Recovery Of Caffeine Research Articles

Ultrasound combined with microwave hydrodiffusion and gravity for enhancement of caffeine extraction from guarana powder.

The extraction of valuable compounds from dried fruits and vegetables by microwave hydrodiffusion and gravity (MHG) requires previous hydration of the plant material. In this work, ultrasound was used to speed up the hydration of guarana powder before MHG extraction and increase caffeine recovery. The humidification step was speeded up with ultrasound taking only 15 min over 60 min without ultrasound. Water and 50% (v/v) ethanol were evaluated as green solvents for humidification, with a higher concentration of caffeine obtained for the hydroalcoholic solution. Ultrasound pretreatment allowed guarana extracts from MHG with two times more caffeine for both solvents evaluated. Therefore, ultrasound can be used in the hydration step before MHG extraction to reduce time and increase caffeine recovery from guarana powder.

Extraction of Caffeine from Spent Coffee Ground by Solid-liquid Extraction

The current research aims to utilize the spent coffee ground as a feedstock which is a waste material with a negative effect on the environment to extract natural bioactive valuable caffeine and determine the effective parameters of the extraction process efficiency in terms of caffeine concentration. The key studied parameters included extraction time 0- 150 min, temperature 25-55˚C, mixing speed (180-450 rpm), pH of suspension (4-9), and solvent type. The results of the experimental work showed that changing the pH of the suspension has a significant impact on the recovery rate of caffeine. When only water was used as a solvent, the concentration of caffeine increased from 135.061 (mg/L) to 2478.179 (mg/L) by increasing the pH of the suspension to 9. Another promising finding is that by changing the solvent type to an aqueous organic solvent, where the recovery of caffeine augmented remarkably. When 20% ethanol-water was utilized as a solvent and at the pH of 6 (the original pH) of the suspension, the concentration of obtained caffeine increased from 135 mg/L to 213 mg/L. Furthermore, increasing the ethanol percentage to 80%, rising the caffeine concentration to 464 mg/L at the same pH. adjusting the pH of the suspension to 7, resulted in rising the obtained caffeine concentration to 2386.13 mg/l with a solvent concentration of 80% ethanol.

Tuneable solvents‐based extraction for the recovery of caffeine from coffee wastewater

AbstractTunable solvents represent a new generation of environmentally friendly solvents with potential applications in the effective extraction of bioactive compounds, including supramolecular solvents (SUPRAS). This study aimed to optimize caffeine extraction from coffee processing wastewater (CWW) using SUPRAS of various compositions. An extreme vertices design was employed to evaluate the SUPRAS composition. The synthesis of SUPRAS involved two amphiphiles (1‐hexanol and decanoic acid) in hydro‐organic solutions of tetrahydrofuran (THF). A statistical modeling approach was used to characterize the process and determine the optimal conditions for potential scale‐up within the coffee processing industry. The results indicated that SUPRAS offer a promising alternative to traditional solvents for extracting caffeine from CWW. The highest experimental extraction rate (~ 62%) was achieved using a 15% 1‐hexanol in a hydro‐organic solution of THF (47% v/v). This mixture corresponded to the optimum predicted by a special cubic statistical model (R2 = 0.9367; Adj‐R2 = 0.8608, and RSME = 3.2795). The percentage of caffeine extracted from CWW is considered acceptable, given the compound's affinity for water and the rapid (1 min) and straightforward approach employed. Moreover, the use of SUPRAS reduced solvent consumption, and the proposed statistical model identified conditions that maximized caffeine extraction while minimizing THF usage. This method can potentially lower process costs and solvent consumption. For large‐scale extraction, centrifugation can be substituted with spontaneous sedimentation. Overall, these findings have significant implications for the valorization of CWW, providing a sustainable and efficient method for the extraction of valuable compounds.

