Effects of supercritical CO2 fluid parameters on chemical composition and yield of carotenoids extracted from pumpkin

Pumpkin is a traditional food that is grown extensively worldwide and is believed to be beneficial to human health due to its high contents of carotenoids. The carotenoids in pumpkin were extracted by organic solvents and by supercritical carbon dioxide (SC-CO₂), and then they were identified, quantified, and compared. β-carotene (31 to 40 g per 100 g of total carotenoids) was the predominate carotenoid in pumpkin. Lutein and lycopene contents were much higher in SC-CO₂ extracts than those in organic solvent extract. Cis-β-carotene increased by more than two times in the SC-CO₂ extracts, even at a relatively low temperature of 40 °C, over those in the solvent extracts, indicating both enhanced solubility and isomerization from trans- to cis-β-carotene. The influences of modifier (10 mL/100 mL), temperature (40-70 °C), and pressure (25-35 MPa) of SC-CO₂ extraction on the change of carotenoid yields were also investigated. The highest yield (109.6 μg/g) was obtained at 70 °C and 35 MPa, with a 73.7% recovery. Selective extraction could be achieved by adjusting the temperature and pressure. Higher proportions of all-trans-β-carotene extracts were achieved at 40 °C under both 25 MPa and 35 MPa conditions. In order to extract more cis-isomers, a higher temperature of 70 °C was preferred.     

Lycopene-rich fractions derived from pink guava by-product and their potential activity towards hydrogen peroxide-induced cellular and DNA damage

Effects of solvent and supercritical carbon dioxide (SC-CO₂) extraction on antioxidant and cytotoxic activities of lycopene-rich fractions of decanted pink guava by-product (decanter) were determined with lycopene-equivalent antioxidant capacity, β-carotene bleaching and MTT (3-(4,5-dimethylthiazol-2yl)-2,5-diphenyl tetrazolium bromide) assays. Extraction with SC-CO₂ gave a higher yield than solvent extraction (3.15 vs. 0.68 mg/100 g dried decanter, corresponding to 42.99 and 33.63 mg of lycopene). No cytotoxicity was found in Chang liver cells supplemented with either extracts (6.25–200 μg/ml). Solvent extract at 25 μg/ml (2.32 μM lycopene) and SC-CO₂ extract at 200 μg/ml (5.09 μM lycopene) had protective effect against hydrogen peroxide-induced cytotoxicity. However, only high concentrations of solvent extract (200 μg/ml; lycopene = 18.65 μM) or lycopene standard (10 μM) protected cells against DNA damage. Supercritical fluid extraction demonstrated a higher yield in lycopene-rich fraction from decanter. These fractions have the potential to be developed as a functional ingredient to prevent oxidative stress and other related diseases.     

Proximate composition and extraction of carotenoids and lipids from Brazilian redspotted shrimp waste (Farfantepenaeus paulensis)

The chemical composition of redspotted shrimp (Penaeus paulensis) waste was investigated. The shrimp waste (freeze-dried heads, shells and tails) was found to have high protein (49% d.w.) and ash (27% d.w.) contents, but a low lipid content (4.9% d.w.) although the latter was higher than those found in other kinds of shrimp captured in Brazil. The fatty acid compositions showed that the lipids had a high content of unsaturated fatty acids, mainly EPA (C20:5; n-3) and DHA (C22:6; n-3). In order to establish an efficient and environmentally friendly recovery process for the astaxanthin (principal carotenoid and antioxidant present in the waste), the following processes were examined: traditional solvent extraction (TSE), super-critical fluid extraction (SC-CO₂) and super-critical fluid extraction with co-solvent (SC-CO₂ + ethanol). The temperature and pressure conditions for all the SC-CO₂ extractions were 50 °C and 30.0 MPa. The results showed that the mixture of 60% (v/v) n-hexane:isopropyl alcohol gave the highest (53 mg/kg waste) carotenoid extraction yield as compared to acetone, SC-CO₂ and SC-CO₂ + ethanol. The SC-CO₂ showed the lowest extraction yield of astaxanthin, but the addition of the entrainer (10% w/w) produced an important effect, increasing the astaxanthin extraction to values of 57.9%, similar to extraction with acetone (63.3%).     

