Diego T. Santos

Carotenoid Pigments Encapsulation: Fundamentals, Techniques and Recent Trends

Supercritical fluids have become an attractive alternative due to environmentally friendly solvents. The meth- ods that use supercritical fluids can be conveniently used for various applications such as extraction, reactions, particle formation and encapsulation. For encapsulation purposes, the processing conditions given by supercritical technology have important advantages over other methods that include harsh treatments with regard to pH, temperature, light, the use of organic solvents, etc. Unstable functional pigments such as carotenoids extracted from natural sources have been en- capsulated to overcome instability problem. Thus, the most used techniques applicable to this intention are described and discussed in this review as well the recent advances and recent trends in this topic that involves the use of supercritical fluids.

Biotechnological production of xylitol in a three-phase fluidized bed bioreactor with immobilized yeast cells in Ca-alginate beads

Cells of Candida guilliermondii entrapped in Ca‐alginate beads were used for xylitol production, from concentrated hemicellulose hydrolyzate of sugarcane bagasse, in a fluidized bed bioreactor (FBR). The maximum xylitol concentration 28.9 g xylitol/L was obtained at a high aeration rate of 600 mL/min after 70 h of fermentation, indicating that the use of high aeration rate in this system is favored for better oxygen transfer into the immobilized cells. The specific xylitol productivity and the xylitol yield were of 0.4 g xylitol/L.h and 0.58 g xylitol/g xylose respectively. The immobilization efficiency at the end of the fermentation was of 65 %. After 90 h of fermentation xylitol productivity and yield decreased to 0.25 g xylitol/L.h and 0.47 g xylitol/g xylose respectively, indicating the beginning of xylitol consumption by the yeast. The use of FBR system with immobilized cells presented high xylitol yield and productivity.

Intensification of bioactive compounds extraction from medicinal plants using ultrasonic irradiation

Extraction processes are largely used in many chemical, biotechnological and pharmaceutical industries for recovery of bioactive compounds from medicinal plants. To replace the conventional extraction techniques, new techniques as high-pressure extraction processes that use environment friendly solvents have been developed. However, these techniques, sometimes, are associated with low extraction rate. The ultrasound can be effectively used to improve the extraction rate by the increasing the mass transfer and possible rupture of cell wall due the formation of microcavities leading to higher product yields with reduced processing time and solvent consumption. This review presents a brief survey about the mechanism and aspects that affecting the ultrasound assisted extraction focusing on the use of ultrasound irradiation for high-pressure extraction processes intensification.

Energetic and economic evaluation of waste glycerol cogeneration in Brazil

Glycerol is an important by-product of biodiesel production. It is used in many industrial segments, but the increasing production of this chemical has become an issue of concern. Many studies have been done to give new applicability to this product; a promising field is the usage of glycerol for energy production. Therefore, this study evaluates the technical and economic feasibility of a new and potential proposal at the national level, the generation of electricity and heat, through a cogeneration system using glycerol. The results demonstrate the viability of this proposal, since the payback on capital invested obtained was approximately 4 years, with the possibility of reduction to 3 years when installed in regions with low infrastructure.

Cell immobilization and xylitol production using sugarcane bagasse as raw material

Sugarcane bagasse pretreated by three different procedures (with 2% [v/v] polyethyleneimine (PEI), with 2% [w/v] NaOH, or with a sequence of NaOH and PEI) was used as cell immobilization carrier for xylitol production byCandida guilliermondii yeast. Fermentations using these pretreated carriers were performed in semidefined medium and in a hydrolysate medium produced from sugarcane bagasse hemicellulose. Sugarcane bagasse pretreated with NaOH was the best carrier obtained with respect to immobilization efficiency, because it was able to immobilize a major quantity of cells (0.30 g of cells/g of bagasse). Fermentation in semidefined medium using the NaOH-pretreated carrier attained a high efficiency of xylose-to-xylitol bioconversion (96% of the theoretical value). From hydrolysate medium, the bioconversion efficiency was lower (63%), probably owing to the presence of other substances in the medium that caused an inadequate mass transfer to the cells. In this fermentation medium, better results with relation to xylitol production were obtained by using PEI-pretreated carrier (xylose-to-xylitol bioconversion of 81% of the theoretical and volumetric productivity of 0.43 g/[L·h]). The results showed that sugarcane bagasse is a low-cost material with great potential for use as cell immobilization carrier in the fermentative process for xylitol production.

