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Works presented

Microstructural study of olive oil oleogels with chitosan and chitin from pickering emulsions
Authorship
S.V.M.
Master in Chemical and Bioprocess Engineering
Defense date
02.19.2025 09:15
Summary
One of the main objectives of the current food industry is to replace harmful fats for health with oils or fats that have similar organoleptic properties and a good nutritional profile. This master's thesis studies the development of oleogels from vegetable oils, specifically from olive oil. The emulsion is created from an aqueous phase of chitosan as a structuring agent and vanillin, which, when reacting with chitosan, forms a Schiff base and creates a three-dimensional network that traps the oil. Additionally, chitin is incorporated in the form of particles to stabilize the emulsion through the Pickering effect. Subsequently, water is removed from the emulsions through convective drying to obtain a dry emulsion, and after crushing it, the final oleogel is obtained. The main objective of this work is to study the impact of chitin particle concentration, 0.5, 1.0, 1.5, and 2.0 percent, on the properties of the emulsion and oleogel, both in the presence and absence of vanillin. The rheological properties of the emulsion were studied through oscillatory tests. First, strain sweeps were conducted to determine the linear viscoelastic regime of the emulsions, and then the mechanical spectra were measured to observe the variation of elastic and viscous modules with frequency. In the oleogel, rheological properties were analyzed through strain and frequency sweeps, along with quality tests such as colorimetry, texture, and oil retention. The rheological tests showed that the emulsions exhibited a predominantly viscous behavior at chitin concentrations lower than 1.5 percent by weight, and at higher concentrations, the behavior was inverted. The rheological behavior of the emulsions was modeled with the Cross-Williamson model for systems without chitin, and an empirical term was added based on particle concentration for systems with chitin, which allowed for the creation of a valid complex viscosity model for the tested concentration range. The droplet size distribution of the emulsions was also analyzed using optical microscopy images, showing that the droplet diameter decreased with increasing chitin concentration. Regarding the oleogels, convective drying at 70 degrees Celsius was modeled using the Page model, verifying that with increasing chitin concentration, the drying time of the emulsions increased. Furthermore, it was observed that chitin particles destabilized the oleogels, resulting in lower oil retention in systems with chitin. Although vanillin had no significant effect on the rheology of the emulsions, its presence in the final oleogel showed a considerable improvement in the determined properties. This is attributed to the endothermic reactions between amino and aldehyde groups, which are favored by the drying temperature. In general, as the amount of chitin increases, the hardness of the oleogel decreases, while its adhesiveness and elasticity increase, reaching a maximum at a chitin concentration of 1.5 percent. Cohesiveness remains almost unchanged. In conclusion, the presence of chitin particles does not improve the quality of oleogels compared to systems without particles, but it does increase the stability of the emulsions, which is relevant at an industrial level.
Direction
MOREIRA MARTINEZ, RAMON FELIPE (Tutorships)
SINEIRO TORRES, JORGE (Co-tutorships)
Court
GARRIDO FERNANDEZ, JUAN MANUEL (Chairman)
MAURICIO IGLESIAS, MIGUEL (Secretary)
GONZALEZ ALVAREZ, JULIA (Member)
Techno-economic analysis of enzymatic PET recycling using immobilized enzyme
Authorship
L.G.G.
Master in Chemical and Bioprocess Engineering
Defense date
02.19.2025 11:15
Summary
Plastics, especially polyethylene terephthalate or PET, have transformed our society, resulting in a large number of advances, although their massive production has caused serious environmental problems. Currently, only a small portion of the plastics produced is correctly recycled, making it necessary to develop solutions that improve the management of this waste. This study performs a techno-economic analysis of the production and application of PET-degrading enzymes, expressed both in encapsulated form using nanospheres and in free form. Specifically, the conceptual design of two industrial plants is proposed, including the stage of production of the E. coli bacteria in which the enzyme will be produced, the separation and purification of the target enzyme, the degradation of the residual plastic, and finally, the purification of the reaction products. After analyzing the costs and economic indicators of the baseline cases, different scenarios are studied in which key parameters are modified, such as the yield of microorganism and enzyme production, and the percentage of plastic degradation. The results indicate that, although economic viability is not achieved in any of the proposed cases, the limiting step of the process is the degradation of the polymer. Once the critical point is identified, the study concludes by proposing different improvement options to achieve economic viability through process optimization and, consequently, turn this technology into a competitive option in the PET recycling market.
Direction
EIBES GONZALEZ, GEMMA MARIA (Tutorships)
LU CHAU, THELMO ALEJANDRO (Co-tutorships)
Court
HOSPIDO QUINTANA, ALMUDENA (Chairman)
FRANCO RUIZ, DANIEL JOSE (Secretary)
GONZALEZ GARCIA, SARA (Member)
Canola oil oleogels obtained by indirect method using hybrid carrageenan as a structuring agent
Authorship
C.I.G.
