Articles publicats (Química, Física i Ciències Ambientals i del Sòl)

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    Open Access
    Effects of roasting and steeping on nutrients and physiochemical compounds in organically grown naked barley teas
    (Elsevier, 2024) Martínez Subirà, Mariona; Meints, Brigid; Tomasino, Elizabeth; Hayes, Patrick
    Barley tea, a popular beverage with cultural traditions in East Asia, has long been esteemed for its flavor, aroma, thirst-quenching properties and perceived health benefits attributed to bioactive compounds. This study investigated the nutritional, bioactive, and antioxidant aspects of three commercial naked barley varieties, focusing on the impact of roasting and subsequent steeping for tea. Roasting did not affect total dietary fiber or β-glucan content. The process reduced sugar content and led to the disappearance of free amino acids, contributing to high levels of acrylamide and color changes. Roasting diminished total phenolic compounds, particularly flavonoids, resulting in reduced antioxidant activity. Metabolite analysis identified compounds in roasted grains that could influence tea flavor and aroma. Roasted barley tea made from these varieties was not a source of dietary fiber or antioxidants, but also contained no acrylamide. Therefore, consumers seeking such benefits from barley are urged to consume whole grain foods.
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    Open Access
    Effects of long-term sewage sludge addition to a calcareous soil on soil organic C fractions and soil functions
    (Elsevier, 2024) Simões-Mota, A.; Barré, P.; Baudin, F.; Poch, Rosa M.; Bruni, E.; Anton, R.; Enrique, A.; Virto, I.
    Soil organic matter (SOM) is a recognized carbon reservoir and paramount in soil functioning and agrosystems productivity. Different management strategies have been established to enhance SOM in arable soils, and one is the application of exogenous organic matter (EOM). Despite significant efforts in recent years, the consequences of EOM addition on increasing soil organic C (SOC) storage and stability in different pedoclimatic contexts remain incompletely understood. In this study, we evaluated the effect of long-term (28 y) sewage sludge (SS) addition to a calcareous soil supporting rainfed extensive crops in a Mediterranean sub-humid area in terms of SOC stabilization and distribution among functional fractions. To that end, we studied total SOM storage and soil fractions in a long-term experiment comparing 4 different doses of SS with mineral fertilization and no-fertilization controls. We compared the concentration, storage and distribution of C using two different fractionation methods (particulate vs. mineral-associated, defined by granulodensimetric fractionation, and active C vs. stable C defined by Rock-Eval® thermal analysis coupled to the machine learning PARTYsoc v2.0 model) on the tilled layer (0–30 cm). Three soil functioning indicators (crops yield, soil microbial biomass C and aggregate stability) were also quantified. We found that SS application, which slightly increased SOC concentration when SS was added, resulted in a net SOC stock gain only with the highest dose used (80 tons/ha), compared to mineral fertilization, suggesting that most of the C added was mineralized. An uneven response of soil fractions was however detected. The coarsest heavy physical fractions > 250 μm and 50–250 μm in size were the most enriched in their C concentration with SS addition, whereas SOC was mostly accumulated as mineral-associated C in the silt-size (2–50 μm) and the 50–250 μm fractions. Regarding thermal fractionation, SS treatments showed C gains between 57 % and 35 % in the active C pool, compared to mineral fertilization. This can be explained considering that the accumulated SOM in mineral-associated fractions corresponded to mean-residence times in the order of 20–40 years. The consequences on soil functioning indicators were not directly related to the amount of SOC stored in the soil, as the highest SOC gains corresponded to the highest dose, but not the highest yields, and some negative correlations were observed between SOC fractions and soil structural stability and microbial biomass. This can be related to some deleterious effects of excessive SS application reducing yields, the soil biological activity and soil structure, and represents an example of the need to decouple the assessment of soil health from that of SOC storage for certain soil management practices. The overall evaluation of the net consequences of long-term SS application indicated that low doses (10 tons/ha) seem a better choice, as they resulted in the highest efficiency in C incorporation, and in a slightly greater increase in SOC concentration than intermediate doses, and equal yields than mineral fertilization, but did not have the negative effects observed in soil functioning with higher doses.
