Integrated Process and Product Design for Sustainable Biorefineries

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Application of a novel approach to modelling the supercritical extraction kinetics of oil from two sets of chia seeds

Publication . Villanueva Bermejo, David; Fornari, Tiziana; Calvo, Maria V.; FONTECHA, JAVIER; Coelho, Jose; Filipe, Rui; Stateva, Roumiana P.

The kinetics of the supercritical fluid extraction of edible and discarded chia seeds was studied and modelled for the first time. The total oil was removed at 45 MPa and 60 degrees C after 240 min. The extraction kinetics was simulated using a dynamic model in gPROMS ModelBuilder environment and the kinetic parameters estimated. Triolein was chosen as a model compound of the chia oil. The agreement between the experimental yields and those calculated by the model was good with deviations in the range (1.2-6.6) %, except at 25 MPa and 60 degrees C (AARD = 9.5%). (C) 2019 The Korean Society of Industrial and Engineering Chemistry.

2020-02-25Journal article

Open access

Fatty acid content in biomasses: state-of-the-art and novel physical property estimation methods

Publication . Sousa, Ana; Andrade, Thalles; Errico, Massimiliano; Coelho, Jose; Filipe, Rui; Matos, Henrique A.

In line with the growing environmental awareness developed along the last decades, modern societies are urged to evolve into sustainable economics where the reuse of organic wastes represents the key feedstock for a green transaction. The oil phase obtained from different biomasses has the potential to be a source of food supplements, medicines, cosmetics, or feedstock for biofuel production. In the present work, the composition of 104 different biomasses including seeds, peels, flowers, plants, and leaves has been reviewed for the lipid content. Based on the most frequent fatty acids screened, experimental data for normal boiling point temperature, normal melting point, critical properties, and acentric factor were collected and compared with the most common estimation methods, which are functions of the molecular structure and interaction between different functional groups. New predictive equations have been proposed to reduce the estimation deviation and to provide simple correlations to be used in simulation software when dealing with biomass processes. For all the properties, the estimations proposed have an absolute average deviation equal to or lower than 4.6%.

2019-11-23Journal article

Restricted access

Supercritical CO2 extraction of spent coffee grounds. Influence of co-solvents and characterization of the extracts

Publication . Coelho, Jose; Filipe, Rui; Robalo, M. Paula; Boyadzhieva, Stanislava; Cholakov, Georgi; Stateva, Roumiana

Spent coffee grounds (SCGs) were extracted with supercritical CO2 at temperatures of 313 K and 333 K, pressures up to 50.0 MPa and different scCO(2) flow rates. The addition of co-solvents isopropanol, ethanol and ethyl lactate decreased the time to achieve the maximum oil yield, to half of that with pure CO2. Analysis of the extracted oils by NMR, showed that caffeine content was (0.56-3.96) % and DUFA and MUFA contents changed within (39.8-42.0) % and (12.9-15.8) %, respectively. The analyses of fatty acids performed by GC-FID revealed the composition of the oils being 76 % of the total constituted by palmitic and linoleic esters. The DPPH antioxidant capacity was improved up to 12.5 times with co-solvents. The kinetics of oil extraction from SCGs with pure scCO(2) was modeled successfully by combining for the first time representation of the oil mixture by a single virtual molecule with group contribution methods.

2020-07-01Journal article

Restricted access

Microwave-assisted extraction of phenolic compounds from spent coffee grounds. Process optimization applying design of experiments

Publication . Coelho, Jose; Robalo, Maria Paula; Boyadzhieva, Stanislava; Stateva, Roumiana

In this study, sustainable technology microwave-assisted extraction (MAE) in association with green solvents was applied to recover phenolic compounds from spent coffee grounds (SCGs). A design of experiments (DOE) was used for process optimization. Initially, a 2(4-1) two level Fractional Factorial Design was used and ratios "solvent to solute" and "ethanol to water" were identified as the significant experimental factors. Consequently, Central Composite Design (CCD) was applied to analyze the effects of the significant variables on the response yield, total polyphenols content (TPC), and antioxidant activity (AA) by the DPPH assay method, and quadratic surfaces to optimize those responses were generated. The values of the significant factors of 16.7 (solvent/solute) and 68.9% (ethanol/water) were optimized simultaneously the yield (%) at 6.98 +/- 0.27, TPC (mg GAE/g) at 117.7 +/- 6.1, and AA (mu mol TE/g) at 143.8 +/- 8.6 and were in excellent agreement with those predicted from the CCD model. The variations of the compositions of the lipids, caffeine, pentacyclic diterpenes, and FAME as a function of the dominant factor % ethanol in the solvent mixture were analyzed by applying NMR and GC-FID, and the results obtained confirmed their determinative significance.

2021-12-02Journal article

Open access