EFFECT OF SUPERCRITICAL CO2 EXTRACTION OF OIL ON PHYSICOCHEMICAL PROPERTIES OF RESIDUAL ATLANTIC MACKEREL (Scomber scombrus) PROTEINS

Protein residue of Atlantic mackerel, an underutilized fish species, was investigated following extraction of oil with supercritical CO₂. Spring mackerel was extracted at 35–55C and 34.5–62.1 MPa for 5 h whereas extraction time of 1–6 h was applied to fall mackerel at 35C/34.5 MPa. Water binding potential of fall mackerel proteins increased with extraction time as oil was removed and that for spring mackerel reached a maximum of 2.2 g H₂O/g protein at 55C and 62.1 MPa. Sarcoplasmic proteins (SAR) became less soluble with increasing extraction temperature and pressure. This change occurred during the first hour of extraction of fall mackerel. Analysis of the SAR by capillary electrophoresis showed that proteins with a molecular weight of 50–100 kDa decreased, while MW> 100 kDa proteins increased with extraction pressure and time for spring and fall mackerel, respectively, suggesting aggregation of proteins. Supercritical CO₂ extraction of lipids from fish muscle shows potential for development of high quality functional proteins.     

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.     

SUPERCRITICAL CARBON DIOXIDE SELECTIVITY TO FRACTIONATE PHENOLIC COMPOUNDS FROM THE DRY ETHANOLIC EXTRACT OF PROPOLIS

The global yield and composition of extracts obtained by supercritical carbon dioxide (SC-CO₂) extraction from a dry ethanolic extract of propolis were measured in order to determine the possibility of using SC-CO₂ to fractionate components of interest present in these extracts. The global yield extraction was measured, and also the concentrations of the following phenolic compounds in the resulting supercritical fluid extracts (SFEs): 3,5-diprenyl-4-hydroxycinnamic acid (known as artepillin C), 3-prenyl-4-hydroxycinnamic acid, 4-hydroxycinnamic acid ( p- coumaric acid) and 4-methoxy-3,5,7-trihydroxyflavone (kaempferide), of which artepillin C was the target component of greatest interest. The results showed extraction yields between 3.82 (at 150 bar) and 13.07% (at 350 bar), which could be highly correlated with the density of the SC-CO₂ at a constant temperature of 60C. The resulting concentrations in the SFE indicated that the selectivity of the carbon dioxide could be manipulated, and it was more selective at lower pressures, although with lower extraction yields.

PRACTICAL APPLICATIONS

Supercritical fluid extraction is an interesting process for the production of natural extracts because it is a clean process, and extractions using carbon dioxide (CO₂) as the solvent have been gaining attention in recent years. This study presented important aspects with respect to the fractionation of a dry ethanolic extract of propolis using supercritical carbon dioxide, and it is important to explore the potential applications of propolis extracts and the biological properties of its fractions in the food, pharmaceutical and cosmetic industries, such as in dental hygiene products, wound healing creams and antibacterial soaps.     

Rheological behaviour of acorn starch dispersions: effects of concentration and temperature

Rheological properties of acorn starch dispersions at different concentrations (4%, 5%, 6% and 7%) were evaluated under steady and dynamic shear conditions. The flow behaviours of the acorn starch dispersions at different temperatures (25, 40, 55 and 70 °C) were determined from the rheological parameters provided by the power law model. The acorn starch dispersions at 25 °C exhibited high shear-thinning fluid characteristics ( n  = 0.23–0.36). Consistency index (K) and apparent viscosity (η_a,100) increased with an increase in starch concentration, and were also reduced with increasing temperature. Within the temperature range of 25–70 °C, the η_a,100 obeyed the Arrhenius temperature relationship with a high determination coefficient ( R ² = 0.97–0.99), with activation energies (E_a) ranging between 16.5 and 19.0 kJ mol⁻¹. Both the power law and exponential type models were employed in order to establish the relationship between concentration and apparent viscosity (η_a,100) in the temperature range of 25–70 °C. Magnitudes of storage ( G' ) and loss ( G ") moduli increased with an increase in the starch concentration and frequency (ω). The magnitudes of G ' were higher than those of G " over most of the frequency range (0.63–62.8 rad s⁻¹). The dynamic (η*) and steady shear (η_a) viscosities of acorn starch dispersion at 7% concentration follow the Cox–Merz superposition rule.     