Ultra-trace detection of caffeine and theophylline with high sensitivity and selectivity using Gd2(MoO4)3 nanosheets

In this study, gadolinium molybdate, Gd2(MoO4)3 (Gam) nanosheets have been substantially synthesized using a hydrothermal method with varying reaction temperatures. PXRD, XPS, and HR-TEM confirmed the crystal phase and morphology of Gam nanosheets. According to CV, LSV, and EIS techniques, Gam (synthesized at 150 ℃) modified GCE possesses excellent electrochemical properties and further has been used for caffeine and theophylline detection. The limit of detection of caffeine was found to be 4.1 nM with a linear range of 0.01 – 0.1 μM and 0.2 – 1.6 μM. Limit of detection of theophylline was calculated to be 11.9 nM with a linear range of 0.03 – 1.5 μM and 2.0 – 4.5 μM. Gam modified GCE was applied for caffeine and theophylline detection in green tea leaves (GS-1) and coca (CS-2) samples and interestingly found capable for caffeine detection without spiking. After spiking, recoveries of caffeine and theophylline in GS-1 were achieved 100.6 – 101.7% and 102.57–105.21% respectively. In CS-2 the recoveries for caffeine and theophylline were found to be 98.3 – 101.8% and 97 – 99.33% respectively. The excellent long-term stability, recyclability, and real sample analysis validated the sensor for biological as well as pharmaceutical samples diagnosis.

Study of caffeine and coumarin extraction kinetics in an aqueous two-phase system based on polyethylene glycol 1500

Caffeine and coumarin are organic compounds of plant origin, which have biological activity and have found wide application in medicine, pharmaceutical, perfumery and food industries. Recovery of caffeine and coumarin from aqueous solutions using liquid-liquid extraction is the most effective method. In the present work the kinetic dependences of caffeine and coumarin in the aqueous two-phase system (ATPS) of PEG 1500 - Na2SO4 - H2O were experimentally obtained. It was established that equilibrium in the system is achieved after 17 minutes for caffeine and after 12 minutes for coumarin. The effect of ultrasound on the extraction rate of caffeine and coumarin in an aqueous two-phase system was also studied.

Spent Coffee Grounds’ Valorization towards the Recovery of Caffeine and Chlorogenic Acid: A Response Surface Methodology Approach

The amount of spent coffee grounds (SCGs) created, represents an environmental challenge worldwide. In this context, the aim of the present study was to exploit the potential of SCGs as a source of bioactive compounds that can be utilized in high value-added products. Thus, a cost-effective and environmentally friendly extraction technique was developed to ensure extracts with high total phenolic content and antioxidant activity, as well as significant amounts of caffeine and chlorogenic acid. Response surface methodology was implemented to evaluate the effects of the main extraction parameters (i.e., time, temperature, and ethanol-to-water ratio) and their interactions on the defined responses. The ethanol ratio was found to be the most significant variable. Then, a set of optimum values was determined (i.e., 7 min, 75 °C, and ethanol:water ratio 5:95), where the predicted values for responses were found to be 5.65% for the yield (Y1), 152.68 mg gallic acid equivalents per L for total phenolic content (Y2), 0.797 μmol Trolox equivalent per mL for the antioxidant activity (Y3), 30.5 ppm for caffeine concentration (Y4), and 17.4 ppm for chlorogenic acid concentration (Y5). Furthermore, the corresponding high experimental values from the validation experiment fitted well to these predictions, clearly clarifying the high potential of SCG extracts for use in high value-added applications.

Study of Influential Parameters of the Caffeine Extraction from Spent Coffee Grounds: From Brewing Coffee Method to the Waste Treatment Conditions

This article aims to study the interest of spent coffee grounds (SCG) valorization through caffeine recovery. In an original way, this study takes into account all the parameters such as (i) the brewing coffee methods (household, coffee shops, etc.); (ii) the storage conditions, in particular the drying step; (iii) the solid/liquid extraction parameters such as the nature of solvent, the temperature, the extraction time and the solid/liquid ratio; and (iv) the liquid/liquid purification parameters such as the nature, the volume and the pH of extraction medium. Results have shown that spent coffee grounds from coffee-shops obtained by percolation contain a higher amount of caffeine than spent coffee grounds from households obtained from spent pods or filters. A drying treatment is not required when extraction is performed under one week after the spent coffee grounds collection with 96.4% of not degraded caffeine. Solid/liquid extraction performed with 25 mL.g−1 SCG of hydroalcoholic solvent (water/EtOH, v/v 60/40) at 60 °C during 15 min have given a caffeine yield up to 4.67 mg.g−1 SCG. When using ethyl acetate, 93.4% of the caffeine has been selectively recovered by liquid/liquid extraction. Finally, the extraction of caffeine for the valorization of spent coffee grounds is a promising and easy way, which fits with an already important and well established market.

