Extraction of coffee diterpenes and coffee oil using supercritical carbon dioxide

Direct Hot Solid-Liquid Extraction (DH-SLE): A High-Yield Greener Technique for Lipid Recovery from Coffee Beans

Soxhlet extraction is a method recommended by the Association of Official Analytical Chemists (AOAC) to determine the lipid content in plant samples. Generally, n-hexane (toxicity grade 5) is used as the solvent (≈300 mL; ≈30 g sample) at boiling temperatures (69 °C) for long times (≤16 h) under a chilled water reflux (≈90 L/h), proportionally aggravated by the number of repetitions and samples determined. In this sense, the technique is neither safe nor sustainable for the analyst or the environment. This article presents the development of an alternative and more sustainable procedure for determining the lipid content in raw Arabica coffee beans. A 33 full factorial design was used to perform direct hot solid-liquid extractions in 4 mL vials, varying the ground grains and solvent ratios, temperatures, and times. An optimal condition resulted in an extractive yield statistically equivalent to Soxhlet, without variation in the composition of the oil fatty acids determined by GC-MS after hole oil transesterification. This procedure was presented as a sustainable alternative to Soxhlet extraction because it does not require water for cooling and needs a smaller volume of solvent (2 mL) and sample mass (0.2 g); it also has a smaller generated residue, as well as requiring a shorter time (1.5 h) and less energy expenditure for extraction.

Coffee Oil Extraction Methods: A Review

Green and roasted coffee oils are products rich in bioactive compounds, such as linoleic acid and the diterpenes cafestol and kahweol, being a potential ingredient for food and cosmetic industries. An overview of oil extraction techniques most applied for coffee beans and their influence on the oil composition is presented. Both green and roasted coffee oil extractions are highlighted. Pressing, Soxhlet, microwave, and supercritical fluid extraction were the most used techniques used for coffee oil extraction. Conventional Soxhlet is most used on a lab scale, while pressing is most used in industry. Supercritical fluid extraction has also been evaluated mainly due to the environmental approach. One of the highlighted activities in Brazilian agribusiness is the industrialization of oils due to their increasing use in the formulation of cosmetics, pharmaceuticals, and foods. Green coffee oil (raw bean) has desirable bioactive compounds, increasing the interest of private companies and research institutions in its extraction process to preserve the properties contained in the oils.

Extraction of Diterpene-Phytochemicals in Raw and Roasted Coffee Beans and Beverage Preparations and Their Relationship

Cafestol and kahweol are expressive furane-diterpenoids from the lipid fraction of coffee beans with relevant pharmacological properties for human health. Due to their thermolability, they suffer degradation during roasting, whose products are poorly studied regarding their identity and content in the roasted coffee beans and beverages. This article describes the extraction of these diterpenes, from the raw bean to coffee beverages, identifying them and understanding the kinetics of formation and degradation in roasting (light, medium and dark roasts) as the extraction rate for different beverages of coffee (filtered, Moka, French press, Turkish and boiled). Sixteen compounds were identified as degradation products, ten derived from kahweol and six from cafestol, produced by oxidation and inter and intramolecular elimination reactions, with the roasting degree (relationship between time and temperature) being the main factor for thermodegradation and the way of preparing the beverage responsible for the content of these substances in them.

The effect of excessive coffee consumption, in relation to diterpenes levels of medium-roasted coffee, on non-high-density lipoprotein cholesterol level in healthy men

