Dynamic supercritical CO2 extraction for removal of cholesterol from anhydrous milk fat

The feasibility of different extraction techniques for the selective removal of cholesterol from anhydrous milk fat (AMF) by supercritical carbon dioxide has been studied. A dynamic extraction system was used to determine both the experimental solubility of anhydrous milk fat in the supercritical solvent and the selectivity of cholesterol over anhydrous milk fat at 40–70°C and 8–40MPa at various stages during extraction. In addition, adsorbents were used for the selective removal of cholesterol from anhydrous milk fat. The results indicate that a direct extraction alone or with several separators in series are not practical, but a selective removal of 97% of the cholesterol from the extracted anhydrous milk fat is possible by using an adsorbent with recovery of solvent and cholesterol. A schematic industrial countercurrent process for the removal of cholesterol and the fractionation of milk fat is proposed.     

Reduction in cholesterol and fractionation of butter oil using supercritical CO2 with adsorption on alumina

Cholesterol reduction together with the fractionation of triglycerides in butter oil was obtained using a combined supercritical CO₂ extraction/alumina adsorption process in a high-pressure apparatus that allows the independent control of temperature and pressure. Cholesterol levels in butter oil fractions extracted at 40 °C and 27.6 MPa were reduced from 2.5 to 0.1 mg g⁻¹ of oil. Butter oil was also fractionated into low-, intermediate- or high-molecular-weight triglycerides. This single-stage combined process is a clear indication of the important technological possibilities with a more efficient multistage fractionation followed by the subsequent blending and formation of desired milk fat products. A comparison of solubility data of pure cholesterol in CO₂ with those for cholesterol contained in butter oil revealed the co-solvency effects of triglycerides on the solvation of cholesterol.     

Temperature and pressure effects on supercritical CO2 extraction of tomato seed oil

Tomato seed oil was extracted with supercritical carbon dioxide in a semibatch-flow extractor within the temperature range 313–343 K and the pressure range 10.8–24.5MPa. The extraction rates increased with pressure, but decreased with temperature increase because of the variation in solvent density and resultant differences in oil solubility. The fatty acid composition of the extracted oil was similar to that of soybean oil.     

Supercritical CO2 Extraction of β-Carotene from Sweet Potatoes

Using supercritical CO₂ to extract β-carotene there was approximately a five-fold or a three-fold increase in amount of carotenoids extracted from freeze-dried tissue relative to the amount extracted from oven-dried or fresh tissue, respectively. The most efficient conditions were at 48°C and 41.4 MPa. Of the total carotenoid content ～20% was inaccessible to supercritical CO₂. The HPLC carotenoid profile of sweet potatoes showed that the unextracted tissue contained 90%β-carotene, primarily as all-trans (ca. 99%). Supercritical CO₂ extracts contained up to 94%β-carotene. The isomer composition of β-carotene of supercritical extracts showed ～ 14% 13-cis and 11% 9-cis.     

Dynamic Changes of Headspace Gases in CO2 and N2 Packaged Fresh Beef

Two independent experiments were conducted to examine the effects of initial packaging/product conditions and storage conditions on in-package headspace pressure changes for modified atmosphere packaged beef during 12 hr storage. Headspace-to-meat volume ratio 1.8 to 5.9, surface area 200--800 cm², sample volume 0.22–0.75L, storage at 3–13°C and initial gas composition 20–100% CO₂ balanced with N₂ were studied. Headspace-to-meat volume ratio was the most important packaging parameter, but surface area and meat volume also affected headspace CO₂ changes. Decreased storage temperature reduced CO₂ concentration remaining in headspace. Higher initial CO₂ concentration resulted in greater concentration changes.     

Supercritical CO2 extraction of grappa volatile compounds

A first study on the recovery of aromatic extracts from grappa by means of supercritical fluid extraction (SFE) on a laboratory plant has been performed, to obtain aroma extracts at low ethanol content. The influence of extraction parameters like pressure, temperature and flow rate have been studied. Extraction yields have been evaluated for ethanol, higher alcohols and esters of short and medium chain acids. A higher aroma volatile compounds extraction has been obtained when the strongest extraction condition has been considered (200 bar, 60 °C, 0.3 kg h⁻¹). Sensory evaluation has indicated as preferred the extract obtained under mild condition (80 bar, 40 °C, 0.3 kg h⁻¹).     