Automated liquid-liquid extraction of organic compounds from aqueous samples using a multifunction autosampler syringe

Liquid-liquid extraction is one of the most widely used and simplest sample preparation techniques. However, consumption of large volumes of organic solvent and manual handling are two major drawbacks of this technique. A multifunction autosampler syringe is introduced which permits automated liquid-liquid extraction in an enclosed operating environment, with low consumption of organic solvents. The device described herein features a micromixer function in addition to common autosampler syringe features like accurate and precise aspirating and dispensing. To test the functionality of the micromixer syringe, manual extraction of caffeine from a tea infusion and semi-automated extraction of dichloroethane from water were carried out. Excellent recoveries of caffeine from a tea infusion (89% recovery with 1.3% RSD) and dichloroethane from water (107% recovery with 10% RSD) were obtained. Two automated workflows were tested using the micromixer syringe mounted in a laboratory autosampler. Standalone automated micro liquid-liquid extraction was performed for sample preparation of selected polychlorinated biphenyl (PCB) congeners prior to comprehensive two-dimensional gas chromatography – electron capture detection analysis. Extraction of PCBs using the described approach used substantially less solvent than a validated solid-phase extraction approach whilst delivering equivalent results for samples with high-level PCBs. Finally, fully automated extraction and GC-MS analysis of polynuclear aromatic hydrocarbons (PAHs) from water samples was performed. Mean recoveries of extraction for PCB and PAH analysis were > 70% using 4 min automated liquid-liquid extractions.

ENHANCEMENT OF CAFFEINE RECOVERY FROM ROASTED COFFEE POWDER BY ENZYME CELLULASE PRETREATMENT, HOT-WATER EXTRACTION AND CO2-ADDING

The efficiency of caffeine recovery during extraction with highpressure hot-water solvent was investigated to find out the conditions for maximum caffeine recovery in roasted coffee powder. In addition, to support the extraction process with high-pressure hot-water solvent, cellulase enzyme pretreatment of roasted coffee powder is also applied and has demonstrated the supporting role of the enzyme in improving caffeine extraction efficiency. CO2 can participate in the extraction process with the role of changing the pH of the solvent at the high temperature and obtained positive results. In the presence of the enzyme cellulase at avalue of 8 UI/g, the pretreatment time was 90 minutes; the extraction process performed at 110oC for temperature and 10 min for the extraction time, the efficiency of caffeine recovery can reach 96,36 ±2,56%.

Extractive Freezing-out of Caffeine from Aqueous Solutions in a Centrifugal Force Field

The effect of the pH of the medium, the volume ratio of the extractant to water on the efficiency of caffeine extraction with acetonitrile from aqueous solutions by extractive freezing-out in a centrifugal force field is studied. The results can be explained in terms of the previously proposed theoretical process model. The highest recovery of caffeine was achieved at pH 6–7. The limit of determination of caffeine in water is 0.015 μg/mL.

3D-Printed Franz cells - update on optimization of manufacture and evaluation.

