Grado en Ciencia y Tecnología de los Alimentos - Trabajos Fin de Grado

Recuperación de la fracción hemicelulósica del rastrojo de maíz mediante tratamiento con agua subcrítica: efecto de las condiciones de operación

Thu, 01 Jan 2026 00:00:00 GMT

Recuperación de la fracción hemicelulósica del rastrojo de maíz mediante tratamiento con agua subcrítica: efecto de las condiciones de operación Eugenio Pires, María En este trabajo se estudió la valorización del rastrojo de maíz como biomasa lignocelulósica mediante tratamientos de hidrólisis con agua subcrítica, con el objetivo de solubilizar selectivamente la fracción de hemicelulosa y obtener productos de valor añadido en forma oligomérica, así como generar un extracto sólido enriquecido en celulosa. Las pruebas se llevaron a cabo en un reactor discontinuo que funcionaba a una presión constante de 50 bar y a temperaturas de 160, 175 y 190 °C durante 60 min. La relación sólido-líquido se mantuvo en un 5 % (p/p). La fracción líquida se caracterizó en términos de carbohidratos solubilizados, sólidos disueltos, productos de degradación y distribución del peso molecular. Los resultados mostraron una clara dependencia de la severidad del tratamiento, identificando las condiciones óptimas de funcionamiento: 160 °C durante 60 min, 175 °C durante 50 min y 190 °C durante 20 min, alcanzando concentraciones máximas de hemicelulosa solubilizada de 4,8; 8,7 y 9,0 mg/mL, respectivamente. El análisis de la distribución del peso molecular mostró que, especialmente a 175 °C durante 5 minutos, la fracción líquida se enriqueció en oligómeros con pesos moleculares predominantemente en el rango de 1-5 kDa, considerados de interés para aplicaciones de mayor valor añadido. En condiciones más severas, se observó un aumento de las fracciones de bajo peso molecular (<1 kDa) y de los productos de degradación, principalmente furfural, asociados a la degradación de los oligómeros. Asimismo, se detectó la formación de ácido acético, atribuida a la desacetilación de la hemicelulosa, junto con una marcada disminución del pH durante los primeros minutos del tratamiento, lo que pone de relieve el papel de la autohidrólisis en el proceso. El análisis del sólido residual reveló una disminución progresiva del contenido de hemicelulosa al aumentar la temperatura, acompañada de un enriquecimiento relativo en celulosa, en consonancia con la solubilización selectiva observada en la fase líquida. En general, los resultados ponen de manifiesto el potencial del agua subcrítica como estrategia sostenible y eficaz para el fraccionamiento selectivo de los residuos de maíz y la producción de productos de valor añadido a partir de biomasa lignocelulósica; This study investigated the valorization of corn stover as lignocellulosic biomass through subcritical water hydrolysis treatments, with the aim of selectively solubilizing the hemicellulose fraction and obtaining value-added products in oligomeric form, as well as generating a solid extract enriched in cellulose. The tests were carried out in a batch reactor operating at a constant pressure of 50 bar and at temperatures of 160, 175, and 190 °C for 60 min. The solidliquid ratio was maintained at 5% (w/w). The liquid fraction was characterized in terms of solubilized carbohydrates, dissolved solids, degradation products, and molecular weight distribution. The results showed a clear dependence on the severity of the treatment, identifying optimal operating conditions: 160 °C for 60 min, 175 °C for 50 min, and 190 °C for 20 min, reaching maximum concentrations of solubilized hemicellulose of 4,8; 8,7 and 9,0 mg/mL, respectively. The molecular weight distribution analysis showed that, especially at 175 °C for 5 min, the liquid fraction was enriched in oligomers with molecular weights predominantly in the range of 1-5 kDa, considered interest for higher value-added applications. Under more severe conditions, an increase in low molecular weight fractions (<1 kDa) and degradation products, mainly furfural, associated with the degradation of oligomers was observed. Likewise, the formation of acetic acid was detected, attributed to the deacetylation of hemicellulose, together with a marked decrease in pH during the first minutes of treatment, which highlights the role of autohydrolysis in the process. Analysis of the residual solid revealed a progressive decrease in hemicellulose content with increasing temperature, accompanied by a relative enrichment in cellulose, consistent with the selective solubilization observed in the liquid phase

Valorización del rastrojo de maíz mediante agua subcrítica: estudio del efecto del empleo de modificadores verdes en la hidrólisis de la matriz lignocelulósica