Fat and Cholesterol Content of Beef Patties as Affected by Supercritical CO2 Extraction

Beef patties (raw, raw freeze-dried, cooked, and cooked freeze-dried) were prepared for treatment with supercritical carbon dioxide extraction (SC-CO). Each type of patty was then assigned to one of four treatments: control, static extraction at 170 atm/50°C, dynamic extraction at 170 atm/50°C and dynamic extraction at 544 atm/40°C. Freeze drying of the patties prior to SC-CO₂ extraction improved removal of fat and cholesterol. Freeze drying enhanced (P<0.01) cholesterol extraction; however, precooking had limited effects (P>0.05) on cholesterol extraction. Supercritical fluid extraction could be effective to reduce the fat and cholesterol content of preformed meat products, without requiring communication of the sample.     

Extraction of sesame seed oil using supercritical CO2 and mathematical modeling

In this work, extraction of sesame oil from sesame seeds using supercritical CO₂ was carried out. The effect of operating parameters such as pressure, temperature, and supercritical CO₂ flow rate and particle size on extraction yield were investigated. An increase in the pressure and the supercritical CO₂ flow rate improved the extraction yield and also shortened the extraction time. The extraction yield increased as the particle size decreased depending on decreasing intraparticle diffusion resistance. The maximum extraction yield obtained was about 85% (relative to Soxhlet extraction by hexane) at 50 °C, 350 bar, 2 mL CO₂/min, 300–600 μm of particle size. Some extraction curves were modeled with two mathematical approaches as shrinking core model and broken and intact core model. The evaluation of model parameters showed that shrinking core model, however, is better than broken and intact cell model.     

Extraction Conditions and Moisture Content of Canola Flakes as Related to Lipid Composition of Supercritical CO2 Extracts

Canola flakes obtained before and after conventional cooking were extracted with supercritical carbon dioxide (SC-CO₂) at 35–75°C and 20.7–62.0 MPa. Moisture content was adjusted to 12.7–42.5% (w/w, moisture-and oil-free basis). Moisture content of residual flakes after extraction was monitored. Amount of extract recovered increased with increasing temperature and pressure, except at 20.7 MPa pressure it decreased with temperature indicating a crossover of the solubility isotherms. Some water was co-extracted with canola oil. Free fatty acid (FFA) concentration of the extracts increased with decreasing pressure due to a decrease in triglyceride (TG) solubility. Oleic and linolenic acids had highest concentrations in the FFA fractions of all extracts. The lowest TG content of extracts was attained at 20.7 MPa and 75°C. The effect of extraction conditions was more pronounced than seed pre-treatments on yield and composition of SC-CO₂ extracts.     

Supercritical CO2 Extraction for Total Fat Analysis of Food Products

Supercritical CO₂ extraction (SFE) is a promising alternative to solvent extraction for the measurement of total fat in food products. Total fat was extracted by SFE from samples of food products of different compositions and fat contents. Results using SFE were statistically compared with those using standard methods. This feasibility study showed very promising results. A suitable method was developed for analysis of full milk powder and dietetic milk powder and recoveries were 97.4 and 98.4% respectively. The content of the major fatty acids of fat extracted with SFE was similar to that of Röse-Gottlieb solvent extraction.     

Pecan Oil Recovery and Composition as Affected by Temperature, Pressure, and Supercritical CO2 Flow Rate

Effects of supercritical CO₂ flow rate, extraction temperature, and pressure were studied on oil recovery, fatty acid composition, and factors that control solute extraction from intact pecan halves. After an initial solubility dominant period, extraction was influenced by diffusion of oil from within the pecan. The effective diffusion coefficient was 9.76 × 10^-12 m²/s. In the first 105 min, more oil was extracted as CO₂ flow increased from 1.0 to 7.5 standard L/min (slpm). Beyond 120 min, increasing CO₂ flow from 4 to 7.5 slpm produced negligible differences in amounts of extracted oil. At 2.5 slpm CO₂ flow and 45–75°C, the oil extracted increased by 60% when pressure increased from 41.3 to 55.1 MPa and yielded slightly more at 66.8 MPa. Temperature, pressure, micrometering valve temperature, cultivar (but not extraction time) affected fatty acid (palmitic, stearic, oleic, linoleic, and linolenic) composition of pecan oil.     

酶辅助超临界CO2提取柚皮甙的研究

研究了以柚皮为原料,酶辅助超临界二氧化碳提取柚皮甙的工艺条件。以提取率为指标,研究了酶处理条件的影响,在单因素实验的基础上,通过正交试验优化酶处理条件。结果表明,在酶处理温度50℃、pH4.0、加酶量3%、处理时间2.5h的条件下,柚皮甙的提取率可达到3.68%,用酶辅助超临界二氧化碳提取法提取所得的菊苣酸较传统提取方法具有提取率高,产品的纯度好,流程简单的优点,相对直接使用超临界二氧化碳提取能够进一步提高提取率的优点。     

Rapid CO2 Evolution Method for Determining Shelf Life of Refrigerated Catfish

The feasibility of a CO₂ evolution method using an IR analyzer to evaluate the shelf life of refrigerated (4deg;C) catfish was investigated. Aerobic plate count (APC), and isoelectric focusing (IEF) of samples were compared with the CO₂ evolution rate (CER) determinations. The increase in CER (25.78 to 195.63 Lg^?1h^?1) for farm raised catfish stored from 0 to 10 days correlated highly with APCs (4.32 to 10.24 log CFU g^?1). The IEF data also confirmed the APC and CER results. Catfish spoilage was evident after 6 days at 4°C. Direct measurement of CER is a rapid and effective method to determine the microbial quality of catfish.     

