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1.
Pacific white shrimp cephalothorax was subjected to pulsed electric field (PEF) pretreatment at different electric field strengths (4, 8, 12 and 16 kV cm−1) and pulse numbers (120, 160, 200 and 240) to enhance the extraction yield of lipids. PEF-treated samples were subsequently subjected to lipid extraction using ultrasound-assisted extraction (UAE) process at ultrasound amplitude of 80% for 25 min in continuous mode. PEF-pretreated samples subjected to UAE rendered the highest lipid yield (30.34 g 100 g−1 solids). PEF pretreatment resulted in reduced lipid oxidation as evidenced by the decreases in peroxide value (PV) and thiobarbituric acid reactive substances (TBARS). Lipids from PEF-pretreated samples extracted using UAE had higher content of PUFAs and carotenoids, including astaxanthin, astaxanthin monoester, astaxanthin diester, canthaxanthin and β-carotene. Overall, PEF pretreatment helped in enhancing the extraction yield of lipids and carotenoids from shrimp cephalothorax and reduce lipid oxidation to some extent.  相似文献   

2.
Pleurotus eryngii polysaccharide (PEP) was obtained using hot water extraction and ethanol precipitation. Three purified polysaccharide fractions (namely PEP1-A, PEP2-A and PEP3-A) were obtained from PEP using DEAE-cellulose-52 chromatography and a gel permeation Sephadex G-100 column. Firstly, this paper examined the characterisation of PEP1-A, PEP2-A and PEP3-A. The corresponding molecular weights were 5.378 × 105, 9.506 × 106 and 4.975 × 105 Da, respectively. PEP1-A, PEP2-A and PEP3-A had similar monosaccharide compositions. PEP1-A was β-configuration, and PEP2-A and PEP3-A were α-configuration. PEP1-A, PEP2-A and PEP3-A had pyran-type rings, (1 → 3) glucose and (1 → 6) galactose linkages. Secondly, PEP, PEP1-A, PEP2-A and PEP3-A possessed antioxidant activities, and PEP was best. Therefore, only PEP was used to study its anti-fatigue activity in vivo. The result proved that PEP had anti-fatigue activity. PEP could be used as a valuable natural food supplement for preventing anti-fatigue or functional food.  相似文献   

3.
Conventional solvent extraction (CE) and ultrasound‐assisted extraction (UAE) in hexane for oil from untreated and enzyme‐treated grape seeds were investigated and compared. Among the output power tested (50, 100 and 150 W) in UAE on untreated seeds, UAE at 150 W for 30 min with liquid‐to‐solid ratio 8:1 (v/w) gave oil extraction yield comparable to CE (ca. 14% w/w) for 6 h with liquid‐to‐solid ratio 12:1 (v/w). CE and UAE at 150 W did not influence the fatty acid profiles of oil. CE oil was found to be the most oxidised. The enzymatic treatments (2, 4 and 6 g per 100 g seeds of Rapidase® Expression) prior to CE enhanced by 2.5% of the oil yield. Enzymatic treatments higher than 2 g per 100 g seeds increased relative value of some fatty acids both in CE and UAE. Enzymatic pretreatment from 2 to 4 g per 100 g seeds significantly improved some physicochemical parameters of oil quality when extracted by CE, but not by UAE.  相似文献   

