Yield evaluation of enzyme hydrolysis and dark fermentation of the brown seaweed Rugulopteryx okamurae hydrothermally pretreated by microwave irradiation

Microwave irradiation has been applied to solubilise the organic matter from the invasive seaweed Rugulopterix okamurae as pretreatment for two conventional biological processes: enzyme hydrolysis (EH) for obtaining reducing sugars (RS) and dark fermentation (DF) for obtaining volatile fatty acids (VFAs). As operational conditions for the microwave pretreatment, temperature and time has been tested between 120 and 220 °C and 5–20 min respectively. The maximum solubilisation yield in terms of DOC (26%) through the microwave pretreatment was registered at 220 °C at 20 min. However, the maximum concentration for RS (1.8 g/L) was obtained at 200 °C at 20 min due to the decomposition of monomeric sugars at high temperature and the total polyphenols (TP) were above 0.25 g/L (where inhibition in dark fermentation begins to be noticiable) at 180 °C. When the pretreated biomass was used for the EH the maximum accumulated RS production was 160 mg-RS/g-biomass, at 220 °C which was a 35% better than the RS production for non-pretreated biomass. In the case of the DF tests, the maximum yield of VFAs obtained with the pretreated biomass was 46.3 mg/g-biomass at 220 °C while the maximum hydrogen yield was obtained at 200 °C (6.6 mL-H2/g-biomass) due to the high level of TP (1.1 g/L) of pretreated biomass at 220 °C. Despite of this toxic effect, the VFAs production at 220 °C was 93% higher than in the non-pretreated biomass

Influence of treatment with chelating-type ion exchange resins on the physical-chemical and sensory characteristics of aged wine vinegars

The presence of metallic ions, mainly iron a copper, in wine derivatives, such as vinegar, can cause health problems for consumers when they are in high concentrations. In very old vinegars can reach concentrations of between 20 and 40 ppm of iron, so it is convenient to reduce them. In the present work, the reduction of the metal content in aged vinegars has been studied through its treatment with chelating-type ion exchange resins, under two modalities, column treatment and batch treatment. It has been proven that this process significantly reduces the metal content, and that it does not greatly affect its principal physical-chemical characteristics. The threated vinegars have been evaluated by the official tasting panel of the Denomination of Origin “Sherry Vinegar”, obtaining very positive results, only with small differences with the untreated ones. All of them were considered as suitable to be commercialized under the protection of that Denomination of Origin

Preliminary Study of Enological Potential and Volatile Compounds of Tintilla de Rota Somatic Variant Grown in a Warm Climate

In an enological market notable for its use of universal varieties, the enological potential of the somatic variant Tintilla de Rota has been studied in a warm climate area from where it originates and has been compared with three universal cultivars and with a reference cultivar in Spain. It has been found that Tintilla de Rota is a grapevine cultivar that can adapt easily to the area where it has been grown traditionally, achieving adequate pH and acidity values while maintaining a moderate sugar content compared to the other varieties studied. Additionally, it has shown high anthocyanin content. In terms of aromatic composition, it has exhibited a content equal to or even higher than the other varieties analyzed in this study in most of the aromatic families studied, with a higher content of compounds such as 1-octanol, benzyl alcohol and citronellol, which can lead to wines with an interesting and distinguished aromatic profile. All these facts confirm the interest in the use of this cultivar and the importance of recovering and enhancing the value of autochthonous cultivars as opposed to other so-called universal varieties

Conversion of Exhausted Sugar Beet Pulp into Fermentable Sugars from a Biorefinery Approach

In this study, the production of a hydrolysate rich in fermentable sugars, which could be used as a generic microbial culture medium, was carried out by using exhausted sugar beet pulp pellets (ESBPPs) as raw material. For this purpose, the hydrolysis was performed through the direct addition of the fermented ESBPPs obtained by fungal solid-state fermentation (SSF) as an enzyme source. By directly using this fermented solid, the stages for enzyme extraction and purification were avoided. The effects of temperature, fermented to fresh solid ratio, supplementation of fermented ESBPP with commercial cellulase, and the use of high-solid fed-batch enzymatic hydrolysis were studied to obtain the maximum reducing sugar (RS) concentration and productivity. The highest RS concentration and productivity, 127.3 g.L-1 and 24.3 g.L-1.h(-1) respectively, were obtained at 50 degrees C and with an initial supplementation of 2.17 U of Celluclast (R) per gram of dried solid in fed-batch mode. This process was carried out with a liquid to solid ratio of 4.3 mL.g(-1) solid, by adding 15 g of fermented solid and 13.75 g of fresh solid at the beginning of the hydrolysis, and then the same amount of fresh solid 3 times every 2.5 h. By this procedure, ESBPP can be used to produce a generic microbial feedstock, which contains a high concentration of monosaccharides