Determination of lutein and zeaxanthin and antioxidant capacity of supercritical carbon dioxide extract from daylily (Hemerocallis disticha)

Lutein and zeaxanthin were extracted from daylily (Hemerocallis disticha) flowers using supercritical fluid extraction-carbon dioxide (SFE-CO₂) at a temperature range of 50–95 °C and pressure range of 300–600 bar. The extracts were analysed by HPLC with a C30 column and an isocratic solvent system: methanol/methyl-tert-butyl ether = 86/14 (v/v). Moreover, the antioxidant capacities of the extracts were evaluated by a 2,2-diphenyl-2-picrylhydrazyl radical scavenging assay and a chemiluminescence assay to measure the scavenging activity of hydrogen peroxide, superoxide anion and hydroxyl radical. The optimal lutein and zeaxanthin extraction could be achieved at 80 °C and 600 bar, and the extraction pressure was the most important parameter for SFE-CO₂. In addition, the extracts had significantly higher antioxidant activities in all antioxidant assays.     

Extraction of α-tocopherol and γ-oryzanol from rice bran

The aim of this research was to study the effect of operating mode (continuous versus batch+continuous), temperature, pressure and solvent on α-tocopherol and γ-oryzanol extraction from rice bran (Oryza sativa Linn.) and compare the efficiency of three extraction methods: SC-CO₂ extraction, solvent extraction and soxhlet extraction. Three sets of experiments were performed. First, extraction using SC-CO₂ was performed over a range of temperatures and pressures (45-65 °C and at 38 and 48 MPa), and at a CO₂ flow rate of 0.45 mL/min. The results showed that the best conditions for α-tocopherol extraction were 55 °C, 48 MPa in the batch+continuous mode. For γ-oryzanol, the best conditions were 65 °C, 48 MPa and in the continuous mode. In the second set of experiments, solvent extraction using hexane and ethanol at 32 and 55-60 °C was studied. The results showed that none of the solvents could extract α-tocopherol; however, ethanol at 55-60 °C was suitable for γ-oryzanol extraction. Finally, soxhlet extraction experiments using hexane for α-tocopherol and ethanol for γ-oryzanol were also performed. In summary, SC-CO₂ was found to be the best solvent for extracting both α-tocopherol and γ-oryzanol from rice bran, because of its higher yields and extraction rate.     

Supercritical fluid extraction of forskolin from Coleus forskohlii roots

Forskolin (FSK), a labdane diterpene compound having high nutraceutical and therapeutic activity has been extracted from dried Coleus forskohlii roots using supercritical carbon dioxide (SC-CO₂). The solubility parameter of FSK, CO₂, and entrainer solvents was calculated and validated with experimental results. Theoretically, pressure and temperature had significant effect on extraction of FSK. A maximum of 50.32% recovery of FSK was obtained after SC-CO₂ extraction at 40 °C, 250 bar and extraction time of 60 min. Use of methanol as an entrainer at 20% v/w of dried C. forskohlii roots under optimized conditions improved the recovery of FSK to 74.29%. The recovery of FSK further increased marginally to 77.08% when pre-treated with ultrasonication and commercial enzyme preparation of Stargen® 002 and Accellerase® 1500.     

Application of response surface methodology to optimise supercritical carbon dioxide extraction of essential oil from Cyperus rotundus Linn.

Supercritical fluid extraction with carbon dioxide (SC-CO₂ extraction) was performed to isolate essential oils from the rhizomes of Cyperus rotundus Linn. Effects of temperature, pressure, extraction time, and CO₂ flow rate on the yield of essential oils were investigated by response surface methodology (RSM). The oil yield was represented by a second-order polynomial model using central composite rotatable design (CCRD). The oil yield increased significantly with pressure (p < 0.0001) and CO₂ flow rate (p < 0.01). The maximum oil yield from the response surface equation was predicted to be 1.82% using an extraction temperature of 37.6 °C, pressure of 294.4 bar, extraction time of 119.8 min, and CO₂ flow rate of 20.9 L/h.     