4.
Cactus pear cladodes processing has potential value for mainstream industries and is equally important for marginal rural communities in arid regions. This work is focused on physico-chemical and rheological properties of Opuntia ficus-indica (OFI) peeled cladodes extracted by conventional method “CE” and using microwave-assisted extraction “MAE.” MAE gave the highest yield extraction (8.13 %, w/w) within the lowest extraction time (500 W/7 min) and provided more protein (×1.03) and carbohydrates (×1.51) than CE. The monosaccharides detected by gas chromatography were arabinose, galactose, rhamnose, xylose, and galacturonic acid. The dialyzed mucilage solution characterized by SEC/MALS/VD/DRI (size-exclusion chromatography coupled with online multi-angle light scattering, viscometer detectors, and differential refractive index) revealed fractions with molecular weight (M w ) ranging from 15.3–15.7?×?106 g mol?1 for the CE extracts and about 16.7–17.5?×?106 g mol?1 for the MAE extracts. Dynamic oscillatory testing has been used to study the rheological properties of mucilage solution within the concentration of 0.50–3.00 % (w/v) at 25 °C. The rheological profiles of CE and MAE showed similar behavior. At low frequency and low mucilage concentration (<2.00 %), the viscous component (G") predominated over the elastic component (G'), while for higher frequencies, the behavior is reversed (G'?>?G"). If safely controlled, alternative energies like microwaves could extract soluble polymers with comparable properties to commercial ones, conventionally extracted.  相似文献   

5.
The present study focuses on the extraction of phenolic compounds, anthocyanin and antioxidants from black jamun pulp by microwave and ultrasound assisted extraction process. The microwave-assisted extraction was carried out for 240 s at microwave power level of 100–400 W. The yield of total anthocyanin and total phenolic content in the microwave assisted extraction process at 400 W power level after an extraction period of 240 s was 8.197 mg of C3G g−1 and 37.671 40.632 mg GAE g−1, respectively. The ultrasound assisted extraction was performed at temperatures of 40, 50, 60, and 70 °C for 150 min. In the ultrasound assisted extraction at a sonication temperature of 70 °C, the yield of anthocyanin was 8.525 mg of C3G g−1, while the yield of the phenolic compound was 47.331 mg GAE g−1. The pseudo-second order model was found to be the most suitable model to represent the extraction kinetics of anthocyanin, phenolic compounds, and antioxidant activity of black jamun pulp. The effective diffusion coefficient for ultrasound assisted extraction of phenolic components, anthocyanin, and antioxidant activity in the temperature range of 40-70 °C was 5.704× 10−12–10.515 10−12, 2.485× 10−12 -8.507× 10−12, and 2.061× 10−12–11.977 × 10−12 m2.s−1 respectively. The negative Gibbs free energy change values for extraction of phenolic compounds and anthocyanin specified that the reaction was feasible and spontaneous. Thermodynamic parameters such as positive enthalpy change and positive entropy change indicated that the ultrasound assisted extraction process was endothermic and irreversible in nature.  相似文献   

6.
In this paper, experimental kinetics of vanilla pods’ solid–liquid extraction were obtained by three different methods: with agitation, without agitation, and microwave-assisted (MAE) without agitation. The extraction kinetics of aroma compounds (vanillin, p-hydroxybenzaldehyde, and p-hydroxybenzoic acid) was measured in vanilla pods (refined) and extracts by high-performance liquid chromatography. Additionally, the equilibrium distribution of aroma compounds between phases and the retained solution by refined pods were experimentally evaluated. A mechanistic model of two simultaneous algebraic equations was fitted to experimental data in order to estimate the aroma compound diffusivities inside the pods and mass transfer coefficients in the extract. The diffusivities in vanilla pods at 50 °C were 4.31?×?10?11, 2.93?×?10?11, and 3.50?×?10?11?m2?s?1 for vanillin, p-hydroxybenzaldehyde, and p-hydroxybenzoic acid, respectively. External mass transfer coefficients were in the order of 1.0?×?10?4?m?s?1 for forced convection extraction and MAE and 3.33?×?10?7?m?s?1 for natural convection extraction.  相似文献   