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    Open Access
    Sustainability assessment after twenty years of sewage sludge application on calcareous soil following N or P criterion
    (MDPI, 2024) Camps-Sague, Francesc; Lavaquiol Colell, Bernat; Bosch Serra, Àngela D.; Molina, Maria Gabriela; Domingo-Olive, Francesc
    Sewage sludge is a valuable source of nutrients when applied to the soil. Research on its agricultural use has been focused on chemical parameters to prevent heavy metal buildup. However, soil quality includes a wider spectrum of indicators. Our aim was to evaluate the impacts of sludge application on the biological and physical soil properties of calcareous soil when sludge is applied in maize monoculture using fertilization dosage criteria determined by N input or soil P thresholds. A control based on mineral fertilization was also included. After 20 years, no differences were found in the biological indicators: earthworm and soil oribatid mite abundances. Five oribatid species were identified, but three predominated: Acrotritia ardua americana, Oribatula (Zygoribatula) excavata and Tectocepheus sarekensis. The latter two showed a maximum number of individuals five months after maize stalks were buried in soil, independent of fertilization treatment. Sludge significantly increased water-stable aggregates (up to 30%), but there was no difference in macroporosity (apparent pore diameter > 30 μm). Under irrigated calcareous soil, sewage sludge applied as fertilizer is a sustainable option, independent of the threshold criterion (N or P) used. Nevertheless, as the P threshold criterion allows for reduced P inputs, it is more sustainable over the long term.
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    Open Access
    Biofortification for space farming: Maximising nutrients using lettuce as a model plant
    (Elsevier, 2024) Burgess, Alexandra J.; Pranggono, Raihannah; Escribà i Gelonch, Marc; Hessel, Volker
    Space exploration requires consideration of the dietary requirements of astronauts. Not only do nutritional requirements differ in space versus Earth, but limitations to payload combined with the length of space missions means that astronauts will need to produce as much food as possible in situ. Lettuce (Lactuca sativa) possesses many traits that make it suitable for space farming. Its small size, quick life cycle, large harvestable fraction and previous successful cultivation aboard the International Space Station (ISS) means that it represents a model plant for space cultivation. Here we discuss the suitability and requirements of lettuce as a dietary source on space missions. Using simplex linear programming, we identify the ration sizes of existing lettuce varieties to optimise nutrient delivery to both men and women on Earth and in Space. Whilst, unsurprisingly, a diet consisting only of lettuce cannot provide full nutrient requirements, there are differences in ration size and composition depending upon gender and location, indicating the importance of group composition when designing farming systems. We then review different routes to the biofortification of lettuce based on current literature and perform the modelling approach to determine portion sizes of theoretical ‘maximally fortified lettuce’, whose nutritional content was predicted based on the combined biofortification strategies. Finally, we conclude with the application of these approaches towards future space farming of a variety of crop species.
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    Open Access
    Constant-pH simulations of a coarse-grained model of polyfunctional weak charged biopolymers
    (MDPI, 2024) Naranjo, David; Blanco, Pablo M.; Garcés, Josep Lluís; Madurga, Sergio; Mas, Francesc
    A coarse-grained model of linear polyfunctional weak charged biopolymers was implemented, formed of different proportions of acid-base groups resembling the composition of humic substances. These substances are mainly present in dissolved organic matter in natural water. The influence of electrostatic interactions computing methods, factors concerning the structure of the chain, different functional groups, and the ionic strength on polyelectrolytes were studied. Langevin dynamics with constant pH simulations were performed using the ESPResSO package and the Python-based Molecule Builder for ESPResSo (pyMBE) library. The coverage was fitted to a polyfunctional Frumkin isotherm, with a mean-field interaction between charged beads. The composition of the chain affects the charge while ionic strength affects both the charge and the radius of gyration. Additionally, the parameters intrinsic to the polyelectrolyte model were well reproduced by fitting the polyfunctional Frumkin isotherm. In contrast, the non-intrinsic parameters depended on the ionic strength. The method developed and applied to a polyfunctional polypeptide model, that resembles a humic acid, will be very useful for characterizing biopolymers with several acid-base functional groups, where their structure, the composition of the different functional groups, and the determination of the main intrinsic proton binding constants and their proportion are not exactly known.