Modelling and Optimization of Simultaneous Saccharification and Fermentation of Agro-Food Residues

In terms of productivity, bioethanol production from agri-food residues can be improved by carrying out simultaneously the two involved stages (enzyme hydrolysis and alcohol fermentation). This is because the shorter the process duration, the higher the overall productivity achieved. In this work, two kinetic models previously developed by the authors have been combined to obtain a general kinetic model for the simultaneous saccharification and fermentation of lignocellulosic materials. The validity of the combined model has been tested using three different agri-food residues: wheat straw, rice husks and exhausted sugar beet pulp. Later, the model has been used to calculate productivity under many different conditions and to optimize the industrial process. After this study, it is concluded that some important operating variables, such as the enzyme dose and the inoculum strength, must be well coupled to obtain the maximal yield from residues. Thus, the overall productivity obtained in the laboratory experiments was under 5 mg of ethanol per gram of solid waste and per hour. However, the simulations in the optimal operating conditions predict productivities up to double that

Valorisation of fungal hydrolysates of exhausted sugar beet pulp for lactic acid production

BACKGROUND Exhausted sugar beet pulp pellets (ESBPP) were used as raw material for lactic acid (LA) fermentation. The enzymatic hydrolysis of ESBPP was performed with the solid obtained after the fungal solid-state fermentation of ESBPP as a source of hydrolytic enzymes. Subsequently, a medium rich in glucose and arabinose was obtained, which was used to produce LA by fermentation. For LA production, two Lactobacillus strains were assayed and the effects of the supplementation of the hydrolysate with a nitrogen source and the mode of pH regulation of the fermentation were investigated. Moreover, a kinetic model for LA fermentation by Lactobacillus plantarum of ESBPP hydrolysates was developed. RESULTS L. plantarum produced a LA concentration 34% higher than that produced by L. casei. The highest LA concentration (30 g L−1) was obtained with L. plantarum when the hydrolysate was supplemented with 5 g L−1 yeast extract and the pH was controlled with CaCO3. The concentration of acetic acid differed depending on the concentration of CaCO3 added, producing its maximum value with 27 g L−1 CaCO3. The proposed kinetic model was able to predict the evolution of substrates and products depending on the variation of the pH in the hydrolysate, according to the amount of CaCO3 added. CONCLUSIONS ESBPP can be valorised to produce LA. A pure LA stream or a mixture of LA and acetic acid, depending on the pH control method of the fermentation, can be produced. Thus, this control is of great interest depending on the destination of the effluent

Added-value biorefinery products from invasive brown seaweed Rugulopteryx okamuare. A kinetic comparison

Since 2015, the coastal area of the Strait of Gibraltar has been colonised by the Asiatic seaweed Rugulopteryx okamurae. The massive coast arrival of this brown macroalgae has seriously affected the economy of the regional fishing and touristic sectors due to its fast spreading as invasive organism. This environmental problem is, in fact, an opportunity to apply the circular economy approach. On the other hand, between 19 and 23 million tonnes of plastic waste are dumped into the sea every year due to its low biodegradability. In this context, bioplastics production through biological processes may provide a solution to this problem. Enzyme hydrolysis is one of the most well-known processes used to obtain monomeric sugars. Many of these, such as glucose D-galactose or D-mannitol are classified as fermentable sugars, which makes them a highly interesting substrate for subsequent biorefinery processes. In fact, one of the possible ways of using sugars is as a substrate for bioplastics precursors synthesis processes, such as polyhydroxyalkanoates (PHA), involving both pure cultures and mixed cultures of microorganisms. However, macroalgae cell structure is hard to fully degradate without the application of a previous pretreatment. The objective of this study is to obtain total reducing sugars (TRS) by enzyme hydrolysis (EH) from the invasive seaweed R. okamurae. In addition, two different pretreatments will also be applied and compared: microwave (MW) and biological (BIO) pretreatments