7.
This study investigated the effects of different extraction methods (i.e. conventional (CE), ultrasound-assisted (UAE), and pulse electric field-assisted (PEFAE)) on the yield and physico-chemical properties of the water-soluble non-starch polysaccharide (WS-NSP) from taro peel (Tp). The use of UAE resulted in a significantly (p ≤ 0.05) higher yield (3.65 g/100 g) than PEFAE (2.25 g/100 g) and CE (2.10 g/100 g). Tp-WS-NSP-UAE and Tp-WS-NSP-PEFAE had fewer impurities indicated by the lower amount of ash (UAE: 0.41; PEFAE: 0.20 g/100 g) and protein (UAE: 0.55; PEFAE: 0.42 g/100 g), had lighter color (UAE: L = 39.13; PEFAE: L = 34.72), and higher degradation temperatures (UAE: 252.68; PEFAE: 251.75 °C) than Tp-WS-NSP-CE (ash: 0.47; protein: 1.23 g/100 g; L = 34.18; < 250 °C). All Tp-WS-NSP samples contained the sugars arabinose, galactose, glucose, and mannose, had comparable functional groups in their FTIR spectra, were amorphous, and exhibited shear-thinning behavior (n < 1).  相似文献   

8.
Migration of low molecular weight substances into foodstuffs is a subject of increasing interest and an important aspect of food packaging because of the possible hazardous effects on human health.The migration of a model substance (diphenylbutadiene) from low-density polyethylene (LDPE) was studied in foodstuffs with high fat contents: chocolate, chocolate spread and margarines (containing 61% and 80% fat).A simplifying mathematical model based on Fick’s diffusion equation for mass transport processes from plastics was used to derive effective diffusion coefficients which take also kinetic effects in the foods into account and to determine partition coefficients between plastic and food. With this model migration levels obtainable under other storage conditions can be predicted. The effective diffusion coefficients for both margarines stored at 5 °C (3.0–4.2 × 10−10 cm2 s−1) and at 25 °C (3.7–5.1 × 10−9 cm2  s−1) were similar to each other, lower than for chocolate spread stored at 5 °C (9.1 × 10−10 cm2 s−1) and higher than the diffusion coefficient for chocolate stored at 25 °C (2.9 × 10−10 cm2 s−1). Good agreement was found between the experimental and the estimated data, allowing validation of this model for predicting diffusion processes in foodstuffs with high fat contents.  相似文献   

9.
The effect of microwave drying technique on moisture content, moisture ratio, drying rate, drying time and effective moisture diffusivity of mint leaves (Mentha spicata L.) were investigated. By increasing the microwave output powers (180–900 W) and the sample amounts (25–100 g), the drying time decreased from 12.50 to 3.0 min and increased from 6.60 to 16 min, respectively. To determine the kinetic parameters, the drying data were fitted to various models based on the ratios of the differences between the initial and final moisture contents and equilibrium moisture content versus drying time. Among of the models proposed, the semi-empirical Midilli et al. model gave a better fit for all drying conditions applied. By increasing the microwave output powers and decreasing the sample amounts, the effective moisture diffusivity values ranged from 3.982 × 10−11 to 2.073 × 10−10 m2 s−1 and from 9.253 × 10−11 to 3.162 × 10−11 m2 s−1, respectively. The activation energy was calculated using an exponential expression based on Arrhenius equation. The relationship between the drying rate constant and effective moisture diffusivity was also estimated; and gave a linear relationship.  相似文献   

10.
《Food chemistry》2002,78(2):255-260
A method based on capillary electrophoresis with electrochemical detection (CE–ED) was developed for the determination of trans-Resveratrol in wines, Chinese medicinal herb Polygonum cuspidatum Sied. et Zucc., and Zijin capsule. The effects of some important factors such as injection time, and applied potential to working electrode were investigated. Operated in a wall-jet configuration, a 300 μm diameter carbon-disk electrode was used as the working electrode, which exhibits good response at +0.85 V (vs. SCE) for trans-Resveratrol. Linearity was obtained in the concentration range from 1.0×10−4 to 5.0×10−7 g/ml. The detection limit (S/N=3) was 5.96×10−8 g/ml. This proposed method has been successfully applied to analyze several actual samples with satisfactory assay results.  相似文献   

