93 research outputs found
Waterproof coatings for hydrophilic foods
[Excerpt] In the food industry, the incorporation of dry or poorly hydrated food components in hydrophilic food matrices has only been possible through the use of two-compartment packaging systems, designed to maintain the components separated until their consumption. The main purpose of this research is to provide a solution to this long-standing problem, through the development of hydrophobic coatings, allowing the incorporation of food components with low water activity (e.g. cereals) in hydrophilic foods. [...]info:eu-repo/semantics/publishedVersio
Multivariable approach on growth of microalgae
Despite the increasing interest in microalgal biomass and its high-value compounds, the number of products that successfully reach the market is still neglectable when compared to the high potential linked to these organisms. High production costs and low productivity both in terms of biomass and metabolites associated with microalgae growth are some of the causes hindering their widespread use and commercialization. The use of high-density cell cultures, for instance, is a strategy that arises as a potential solution to overcome these challenges. However, the optimization of growth parameters individually, may not be suitable since it does not take into account the interactions and synergies between different variables.
This work aims at optimizing the culture conditions of a heterotrophic Chlorella vulgaris sp. in order to enhance both biomass concentration. For that purpose, a multivariable approach was developed envisaging the optimization of 24 independent variables simultaneously through Design of Experiment tools using the Protimiza Experimental Design software. The composition (i.e., concentration of 20 macro- and micronutrients, including the organic carbon source) and pH of the culture medium, starting inoculum, agitation, and temperature were the parameters studied.
The variation of culture conditions allowed obtaining significant differences on growth kinetics. Biomass concentration ranged between 0.2 and 18.7 g.L-1, while biomass productivity presented a 52-fold variation when considering its minimum and maximum values. Besides the impact of different conditions on C. vulgaris growth, these trials also enabled to determine which variables played a statistically significant role on both biomass concentration and productivity, with a confidence level of 95 %. The concentration of the sources of nitrogen, organic carbon and magnesium have shown a significant impact over biomass concentration, being the source of nitrogen the most relevant parameter. On the other hand, the concentration of the sources of nitrogen and magnesium, as well as the pH of the culture medium, proved to be determinant to biomass productivity. However, in this case, the pH was found to have the dominant effect.This study was supported by the Portuguese Foundation for Science and Technology (FCT) under the scope of the strategic funding of UIDB/04469/2020 unit. This work is funded by ERDF Funds through the Competitiveness factors Operational program – COMPETE and by National Funds through the FCT - Foundation for Science and Technology under the project AgriFood XXI (NORTE- 01-0145-FEDER-000041). This research work was supported by ALGAVALOR - Lisboa 01-0247-FEDER-035234, supported by Operational Programme for Competitiveness and Internationalization (COMPETE2020), by Lisbon Portugal Regional Operational Programme (Lisboa 2020) and by Algarve Regional Operational
Programme (Algarve 2020) under the Portugal 2020 Partnership Agreement, through the European Regional Development Fund (ERDF). Filipe Maciel and Leandro Madureira acknowledge the Foundation for Science and Technology (FCT) for their fellowships (SFRH/BD/133005/2017 and SFRH/BD/151474/2021, respectively).info:eu-repo/semantics/publishedVersio
Multivariable optimization process of heterotrophic growth of Chlorella vulgaris
Microalgae have received increasing attention as one of the most promising feedstocks in the development of new healthier food products and different strategies have been attempted to improve their growth. However, the high production costs and low productivities, commonly associated with photoautotrophic growths, are still a big challenge. In this study, a two-step optimization strategy was carried out in order to maximize the biomass production of a Chlorella vulgaris strain used at industrial scale under heterotrophic conditions. From a total of 24 independent variables, which were studied simultaneously, 10 have presented a positive effect over Xmax, while the remaining have shown to be negative. The amount