morphology were confirmed by TEM showing a well-defined spherical form. Structures at these conditions showed to be stable at least for 30 or 90 days, when stored at 25 or 4 ºC, respectively. Hence, α-La–Lys supramolecular structures showed properties that indicate that they are a promising delivery system for food and pharmaceutical applications.
    Full-text · Article · Jul 2016 · Food Hydrocolloids
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    [Show abstract] [Hide abstract] ABSTRACT: β-Lactoglobulin (β-Lg) is the major protein fraction of bovine whey serum and a primary gelling agent. β-Lg has a high nutritional value, is stable at low pH being highly resistant to proteolytic degradation in the stomach, besides, it has the ability of acting as an encapsulating agent. This study aims at assessing the ability of β-Lg nanostructures to associate a nutraceutical - i.e. riboflavin - and release it in a controlled manner throughout an in vitro gastrointestinal (GI) system. For this reason β-Lg nanostructures loaded with riboflavin were critically characterized in terms of their morphology (i.e. size, polydispersity, ζ-potential and shape) by dynamic light scattering (DLS) and transmission electron microscopy (TEM), and efficiency to associate to riboflavin through spectrofluorimetry. Furthermore, these nanocomplexes were evaluated in an in vitro GI model, simulating the physiological conditions. Stable β-Lg nanostructures were obtained at pH 6, of spherical shape, characterized by particle size of 172±1 nm, low polydispersity (i.e. PDI of 0.06±0.02), ζ-potential of -32±3 mV and association efficiency (AE) of 26±1 %. β-Lg nanostructures showed to be stable upon their passage throughout stomach (i.e. particle size, PDI and ζ potential of 248±10 nm, 0.18±0.03 and 18±3 mV, respectively). Concerning their passage throughout the intestine, such nanostructures were mostly degraded in the duodenum. Regarding riboflavin, a release of about 11 % was observed after their passage through stomach, while 35 %, 38 % and 5 % were the released percentages of the total riboflavin associated observed after passage through duodenum, jejunum and ileum, respectively. Hence, β-Lg nanostructures showed to be suitable carriers for riboflavin until the intestine, where their degradation occurs. β-Lg also showed to be structurally stable, under food simulant conditions (yoghurt simulant, composed of 3 % acetic acid), over 14 days, with a protective effect upon riboflavin activity, releasing it in a 7 day period.
    Full-text · Article · Feb 2016 · Food Hydrocolloids
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    João M. Rocha · F. Xavier Malcata
    [Show abstract] [Hide abstract] ABSTRACT: Besides water, maize and rye flour are the main constituents of broa - a unique sourdough bread, manufactured following traditional protocols at the farm level in Portugal. Mother-dough, i.e., a piece of leavened dough kept aside from batch to batch under refrigeration conditions, constitutes the only starter culture used throughout breadmaking. Maize and rye flour, as well as mother-dough, were accordingly assayed for their microbiological profiles throughout storage time, to characterize the evolution in viability of the adventitious microorganisms: total viable counts, as well as viable yeasts, molds, gram-negative rods, gram-positive rods (endospore-forming and nonsporing) and gram-positive cocci (catalase+ and catalase-). In general, all microbial groups exhibited an outstanding resistance to storage, so use of mother-dough appears technologically effective in this form of breadmaking, and an appropriate storage of flour does not convey any important changes to their microbiological profile.
    Full-text · Article · Jan 2016 · Journal of Food Quality
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    A. Catarina Guedes · Isabel Sousa-Pinto · F. Xavier Malcata
    [Show abstract] [Hide abstract] ABSTRACT: Fisheries are the most important sources of feedstock for fishmeal. Only a small percentage of global fish production is indeed channeled to human consumption, with the remainder being used for fish and animal feed. Fishmeal is a protein-rich food, and sets the basis for any balanced formulation used in commercial aquaculture. For several reasons there is a definite need for a new source of nutritious fish food. Therefore, the potential use of unconventional feed ingredients, such as microalgae, as feed inputs to replace high cost feed stuffs has been increasing. Microalgae are a more reliable and less volatile source of protein, and their availability is not dependent on fish captures. This provides industry with a better control of their costs, and supports a potential for future investment due to the reduction of risk in aquaculture farming operations.