Laboratory in vitro permeation processes require the use of modified Franz type diffusion cells which are conventionally fabricated from glass. Fragility and high cost are frequently associated with this type of laboratory apparatus. The purpose of our present research was to develop a simple, economical and versatile approach to manufacture Franz type cells using additive manufacturing (AM). Graphical Franz diffusion cell designs were reproduced with a stereolithography (SLA) 3D printer and assessed over a minimum period of 24 h. The surface morphology of AM printouts was analysed before and after compatibility studies using scanning electron microscopy (SEM). Comparative permeation studies in both glass and AM Franz type diffusion cells were conducted using a caffeine solution (1.5 mg mL-1 ), applied to a model silicone membrane. Testing of the 3D printed scaffolds confirmed similar recovery of the permeant when compared to glass cells: 1.49 ± 0.01 and 1.50 ± 0.01 mg mL-1 , respectively, after 72 h. No significant differences were visible from the SEM micrographs demonstrating consistent, smooth and non-porous surfaces of the AM Franz cells' core structure. Permeation studies using transparent 3D printed constructs resulted in 12.85 ± 0.53 µg cm-2 caffeine recovery in the receptor solution after 180 min with comparable permeant recovery, 11.49 ± 1.04 µg cm-2 , for the glass homologues. AM constructs can be considered as viable alternatives to the use of conventional glass apparatus offering a simple, reproducible and cost-effective method of replicating specialised laboratory glassware. A wider range of permeants will be investigated in future studies with these novel 3D printed Franz diffusion cells.

High intensity ultrasound assisted decaffeination process of coffee beans in aqueous medium.

The purpose of this study was to determine the influence of ultrasound intensity, pulse and temperature on extraction of caffeine, from Arabica coffee beans using water as solvent, and ultrasound frequency of 24kHz. A central composite design was used, using ultrasound intensity (31.5-105Wcm-2), pulse (0.30-1) and extraction temperature of the extraction (30-60°C) as independent factor. The caffeine recovery and caffeine diffusion coefficient were response variables. The ultrasound intensity and extraction temperature significantly influenced the caffeine recovery rate and the diffusion coefficient of caffeine. Activation energy of 48.95kJmol-1 for the caffeine diffusion coefficient in ultrasound assisted extraction was observed. The best results were obtained at 68.25-105Wcm-2 ultrasound intensity and 60°C temperature, corresponding to caffeine recovery of 58.4-69.4% and diffusion coefficient of 8.92-10.57 × 10-11m2s-1. The pulse effect was not significant in the range of the studied variables.

Vacuum membrane distillation for the treatment of coffee products

Vacuum Membrane Distillation (VMD) was applied in two production lines of the coffee industry: the concentration of the coffee extract and the dehydration and recovery of caffeine.Experiments were carried out by using a commercial flat microporous membrane made of polypropylene (0.2 μm pore size). Both systems worked with a vacuum value of 4 mbar, while the temperature was fixed at 45 °C and at 27 °C for the caffeine recovery and the coffee extract concentration, respectively. Starting from an extract of 13 wt%, it was possible to concentrate it up to the values needed for the instantaneous/soluble coffee production, while dry caffeine was recovered from a 0.1–0.3 wt% aqueous feed. In both case studies, a pure distillate stream, able to be re-used in the plant, was obtained.

A new synthetic route to molecularly imprinted ORMOSIL: Characterization and evaluation

ABSTRACTA new strategy for synthesis of molecularly imprinted organically modified silica (MIORMOSIL) has been described. The MIORMOSIL was prepared by reacting vinyl acetate and 3-(trimethoxysilyl) propyl methacrylate, followed by condensation and hydrolysis with tetraethyl orthosilicate in the presence of caffeine. The ORMOSIL was characterized by SEM, FTIR, 29Si MAS NMR, 13C MAS NMR, TGA, nitrogen adsorption/desorption and tested to extract analyte from coffee samples. The percentage recovery of caffeine 88 ± 5% (n = 9), limits of detection and quantification, 5.14 × 10–4 and 1.71 × 10−3 mmolL−1 respectively, were achieved. Cross reactivity studies for theophylline and theobromine showed high recovery (77% and 82% respectively).Abbreviations: HMIP: Molecularly Imprinted ORMOSIL; HNIP: non imprinted ORMOSIL; TMSPM: 3-(Trimethoxysilyl)propylmethacrylate

Fluorescence Based Turn-on Probe for the Determination of Caffeine Using Europium-Tetracycline as Energy Transfer Complex.