This study was designed to determine the levels of coffee oil and diterpenes and evaluate the correlation between the effect of excessive roasted coffee consumption on non-high-density lipoprotein cholesterol (non-HDL) and the roasting degree effect on the levels of coffee oil and diterpenes extracted from Coffea arabica. The coffee oil and diterpenes were extracted using soxhlet and liquid-liquid extraction. Sixty-six healthy normolipidemic male participants were assigned for this study which consisted of two stages. The first stage is the coffee abstaining stage where subjects were requested to abstain from drinking coffee for 2 weeks. The second stage is the coffee drinking stage which consisted of groups (the control group and coffee-drinking group). The levels of TC, TG, LDL-C, HDL-C, and non-HDL were determined in all participants before and after the experiment. The results indicated that the coffee roasting degree demonstrated a significant increase in the levels of coffee oil and diterpenes ranging from 9.31% (green coffee) to 15.64% (dark roast) and from 0.205% (green coffee) to 0.300% (dark roast) for diterpenes. In conclusion, the current study revealed that excessive consumption of medium roasted coffee was associated with elevated non-HDL levels in normotensive nonsmoker healthy men which might be attributed to the positive association between the degree of roasting and diterpenes levels.

The Agro-Economic Feasibility of Growing the Medicinal Plant Euphorbia peplus in a Modified Vertical Hydroponic Shipping Container

Vertical farming is considered as a potential solution to increase yield while decreasing resource use and pesticide impacts compared to conventional agriculture. However, the profitability of cultivating ordinary leafy green crops with low market prices in vertical farming is debated. We studied the agronomic feasibility and viability of growing a medicinal plant—Euphorbia peplus—for its ingenol-mebutate content in a modified shipping container farm as an alternative crop cultivation system. The impacts of three hydroponic substrates, three light intensities, three plant localizations and two surface areas on E. peplus yield and cost were tested in several scenarios. The optimization of biomass yield and area surface decreased the cultivation cost, with fresh crop cost per kg ranging from €185 to €59. Three ingenol-mebutate extraction methods were tested. The best extraction yields and cheapest method can both be attributed to ethyl acetate at 120 °C, with a yield of 43.8 mg/kg at a cost of €38 per mg. Modeling of the profitability of a pharmaceutical gel based on ingenol-mebutate showed that economic feasibility was difficult to reach, but some factors could rapidly increase the profitability of this production.

Analysis of Phytosterols Content in Italian-Standard Espresso Coffee

This study aims to assess for the first time the content of phytosterols (PS) in espresso coffee (EC) to deepen the knowledge about the phytochemicals and health potentials of coffee brews. PS were extracted by hot saponification from 14 EC samples produced with coffee originating from 13 coffee-producing countries. PS were identified and quantified by high-performance liquid chromatography (HPLC) after derivatization. Among the detected PS, β-sitosterol (4.1–18.2 mg/L) was the most abundant followed by stigmasterol (1.1–4.9 mg/L), campesterol (0.9–4.7 mg/L), and cycloartenol (0.3–2.0 mg/L). Total PS fraction ranged from 6.5 mg/L to 30.0 mg/L with an average level of 15.7 ± 5.8 mg/L. Therefore, a standard cup of EC (25 mL) could provide 0.4 ± 0.1 mg of PS.

Supercritical Fluid CO2 Extraction and Microcapsule Preparation of Lycium barbarum Residue Oil Rich in Zeaxanthin Dipalmitate

The scope of this investigation aimed at obtaining and stabilizing bioactive products derived from Lycium barbarum seeds and peels, which were the byproducts in the processing of fruit juice. Zeaxanthin dipalmitate is a major carotenoid, comprising approximately 80% of the total carotenoid content in the seeds and peels. The method of obtainment was supercritical fluid CO₂ extraction, studying different parameters that affect the oil yield and content of zeaxanthin dipalmitate. The optimized protocol to enact successful supercritical fluid CO₂ extraction included optimum extraction pressure of 250 bar, temperature at 60 °C over a time span of 2.0 h, and a CO₂ flow of 30 g/min, together with the use of a cosolvent (2% ethanol). The yields of oil and zeaxanthin dipalmitate under these optimal conditions were 17 g/100 g and 0.08 g/100 g, respectively. The unsaturated fatty acids were primarily linoleic acid (C18:2), oleic acid (C18:1), and γ-linolenic acid (C18:3), with their contents being as high as 91.85 ± 0.27% of the total fatty acids. The extract was a red-colored oil that was consequently microencapsulated through spray-drying with octenylsuccinate starch, gum arabic, and maltodextrin (13.5:7.5:3, w/w) as wall materials to circumvent lipid disintegration during storage and add to fruit juice in a dissolved form. The mass ratio of core material and wall material was 4:1. These materials exhibited the highest microencapsulation efficiency (92.83 ± 0.13%), with a moisture content of 1.98 ± 0.05% and solubility of 66.22 ± 0.24%. The peroxide content level within the microencapsulated zeaxanthin dipalmitate-rich oil remained at one part per eight in comparison to the unencapsulated oil, following fast-tracked oxidation at 60 °C for 6 weeks. This indicated the potential oxidation stability properties of microcapsule powders. Consequently, this microencapsulated powder has good prospects for development, and can be utilized for a vast spectrum of consumer health and beauty products.