of (NH4)2SO4 (6.3 g L1), MgSO4·7H2O (0.7 g L1), and C6H12O6 (50% w/v) in the culture medium has revealed to be the only factors with a significant impact on biomass concentration, with optimum values of 25.5, 64.6, and 75 ml.L1, respectively. The optimized medium resulted in an improvement of the Xmax by 99.6% when compared to the growth medium applied at industrial scale, proving the success of this strategy. Additionally, the carbohydrates production was enhanced by 48.0%.This study was supported by the Portuguese Foundation for Science and Technology (FCT) under the scope of the strategic funding of UIDB/04469/2020 unit and by LABBELS – Associate Laboratory in Biotechnology, Bioengineering and Microelectromechanical Systems, LA/P/0029/2020. This work was funded by NORTE2020 Funds through the SUPPORT SYSTEM FOR SCIENTIFIC AND TECHNOLOGICAL RESEARCH - "STRUCTURED R & D & I PROJECTS" - HORIZON EUROPE under the project NORTE-01-0145-FEDER-000070. This research work was supported by ALGAVALOR - Lisboa-01-0247-FEDER-035234, supported by Operational Programme for Competitiveness and Internationalization (COMPETE2020), by Lisbon Portugal Regional Operational Programme (Lisboa 2020) and by Algarve Regional Operational Programme (Algarve 2020) under the Portugal 2020 Partnership Agreement, through the European Regional Development Fund (ERDF). Filipe Maciel and Leandro Madureira acknowledge the FCT for their fellowships (SFRH/BD/133005/2017 and SFRH/BD/151474/2021, respectively).info:eu-repo/semantics/publishedVersio
Hybrid gels: influence of water and oil phase on textural and rheological properties
The 19th Gums & Stabilisers for the Food Industry Conference: Hydrocolloid MultifunctionalityHybrid gels are biphasic systems formed by conjugating hydrogels and oleogels. The mixture
of water-based and oil-based gels provides distinct and unique characteristics to hybrid gels,
and based on the structurant molecules and mixture ratio used during their production,
different textural and rheological properties can be obtained. Hybrid gels remain a very
recent topic concerning pharmaceutical and food applications and despite recent studies on
the use of hybrid gels for controlled delivery of compounds (pharmaceutical applications)
these structures are still under-studied in regard to their food application possibilities [1, 2].
To improve knowledge and expanding ways to use these systems, it is important to
understand how these gels behave regarding textural and rheological properties. Also, the
knowledge on their micro and nanostructure allows tailoring their properties and thus
maximizing their applicability in foodstuffs. We report on how the combination of a beeswaxbased
oleogel and a sodium alginate-based hydrogel influences the gel structural properties
at macroscopic (rheological and textural), microscopic (optical microscopy) and molecular (Xray
diffraction) levels. Different ratios of both hydrogel and oleogel were used in order to
evaluate the hybrid gels’ behaviour in terms of morphological, textural, rheological and
polymorphic properties. Differences regarding oleogel particles distribution in the hydrogel
matrix were noticed with the increase of oleogel fraction. A more disarranged distribution of
oleogel particles was observable for the 50:50 ratios of hydrogel and oleogel. X-ray
diffraction data unveiled that once polycrystallinity is reached (in hybrid gels) these patterns
remain persistent for all tested ratios. Oleogel showed d-spacings in the range of 3.74 to 8.04
Ă…. Hybrid gel samples (and hydrogel control) are semi-crystalline, displaying spacings
ranging in intervals of d (001) 6.99 – 7.18 Å; d (002) 3.09 – 3.23 Å and d (003) 2.45 – 2.46 Å,
respectively. The samples with increasing oleogel ratio revealed a firmness decrease and a
consequent reduction of spreadability values. Consequently, is observed less adhesivity for
these samples, due to a more pronounced disaggregated structure. For all hybrid gels a gellike
behaviour (G´ > G´´) was observed. Results showed that it is possible to modify the
hybrid gels’ rheological and textural behaviour by a controlled mixture ratio of oleogels and
hydrogels. This opens the possibilities of food applications for this kind of systems.info:eu-repo/semantics/publishedVersio
Staphylococcus aureus Survives with a Minimal Peptidoglycan Synthesis Machine but Sacrifices Virulence and Antibiotic Resistance