Pressurised hot water extraction with on-line particle formation by supercritical fluid technology

In this work, an on-line process for pressurised hot water extraction (PHWE) of antioxidants from plants as well as drying of the extract in one step by particle formation based on the use of supercritical carbon dioxide (SC-CO₂) has been developed. This process has been called WEPO®, water extraction and particle formation on-line. With this process, dried extracts from onion with the same composition of quercetin derivatives as non-dried extracts have been obtained as a fine powder with spherical particles from 250 nm to 4 μm in diameter. The major compounds present in the extract were quercetin-3,4′-diglucoside, quercetin-4′-glucoside and quercetin. An auxiliary inert gas (hot N₂) was used to enhance the drying process. Parameters such as temperature (120 °C), SC-CO₂ and N₂ pressures (80 and 12.5 bar, respectively) and flow rate of SC-CO₂ (10 ml/min), have been settled by trial-and-error in order to achieve a fine and constant spray formation. Water content, size and morphology, antioxidant capacity and quercetin content of the particles were studied to evaluate the efficiency of the WEPO process. Results were compared with the ones from extracts obtained by continuous flow PHWE followed by freeze-drying. Results showed that both processes gave similar results in terms of antioxidant capacity, concentration of quercetin derivatives and water content, while only WEPO was able to produce defined spherical particles smaller than 4 μm.     

Optimisation of accelerated solvent extraction of antioxidant compounds from rosemary (Rosmarinus officinalis L.), marjoram (Origanum majorana L.) and oregano (Origanum vulgare L.) using response surface methodology

The present study optimised the accelerated solvent extraction (ASE) conditions (Dionex ASE® 200, USA) to maximise the antioxidant capacity of the extracts from three spices of Lamiaceae family; rosemary, oregano and marjoram. Optimised conditions with regard to extraction temperature (66–129 °C) and solvent concentration (32–88% methanol) were identified using response surface methodology (RSM). For all three spices results showed that 129 °C was the optimum temperature in order to obtain extracts with high antioxidant activity. Optimal methanol concentrations with respect to the antioxidant activity of rosemary and marjoram extracts were 56% and 57% respectively. Oregano showed a different response to the effect of methanol concentration and was optimally extracted at 33%. The antioxidant activity yields of the optimal ASE extracts were significantly (p < 0.05) higher than solid/liquid extracts. The predicted models were highly significant (p < 0.05) for both total phenol (TP) and ferric reducing antioxidant property (FRAP) values in all the spices with high regression coefficients (R²) ranging from 0.952 to 0.999.     

Optimization of oven drying conditions for lycopene content and lipophilic antioxidant capacity in a by-product of the pink guava puree industry using response surface methodology

Response surface methodology (RSM) was applied to optimize the oven drying conditions for lycopene content (Y₁) and lipophilic antioxidant capacity (Y₂) in decanter, a by-product of the pink guava puree industry. Two-factor central composite design was employed to determine the effects of two independent variables, namely temperature (X₁: 50-80 °C) and drying time (X₂: 4-6 h). Lycopene content and lipophilic antioxidant capacity were measured using high-performance liquid chromatography (HPLC) and the ABTS radicals scavenging assay, respectively. A β-carotene bleaching assay was also applied to measure the antioxidant activity. Response surface plots showed that an increase in temperature and time significantly reduced the response variables. The optimum oven conditions for drying of decanter with minimum lycopene degradation were 43.8 °C for 6.4 h, with a predicted lycopene content of 14 mg/100 g and antioxidant capacity of 21 μmol LE/100 g. To validate the optimized model, the experimental values were compared with the predicted values to check the adequacy of the model. The experimental values were found to be in agreement with those predicted, indicating the suitability of the model for optimizing the oven drying conditions for decanter.     

Addition of ethanol to supercritical carbon dioxide enhances the inactivation of bacterial spores in the biofilm of Bacillus cereus

Supercritical carbon dioxide (SC-CO₂) was used to inactivate Bacillus cereus spores inside biofilms, which were grown on stainless steel. SC-CO₂ treatment was tested using various conditions, such as pressure treatment (10–30 MPa), temperature (35–60 °C), and time (10–120 min). B. cereus vegetative cells in the biofilm were completely inactivated by treatment with SC-CO₂ at 10 MPa and at 35 °C for 5 min. However, SC-CO₂ alone did not inactivate spores in biofilm even after the treatment time was extended to 120 min. When ethanol was used as a cosolvent with SC-CO₂ in the SC-CO₂ treatment using only 2–10 ml of ethanol in 100 ml of SC-CO₂ vessel for 60–90 min of treatment time at 10 MPa and 60 °C, B. cereus spores in the biofilm were found to be completely inactivated in the colony-forming test. We also assessed the viability of SC-CO₂-treated bacterial spores and vegetative cells in the biofilm by staining with SYTO 9 and propidium iodide. The membrane integrity of the vegetative cells was completely lost, while the integrity of the membrane was still maintained in most spores. However, when SC-CO₂ along with ethanol was used, both vegetative cells and spores lost their membrane integrity, indicating that the use of ethanol as a cosolvent with SC-CO₂ is efficient in inactivating the bacterial spores in the biofilm.     