    Full-text · Chapter · Dec 2015
  • Alirio Rodrigues · F. Xavier Malcata · A. Alves
    No preview · Article · Dec 2015 · Biochemical Engineering Journal
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    [Show abstract] [Hide abstract] ABSTRACT: The development of bio-based nanostructures as nanocarriers of bioactive compounds to specific body sites has been presented as a hot topic in food, pharmaceutical and nanotechnology fields. Food and pharmaceutical industries seek to explore the huge potential of these nanostructures, once they can be entirely composed of biocompatible and non-toxic materials. At the same time, they allow the incorporation of lipophilic and hydrophilic bioactive compounds protecting them against degradation, maintaining its active and functional performance. Nevertheless, the physicochemical properties of such structures (e.g., size and charge) could change significantly their behavior in the gastrointestinal (GI) tract. The main challenges in the development of these nanostructures are the proper characterization and understanding of the processes occurring at their surface, when in contact with living systems. This is crucial to understand their delivery and absorption behavior as well as to recognize potential toxicological effects. This review will provide an insight into the recent innovations and challenges in the field of delivery via GI tract using bio-based nanostructures. Also, an overview of the approaches followed to ensure an effective deliver (e.g., avoiding physiological barriers) and to enhance stability and absorptive intestinal uptake of bioactive compounds will be provided. Information about nanostructures’ potential toxicity and a concise description of the in vitro and in vivo toxicity studies will also be given.
    Full-text · Article · Dec 2015 · Food Engineering Reviews
  • [Show abstract] [Hide abstract] ABSTRACT: Formation of whey protein isolate protein aggregates under the influence of moderate electric fields upon ohmic heating (OH) has been monitored through evaluation of molecular protein unfolding, loss of its solubility, and aggregation. To shed more light on the microstructure of the protein aggregates produced by OH, samples were assayed by transmission electron microscopy (TEM). Results show that during early steps of an OH thermal treatment, aggregation of whey proteins can be reduced with a concomitant reduction of the heating charge—by reducing the come-up time (CUT) needed to reach a target temperature—and increase of the electric field applied (from 6 to 12 V cm−1). Exposure of reactive free thiol groups involved in molecular unfolding of β-lactoglobulin (β-lg) can be reduced from 10 to 20 %, when a CUT of 10 s is combined with an electric field of 12 V cm−1. Kinetic and multivariate analysis evidenced that the presence of an electric field during heating contributes to a change in the amplitude of aggregation, as well as in the shape of the produced aggregates. TEM discloses the appearance of small fibrillar aggregates upon the influence of OH, which have recognized potential in the functionalization of food protein networks. This study demonstrated that OH technology can be used to tailor denaturation and aggregation behavior of whey proteins due to the presence of a constant electric field together with the ability to provide a very fast heating, thus overcoming heat transfer limitations that naturally occur during conventional thermal treatments.