不同提取方法对杜仲籽油质量的影响

本文旨在研究索氏提取法、亚临界萃取法、超临界CO₂萃取法对杜仲籽油得率、主要理化指标及脂肪酸组成的影响。结果表明:索氏提取法、亚临界萃取法和超临界CO₂萃取法提取杜仲籽油的油得率分别为34.47%、28.42%、18.68%。索氏提取法得到的杜仲籽油过氧化值((0.087±0.002) g/100 g)和酸价((1.64±0.02) mg/g)最高,相对密度(0.87±0.01)和碘值((190.4±0.8) g/100 g)最低,提取的杜仲籽油品质最差;与索氏提取法相比,超临界CO₂萃取法和亚临界萃取法提取的杜仲籽油表现出较好的产品特性。不同方法提取的杜仲籽油的颜色有显著性差异(P<0.05),超临界CO₂萃取法提取的杜仲籽油亮度最高,颜色最好。气相色谱分析三种方法提取的杜仲籽油的主要脂肪酸种类基本相同,以油酸、亚油酸、α-亚麻酸为主,但各种脂肪酸的含量有所差异,其中不饱和脂肪酸含量为:超临界CO₂萃取法 > 索氏提取法 > 亚临界萃取法。经综合评价得出,超临界CO₂法萃取法提取的杜仲籽油品质较高,如果综合考虑成本因素和工业化操作方便程度,亚临界萃取法也是杜仲籽油提取的一种新型绿色工艺。本研究为杜仲籽油的开发和利用奠定了理论基础。     

Improved Firmness in Calcified Diced Tomatoes by Temperature Activation of Pectin Methylesterase

ABSTRACT: The effects of temperature and calcium on pectin methylesterase (PME) activity and texture in tomato pericarp material were examined. Heating thin slices of pericarp to temperatures between 50°C and 75°C led to the rapid evolution of methanol from the material, indicating an activation of PME. This activity was further stimulated when CaCl₂ (up to 2.0% w/v) was added. When applied to half-inch diced tomato pericarp, the same conditions that led to the activation of PME also improved firmness. Diced tomatoes treated for 5 min with 0.5% CaCl₂ at 70°C were 2.5 times firmer than diced tomatoes treated with CaCl₂ at room temperature. This improvement in texture by treating with CaCl₂ at elevated temperatures was only apparent when the tomatoes received a subsequent 100°C treatment. Heating tomatoes to 70°C either before or after the CaCl₂ treatment also improved firmness through a subsequent high-temperature treatment, but to a lesser extent than heating during the CaCl₂ treatment. These results are consistent with the model that heating to 70°C greatly increases PME activity, leading to extensive pectin de-esterification and increased calcium cross-linking of the pectins in the middle lamella. Production of thermally processed diced tomatoes with improved firmness should be possible by increasing the temperature during and after calcium treatment.     

提取方法对奇亚籽油品质特性的影响

以奇亚籽为原料,分别采用压榨法、溶剂浸提法、水酶法和超临界CO₂萃取法提取奇亚籽油,对比分析不同方法提取奇亚籽油的理化性质、脂肪酸组成、油脂氧化稳定性、酚类物质含量及体外抗氧化能力等品质特性。结果表明:4种方法中,超临界CO₂萃取法的油脂得率最高(85.5%),其次是溶剂浸提法(65.8%)和压榨法(40.9%),水酶法最低(33.2%)。超临界CO₂萃取的奇亚籽油品质最佳,色泽为黄值70红值4.3灰值0.3,酸价为1.10 mg KOH/g、过氧化值为0.0137 g/100 g,含有不饱和脂肪酸总质量分数为88.22%,其中亚油酸18.36%,亚麻酸69.86%;其氧化速度最慢在30 h后过氧化值达到0.25 g/100 g;总酚含量为106.45 mg/kg,黄酮含量为222.09 mg/kg。超临界CO₂萃取的奇亚籽油在相同质量浓度下的DPPH自由基清除能力(IC₅₀ 28.04 mg/mL)与ABTS+·清除能力(IC₅₀ 33.70 mg/mL)优于压榨法、溶剂浸提法和水酶法;对超氧阴离子自由基清除能力(IC₅₀ 10.08 mg/mL)优于溶剂浸提法、水酶法,略低于压榨法。     

Residual NO−3 NO−2, carbonyl and TBA values of Turkish soudjouk manufactured by adding different starter cultures and using different ripening temperatures

No standard technologically based manufacturing method exists for dry, fermented, spicy Turkish style sausage (soudjouk) and current techniques yield techniques yield unacceptable, mostly rancid and putrid products with high levels of residual NO⁻₃ and NO⁻₂. A standard method of soudjouk processing was developed. Three different starter cultures ( Lactobacillus plantarum, L. plantarum+Micrococcus aurantiacus, L. plantarum+M. aurantiacus+Debaryomyces hansenii ) were added to the soudjouk mixture and ripened at three different temperatures (12–14, 16–18 and 20–22°C). The addition of mixed cultures significantly reduced the residual NO⁻₃ and NO⁻₂ levels, increased the lipid soluble carbonyl levels, and produced low thiobarbituric acid values in the ripened soudjouks. For better quality characteristics, addition of D . hansenii is advisable and a ripening temperature of 20-22°C should be used.     