The study describes a simple and sensitive fluorometric sensor based on the enhancement of fluorescence intensity of Europium ion (Eu(3+)) - tetracycline (TC) charge transfer complex on addition of caffeine. The Eu(3+)-TC ternary complex has a characteristic emission peak at 615nm (λex=375nm), the intensity of which increases with increase in concentration of caffeine. The caffeine sensor assay was found to be linear in the range of 0.0515mM to 51.5mM. The limit of detection and quantification were found to be 0.0515mM and 0.382mM, respectively. A caffeine recovery of 90 to 110% in biological samples (serum and urine) indicated minimal interference by commonly present excipients in the samples. Rosenthal plots to calculate the binding capacity of caffeine with the Eu(3+)- TC complex revealed an association constant (K) of 238 x 10(3)L/mol and binding number (N) of 1.9. Bland-Altman plot comparing the developed assay and HPLC showed good agreement between values obtained by both the methods. The proposed fluorescent chemical sensor is a rapid and convenient method to determine caffeine with excellent recovery and low detection limit. The probable reaction mechanism for the formation of the turn on fluorescent probe enhancer is discussed.

Synthesis and Properties of Caffeine Molecularly Imprinted Polymers Based on Konjac Glucomannan

A novel molecularly imprinted polymers (MIPs) for caffeine based on konjac glucomannan (KGM) was prepared using grafted copolymer of KGM/acrylic acid as a functional monomer, N,N′-methylenebisacrylamide as a cross-linker, and caffeine as a template. The recognition sites in MIPs were confirmed by Fourier transform infrared spectroscopy and the morphology of MIPs was characterized by scanning electron microscopy. Compared with nonimprinted polymers (NIPs), the obtained MIPs showed high adsorption capacity and good selectivity for caffeine. The maximum adsorption (Qmax) of MIPs and NIPs for caffeine was 62.97 and 21.67 mg/g, respectively. The selective factor (α) of MIPs and NIPs was 2.50 and 0.91, respectively. Adsorption isotherm of MIPs followed the Langmuir equation. In addition, the obtained materials were packed on solid-phase extraction (SPE) cartridges and evaluated as a sorbent for selective trapping and preconcentration of caffeine from real beverage samples. Under the optimized extraction conditions, recoveries of caffeine ranging from 91.3 to 99.2% was achieved.

A Conceptual Demonstration of Decaffeination via Nanofiltration

This study aims to evaluate the feasibility of using novel nanofiltration (NF) membranes for decaffeination of coffee wherein caffeine present in the feed solution is recovered at the permeate of the membrane. The NF hollow fiber membranes were fabricated and tested with model solutions to evaluate the recovery of caffeine as functions of molecular weight/size of organic molecules, caffeine concentration, and feed temperature. The results show that the recovery of caffeine and the permeate flux decrease with an increase in molecular weight/size of the organic molecules and the caffeine concentration in the feed. On the other hand, both recovery and flux increase with increasing feed temperature. Decaffeination of coffee is subsequently demonstrated at 55 °C using a roasted coffee solution wherein a 25% reduction of caffeine is achieved with a volume reduction factor of ∼1.2.

Pressurized liquid extraction of caffeine and catechins from green tea leaves using ethyl lactate, water and ethyl lactate + water mixtures

