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.     

Extraction of Poppy Seed Oil Using Supercritical CO2

ABSTRACT: Extraction of poppy seed oil with supercritical carbon dioxide (SC-CO₂) was performed and the effect of extraction conditions on oil solubility and yield as well as oil composition was evaluated. Within the temperature (50 to 70 °C) and pressure (21 to 55 MPa) ranges studied, 55 MPa/70 °C gave the highest oil solubility (24.1 mg oil/g CO₂) and oil yield (38.7 g oil/100g seed). Fatty acid composition of the oil obtained with SC-CO₂ at 55 MPa/70 °C was similar to that of petroleum ether-extracted oil ( p > 0.05) with linoleic acid making up 69.0 to 73.7% of fatty acids. Tocol content of the SC-CO₂-extracted oils varied from 22.37 to 33.35 mg/100 g oil, which was higher than that of petroleum ether-extracted oil (15.28 mg/100 g oil). Poppy seed oil may have potential in the rapidly growing specialty oil market.     

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.     

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.     

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).     

Pecan Kernel Breakage and Oil Extracted by Supercritical CO2 as Affected by Moisture Content

During supercritical CO₂ extraction of oil from pecans, kernel breakage frequently occurs when the depressurization time is short. The purpose of this study was to investigate the effects of initial moisture content of pecan kernels and moisture equilibration time on pecan breakage and oil recovery when extracting with supercritical CO₂. Initial pecan moisture content, adjusted to 3.5% to 11.0%, had a significant effect on breakage when using a short depressurization time. With higher pecan moisture, less kernel breakage occurred. Increasing moisture equilibration time from 1 to 48 h reduced kernel breakage and produced an average of 30% more oil during extraction. Moisture content did not significantly affect the amount of oil extracted.     

Pasteurization of Beer by a Continuous Dense-phase CO2 System

ABSTRACT: Effects on beer quality were studied after pasteurization by a continuous dense-phase carbon dioxide (DPCD) system. Changes in haze formation, foaming capacity and stability, and objective and subjective aroma and flavor were evaluated, after validation of a 5-log reduction in yeast populations. A maximum log reduction in yeast populations of 7.38 logs was predicted at 26.5 MPa, 21°C, 9.6% CO₂, and 4.77 min residence time. Haze was reduced by DPCD pasteurization from 146 nephelometric turbidity units (NTU) to 95 NTU. At this same treatment combination, aroma and flavor of beer sample means were not considered significantly different ( P = 0.3415) from fresh beer sample means when evaluated in a difference from control test, using fresh beer as the reference. Foam capacity and stability were affected minimally by CO₂ processing; however, changes would most likely be unnoticed by consumers.     

Modeling of O2and CO2 Exchange Dynamics in Modified Atmosphere Packaging of Burlat Cherries

ABSTRACT: A simple mathematical model has been applied to estimate the optimal conditions for modified atmosphere packaging (MAP) of Burlat cherries. The model describes gas exchange in flexible packages, taking into account the respiration rate of the fruit and the transmission rate of gases through the film. The model predicts the evolution of the gas composition inside the package at different conditions. To verify experimentally the model estimations, Burlat cherries were packaged in air and in 3 mixtures of gases at 2 temperatures using 3 different films. Experimental results agree satisfactorily with the predicted values if the O₂ concentration is higher than 2 %.     

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.     

Review of Dense Phase CO2 Technology: Microbial and Enzyme Inactivation, and Effects on Food Quality

ABSTRACT Dense phase CO₂ (DPCD) is a non‐thermal technology that can inactivate certain microorganisms and enzymes at temperatures low enough to avoid the thermal effects of traditional pasteurization. This technology has been investigated over the past 50 y, particularly in the past 2 decades, and its effects on vegetative cells and spores of various microorganisms including pathogens, spoilage bacteria, yeasts, and molds, and various enzymes of importance to foods have been demonstrated. Many liquid foods retained freshlike sensory, nutritional, and physical properties after DPCD treatment. This article is a review of mechanisms of microbial reduction, enzyme inactivation, DPCD treatment systems, both experimental and commercial, and examples of applications with effects on quality attributes.     

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.     

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.