SubcriticalWater – a Perspective ReactionMedia for Biomass Processing to Chemicals: Study on Cellulose Conversion as aModel for Biomass

Biomass and water are recognized as a key renewable feedstock in sustainable production of chemicals, fuels and energy. Subcritical water (SubCW), or commonly referred as hot compressed water (HCW), is the water above boiling and below critical point (CP; 374 °C, 22.1 MPa). It has gained great attention in the last few decades as a green, cheap, and nontoxic reagent for conversion of biomass into valuable chemicals. In this paper, hydrothermal reactions of cellulose, as the model biomass substance, with subcritical water at mild temperature and pressure regimes have been studied. The experiments were done in a batch reactor in the temperature range of 220 ° – 300 °C. The main products distributed in liquid, gaseous and solid phase were separated and quantified. The conversions to each group of products were found strongly dependent on the temperature and residence time

Antioxidant, Radical Scavenging and Antimicrobial Activities of Red Onion (Allium cepa L) Skin and Edible Part Extracts

The antioxidant, radical scavenging and antimicrobial activities of extracts from skin and edible part of red onion have been investigated. Crude extracts of red onion were obtained separately with acetone, ethanol and mixtures of solvents with water. The amounts of isolated phenolic compounds and quercetin from onion skin were approximately 3 to 5 times higher as from the onion edible part. Antioxidant and radical scavenging activities of onion skin extracts were generally high, results were comparable to that of BHT. Extracts from onion edible part showed somewhat lower activity. Furthermore, high activity of skin extracts against bacteria Escherichia coli, Pseudomonas fluorescens and Bacillus cereus and fungi Aspergillus niger, Trichoderma viride and Penicillium cyclopium was observed. Antimicrobial activity of edible part extracts against tested microorganisms is generally lower, while for Escherichia coli no growth inhibition was observed

Hydrothermal Degradation of Fats, Carbohydrates and Proteins in Sunflower Seeds after Treatment with Subcritical Water

In this study, the hydrothermal degradation of fats, carbohydrates and proteins in sunflower seeds after treatment with subcritical water was observed. Sunflower seeds were subjected to subcritical water in a wide temperature range (130–240 °C) for periods from 5 to 120 minutes. The oil- and water-soluble phases were analysed for products of hydrothermal degradation. Oil stability was investigated by analysing the content of free fatty acids using gas chromatography. The water-soluble phase was analysed for the presence of any formed amino acids, and the amount of carbohydrates remaining after treatment was determined. Total amino acids and carbohydrates were determined using the ninhydrin and phenol/sulphuric acid spectrophotometric methods, respectively. The results show that oils are the most stable macronutrient present in sunflower seeds. Only small amounts of free fatty acids had formed during processing but the amount drastically started to increase at 240 °C. Proteins seem to be less stable than oils, whereas carbohydrates have proven to be very susceptible to hydrothermal degradation

Integrated Process to Obtain Anthocyanin Enriched Palm-Fat Particles from Elderberry Juice

Two novel technologies were applied in order to investigate concentration and formulation of anthocyanins for potential use in food industry. Integrated membrane process technology was applied for concentrating elderberry juice. In the first step, the juice was clarified by microfiltration, followed by a pre-concentration step with reverse osmosis. Finally, the juice was concentrated to the end concentration of 56 °Brix by osmotic distillation. The elderberry juice concentrate was formulated in a powderous form by a high-pressure process — Particles from Gas Saturated Solution (PGSS™) — using supercritical CO2. The applied carrier material was palm fat. The products with different anthocyanin-carrier ratios were measured for their colour properties (lightness, hue angle, and saturation). Colour stability was monitored for prolonged storage at different conditions (light/dark and ambient temperature/ refrigerator). The obtained powderous anthocyanin-palm fat products showed good colour stability, which gives good bases for potential applications in the future

Sustainable Processes Using Sub- and Super Critical Fluids

Abstract“Process intensification” as a part of necessary sustainable development and “green” revolution uses also high pressure as a processing tool. The main impetus for this is on one way driven by environmental concerns to reduce the usage of conventional solvents and energy. On the other hand high pressure is a tool to design and produce the products with completely new and specified properties. Extraction of substances from plant materials and their “in situ” formulation in products with specific properties is at the moment one of the very promising applications of supercritical fluids. Other advanced processes are polymer processing in/with supercritical fluids, use of sub-and supercritical fluids as sustainable reaction media, etc. The presentation will give also a limited overview of processes and applications of sub-and supercritical fluids as green processing media. For these processes recent advances and trends of developments will be presented. There are several processes using sub- and supercritical fluids which are already developed to the commercial scale, like dry cleaning, high pressure sterilization, jet cutting, thin-film deposition for microelectronics, separations of value-added products from fermentation broths in biotechnology fields and as the solvent in a broad range of synthesis. All of these applications lead to sustainable manufacturing methods that are not only ecologically preferable but also give the products with very special properties. One of the most important advantages of the use of supercritical fluids is selective extraction of components or fractionation of total extracts. This is possible by the use of different gases for isolation/fractionation of components and/or by changing process parameters. Phase equilibria of sunflower and soybean oils in propane and sulphur hexafluoride (SF6) have been investigated. For both systems, the transition of the two-phase system to one-phase system was observed visually at 25°C and 40°C and at different system compositions generally in the range of 0.2–0.7 weight fraction of propane. High-pressure vapor−liquid-phase equilibria (P−T−x−y) for the soybean oil−SF6 and sunflower oil−SF6 systems were investigated at temperatures of (25°C and 40°C) in the pressure range from (1 to 50) MPa. The phase behavior of two vegetable oils in sulfur hexafluoride (SF6) was studied using an isothermal−analytical method in combination with a visual-synthetic method using a variable-volume cell. Moreover, the phase inversions for the vegetable oil−SF6 systems were also recorded at both temperatures under investigation