Ethyl-lactate (ethyl 2-hydroxy-propanoate) is a bio-renewable agrochemical solvent, very suitable and environmental benign for food applications, permitted by the U.S. Food and Drug Administration as pharmaceutical and food additive. In previous work, the authors demonstrated that pressurized liquid extraction (PLE) using ethyl lactate is a suitable alternative to remove caffeine from vegetal materials, e.g. green coffee beans and green tea leaves. The solubility of caffeine in ethyl lactate+water mixtures, at ambient temperature and pressure, exhibits a substantial increase for 60:40% ethyl lactate+water mixtures (data reported in this work). This result motivated the analysis of the effect of the ethyl lactate+water mixtures for the decaffeination target.Furthermore, in the case of green tea, the removal of caffeine reducing the extraction of catechins is desirable due to the adverse effects of caffeine on health, while catechins are high valued functional food ingredients. Thus, the use of ethyl lactate, water and ethyl lactate+water mixtures to attain this objective, i.e. the removal of caffeine form green tea leaves minimizing the extraction of catechins, was studied in this work.PLE was carried out in the temperature range 373–473K and using different ethyl lactate+water mixtures. Extraction yield and recovery of key bioactive compounds (caffeine and monomeric catechins) were determined and compared, and the caffeine/catechins selectivity of the different solvents employed was estimated.High extraction yields were obtained with a mixture containing 25:75% of ethyl lactate+water, with values around 1.5 and 3.5 times higher than, respectively, the yields obtained with water and ethyl lactate. Yet, pure ethyl lactate proved to be the most selective solvent to extract caffeine from green tea leaves, minimizing the co-extraction of catechins, with a caffeine/catechins selectivity of 2.8 to 5.5 in the range 373–423K. At these temperatures, with short extraction times (20min) the recovery of caffeine is in the range 53–76% but only 26–36% of catechins present in the tea leaves were removed.

Effect of cosolvents (ethyl lactate, ethyl acetate and ethanol) on the supercritical CO2 extraction of caffeine from green tea

This paper reports experimental data to analyze the effect of different green cosolvents, namely ethyl lactate, ethyl acetate and ethanol, on the supercritical carbon dioxide (SCCO2) extraction of caffeine from green tea leaves.The experiments were carried out in a pilot-scale plant using two different approaches: a static procedure in which the cosolvent was introduced in the extraction cell soaking the vegetal material and then SCCO2 was pumped, and a dynamic assay in which the cosolvent was pumped and mixed with SCCO2 before introduction into the extraction cell. The overall caffeine recovery from plant matrix was determined for all experiments at the same extraction conditions (30MPa and 343K). Additionally, the overall extraction curves of the static experiments were determined at the same process conditions, and the mass transfer model of Sovová was utilized to adjust the kinetic data and to determine the mass transfer coefficients.The highest caffeine yield was obtained with ethyl lactate in both static and dynamic extractions (13.0 and 14.2mg/g of tea, respectively), followed by ethanol (10.8mg/g with the static method and 8.8mg/g with the dynamic method). The yield obtained with ethyl acetate in both extraction approaches was lower than 7mg/g. These data reinforce previous results obtained by the authors regarding the competence of ethyl lactate in the extraction of caffeine from natural materials.

Does volumetric absorptive microsampling eliminate the hematocrit bias for caffeine and paraxanthine in dried blood samples? A comparative study

Volumetric absorptive microsampling (VAMS) is a novel sampling technique that allows the straightforward collection of an accurate volume of blood (approximately 10μL) from a drop or pool of blood by dipping an absorbent polymeric tip into it. The resulting blood microsample is dried and analyzed as a whole. The aim of this study was to evaluate the potential of VAMS to overcome the hematocrit bias, an important issue in the analysis of dried blood microsamples. An LC-MS/MS method for analysis of the model compounds caffeine and paraxanthine in VAMS samples was fully validated and fulfilled all pre-established criteria. In conjunction with previously validated procedures for dried blood spots (DBS) and blood, this allowed us to set up a meticulous comparative study in which both compounds were determined in over 80 corresponding VAMS, DBS and liquid whole blood samples. These originated from authentic human patient samples, covering a wide hematocrit range (0.21–0.50). By calculating the differences with reference whole blood concentrations, we found that analyte concentrations in VAMS samples were not affected by a bias that changed over the evaluated hematocrit range, in contrast to DBS results. However, VAMS concentrations tend to overestimate whole blood concentrations, as a consistent positive bias was observed. A different behavior of VAMS samples prepared from incurred and spiked blood, combined with a somewhat reduced recovery of caffeine and paraxanthine from VAMS tips at high hematocrit values, an effect that was not observed for DBS using a very similar extraction procedure, was found to be at the basis of the observed VAMS-whole blood deviations. Based on this study, being the first in which the validity and robustness of VAMS is evaluated by analyzing incurred human samples, it can be concluded that VAMS effectively assists in eliminating the effect of hematocrit.