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Projeto de investigação
Forest Research Centre
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O montado e a cortiça. Livro de Resumos
Publication . Paulo, Joana Amaral; Pereira, Helena; Oliveira, Vanda
Paddy rice stored under hermetic conditions: The effect of relative humidity, temperature and storage time in suppressing Sitophilus zeamais and impact on rice quality
Publication . Carvalho, Maria Otilia; Fradinho, Patrícia; Martins, M.João; Magro, Ana; Raymundo, Anabela; Sousa, Isabel
The aim of this study was to analyse the effect of relative humidity in suppressing Sitophilus zeamais, in
paddy rice stored under hermetic conditions, during four and seven months, at different average temperatures,
as well as the impact on rice quality.
Hermetic bags, GrainPro® SuperGrainbag® Farm™, were used to store two rice varieties under three
different relative humidities: 67%, 75% and 85% RH, and average temperatures of 14 C, 17 C and 24 C,
both monitored by Hobo® Data loggers, with the probe placed inside the bags. CheckpointII Portable O2
and CO2 Gas Analyzer was used to assess gas contents on the top and bottom of each bag. At the end of
the trials, paddy samples were collected to estimate water activity (aw). The rheology behaviour of rice
pastes prepared with race flour obtained from the different treatments was also evaluated, using a
controlled stress rheometer.
The results showed that the response of the stored-product insects changes with environmental
conditions, O2 and CO2 contents. Other parameters were considered; aw increased with relative humidity
and temperature, but decreased with storage time. The relative humidity played an important role,
together with the increase of temperature, in suppressing insect populations. A modified atmosphere
was naturally produced inside the hermetic bag, under 85% RH, with low O2 and high CO2 contents, at
different average temperatures, 14 C and 17 C. These results demonstrated that S. zeamais can survive,
but has no progeny. Under the same conditions, but at the higher average temperature of 24 C,
S. zeamais attained 100% mortality before producing progeny.
The increase on respiration rate, registered by CO2 increase and O2 decrease, for higher RH values,
reduced the viscoelastic functions and changed the starch gelatinization point of Indica and Japonica rice.
The results obtained showed that storing paddy hermetically, at low relative humidity, did not change
atmospheric content and maintained the viscoelastic functions of the rice pastes
Translating the agricultural N surplus hazard into groundwater pollution risk: Implications for effectiveness of mitigation measures in nitrate vulnerable zones
Publication . Cameira, Maria; Rolim, João; Valente, Fernanda; Mesquita, Marta; Dragosits, Ulrike; Cordovil, Cláudia
In the Nitrate Vulnerable Zones farmers are required to implement measures to reduce the nitrogen (N) surplus.
Nevertheless, in some cases the status of the water bodies show that the effect of these measures remains
insufficient despite the global decrease in N surpluses. The present work aims to contribute with a method that
produces an appropriate indicator for the N mitigation measures effectiveness for reducing groundwater nitrate
pollution. The Global Risk Index (GRI) results from overlaying the agricultural N surplus hazard and aquifer
vulnerability. It includes both irrigation activity and precipitation contribution to water recharge calculated at
the municipality level. It integrates a range of regional datasets combined with monitored nitrate (NO3 ) concentrations
in groundwater under a GIS framework. Results show that the pollution status of the Tagus
Vulnerable Zone (TVZ) aquifers has been aggravating in spite of the overall reduction in the N surpluses that
resulted from the implementation of the Nitrates Directive measures. Twelve years after the TVZ designation, the
GRI indicates high and moderate NO3- pollution risk, respectively in 33 % and 66 % of the territory. Scenario
analysis indicates the potential of targeted measures for ending high risk areas and reducing moderate risk areas
to 13 %. This supports that N mitigation measures must be reformulated and spatially targeted according to site
specific hazards and vulnerabilities
Chemical characterization of lignocellulosic materials by analytical pyrolysis
Publication . Lourenço, Ana; Gominho, Jorge; Pereira, Helena
Analytical pyrolysis is used to chemically study complex molecular materials
and is applied in a wide range of fields. Pyrolysis is a thermochemical process
associated to the breaking of chemical bonds using thermal energy, transforming
a nonvolatile compound into a volatile degradation mixture. This chapter
refers to analytical pyrolysis of lignocellulosic materials, i.e., when pyrolysis is
used for chemical characterization, applied to samples with small particle sizes,
at 500–650°C, and with short residence times. The reactions that occur during
pyrolysis of the structural components are discussed regarding the mechanisms
and the pyrolysis products obtained from cellulose, hemicelluloses, and lignin.
A compilation of data is made on the characterization of lignocellulosic materials
using Py-GC/FID(MS) or Py-GC/MS as analytical tools including woods and
barks of several species. The pyrogram profiles and important parameters on lignin
chemical composition such as the H:G:S relation and the S/G ratio are summarized.
Analytical pyrolysis is a versatile methodology that may be applied to characterize
the lignin directly on the lignocellulosic material or after isolation from the cell wall
matrix (e.g., as MWL or dioxane lignin) or from pulps or spent liquors. It is therefore
an excellent tool to study lignin compositional variability in different materials
and along various processing pathways.
Compositional variability of lignin in biomass
Publication . Lourenço, Ana; Pereira, Helena
The objective of this chapter is to provide a concise overview of lignin composition and
structure in different species and materials (wood, barks and nonwood plants). It includes
a brief review on the lignin precursors and their polymerization as well as of the analytical
tools used for lignin characterization from wet chemical to spectroscopic methods. Wood
of gymnosperms is characterized by high lignin content (25–35%) and a HG-type of lignin
with more guaiacyl (G) units and a small portion of p-hydroxyphenyl (H) units. Wood of
angiosperms has a lignin content of 15–28%, with a GS-lignin having different proportions
of syringyl (S) units. Nonwoody monocotyledon species have different lignin content
(9–20%) and a HGS type of lignin, characterized by a high proportion of H units. Bark
lignin content ranges from 13 to 43% and is of HGS-type with species-specific composition
and different in the bark components, phloem and cork. Lignin composition and macromolecular
structure are key issues to understand the properties of lignocellulosic materials
and to design a lignin-based pathway within biomass biorefineries. The available information
on lignin composition is still limited to a few species and plant components. This is
certainly an area where more research is needed.
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Entidade financiadora
Fundação para a Ciência e a Tecnologia
Programa de financiamento
6817 - DCRRNI ID
Número da atribuição
UID/AGR/00239/2013