Effects of supercritical carbon dioxide extraction parameters on virgin coconut oil yield and medium-chain triglyceride content

The extraction of coconut oil has been performed using supercritical carbon dioxide (SC-CO₂). The extractions were performed at pressure and temperature ranges of 20.7–34.5 MPa and 40–80 °C, respectively. It was observed that almost all (more than 99%) of the total oil could be extracted. Response surface methodology (RSM) was applied to evaluate the effects of the parameters (pressure, temperature and CO₂ consumption) on the extraction yield and medium-chain triglycerides (MCTs), in terms of the fatty acid content in the extracted oil. A correlation was established with p-values for both responses significant at the 95% confidence level.     

Response surface optimisation for the extraction of phenolic compounds and antioxidant capacities of underutilised Mangifera pajang Kosterm. peels

The optimum extraction conditions for highest recovery of total phenolics content (TPC) and antioxidant capacities (AC) were analysed for Mangifera pajang peels (MPP), using response surface methodology. The effects of ethanol concentration (X₁: 20–80%), extraction temperature (X₂: 30–65 °C) and liquid-to-solid ratio (X₃: 20–50 mL/g) on the recovery of total phenolics (Y₁) and antioxidant capacity (Y₂) were investigated. A second order polynomial model produced a satisfactory fitting of the experimental data with regard to total phenolic content (R² = 0.9966, p < 0.0001) and antioxidant capacity (R² = 0.9953, p < 0.0001). The optimum extraction conditions for TPC were 68%, 55 °C and 32.7 mL/g, and for AC were 68%, 56 °C and 31.8 mL/g, respectively. Predicted values for extraction of TPC and AC agreed well with the experimental values. Liquid chromatography–mass spectrometry of the optimally obtained extracts from MPP revealed the major phytochemicals as mangiferin, gallic acid, catechin and epicatechin.     

Effect of extraction conditions on lycopene extractions from tomato processing waste skin using response surface methodology

Skin, rich in lycopene, is an important component of waste originating from tomato paste manufacturing plants. A central composite design with five independent variables, namely solvent/meal ratio (20:1, 30:1, 40:1, 50:1, and 60:1 v/w); number of extractions (1, 2, 3, 4 and 5); temperature (20, 30, 40, 50 and 60 °C); particle size (0.05, 0.15, 0.25, 0.35 and 0.43 mm); extraction time (4, 8, 12, 16 and 20 min) was used to study their effects on lycopene extraction. The experimental values of lycopene ranged between 0.639 and 1.98 mg/100 g. The second order model obtained for extracted lycopene revealed a coefficient of determination (R²) of 0.99 and a standard error of 0.03. Maximum lycopene (1.98 mg/100 g) was extracted when the solvent/meal ratio, number of extractions, temperature, particle size and extraction time were 30:1 v/w, 4, 50 °C, 0.15 mm and 8 min, respectively.     

Direct application of supercritical carbon dioxide for the reduction of Cronobacter spp. (Enterobacter sakazakii) in end products of dehydrated powdered infant formula

The objective of this study was to develop a viable new method for inactivation of Cronobacter spp. that could be applied directly to dehydrated powdered infant formula (PIF) using supercritical carbon dioxide (SC-CO₂). Samples inoculated with Cronobacter spp. were subjected to SC-CO₂ treatment under various conditions (temperature: 63, 68, and 73°C; pressure: 15, 20, and 25 MPa; time: 10, 20, and 30 min). The survival of Cronobacter spp. was assayed, as were any changes in the quality of the treated PIF. Inactivation of Cronobacter spp. by SC-CO₂ was enhanced as temperature and pressure conditions increased (>6.32 log₁₀ cfu/g). In a validation assay using low-level inoculation (3.21 log₁₀ cfu/g), treatment at 73°C and 15 MPa for 30 min, 20 MPa for 20 and 30 min, or 25 MPa for 20 and 30 min reduced Cronobacter spp. to undetectable levels, with no recovery of cell viability. There was no significant change in water activity, pH, and color of the treated PIF. Overall, the optimum conditions for elimination of Cronobacter spp. were determined to be 73°C and 20 MPa for 20 min. These parameters for effective SC-CO₂ treatment are feasibly applicable to end product of dehydrated PIF. The results of our study may contribute to the development of an efficient method for improving the microbiological safety of PIF.     