11.
Extrusion processing has been used to modify the functional properties of proteins. The protein-protein interactions, surface hydrophobicity, and rheological properties of milk protein concentrate extruded using dies of different geometries (circular, annular and slit) were quantified. With the same extrusion treatment history prior to the die, extrudates generated using dies with higher wall shear (slit 1.4 × 104 s−1 > annular 1.1 × 104 s−1 > circular 2.9 × 103 s−1) showed greater protein extractability, higher index of surface hydrophobicity, and enhanced water solubility index indicating significant breakdown of protein aggregates. Higher viscoelastic moduli (G' and G") and apparent viscosity were observed for slit die extrudate dispersions. However, low flow behavior indices (0.04–0.23(−)) and a high viscous activation energy (43 kJ/mol) of slit die extrudate dispersions implied their shear and temperature sensitivity, respectively. Thus, extrudate functionality can be optimized by selection of the appropriate die design.  相似文献   

12.
《Food Hydrocolloids》2007,21(5-6):747-755
The effect of bovine serum albumin (BSA) on the heat-induced denaturation, aggregation and subsequent acid-induced gelation of β-lactoglobulin (β-lg) was investigated in this work. Changes in the denaturation kinetics of β-lg during heating at 78 °C were determined by monitoring the disappearance of the native protein by reverse-phase chromatography. Replacing β-lg with increasing amounts of BSA, while keeping the total protein concentration constant at 5% (w/w), significantly increased the denaturation rate of β-lg from 2.57±0.30×10−3(g L−1)(1−n)s−1 to 5.07±0.72×10−3(g L−1)(1−n)s−1 (β-lg: BSA ratio of 3:1 w/w). The reaction order for β-lg was 1.40±0.09. Partial replacement of β-lg with BSA (β-lg: BSA ratio of 3:1 w/w) significantly increased the reaction order to 1.67±0.13. Heat-induced aggregates between β-lg and BSA were studied by dynamic light scattering, two-dimensional electrophoresis and size exclusion chromatography. The partial replacement of β-lg with BSA significantly changed the gelling properties of the acid-induced gels. A rapid rate of acidification resulted in a significant decrease, while a slow acidification rate resulted in a significant increase in gel strength. Size exclusion chromatography demonstrated that intermolecular disulphide bond formation occurred during both heat-induced denaturation/aggregation and subsequent acid-induced gelation. Results clearly indicate that BSA contributed to the formation of these disulphide bonds.  相似文献   

13.
This article presents the first report on the extraction and quantification of α-tocopherol from the fronds of the oil palm (Elaeis guineensis Jacq). In this study, the optimization, kinetic, and thermodynamic data of α-tocopherol extraction by sonication are presented. Response surface methodology coupled with central composite design was used to optimize the experimental conditions for α-tocopherol extraction. Three independent variables, namely sample/solvent ratio (1:20–1:40 g/ml), extraction temperature (30–50 °C), and extraction time (20–50 min) were studied. For optimum conditions of 39.31 °C (~40 °C), 50 min, and 1:23.63 g/mL (~1:20 g/mL), total tocols and α-tocopherol optimal concentrations were 346.49 μg/g oil palm fronds (OPFs) by dry weight (DW) and 28.41 μg/g OPF DW, respectively. The effects of extraction temperature and tocol concentrations on the extraction kinetics and thermodynamic parameters were also studied. From the mass transfer rate equation, the kinetic and thermodynamic data obtained from the ultrasonic-assisted extraction (UAE) of α-tocopherol from OPF were activation energy, E a (104.6 kJ mol?1), UAE rate constant, k (6.886?×?10?3 min?1), ΔH (+0.818 kJ mol?1), ΔS (+27.22 J mol?1 K?1), and ΔG (?8.52 J mol?1). According to this study, the UAE of α-tocopherol from OPF is endothermic, irreversible, and spontaneous.  相似文献   