Evaluation of the use of multiflora bee pollen on the volatile compounds and sensorial profile of Palomino fino and Riesling white young wines

This study investigates the impact of bee pollen on volatile compounds, odour activity values and sensory profiles in Palomino fino and Riesling young white wines. Commercial bee pollen was added to grape must using six different doses (0 (control), 0.1, 0.25, 1, 5, 10 and 20 g/L) and fermented under controlled conditions. Volatile compounds were determined with GC and GC–MS chromatography and sensorial analysis using a qualified panel of tasters. Bee pollen produces an increase in volatile compounds depending on the grape variety and the dose applied. It also increases the synthesis of higher alcohols, methanol, esters, acetaldehyde and terpenes, reducing alcohols and fatty acids. Wines with low doses (0.1 and 0.25 g/L) showed the higher OAV values (fruity and floral) and scores in overall judgment for the sensory evaluation. High pollen doses decrease fruity character and could result in deviations affecting the sensorial quality.12 página

Influence of treatment with chelating-Type ion exchange resins on the physical-chemical and sensory characteristics of aged wine vinegars

La presencia de iones metálicos, fundamentalmente hierro y cobre, en productos derivados del vino, como el vinagre, puede originar problemas para la salud del consumidor cuando su concentración es elevada, además de defectos en la calidad del producto. En vinagres de vino envejecidos, se pueden alcanzar concentraciones de hasta 20 y 40 ppm de hierro, que es aconsejable reducir. En el presente trabajo se ha estudiado la reducción del contenido en metales en vinagres de vino envejecidos mediante su tratamiento con resinas de intercambio iónico tipo quelante, bajo dos modalidades, tratamiento en columna y tratamiento en batch (por lotes). Se ha comprobado que dicho proceso reduce significativamente el contenido en metales, y que no afecta en gran medida a sus principales características físico-químicas. Los vinagres tratados han sido evaluados por el panel de cata oficial de la Denominación de Origen “Vinagre de Jerez”, obteniéndose resultados muy positivos, en cuanto a que se observan diferencias muy pequeñas con los no tratados y que todos ellos se consideraron aptos para su comercialización bajo el amparo de dicha Denominación de Origen. The presence of metallic ions, mainly iron a copper, in wine derivatives, such as vinegar, can cause health problems for consumers when they are in high concentrations. In very old vinegars can reach concentrations of between 20 and 40 ppm of iron, so it is convenient to reduce them. In the present work, the reduction of the metal content in aged vinegars has been studied through its treatment with chelating-Type ion exchange resins, under two modalities, column treatment and batch treatment. It has been proven that this process significantly reduces the metal content, and that it does not greatly affect its principal physical-chemical characteristics. The threated vinegars have been evaluated by the official tasting panel of the Denomination of Origin "Sherry Vinegar", obtaining very positive results, only with small differences with the untreated ones. All of them were considered as suitable to be commercialized under the protection of that Denomination of Origin

Creation of Immersive Resources Based on Virtual Reality for Dissemination and Teaching in Chemical Engineering

Chemical Engineering is a complex discipline that is mainly applied to the industrial context, which makes it difficult to approach real equipment and systems in the classroom to students. Nevertheless, Information and Communication Technologies (ICTs) are particularly useful to encourage active and autonomous learning, normally associated with deeper levels of engagement and understanding of the subjects taught. In this way, several studies have demonstrated that immersion has the potential to increase learning experiences and improve creativity and engagement, Virtual Reality (VR) being a remarkable example. In this context, we created and shared with students two immersive resources based on VR: (a) a laboratory 360 degrees video tour, which was used to disseminate the Chemical Engineering Degree in an Open Door Days organized for high school students; and (b) an experiential learning tool integrated with Moodle, which was available previously to face-to-face practical lessons of the subject Separation Operations. In both cases, the feedback from the participant students was positive. High school students increased their interest in Chemical Engineering Degree after viewing the 360 degrees video, meanwhile undergraduate students found the immersive tool useful in the subsequent performance of real practical activities. From the perspective of professors, creation of these resources required purchase of equipment, time and effort, but they were highly valued as a tool for disseminating and supporting teaching, being an initial starting point for the creation of more enhanced VR-based materials