New trends in coffee diterpenes research from technological to health aspects

The coffee oil is rich in diterpenes, mainly cafestol and kahweol, which are predominantly present in the esterified form with different fatty acids. Despite their beneficial effects including anti-angiogenic and anti-carcinogenic properties, they have been also associated with negative consequences such as elevation of blood cholesterol. Considering the coffee, it is an important human beverage with biological effects, including potentially health benefits or risks. Therefore, it may have important public health implications due to its widespread massive consumption, with major incidence in the varieties Arabica and Robusta. According to literatures, cafestol (182-1308 mg/100 g), kahweol (0-1265 mg/100 g) and 16-O-methycafestol (0-223 mg/100 g) are the main diterpenes in green and roasted coffee beans. Nevertheless, the coffee species, genetic background, and technological parameters like roasting and brewing have a clear effect on coffee diterpene content. Besides that, bibliographic data indicated that limited studies have specifically addressed the recent analytical techniques used for determination of this class of compounds, being HPLC and GC the most common approaches. For these reasons, this review aimed to actualize the occurrence and the profile of diterpenes in coffee matrices, focusing on the effect of species, roasting and brewing and on the other hand, introduce the current state on knowledge regarding coffee diterpenes determination which are nowadays highly regarded and widely used. In general, since diterpenes exhibit different health effects depending on their consumption dosage, several parameters needs to be carefully analyzed and considered when comparing the results.

Acute and subacute (28 days) toxicity of green coffee oil enriched with diterpenes cafestol and kahweol in rats

Green coffee oil enriched with cafestol and kahweol was obtained by supercritical fluid extraction using carbon dioxide while its safety and possible effects from acute and subacute treatment were evaluated in rats. For acute toxicity study, single dose of green coffee oil (2000 mg/kg) was administered by gavage in female rats. For subacute study (28 days), 32 male rats received different doses of green coffee oil extract (25, 50, and 75 mg/kg/day). In the acute toxicity study, main findings of this treatment indicated no mortality, body weight decrease, no changes in hematological and biochemical parameters, and relative weight increase in heart and thymus, without histopathological alterations in all assessed organs. All these findings suggest that LD₅₀ is higher than aforesaid dose. In the subacute toxicity, main findings showed body weight decrease mainly at the highest dose without food consumption change, serum glucose and tryglicerides levels decrease, and relative weight increase in liver. As evidenced in histopathological pictures, no changes were observed at all treated doses. Our study suggest that green coffee oil can be explored to clinically develop new hypocholesteromic and hypoglycemic agents. However, further studies evaluating long-term effects are needed in order to have sufficient safety evidence for its use in humans.

An innovative method of extraction of coffee oil using an advanced microwave system: in comparison with conventional Soxhlet extraction method

Abstract

The production of energy and chemicals from waste biomass is an attractive alternative by comparison with first-generation biofuels and fossil feedstocks. This paper investigates oil extraction from spent coffee grounds (SCG) by means of an advanced microwave process and compares this with a conventional Soxhlet extraction (SE) method. Microwave-assisted oil extraction (MAE) from SCG was performed over different durations, varying solvent volumes and extraction temperatures. It was found that each of these parameters had an effect on the process, with the largest yield being over 11.54 wt%, oil extracted in 10 min using 160 mL of hexane at 95 °C. In 10 min, MAE was successful in extracting more oil than SE. MAE achieved a 24-fold decrease in duration for the extraction compared with SE and used less solvent per gram of oil produced. It is proposed that a certain moisture content in the SCG would be beneficial to the extraction process and might it also play a role in the heating process. The extracted oil can be converted into biodiesel and biochemicals leaving the remaining solids suitable for processing into bioethanol, fertiliser, adsorptive material and fuel pellets.