The increase of CO2 permeability of paper packaging with increasing hydration

CO₂ transport through hydrated paper was studied using gas chromatography to measure CO₂ permeability (P) and diffusivity (D). With increasing water content from 0 to 0.8 g water/g paper, P and D increased from 3.47 to 9.03 × 10⁻⁶ m³ m⁻² s⁻¹ bar⁻¹ and from 1.35 to 3.51 × 10⁻⁵ m² s⁻¹, respectively. This resulted from structural changes in the cellulose network as reported in the literature; water sorption isotherms were used to explain these changes using BET theory.     

Mathematical modelling of O2 consumption and CO2 production rates of whole mushrooms accounting for the effect of temperature and gas composition

Investigation of respiration rate of fresh produce, under different gas composition and temperatures, and respective mathematical modelling is central for the modified atmosphere packaging design. This work investigates the effect of temperature (4, 8, 12, 16, 20 °C) and gas composition (O₂ between 3 to 21% and CO₂ between 0 to 15%) on respiration rate of whole mushrooms. Oxygen and carbon dioxide respiration rates increased significantly (3–4 fold) as the temperature elevated from 4 to 20 °C and were in the range of 13.23 ± 3.12 to 102.41 ± 2.132 mL kg⁻¹ h⁻¹) and 14.33 ± 1.56 to 97.02 ± 2.51 mL kg⁻¹ h⁻¹) respectively. Low O₂ and high CO₂ levels reduced O₂ consumption and CO₂ production rates of whole mushrooms on average by a circa 47–60% at all temperatures as compared to the respiration rate at ambient air. Mathematical models were developed for RO₂ and RCO₂, by combining the Arrhenius and Michaelis–Menten uncompetitive equations. These models predicted well, O₂ consumption and CO₂ production rates of whole mushrooms as a function of both temperature and gas composition.     

Postharvest CO2 and Ethylene Production and Quality Maintenance of Fresh-Cut Kiwifruit Slices

The quality attributes and gas production of fresh-cut kiwifruit slices (Actinidia deliciosa cv. Hayward) were studied to identify the optimum ranges of storage temperature, relative humidity, and atmospheric composition. Also the effects of wounding, C₂H₄ addition or removal, and chemical treatments (calcium, ascorbic acid, citric acid) on deterioration rate were investigated. Flesh softening was the major quality loss of stored fresh-cut kiwifruit slices. Fresh-cut kiwifruit slices had a shelf-life of 9–12 days if treated with 1% CaCl₂ or 2% Ca lactate, and stored atO-2°C and >90% relative humidity in an C₂H₄-free atmosphere of 2 to 4 kPa O₂ and/or 5to10kPaCO₂.     

Static, Controlled (CO2) Atmosphere Packaging of Retail Ready Pork

Wrapped boneless pork loin roasts and slices were stored at 4°in bulk under constant CO₂ concentrations of 50% and 100% for 1 and 2 wks. Samples stored under 50% CO₂ for 2 wks could subsequently be displayed (aerobic) for 3 days without becoming unacceptable or for 6 days if previously held under 100% CO₂ for 14 days. Aerobic shelf-life at 4°of the latter samples equalled that of fresh pork chops under simulated retail display. Physicochemical characteristics during storage did not limit acceptability. Reusable master packs have application for distribution of retail ready cuts under controlled atmosphere packaging.     

Gibberellic Acid and CO2 Additive Effect in Retarding Postharvest Senescence of Parsley

We studied the effect of CO₂ and gibberellic acid (GA₃) on postharvest senescence of parsley ( Petroselinum crispum Mill.) and on ethylene induced senescence. GA₃ or CO₂ treatment retarded, with a similar efficiency, chlorophyll and protein degradation, amino acids accumulation and respiration rate. Treatment with GA₃ and CO² together resulted in an additive senescence retarding effect. The promoting effect of ethylene on senescence could be retarded with either CO₂ or GA₃. Thus, GA₃ and CO₂ could provide an effective means for maintaining fresh produce quality in parsley.