    No preview · Article · Nov 2015 · Food and Bioprocess Technology
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    [Show abstract] [Hide abstract] ABSTRACT: Microalgae are well known for their biotechnological potential, namely with regard to bioactive lipidic components-especially carotenoids and polyunsaturated fatty acids (PUFA), well-known for therapeutic applications based on their antioxidant capacity. The aim of this work was to evaluate the influence of four distinct food-grade solvents upon extractability of specific lipidic components, and on the antioxidant capacity exhibited against both synthetic (2,2-diphenyl-1-picrylhydrazyl (DPPH(•)) and 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid (ABTS(+•))) and biological reactive species (O₂(•)⁻ and (•)NO⁻). A eukaryotic microalga (Scenedesmus obliquus (M2-1)) and a prokaryotic one (Gloeothece sp.) were used as case studies. Concerning total antioxidant capacity, the hexane:isopropanol (3:2) and acetone extracts of Sc. obliquus (M2-1) were the most effective against DPPH(•) and ABTS(+•), respectively. Gloeothece sp. ethanol extracts were the most interesting scavengers of O₂(•)⁻, probably due the high content of linolenic acid. On the other hand, acetone and hexane:isopropanol (3:2) extracts were the most interesting ones in (•)NO⁻ assay. Acetone extract exhibited the best results for the ABTS assay, likely associated to its content of carotenoids, in both microalgae. Otherwise, ethanol stood out in PUFA extraction. Therefore, profiles of lipidic components extracted are critical for evaluating the antioxidant performance-which appears to hinge, in particular, on the balance between carotenoids and PUFAs.
    Full-text · Article · Oct 2015 · Marine Drugs
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    Full-text · Dataset · Sep 2015
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    Full-text · Dataset · Sep 2015
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    Full-text · Dataset · Sep 2015
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    Full-text · Dataset · Sep 2015
  • [Show abstract] [Hide abstract] ABSTRACT: In recent years, microalgae-based carbon-neutral biofuels (i.e., biodiesel) have gained considerable interest due to high growth rate and higher lipid productivity of microalgae during the whole year, delivering continuous biomass production as compared to vegetable-based feedstocks. Therefore, biodiesel was synthesized from three different microalgal species, namely Tetraselmis sp. (Chlorophyta) and Nannochloropsis oculata and Phaeodactylum tricornutum (Heterokontophyta), and the fuel properties of the biodiesel were analytically determined, unlike most studies which rely on estimates based on the lipid profile of the microalgae. These include density, kinematic viscosity, total and free glycerol, and high heating value (HHV), while cetane number (CN) and cold filter plugging point (CFPP) were estimated based on the fatty acid methyl ester profile of the biodiesel samples instead of the lipid profile of the microalgae. Most biodiesel properties abide by the ASTM D6751 and the EN 14214 specifications, although none of the biodiesel samples met the minimum CN or the maximum content of polyunsaturated fatty acids with ≥4 double bonds as required by the EN 14214 reference value. On the other hand, bomb calorimetric experiments revealed that the heat of combustion of all samples was on the upper limit expected for biodiesel fuels, actually being close to that of petrodiesel. Post-production processing may overcome the aforementioned limitations, enabling the production of biodiesel with high HHV obtained from lipids present in these microalgae
    No preview · Article · Aug 2015 · Journal of Applied Phycology
  • [Show abstract] [Hide abstract] ABSTRACT: The increasing market of probiotics from plant matrices justifies the interest on fermented olives – not only for their nutritional properties, but also because they contain health-promoting phytochemicals (such as phenolic compounds) that exhibit antibacterial, antiproliferative, anticarcinogenic and anti-inflammatory properties. Additionally, olives have proven a good source and carrier of Lactobacillus strains with probiotic characteristics. However, studies focusing on the combined effect of phenolic compounds with wild probiotic bacteria have not been yet carried out. Hence, the aim of this work was to set up the combination of native olive phenolic compounds, e.g. oleuropein and hydroxytyrosol, on the recommended levels for a daily dose of olives containing probiotic bacteria – and their effect on the attachment ability and action against pathogens in situ. Tests on the health benefits of these compounds, viability and adhesion capacity of probiotic bacteria, and consequent biofilm formation, composition and relationship with adhesivity on Caco-2 model were performed.