Thu, 01 Jan 2026 00:00:00 GMT

Valorización del rastrojo de maíz mediante agua subcrítica: estudio del efecto del empleo de modificadores verdes en la hidrólisis de la matriz lignocelulósica García Medina, Silvia En este trabajo se ha estudiado la valorización del rastrojo de maíz empleando agua subcrítica (SW – subcritical water) como medio de reacción, evaluando el efecto de la adición de modificadores verdes. Los experimentos se realizaron en un reactor discontinuo a 175 ºC y 50 bar durante 1 h, empleándose como modificadores etanol (al 20 y 40%, v/v) y un disolvente eutéctico natural profundo (NADES, por sus siglas en inglés) hidrófobo formado por mentol y ácido láurico (relación molar 2:1), al 5% (v/v). Los resultados se compararon con los obtenidos tras el tratamiento con SW, analizando las muestras líquidas y sólidas obtenidas. En la fracción líquida se observó mayor solubilización de hemicelulosa que de celulosa, con una concentración oligomérica de xilosa cinco veces superior a la de glucosa. La adición de etanol favoreció la hidrólisis y promovió la degradación específica de la lignina, evidenciada por el incremento de compuestos fenólicos, destacando el ácido ferúlico y el ácido p-cumárico, que alcanzaron máximos de 129.3 mg/mL y 18.9 mg/mL, respectivamente. La liberación de estos ácidos confirmó el inicio de la deslignificación. El análisis del residuo sólido mostró diferencias según el modificador empleado. Con el etanol al 40 % (v/v) se registró una reducción significativa de lignina (33.3 % insoluble y 4.3 % soluble) y con el empleo de SW o etanol al 40 % se produjo un enriquecimiento de celulosa del 15 %. En cambio, el uso de NADES presentó menor eficacia en la extracción de compuestos de interés (como derivados de la lignina) y dificultades en las etapas de separación y recuperación debido a su carácter hidrofóbico. Los resultados desvelan el potencial del agua subcrítica (junto con la adición de modificadores como el etanol) como medida para favorecer la hidrólisis del rastrojo de maíz, convirtiéndose en una estrategia sostenible para solucionar el problema de la recalcitrancia de la biomasa lignocelulósica, que limita la recuperación de compuestos de interés; In this study, the valorization of corn stover was investigated using subcritical water (SW) as the reaction medium, evaluating the effect of adding green modifiers. The experiments were carried out in a batch reactor at 175 ºC and 50 bar for 1 h, using ethanol (at 20 and 40%, v/v) and a hydrophobic natural deep eutectic solvent (NADES) composed of menthol and lauric acid (2:1 molar ratio) at 5% (v/v) as modifiers. The results were compared with those obtained after treatment with SW, analyzing the liquid and solid samples generated. In the liquid fraction, greater solubilization of hemicellulose than cellulose was observed, with an oligomeric xylose concentration five times higher than that of glucose. The addition of ethanol enhanced hydrolysis and promoted selective lignin degradation, as evidenced by the increase in polyphenolic compounds, particularly ferulic acid and p-coumaric acid, which reached maximum values of 129.3 mg/mL and 18.9 mg/mL, respectively. The release of these acids confirmed the onset of delignification. Analysis of the solid residue revealed differences depending on the modifier used. With 40% (v/v) ethanol, a significant reduction in lignin content (33.3% insoluble and 4.3% soluble lignin) was observed, and with the use of SW or 40 % ethanol led to a 15% enrichment in cellulose. In contrast, the use of NADES showed lower efficiency in extracting compounds of interest (such as derivates of lignin) and presented difficulties during the separation and recovery stages due to its hydrophobic nature. These results highlight the potential of subcritical water as a strategy to enhance corn stover hydrolysis, representing a sustainable approach to overcome the recalcitrance of lignocellulosic biomass, which limits the recovery of valuable compounds

Estudio de la recuperación de ácido láctico a partir de hidrolizados de rastrojo de maíz mediante un proceso de ultrafiltración asistida con niosomas

Thu, 01 Jan 2026 00:00:00 GMT

Estudio de la recuperación de ácido láctico a partir de hidrolizados de rastrojo de maíz mediante un proceso de ultrafiltración asistida con niosomas Fernández Pozos, Noelia This study investigates the recovery and purification of lactic acid from corn stover subcritical water hydrolysates using a hybrid separation process based on niosome-assisted ultrafiltration. Agricultural residues such as corn stover represent abundant lignocellulosic biomass that can be valorised to produce high-value chemicals within a more sustainable biorefinery framework. However, hydrolysates generated during thermochemical treatment contain complex mixtures of organic acids and degradation products, making selective separation of lactic acid challenging. In this work, different sorbitan-based niosomes were formulated using Span 60, Span 80 and Tween 80, and their physicochemical properties were characterized through particle size distribution and zeta potential measurements. Ultrasonication time strongly influenced vesicle formation, and stable systems were obtained after approximately 45 minutes of treatment. Encapsulation experiments performed with synthetic solutions showed that the non-dissociated form of lactic acid exhibited higher encapsulation efficiencies than the lactate form, particularly for Span 60-based niosomes. The influence of competing organic acids such as formic and acetic acids was also evaluated, revealing a decrease in selectivity under multicomponent conditions. Niosome-assisted ultrafiltration experiments were subsequently conducted using Span 60 niosomes and a tubular ceramic membrane with both synthetic and real corn stover hydrolysate. Process performance was assessed through permeate flux and retention factors for the different organic acids. Results showed that operational parameters such as pH and contact time significantly affected separation efficiency. Acidic conditions favoured higher retention due to increased encapsulation of the protonated acid species, while longer contact times up to 1.5 h did not modify retention values, indicating that this contact time was sufficient to reach equilibrium between the continuous phase and the niosomal vesicles. Overall, the results demonstrate that niosome-assisted ultrafiltration constitutes a promising solvent-free for the recovery of lactic acid from lignocellulosic hydrolysates, contributing to the development of sustainable biomass valorisation processes within future biorefineries and circular bioeconomy systems