Subcritical and supercritical technology for the production of second generation bioethanol

Abstract There is increased interest in reducing our reliance on fossil fuels and increasing the share of renewable raw materials in our energy supply chain due to environmental and economic concerns. Ethanol is emerging as a potential alternative to liquid fuels due to its eco-friendly characteristics and relatively low production costs. As ethanol is currently produced from commodities also used for human and animal consumption, there is an urgent need of identifying renewable raw materials that do not pose a competitive problem. Lignocellulosic agricultural residues are an ideal choice since they can be effectively hydrolyzed to fermentable sugars and integrated in the context of a biorefinery without competing with the food supply chain. However, the conventional hydrolysis methods still have major issues that need to be addressed. These issues are related to the processing rate and generation of fermentation inhibitors, which can compromise the quality of the product and the cost of the process. As the knowledge of the processes taking place during hydrolysis of agricultural residues is increasing, new techniques are being exploited to overcome these drawbacks. This review gives an overview of the state-of-the-art of hydrolysis with subcritical and supercritical water in the context of reusing agricultural residues for the production of suitable substrates to be processed during the fermentative production of bioethanol. Presently, subcritical and/or supercritical water hydrolysis has been found to yield low sugar contents mainly due to concurrent competing degradation of sugars during the hydrothermal processes. In this line of thinking, the present review also revisits the recent applications and advances to provide an insight of future research trends to optimize on the subcritical and supercritical process kinetics.

Extraction of Volatile Oils by Supercritical Fluid Extraction: Patent Survey

This review will cover the application of supercritical of fluid extraction (SFE) for obtaining volatile oils (VOs) from aromatic, spice and medicinal plants. A brief discussion of advantages and disadvantages of SFE for obtaining these very complex mixtures of substances will be presented. The chemical profile of volatiles oils obtained by SFE will be compared with that obtained by the conventional process, that is, steam distillation. Applications of SFE to obtain clove and chamomile volatiles oils based on the LASEFIs experience will also be considered. Finally, we will successively detail the patent evolution over time involving extraction of VOs by SFE that have been claimed.

Economic Analysis of an Integrated Annatto Seeds-Sugarcane Biorefinery Using Supercritical CO2 Extraction as a First Step

Recently, supercritical fluid extraction (SFE) has been indicated to be utilized as part of a biorefinery, rather than as a stand-alone technology, since besides extracting added value compounds selectively it has been shown to have a positive effect on the downstream processing of biomass. To this extent, this work evaluates economically the encouraging experimental results regarding the use of SFE during annatto seeds valorization. Additionally, other features were discussed such as the benefits of enhancing the bioactive compounds concentration through physical processes and of integrating the proposed annatto seeds biorefinery to a hypothetical sugarcane biorefinery, which produces its essential inputs, e.g., CO2, ethanol, heat and electricity. For this, first, different configurations were modeled and simulated using the commercial simulator Aspen Plus® to determine the mass and energy balances. Next, each configuration was economically assessed using MATLAB. SFE proved to be decisive to the economic feasibility of the proposed annatto seeds-sugarcane biorefinery concept. SFE pretreatment associated with sequential fine particles separation process enabled higher bixin-rich extract production using low-pressure solvent extraction method employing ethanol, meanwhile tocotrienols-rich extract is obtained as a first product. Nevertheless, the economic evaluation showed that increasing tocotrienols-rich extract production has a more pronounced positive impact on the economic viability of the concept.

Pressurized Liquid Extraction as a Promising and Economically Feasible Technique for Obtaining Beta-Ecdysone-Rich Extracts from Brazilian Ginseng (Pfaffia glomerata) Roots

Pressurized liquid extraction was used to obtain beta-ecdysone-rich extracts from Brazilian ginseng (Pfaffia glomerata) roots. The effects of temperature, pressure, and solvent on extraction yield, beta-ecdysone content, and antioxidant activity were determined. Extraction yield increased with temperature up to 25% (dry basis) while the selectivity decreased. The use of Ethanol:Water (80:20 v/v) as solvent produced extracts with the highest antioxidant activity. Beta-ecdysone recovery was maximized using pure ethanol. In the first hour of extraction, approximately 70% of the total yield and 74% of the total beta-ecdysone mass is obtained. The cost of manufacturing significantly decrease as the extractor capacity increased.

Optimization of Supercritical Fluid Extraction of Antioxidant Compounds from Venezuelan Rosemary Leaves

Abstract The extraction of the antioxidant compounds from rosemary can be achieved by means of various processes, such as hydrodistillation, soxhlet extraction, microwave-accelerated hydrodistillation (MAHD) and supercritical fluid extraction (SFE). The aim of our study was to optimize SFE variables such as extraction pressure, extraction temperature and static extraction time for the maximum extraction of carnosol and carnosic acid from Venezuelan rosemary (Rosmarinus officinalis L.) leaves by using 23 full factorial and Box-Behnken designs and Response Surface Methodology (RSM). The chemical characterization of the supercritical fluid extracts was achieved by high-performance liquid chromatography (HPLC), and the antioxidant activity was determined by the peroxide index assay. For the extraction of carnosol, the variables of extraction temperature and static extraction time were statistically significant, and for the extraction of carnosic acid, only the extraction temperature-static extraction time interaction was significant. At a fixed pressure, the highest extraction of carnosol and carnosic acid were achieved when the operational extraction conditions of extraction temperature and static extraction time were set at 48°C for 69 min and 64°C for 57 min, respectively. SFE extracts presented higher antioxidant activities than commercial and soxhlet extracts, and pure dibutyl hidroxytoluene (BHT). Since the carnosic acid/carnosol ratios presented in our SFE extracts are higher than those from other countries, possibly it would be expected that higher antioxidant activity values would be obtained for the Venezuelan extracts.