Water desorption isotherms of two varieties of sweet potato

Water desorption isotherms were determined for New Zealand sweet potato at 25, 40 and 55°C, and for Philippines sweet potato at 28°C. The isotherms were sigmoid in shape and of type II according to the BET classification. The data were fitted to eight two-parameter equations reported in the literature. The effect of water activity, a_w, and temperature, T °C, on the equilibrium moisture content, M _e g water/100g dry solids, was best described for New Zealand sweet potato by: Me = 20.51 T-^0.204 (a_w/(1-a_w)0.39 for a_w= 0.06–0.81     

Reduction of Streptococcus thermophilus in a whey protein isolate by low moisture extrusion cooking without loss of functional properties

A whey protein isolate powder (WPI) (4–5% water) inoculated with 5x10⁵ viable Streptococcus thermophilus per g, was continuously processed in a twin screw extruder under the following conditions (barrel length = 500 or 1000 mm; screw profile = forward transport and compression elements; moisture content during extrusion = 4–5%; feed rate = 10 kg h^-1; barrel temperature ( T_b ) = 80–204°C; speed of screw rotation = 50 r.p.m.). The minimum residence time determined by pulse injection of erythrosin was 20–25 s (500 mm barrel) or 35–40 s (1000 mm barrel).
Reduction values of viable Streptococcus thermophilus of 10^4.2-fold (500 mm barrel, T_b = 143°C) or 10^4.9-fold (1000 mm barrel, T_b = 133°C) were obtained without any modification of protein solubility or gelling properties. WPI extruded at the highest barrel temperatures (182–204°C) underwent limited browning and reduction of protein solubility. Gel permeation and hydrophobic interaction chromatography of the soluble constituents did not show any aggregates of β-lactoglobulin or α-lactalbumin.
Gels prepared from control or extruded WPI ( T_b 143°C with a barrel length = 500 mm or T_b 133°C with a barrel length = 1000 mm) were identical, as judged by scanning electron microscopy and rheological evaluations.     

The Effects of Residual Oxygen on the Storage Life of Retail-Ready Fresh Beef Steaks Masterpackaged Under a CO2 Atmosphere

ABSTRACT:  Retail-packed rump ( Gluteus medius , GM) and striploins ( Longissiumus dorsi, LD) steaks were masterpackaged under carbon dioxide (CO₂) and stored at 1 °C ± 1 °C for 14, 28, 35, and 42 d. A commercial oxygen (O₂) scavenger (ATCO HV1000®, Standa Industrie, Caen, France) was used in the masterpacks to achieve an O₂-free atmosphere. Similar packages without the O₂ scavengers were also prepared. At each storage time, 2 masterpacks of each treatment were opened and the retail trays were placed in a display case at 4 °C ± 2 °C for 1 and 48 h for microbiological and sensorial evaluations. The low growth rate of aerobic psychrotrophic flora on the stored beefsteaks demonstrated the bacteriostatic effect of CO₂ during storage. The maximum level of psychrotrophic aerobic bacteria reached during storage was approximately 10⁶ CFU/g. The steaks stored in masterpacks with scavengers bloomed to the desirable red color associated with freshly cut meat in the display case for all of the storage periods, except in the case of GM steaks, which showed a cycle of transient discoloration. GM and LD steaks were well accepted (65% and 82%, respectively) after 42 d under CO₂ at 1 °C ± 1 °C. The GM and LD steaks stored without the O₂ scavenger showed variable fractions of discoloration that significantly detracted from the appearance of the samples.     

Potential of oregano essential oil and MAP to extend the shelf life of fresh swordfish: a comparative study with ice storage