Graphic Abstract

Valorization of spent coffee grounds recycling as a potential alternative fuel resource in Turkey: An experimental study

In this study, recycling of spent coffee grounds (SCG) as a potential feedstock for alternative fuel production and compounds of added value in Turkey was assessed. The average oil content was found (≈ 13% w/w). All samples (before and after extraction) were tested for scanning electron microscopy (SEM), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), X-ray diffraction (XRD), calorific value, surface analysis and porosity, Fourier transform infrared (FT-IR), and elemental analysis to assess their potential towards fuel properties. Elemental analysis indicated that carbon represents the highest percentages (49.59% and 46.42%, respectively), followed by nitrogen (16.7% and 15.5%), hydrogen (6.74% and 6.04%), and sulfur (0.851% and 0.561%). These results indicate that SCG can be utilized as compost, as it is rich in nitrogen. Properties of the extracted oil were examined, followed by biodiesel production. The quality of biodiesel was compared with American Society for Testing and Materials (ASTM) D6751 standards, and all the properties complied with standard specifications. The fatty acid compositions were analyzed by gas chromatography. It was observed that coffee waste methyl ester (CWME) is mainly composed of palmitic (35.8%) and arachidic (44.6%) acids, which are saturated fatty acids. The low degree of unsaturation provides an excellent oxidation stability (10.4 hr). CWME has also excellent cetane number, higher heating value, and iodine value with poor cold flow properties. The studies also investigated blending of biodiesel with Euro diesel and butanol. Following this, a remarkable improvement in cloud and pour points of biodiesel was obtained. Spent coffee grounds after oil extraction is an ideal material for garden fertilizer, feedstock for ethanol, biogas production, and as fuel pellets. The outcome of such research work produces valuable insights on the recycling importance of SCG in Turkey.

IMPLICATIONS

Coffee is a huge industry, and coffee has been widely used due to its refreshing properties. This industry generates large quantities of waste. Therefore, recycling of spent coffee grounds for producing alternative fuels and compounds of added value is crucial. Elemental analysis indicated that coffee waste can be utilized as compost, as it is rich in nitrogen. Coffee waste after oil extraction is an ideal feedstock for ethanol and biogas production, garden fertilizer, and as fuel pellets. The low degree of unsaturation provides excellent oxidation stability. Its biodiesel has also excellent cetane number, higher heating value, and lower iodine value.

Estudio comparativo de las fracciones lipídicas de Bactris gasipaes Kunth (chontaduro) obtenidas por extracción soxhlet y por extracción con CO2 supercrítico

Se determinó el efecto de dos métodos diferentes de extracción sobre el rendimiento y composición de extractos lipídicos de pulpa de chontaduro o pejibaye (Bactris gasipaes Kunth), cosechados en cuatro diferentes localidades de la región pacífica colombiana. Los métodos de extracción evaluados fueron Soxhlet con hexano, y extracción por fluido supercrítico con CO2 (EFS CO2) a 26,890 MPa y 330 K. Para los cuatro ecotipos o cultivos estudiados, los resultados muestran un mayor rendimiento de extracción por el método EFS CO2 (4,03-8,28% p/p) en comparación al método Soxhlet (1,5-2,73% p/p). Por otro lado, la caracterización de los lípidos de los diferentes ecotipos, realizada a través de cromatografía de gases con detector de ionización de llama (FID), muestra un alto contenido de ácidos grasos insaturados, similar al aceite de oliva y otras oleaginosas: 36,23-51,89% p/p de ácido oleico, 2,38-8,82% p/p de ácido linoleico, y 0,22-1,58% p/p de ácido linolénico, no presentando diferencias significativas de dichos contenidos para ambos métodos. Del mismo modo, el contenido de lípidos del fruto de chontaduro, corroboran su potencial como una muy buena fuente de ácidos grasos esenciales.