Many important cellular processes are performed by molecular machines, composed of multiple proteins that physically interact to execute biological functions. An example is the bacterial peptidoglycan (PG) synthesis machine, responsible for the synthesis of the main component of the cell wall and the target of many contemporary antibiotics. One approach for the identification of essential components of a cellular machine involves the determination of its minimal protein composition. Staphylococcus aureus is a Gram-positive pathogen, renowned for its resistance to many commonly used antibiotics and prevalence in hospitals. Its genome encodes a low number of proteins with PG synthesis activity (9 proteins), when compared to other model organisms, and is therefore a good model for the study of a minimal PG synthesis machine. We deleted seven of the nine genes encoding PG synthesis enzymes from the S. aureus genome without affecting normal growth or cell morphology, generating a strain capable of PG biosynthesis catalyzed only by two penicillin-binding proteins, PBP1 and the bi-functional PBP2. However, multiple PBPs are important in clinically relevant environments, as bacteria with a minimal PG synthesis machinery became highly susceptible to cell wall-targeting antibiotics, host lytic enzymes and displayed impaired virulence in a Drosophila infection model which is dependent on the presence of specific peptidoglycan receptor proteins, namely PGRP-SA. The fact that S. aureus can grow and divide with only two active PG synthesizing enzymes shows that most of these enzymes are redundant in vitro and identifies the minimal PG synthesis machinery of S. aureus. However a complex molecular machine is important in environments other than in vitro growth as the expendable PG synthesis enzymes play an important role in the pathogenicity and antibiotic resistance of S. aureus
Global assessment of marine plastic exposure risk for oceanic birds
Plastic pollution is distributed patchily around the world’s oceans. Likewise, marine organisms that are vulnerable to plastic ingestion or entanglement have uneven distributions. Understanding where wildlife encounters plastic is crucial for targeting research and mitigation. Oceanic seabirds, particularly petrels, frequently ingest plastic, are highly threatened, and cover vast distances during foraging and migration. However, the spatial overlap between petrels and plastics is poorly understood. Here we combine marine plastic density estimates with individual movement data for 7137 birds of 77 petrel species to estimate relative exposure risk. We identify high exposure risk areas in the Mediterranean and Black seas, and the northeast Pacific, northwest Pacific, South Atlantic and southwest Indian oceans. Plastic exposure risk varies greatly among species and populations, and between breeding and non-breeding seasons. Exposure risk is disproportionately high for Threatened species. Outside the Mediterranean and Black seas, exposure risk is highest in the high seas and Exclusive Economic Zones (EEZs) of the USA, Japan, and the UK. Birds generally had higher plastic exposure risk outside the EEZ of the country where they breed. We identify conservation and research priorities, and highlight that international collaboration is key to addressing the impacts of marine plastic on wide-ranging species
The ABC130 barrel module prototyping programme for the ATLAS strip tracker
For the Phase-II Upgrade of the ATLAS Detector, its Inner Detector,
consisting of silicon pixel, silicon strip and transition radiation
sub-detectors, will be replaced with an all new 100 % silicon tracker, composed
of a pixel tracker at inner radii and a strip tracker at outer radii. The
future ATLAS strip tracker will include 11,000 silicon sensor modules in the
central region (barrel) and 7,000 modules in the forward region (end-caps),
which are foreseen to be constructed over a period of 3.5 years. The
construction of each module consists of a series of assembly and quality
control steps, which were engineered to be identical for all production sites.
In order to develop the tooling and procedures for assembly and testing of
these modules, two series of major prototyping programs were conducted: an
early program using readout chips designed using a 250 nm fabrication process
(ABCN-25) and a subsequent program using a follow-up chip set made using 130 nm
processing (ABC130 and HCC130 chips). This second generation of readout chips
was used for an extensive prototyping program that produced around 100
barrel-type modules and contributed significantly to the development of the
final module layout. This paper gives an overview of the components used in
ABC130 barrel modules, their assembly procedure and findings resulting from
their tests.Comment: 82 pages, 66 figure
Qual a direção da convergência na produtividade da mão de obra na agropecuária de Minas Gerais?
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