Comparison of lycopene stability in water- and oil-based food model systems under thermal- and light-irradiation treatments

Lycopene can undergo degradation via isomerization and oxidation during processing and storage. These degradative reactions affect its bioactivity and health benefit functionality. Degradation kinetics and isomerization of lycopene in water- and oil-based tomato model systems were investigated as a function of thermal treatments and light irradiation. Results showed that 80 and 100 °C heating favoured the stability of lycopene in oil-based tomato products. The high heating temperatures (120 and 140 °C) increased isomerization of lycopene and resulting in degradation of total lycopene and cis-isomers in both water- and oil-based tomato products. However, the levels of degradation of total lycopene contents and cis-isomers were greater in water-based samples than in oil-based model systems under different treatments. Heat and light both promoted lycopene isomerization of the all-trans form to the cis-isomers and further oxidation of cis-isomers. The major effect of thermal degradation and photosensitized oxidation was a significant decrease in the total lycopene content, especially the content of cis-isomers. These research results could be useful in assisting industry to improve processing technology and to improve the nutritional value and health-benefits of tomato-based foods.     

Functional food oil coloured by pigments extracted from microalgae with supercritical CO2

A functional food oil, rich in fatty acids and antioxidants, coloured with pigments (carotenoids) extracted with supercritical CO₂ from the microalga Chlorella vulgaris, was produced, having in view its use in food industry (namely for derived seafood). The supercritical fluid extraction (SFE) was carried out in order to study the effect of several modifiers (oil mixed with the microalga and ethanol with the supercritical CO₂), the degree of crushing of the microalga and the supercritical fluid flow rate, at a pressure of 300 bar and temperature of 40 °C. Moreover, the microalga pigments were also extracted with acetone and with vegetable oil at room and high temperature. The recovery of carotenoids was 100% with oil at room temperature for 17 h, 70% with oil at 100 °C for 30 min, 69% with supercritical CO₂ at 40 °C and 300 bar. In SFE the degree of crushing strongly influenced the extraction recovery and higher pigment recoveries were obtained with well crushed biomass.     

Extraction of alkylresorcinols from wheat bran with supercritical CO2

The supercritical fluid extraction (SFE) of wheat bran alkylresorcinols has been studied. Extractions were carried out at 40.0 MPa. The effect of particle size, static extraction pretreatment with supercritical CO₂ (SC-CO₂) and extraction temperature on the extraction kinetics was investigated. The extraction yield increased as the particle size decreased and with temperature. Extraction curves present a faster and linear initial extraction period followed by a slower extraction period. Based on these results the approximate mathematical model of Sovová was successfully applied to describe the extraction curves. The total content of alkylresorcinols was determined and compared with the alkylresorcinol content obtained by conventional organic solvent extraction. Due to the amphiphilic nature of these resorcinolic lipids, the extraction yield was higher for polar organic solvents than for SC-CO₂. Characterization of supercritical extracts was also performed by determining the fatty acid composition and antioxidant activity.     

Ethanol modified supercritical fluid extraction and antioxidant activity of cajaninstilbene acid and pinostrobin from pigeonpea [Cajanus cajan (L.) Millsp.] leaves

Supercritical fluid carbon dioxide (SF-CO₂) extraction (SFE) of cajaninstilbene acid (CSA) and pinostrobin (PI) from pigeonpea leaves and antioxidant activity were investigated for the first time. SFE gave higher extraction yields than conventional heat-refluxing extraction (HRE) because of the severe breakage of cell morphology caused by SF-CO₂, which was observed by scanning electron microscopy (SEM). CO₂ flow rate, modifier composition and liquid to solid ratio were firstly optimised, 12 kg/h, and 80% EtOH with a liquid to solid ratio of 10 ml/g raw material exhibited better extraction performance. Then a central composite design (CCD) combined with response surface methodology was used to study the effects of extraction pressure, temperature and time on the extraction yields of CSA and PI, the optimal parameters were 30 MPa, 60 °C and 2 h. An antioxidant activity investigation showed SFE extracts exhibited better free radical-scavenging activity than HRE extracts with an IC₅₀ value of 0.2259 mg/ml.