Ultrasound-assisted production of biodiesel and ethanol from spent coffee grounds

This study evaluates the production of biodiesel and ethanol from spent coffee grounds (SCG). The extraction of oil from SCG, biodiesel production and ethanol production processes were studied. The liquid-to-solid ratio and temperature were evaluated in the ultrasound-assisted extraction of the oil from SCG. The highest yield (12%) was obtained using 4 mL g(-1) liquid-to-solid ratio at 60°C for 45 min. The process to produce biodiesel showed a yield of 97% into fatty acid methyl esters (FAME). The highest glucose yield (192 mg g SCG(-1)) was obtained by hydrolysis with 0.4 mol L(-1) sulfuric acid at 121°C for 15 min. The hydrolysate was used as fermentation medium for ethanol production by Saccharomyces cerevisiae obtaining 19.0 g L(-1) at 10h of process of ethanol with a yield of ethanol and productivity of 0.50 g g(-1) and 1.90 g L(-1)h(-1), respectively. Spent coffee grounds were considered a potential feedstock for biodiesel and ethanol production.

Combi-protein coated microcrystals of lipases for production of biodiesel from oil from spent coffee grounds

Background

Replacing chemical catalysts with biocatalysts is a widely recognized goal of white biotechnology. For biocatalytic processes requiring low water containing media, enzymes for example commercial preparations of lipases, show low catalytic efficiencies. Some high activity preparations for addressing this concern have been described. Protein coated microcrystals (PCMC) constitute one such preparation. The present work describes a Combi-PCMC for synthesis of biodiesel from the oil extracted from spent coffee grounds.

Results

Different lipases were screened for biodiesel synthesis from crude coffee oil out of which Novozym 435 gave the best conversion of 60% in 4 h. Optimization of reaction conditions i.e. % water, temperature and purification of coffee oil further enhanced conversion upto 88% in 24 h. A mixture of Novozym 435 and a cheap commercially available 1,3-specific lipase RMIM (from Mucor miehei) was used in different ratios and 1:1 was found to be the best trade-off between conversion and cost. The commercial preparations then were replaced by a novel biocatalyst design called Combi-Protein coated microcrystals (Combi-PCMC) wherein CAL B and Palatase were co-immobilized with K2SO4 as the core and this performed equivalent to the commercial preparations giving 83% conversion in 48 h.

Conclusion

Coffee oil extracted from spent coffee grounds could be used for the synthesis of biodiesel by using appropriate commercial preparations of lipases. The expensive commercially immobilized preparations can also be replaced by a simpler and inexpensive immobilization design called combi-PCMC which synergizes the catalytic action of a nonspecific lipase CAL B and a free form of 1,3-specific lipase from Mucor miehei.

Evaluation of kahweol and cafestol in coffee tissues and roasted coffee by a new high-performance liquid chromatography methodology

A reverse phase high-performance liquid chromatography (HPLC) method was developed for the simultaneous quantification of kahweol and cafestol in tissues of fresh fruits, leaves, and roasted coffee beans. The best resolution was obtained with isocratic elution of acetonitrile/water (55/45% v/v) and UV detection. A single sample preparation method carried out by direct saponification and extraction with organic solvent was standardized for all matrices. Good recovery (average of 99% for kahweol and 94% for cafestol), repeatability, and linearity were obtained. Detection limits of 2.3 and 3.0 mg/100 g were observed for kahweol and cafestol. The HPLC method was effective in quantifying these diterpenes in the different coffee matrices. The endosperm and perisperm of Coffea arabica cv. IAPAR 59 showed elevated amounts of kahweol as compared to the pericarp and leaves. On the other hand, cafestol was detected in all samples except in leaves from Coffea canephora cv. Apoatā.