ABSTRACT:  The present study evaluated the effect of modified atmosphere packaging (MAP, 5% O₂/50% CO₂/45% N₂; treatment M), the addition of oregano oil (0.1%, v/w; treatment AO) as a natural preservative, as well as their combination (treatment MO) on the quality and shelf life extension of fresh Mediterranean swordfish fillets during a refrigerated storage (4 °C) period of 18 d. Simultaneously, swordfish fillets were stored under aerobic conditions (control treatment A, 4 °C) and on ice (usual commercial method of preservation, treatment I, 0 °C). Among the 5 treatments examined in the present study, the most effective one to inhibit the microbial and sensory spoilage proved to be the MO treatment, achieving a shelf life extension of 8 to 9 d. The dominant bacteria in the microflora of swordfish, irrespective of treatment, were the Pseudomonads and the H₂S-producing bacteria, while both lactic acid bacteria (LAB) and the Enterobacteriaceae produced the lowest populations in swordfish samples kept on ice. Among the chemical indices examined, thiobarbituric acid (TBA) values showed no specific trend of lipid oxidation for swordfish, irrespective of treatment. Final trimethylamine nitrogen (TMA-N) and total volatile basic nitrogen (TVB-N) values for treatments, A, AO, M, and MO ranged between 1.33 and 14.29 mg N/100 g and 14.11 to 55.52 mg N/100 g, respectively, whereas for I samples they remained almost unchanged during storage. Sensory analysis (taste attribute) correlated well with microbiological analysis, indicating a shelf life of approximately 5 to 6 d for control, 10 to 11 d for AO, 12 d for I, 13 d for M, and 14 d for MO samples.     

EXTRACTION OF VICTORIA AND RED GLOBE GRAPE SEED OILS USING SUPERCRITICAL CARBON DIOXIDE WITH AND WITHOUT ETHANOL

SFE of the oils of two varieties of grape seeds (Victoria and Red Globe) was performed in a flow apparatus at 40C and 250 bar. The effect of the solvent on the extraction yield was studied using CO₂ and CO₂ modified with ethanol, and the yield of extraction was compared with conventional extraction methods (Bligh and Dyer and Soxhlet using hexane). SC CO₂  +  ethanol extracted higher lipid amounts from both varieties, compared with SC CO₂ extraction. The comparison between SFE and conventional extraction methods showed that the highest extraction yield was obtained with SC CO₂  +  ethanol (10%, w/w) (14.7 and 11.8% for Red Globe and Victoria grape seeds, respectively), while pure SC CO₂ afforded the lowest lipid yields. The fatty acid compositions of the oils obtained by SFE were analyzed. Fractions containing higher proportions of PUFAs were obtained at lower solvent/dry grape seed ratios, while fractions richer in SFAs and MUFAs were obtained at higher solvent/dry grape seed ratios.

PRACTICAL APPLICATIONS

SFE could fractionate grape seed oil and afford various grades of oil containing different proportions of fatty acids. The highest grape seed lipid yield obtained was with SC CO₂ + ethanol, making this solvent a promising and powerful one for grape seed oil extraction, showing a great advantage compared with conventional extraction methods.     

Solubilization of wheat gluten with sodium hydroxide

The solubility of wheat gluten may be increased greatly by treatment with 0.25 M sodium hydroxide. At temperatures of 40°C and above, the solubility of the protein exceeds 100 mg/ml in a reaction time of 6 hr or less. The products from the reaction of 60°C and 80°C were darker than the original gluten and had an unpleasant odour of H₂S on dissolution in water. They also contained traces of lysinoalanine. The 40°C reaction product was about the same colour as gluten, and its solutions in water did not smell of H₂S. Reaction of gluten at 20°C also caused a large increase in solubility, but after 24 hr the solubility was only 77 mg/ml. This product was also of the same colour as gluten, and did not smell of H₂S in solution. Neither the 20°C nor the 40°C products contained detectable traces of lysinoalanine. For reasons of flavour, colour, lysinoalanine content and economy of time, the optimum reaction conditions are 6 hr at 40°C.     

Fate of Aflatoxin M1 during Manufacture and Storage of Feta Cheese

ABSTRACT:  The effect of feta cheese manufacture on aflatoxin M₁ (AFM₁) content was studied using an enzyme immunoassay technique. Feta cheese was made from milk spiked with 1 and 2 μg AFM₁ per kilogram milk. Pasteurization at 63 °C for 30 min caused <10% destruction of AFM₁. During cheese making, the remaining AFM₁ in milk was partitioned between curd and whey with two-thirds retained in the curd and one-third going into the whey. Cheeses were then stored for 2 mo in 8%, 10%, and 12% brine solutions at 6 and 18 °C. There was a 22% to 27% reduction of AFM₁ during the first 10 d of storage, with slightly more loss as salt concentration increased and when the cheese was stored at 18 °C. Further storage caused only slight decrease in AFM₁ and after 30 d of brining there was no difference in AFM₁ content of the cheese based upon salt concentration of the brine. At 18 °C, no further losses of AFM₁ occurred after 30 d, and at 6 °C, there was continued slight decrease in AFM₁ levels until 50 d. After 60 d of brining, there was a total loss of 25% and 29% of the AFM₁ originally present for cheese brined at 6 and 18 °C, respectively. Thus, the combination of pasteurization, conversion of milk into feta cheese, and at least 50 d storage of cheese in brine caused a total loss of about 50% of the AFM₁ originally present in the raw milk.     