Estudios de adsorción y desorción de furfural empleando carbón activo y Amberlite XAD-4

Estudios de adsorción y desorción de furfural empleando carbón activo y Amberlite XAD-4 Herrero Camargo, Sara The valorisation of solid agricultural waste remains a current challenge. The concept of a biorefinery arises from increasing concerns about environmental issues, as it is an efficient and sustainable way to produce valuable organic compounds from lignocellulosic byproducts, thereby maximizing their value. Corn is the most widely produced cereal globally, and Spain contributes approximately four million tons. Additionally, it is estimated that by 2030, global production of this cereal will increase by 160 million tons, reaching 1.3 billion tonnes. Corn stover has a high content of hemicellulose, cellulose, and lignin, making it a good raw material for the production of furfural. Furfural is a heterocyclic organic compound identified as a platform chemical with various subsequent applications: as an extractant, fungicide, raw material in the synthesis of various chemicals, and as a flavour and fragrance enhancer in the food industry. It is also a precursor to many other compounds of interest, such as succinic acid and furfuryl alcohol. Furfural is produced from the hydrolysis of hemicellulose, generally through acid hydrolysis and dehydration of xylose. This study analysed the selective recovery of furfural from corn stover subcritical water hydrolysates using an adsorption/desorption process, which are more environmentally and economically sustainable hydrolysis and purification methods. Specifically, this work evaluated the effect of the type of adsorbent, the mass/volume ratio, and the presence of impurities (mainly xylose and carboxylic acids) on the furfural adsorption yield, as well as compared batch and fixed bed treatments. After the study, under optimal working conditions (5 g of XAD-4, 75 ml of furfural hydrolysate, adsorption process at 25°C for 60 min, desorption process at 50°C for 30 min, and in a fixed bed), the results showed that the most selective adsorbent for furfural recovery was the Amberlite XAD-4 polymeric resin, with a furfural recovery from the corn waste subcritical water hydrolysate of 66.2% and a purity close to 91.3%.; The valorisation of solid agricultural waste remains a current challenge. The concept of a biorefinery arises from increasing concerns about environmental issues, as it is an efficient and sustainable way to produce valuable organic compounds from lignocellulosic byproducts, thereby maximizing their value. Corn is the most widely produced cereal globally, and Spain contributes approximately four million tons. Additionally, it is estimated that by 2030, global production of this cereal will increase by 160 million tons, reaching 1.3 billion tons. Corn agricultural waste, such as stalks and leaves, have a high content of hemicellulose, cellulose, and lignin, making them a good raw material as biomass for the production of furfural. Furfural is a heterocyclic organic compound identified as a platform chemical with various subsequent applications: as an extractant, fungicide, raw material in the synthesis of various chemicals, and as a flavor and fragrance enhancer in the food industry. It is also a precursor to many other compounds of interest, such as succinic acid and furfuryl alcohol. Furfural is produced from the hydrolysis of hemicellulose, generally through acid hydrolysis and dehydration of xylose.This study analyzed the selective recovery of furfural from corn waste subcritical water hydrolysates using an adsorption/desorption process, which are more environmentally and economically sustainable hydrolysis and purification methods. Specifically, this work evaluated the effect of the type of adsorbent, the mass/volume ratio, and the presence of impurities (mainly xylose and carboxylic acids) on the furfural adsorption yield, as well as compared batch and fixed bed treatments. After the study, under optimal working conditions (5 g of XAD-4, 75 ml of furfural hydrolysate, adsorption process at 25°C for 60 min, desorption process at 50°C for 30 min, and in a fixed bed), the results showed that the most selective adsorbent for furfural recovery was the Amberlite XAD-4 polymeric resin, with a furfural recovery from the corn waste subcritical water hydrolysate of 66.2% and a purity close to 91.3%.