    No preview · Article · Jul 2015 · Food Science and Technology
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    [Show abstract] [Hide abstract] ABSTRACT: Whey proteins are widely used as nutritional and functional ingredients in formulated foods because they are relative inexpensive, generally recognized as safe (GRAS) ingredient and possess important biological, physical and chemical functionalities. Denaturation and aggregation behavior of these proteins is of particular relevance toward manufacture of novel nanostructures with a number of potential uses. When these processes are properly engineered and controlled, whey proteins may be formed into nanohydrogels, nanofibrils or nanotubes and be used as carrier of bioactive compounds. This review intends to discuss the latest understandings of nanoscale phenomena of whey protein denaturation and aggregation that may contribute for the design of protein nanostructures. Whey protein aggregation and gelation pathways under different processing and environmental conditions such as microwave heating, high voltage and moderate electrical fields, high pressure, temperature, pH and ionic strength were critically assessed. Moreover, several potential applications of nanohydrogels, nanofibrils and nanotubes for controlled release of nutraceutical compounds (e.g. probiotics, vitamins, antioxidants and peptides) were also included. Controlling the size of protein networks at nanoscale through application of different processing and environmental conditions can open perspectives for development of nanostructures with new or improved functionalities for incorporation and release of nutraceuticals in food matrices.
    Full-text · Article · Jun 2015 · Critical reviews in food science and nutrition
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    [Show abstract] [Hide abstract] ABSTRACT: Use of probiotic bacteria and consumes in large - in novel foods to provide beneficial health effects has attracted an increasing interest by the food industry and fermented olives are an excellent example of a new generation of those foods from plant origin so as to assure maximum viability by the time of ingestion during processing and storage of food products, as well as during transit through the gastrointestinal tract.Our study focused on production, characterization and assessment of efficacy of microencapsulation upon survival of probiotic strains and sensory properties of the final olive paste throughout refrigerated storage. Microencapsulation appears to be an effective technique for strain survival, depending on the operating temperature and experimental results on tolerance to gastrointestinal-like conditions, and ability to adhere to intestinal epithelium is thereby presented and discussed. The sensory panel rated all experienced matrices as good, including overall acceptance without significant preference between them. However, the success of microencapsulation was more limited when incorporated into olive paste. Free cells of Lactobacillus plantarum 33 proved able to survive in olive paste during storage at refrigerated temperatures.
    Full-text · Article · May 2015 · Food Research International
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    Mohamed Abdel Hamid Rabie · Ali A. Abdel Galeel · Francisco Xavier Malcata
    [Show abstract] [Hide abstract] ABSTRACT: Edam-type curd slurry inoculated with 1% Lactococcus lactis subsp. lactis KF147 as control and further added with Propionibacterium shermanii PS-4 + Bifidobacterium bifidum DSM 20082 (1:1), P. shermanii PS-4 + Lactobacillus acidophilus ATCC4356 or P. shermanii PS-4 + B. bifidum DSM 20082 + Lactobacillus acidophilus ATCC4356 (1:1:1), at a rate of 1%, were studied for their effect upon biogenic amine and proteolysis pattern during incubation at 30C for 21 days. Results showed no significant influence of any combination of probiotic microorganisms on total solids, salt and fat of Edam-type curd slurries, but some effect on pH and soluble nitrogen fractions; presence of P. shermanii + B. bifidum + Lactobacillus acidophilus led to the highest concentration (7.9%) of water-soluble nitrogen by the end of incubation. When inoculation included B. bifidum, a significant decrease in total biogenic amines (from 447 to 37 mg/kgDW) was observed by 21 days – with histamine decreasing from 84 to 25 and tyramine from 359 to 6 mg/kgDW.Practical ApplicationsThis study was aimed at investigating proteolysis and biogenic amine formation by selected probiotic bacteria added to Edam-type curd slurry. The nitrogen fractions and biogenic amines in control increased significantly throughout incubation at 30C. Inocula of P. shermanii + L. acidophilus + B. bifidum (1:1:1) could effectively reduce biogenic amine contents, especially histamine and tyramine. This observation has potential public health impact because regular curds are often above the maximum legal threshold in regions with warm weather and poor cold storage network. Furthermore, addition of probiotic L. acidophilus and B. bifidum improved the overall flavor profile, owing to extra soluble nitrogen produced.
