Strategic Project - LA 6 - 2011-2012

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Publications

Autohydrolysis of Annona cherimola Mill. seeds: optimization, modeling and products characterization

Publication . Branco, Pedro C.; Dionísio, Ana; Ivone, Torrado; Carvalheiro, Florbela; Castilho, Paula C.; Duarte, Luís C.

Annona cherimola Mill. seeds are a residue of the industrial processing of this fruit, for which, presently, there is no industrial application. They have a considerable amount of oil, which can be converted into biodiesel, but the remaining lignocellulosic fraction still needs relevant added-value valorization routes. In this work, the selective hemicelluloses removal by autohydrolysis was optimized aiming to maximize the yield of oligosaccharides with potential applications in food, pharmaceutical and cosmetic industries. A maximum of 10.4 g L-1 of oligosaccharides was obtained, for a severity factor of 3.6, where 74.5% of the original hemicellulose was solubilized. The process kinetics is presented, modeled (based on the Arrhenius equation) and its scale-up is discussed. The hydrolyzate shelf-life was evaluated and the produced oligosaccharides are stable at room temperature for, at least, 3 weeks. Furthermore, all oligosaccharides are also stable at 100 °C for 1 h, in pH values between 1 and 11, enabling their industrial processing, and at 37 °C for 3 h, in pH values between 1 and 3, thus indicating its potential classification as non-digestible oligosaccharides. The remaining cellulose enriched solids presented an increased enzymatic digestibility (as a function of the autohydrolysis severity) that assures its efficient use in subsequent processes (e.g., bioethanol production). The upgrade route developed in this work in combination to the previously reported use of A. cherimola seed oil for biodiesel production can lead to an integrated zero-waste valorization strategy within the biorefinery framework.

2015Journal article

Open access

Protein profiling as early detection biomarkers for TiO2 nanoparticle toxicity in Daphnia magna

Publication . Sá-Pereira, Paula; Diniz, Mário S.; Moita, Liliana; Pinheiro, Teresa; Mendonça, E.; Paixão, Susana M.; Picado, Ana

ABSTRACT: The mode of action for nanoparticle (NP) toxicity in aquatic organisms is not yet fully understood. In this work, a strategy other than toxicity testing was applied to Daphnia magna exposed to TiO2-NPs: the use of nuclear microscopy and the assessment of protein profile. D. magna is a keystone species broadly used as a model system in ecotoxicology. Titanium (Ti) was found in the D. magna digestive tract, mainly in the gut. The penetration of Ti into the epithelial region was greater at higher exposure levels and also observed in eggs in the brood pouch. The protein profile of individuals exposed to different concentrations showed that 2.8 and 5.6 mg/L TiO2-NP concentrations induced an over-expression of the majority of proteins, in particular proteins with molecular weight of similar to 120, 85 and 15 kDa, while 11.2 mg/L TiO2-NP had an inhibitory effect on protein expression. The Matrix-assisted laser desorption ionization with tandem time of flight mass spectrometry (MALDI-TOF/TOF MS) analysis of these proteins consistently identified them as vitellogenin (Vtg)-like proteins, associated with enzymes involved in redox balance. These results indicate that Vtg-like proteins are up-regulated in D. magna exposed to TiO2-NPs. Vitellogenesis is associated with the reproduction system, suggesting that TiO2-NP exposure can impair reproduction by affecting this process. The precise mode of action of TiO2-NPs is still unclear and the results from this study are a first attempt to identify specific proteins as potential markers of TiO2-NP toxicity in D. magna, providing useful information for future research.

2018Journal article

Open access