Master in Chemical and Bioprocess Engineering
Defense date
02.19.2025 10:15
Summary
In recent decades, humans have been making a considerable effort to improve their health and living conditions. One of the ways to achieve this is related to eating habits. Replacing saturated fats with unsaturated fats reduces the chances of suffering from heart disease and overweight. However, saturated fats have a series of mechanical and organoleptic characteristics that oils do not have. Therefore, this work focuses on the investigation of oil structuring techniques that achieve a final product with the best of both worlds. The preparation and study of canola oil emusion gels has been carried out using carrageenan as a structuring agent. This process involves the application of the emulsion template method, due to the difficulty of dispersing the oil in the aqueous phase that contains the gelling agent. For its part, carrageenan has been extracted from the Chondrus crispus algae species using a hot bath immersion technique, and its molecular weight has been determined by capillary viscometry. The determination of mechanical properties under different conditions is essential. For this reason, rheological studies have been carried out on the emulsion and gels that allow these properties to be related to the variation in the concentration of carrageenan, salt and the oil water ratio, as well as determining the thermal reversibility and hysteresis phenomena of the gels. Furthermore, taking into account the potential applications in the food and pharmaceutical industries, oil and water retention, texture and colour tests have been carried out, within a quality control process, and the results have shown a relationship with reheology. The results obtained are promising, thanks to which, future challenges are proposed in order to achieve the use of these gels at an industrial level in the short term.
Direction
SINEIRO TORRES, JORGE (Tutorships)
MOREIRA MARTINEZ, RAMON FELIPE (Co-tutorships)
Court
GONZALEZ ALVAREZ, JULIA (Coordinator)
GARRIDO FERNANDEZ, JUAN MANUEL (Chairman)
GONZALEZ GARCIA, SARA (Secretary)
Technoeconomic and environmental analysis of a biorefinery focused on the valorization of olive stones
Authorship
S.C.A.
Master in Chemical and Bioprocess Engineering
Defense date
02.19.2025 09:45
Summary
Climate change represents a crucial challenge for agriculture, affecting food availability due to climate variability and alterations in rainfall patterns. The olive is one of the main crops in our country, with Spain being the world's largest producer of both table olives and olive oil. Specifically, in 2023 around 767,000 tons of olive oil were produced in Spain. The olive oil production process involves the generation of waste streams, such as olive pits, branches or leaves, which together account for up to 10 per cent of the weight of the olive. This study focuses on the search for a new life for this waste in accordance with the principles of the circular economy. To do this, the design of a biorefinery will be carried out for the valorization of this waste according to experimental data, also proceeding to its simulation, its environmental profile will be identified, and finally, a techno-economic analysis of the system will be carried out.
Direction
GONZALEZ GARCIA, SARA (Tutorships)
Court
GARRIDO FERNANDEZ, JUAN MANUEL (Chairman)
MAURICIO IGLESIAS, MIGUEL (Secretary)
GONZALEZ ALVAREZ, JULIA (Member)
Assessment of the quality of industrial wastewater treated by reverse osmosis and its reuse feasibility
Authorship
A.L.D.L.T.
Master in Chemical and Bioprocess Engineering
Defense date
02.19.2025 11:45
Summary
Industrial wastewater poses a significant environmental challenge. While each industry generates its own specific wastes, all industries, regardless of sector, produce wastewater. Industrial discharges are regulated by laws that set maximum limits for various pollutants, along with acceptable ranges for parameters such as pH, conductivity, and temperature. However, even when these regulations are met, the large volumes of discharge can still raise environmental concerns. Additionally, water scarcity, exacerbated by climate change, further affects communities and ecosystems. Consequently, it is crucial to implement policies that minimize the use of natural resources to ensure long-term sustainability. The Pontevedra pulp mill operates its own water treatment plant, which processes the wastewater generated during production before discharging into the Pontevedra estuary. To address these issues, the plant has recently upgraded its tertiary treatment system by incorporating a reverse osmosis stage. This enhancement allows for the recirculation of a portion of the treated water, significantly reducing both the intake of fresh water and the volume of wastewater discharged. The aim of this project is to analyze the improvement in water quality achieved through the reverse osmosis system and determine whether the treated water resembles the fresh water used in the production process. Additionally, considering the high energy costs associated with this system, energy costs will be evaluated, and potential solutions to reduce these costs will be explored.
Direction
MOSQUERA CORRAL, ANUSKA (Tutorships)
Raposo Fernández, Fernanda (Co-tutorships)
Court
HOSPIDO QUINTANA, ALMUDENA (Chairman)
FRANCO RUIZ, DANIEL JOSE (Secretary)
GONZALEZ GARCIA, SARA (Member)
Validation of design and scaling heuristics integrating environmental externalities
Authorship
A.P.C.
Master in Chemical and Bioprocess Engineering
Defense date
02.19.2025 10:45
Summary
Early stage evaluations are of interest in validating the current reliability of design heuristics in chemical engineering by anticipating the technical, economic and environmental viability of a project from a holistic perspective. Their development depends on the maturity of a technology, so this document addresses their application to two representative case studies. Initially, the suitability of the typical factor between the reflux ratio and its minimum value is tested in a distillation column with a double analysis in a large-scale azeotropic system in a tray unit, and packed contact in a typical production in the fine chemicals sector. In a second evaluation, the most suitable scale up methods are reviewed for a hypothetical industrial plant of polyhydroxyalkanoates with mixed microbial cultures and a residual organic substrate based on pilot experimental records. The results obtained in the mature technology demonstrated a favourable balance between separation efficiency and operating costs at lower reflux ratios, addressing a higher initial investment to prioritise a reduction in emissions and process costs. Regarding the case study of the emerging system, the process engineering scale up heuristics were found to be optimal in terms of applicability and uncertainty, while the economic and carbon footprint analysis pointed to acidification conversion, intracellular product extraction and raw material acquisition costs as the main limitations for its introduction into the market.
Direction
HOSPIDO QUINTANA, ALMUDENA (Tutorships)
MAURICIO IGLESIAS, MIGUEL (Co-tutorships)
Court
GONZALEZ ALVAREZ, JULIA (Chairman)
FRANCO RUIZ, DANIEL JOSE (Secretary)
GONZALEZ GARCIA, SARA (Member)