    Full-text · Article · Apr 2015 · Journal of Food Processing and Preservation
  • [Show abstract] [Hide abstract] ABSTRACT: Yacon [Smallanthus sonchifolius (Poepp. and Endl.) H. Robinson; Asteraceae] roots have been shown to be a source of prebiotic compounds. However, there are no known studies concerning processed yacon roots. The objective of this study was to investigate the potential prebiotic activity of yacon tuber flour. For this purpose, an aqueous extract was tested for selection of yacon incorporation and sterilization method and selection of the most favourable concentration to be tested for prebiotic activity. Once these conditions were identified, the potential prebiotic activity of the yacon extract was evaluated by determination of viable cell numbers and metabolic activity against four probiotic strains, namely, Enterococcus faecium 32, Bifidobacterium animalis Bo, Lactobacillus acidophilus Ki and Lactobacillus casei L26). Results showed that the best incorporation and sterilization method was to autoclave the supernatant, resultant from the yacon tuber flour suspension, at 121 °C for 20 min and add it to sterilized basal medium. For the confirmation of potential prebiotic activity, de Man-Rogosa-Sharpe (MRS) medium without a conventional carbon source (negative control), with 2% (w/v) glucose per se (positive control) and associated with 1% (w/v) yacon tuber flour were chosen. Yacon tuber flour revealed a potential prebiotic activity upon the growth of the probiotic strains tested, probably due to its fructooligosaccharides (FOS) content.
    No preview · Article · Apr 2015 · Food and Bioproducts Processing
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    [Show abstract] [Hide abstract] ABSTRACT: The objective of this research work was to investigate the antioxidant properties of sterilized yacon tuber flour. The results revealed for the first time the high antioxidant activity of sterilized yacon flour. The best extract obtained by boiling 8.9% (w/v) of yacon flour in deionised water for 10min exhibited a total antioxidant capacity of 222±2mg (ascorbic acid equivalent)/100g DW and a total polyphenol content of 275±3mg (gallic acid equivalent)/100g DW associated to the presence of four main phenolic compounds: chlorogenic acid, caffeic acid, coumaric acid and protocatechuic acid, as well as the amino acid tryptophan. The most abundant was chlorogenic acid, followed by caffeic acid. Biological assays revealed that the extract had indeed antioxidant protection, and no pro-oxidant activity. In conclusion, sterilized yacon tuber flour has the potential to be used in the food industry as a food ingredient to produce functional food products. Copyright © 2015. Published by Elsevier Ltd.
    Full-text · Article · Apr 2015 · Food Chemistry

Publication Stats

11k Citations
912.25 Total Impact Points

Institutions

  • 1988-2015
    • Universidade Católica Portuguesa
      • • Escola Superior de Biotecnologia
      • • Centro de Biotecnologia e Química Fina
      Lisboa, Lisbon, Portugal
  • 2012-2014
    • University of Porto
      • Laboratory for Process, Environmental and Energy Engineering
      Oporto, Porto, Portugal
  • 2011-2013
    • University of Aveiro
      • CICECO - Centre for Research in Ceramics and Composite Materials
      Aveiro, Aveiro, Portugal
    • New University of Lisbon
      • Institute of Chemical and Biological Technology (ITQB)
      Lisboa, Lisbon, Portugal
    • Elsevier B.V.
      Philadelphia, Pennsylvania, United States
  • 2010-2012
    • Instituto Superior da Maia
      Oporto, Porto, Portugal
  • 2010-2011
    • Centro de Biotecnologia Agricola e Agro-Alimental do Alentejo
      Beja, Beja, Portugal
  • 2006
    • Escola Superior Artística do Porto
      Oporto, Porto, Portugal
  • 1991-1992
    • University of Wisconsin–Madison
      • Department of Chemical and Biological Engineering
      Madison, Wisconsin, United States