Ultrastructural and Changes in Pectin Composition of Sweet Cherry from the Application of Prefreezing Treatments

ABSTRACT: Thermal and calcium pretreatments applied to preserve the sweet cherry texture by the freezing/thawing process produced biochemical changes in the pectic substances and ultrastructural alterations to the cells and tissues, which were visible under scanning electron microscopy. Partial dehydration of the epidermic tissue caused by calcium (100 m M CaCl₂) and thermal (50 °C/10 min) pretreatment attenuated the surface damage produced by freezing. However, pretreatment at 70 °C/2 min caused partial destruction of the epidermic tissue and plasmolysis of the parenchymatic cells. After freezing, the cell walls in the parenchymatic tissue of the fruits pretreated with 100 m M CaCl₂ exhibited swelling as a result of gelling of the cell-wall pectic material. Thermal pretreatments increased the ethylenediaminetetraacetic acid (EDTA)-soluble pectin fraction and reduced the degree of pectin esterification. Thermal treatments at 70 °C, without immersion in calcium, reduced the water- and pectinase-soluble pectin fractions, whereas immersion in calcium prevented depolymerization of these fractions. Immersion in 100 m M CaCl₂ increased the water-soluble pectin fraction.     

Inactivation Efficiency of Enzymes in Buffered System by Continuous Method with Microbubbles of Supercritical Carbon Dioxide

ABSTRACT: Continuous method with microbubbles of supercritical carbon dioxide (SC-CO₂) was applied to enzyme inactivation in a buffer system, which has a buffer capacity similar to commercial liquid foods (natural juices, fruit drinks, Japanese sake). By continuous treatment with microbubbles of SC-CO₂, α-amylase and acid protease were effectively inactivated rather than by heat treatments. Compared with the inactivation efficiencies of these enzymes in deionized water by continuous treatment with microbubbles of SC-CO₂, that of α-amylase was slightly lower, but that of acid protease was not in the buffer system. These results suggest that this method enables the effective inactivation of enzymes, although inactivation efficiency by this method was affected by initial pH and the buffer action of samples.     

Shelf Life and Microbial Quality of Fresh-cut Mango Cubes Stored in High CO2 Atmospheres

ABSTRACT: Fresh-cut'Carabao'and'Nam Dokmai'mango cubes were stored in air or in high CO₂ atmospheres (3%, 5%, and 10%) at 5 °C and 13 °C. Freshly sliced'Carabao'mango cubes had a lower respiration rate and total bacterial count and higher L-ascorbic acid content and firmness than'Nam Dokmai'mango cubes. The shelf life of fresh-cut mango, based on browning discoloration and water-soaked appearance, was 6 d at 5 °C and 4 d at 13 °C for'Carabao'and 2 d at 5 °C and less than 1 d at 13 °C for'Nam Dokmai'. High CO₂ atmospheres retarded the development of water-soaked'Carabao'cubes at 5 °C and 13 °C and'Nam Dokmai'cubes at 5 °C. Texture of'Carabao'cubes was enhanced by high CO₂, but ethanol and L-ascorbic acid contents were not affected at 5 °C and 13 °C. Total bacterial count was lower in'Carabao'cubes than in'Nam Dokmai'cubes during storage at both temperatures, and a 10% CO₂ only reduced the bacterial count on'Carabao'and'Nam Dokmai'cubes stored at 13 °C. Bacterial flora in'Nam Dokmai'mango cubes consisted mostly of Gram-negative rods assigned primarily to phytopathogenic bacteria such as Pantoea agglomerans and Burkholderia cepacia . The genera of bacteria isolated from cubes stored in 10% CO₂ were similar to those from cubes on the initial day.     

Modeling of Calcium Chloride and Pectin Methylesterase Prefreezing Treatments of Strawberries and Jams

ABSTRACT: :
Different calcium chloride (CaCl₂) and pectin methylesterase (PME) prefreezing treatments in a vacuum were used to clarify the most effective prefreezing factors for strawberries and traditional jams. Fractional factorial design and modeling were used. CaCl₂ had the greatest effect on the majority of the 15 studied responses ( p < 0.001). The pretreatment time should be short (about 5 to 10 min), the temperature low (less than 20 °C), the vacuum level high (pressure less than 10 kPa), the CaCl₂ concentration moderate (about 1%) and the dosage of PME comparatively low (about 50 to 100 nkat/g) in order to yield high quality frozen strawberries for jam making.