14.
The aim of the present study was to evaluate and compare the phenolic content and antioxidant and antimicrobial properties of olive leaf extracts obtained by ultrasound-assisted extraction (UAE) and conventional extraction (CSE). UAE of olive leaf extracts yielded a higher total phenolic content (TPC) and total flavonoid content (TFC) of 14.31% and 19.50%, respectively. Higher antioxidant activities were found from the extracts prepared with UAE (for 18.5%, 12.5%, 10.9% and 17.6% higher determined by DPPH, ABTS, FRAP and CUPRAC methods, respectively). Good antibacterial inhibitory activity (as MIC and MBC) was observed against both Y. enterocolitica and S. aureus (1.40 ± 0.40 mg mL−1 and 4.00 ± 1.60 mg mL−1, respectively) with the extract prepared with UAE. In conclusion, olive leaf extracts prepared with UAE exhibited higher antioxidant and antimicrobial activities against common food-borne pathogens than CSE extracts and thus could be beneficial in ensuring food quality and food safety.  相似文献   

15.
Tomato waste is an excellent source of nutrients, micronutrients, and bioactive compounds. Some extraction technologies have been used to recover these pigments for their proven biological activities. In this study, solid-state fermentation with Aspergillus niger GH1 was used as a bioprocess for carotenoid extraction and recovery in tomato waste. The chemical composition was evaluated, in addition to the viability of the tomato waste as a solid-fermentation substrate. The results showed that at 70% humidity, pH 4.0, 30 °C, 1 × 106 spores/g of inoculum concentration, and 36 h of fermentation gave the optimal yield. A biomass/carotenoids ratio of 0.164 mg/L of total carotenoids was realized. The number of carotenoids extracted from tomato waste was improved from 0.062 mg/L from zero hours of fermentation to 0.164 mg/L of total carotenoids after 36 h of fermentation. Solid-state fermentation with Aspergillus niger GH1 was a viable approach to enhance the extraction and recovery of carotenoids.  相似文献   

16.
The study compared high-pressure, microwave, ultrasonic, and traditional extraction techniques. The following extraction conditions were implemented: microwave-assisted extraction (MAE) at 900 W power for durations of 30, 60, and 90 s; ultrasonic-assisted extraction (UAE) at 100% amplitude for periods of 5, 10, and 15 min; and high-pressure processing (HPP) at pressures of 400 and 500 MPa for durations of 1, 5, and 10 min. The highest yield in terms of total phenolic content (PC) was obtained in UAE with a value of 45.13 ± 1.09 mg gallic acid equivalent (GAE)/100 g fresh weight (FW). The highest PC content was determined using HPP-500 MPa for 10 min, resulting in 40 mg GAE/100 g, and MAE for 90 s, yielding 34.40 mg GAE/100 g FW. The highest value of antioxidant activity (AA) was obtained by UAE in 51.9% ± 0.71%. The PCs were identified through the utilization of Fourier transform infrared (FTIR) spectroscopy and high-performance liquid chromatography (HPLC). Utilizing multivariate analysis, the construction of chemometric models were executed to predict AA or total PC of the extracts, leveraging the information from IR spectra. The FTIR spectrum revealed bands associated with apigenin, and the application of HPP resulted in concentrations of 5.41 ± 0.25 mg/100 g FW for apigenin and 1.30 ± 0.15 mg/100 g FW for protocatechuic acid. Furthermore, HPLC analysis detected the presence of protocatechuic acid, caffeic acid, p-coumaric acid, and apigenin in both green extraction methods and the classical method. Apigenin emerged as the predominant phenolic compound in peach extracts. The highest concentrations of apigenin, p-coumaric acid, and protocatechuic acid were observed under HPP treatment, measuring 5.41 ± 0.25, 0.21 ± 0.04, and 1.30 ± 0.15 mg/kg FW, respectively.  相似文献   

17.
Equilibrium and dynamic water sorption properties of sponge cakes with varying porosity (86–52%) and fat content (0–0.30 g/g d.b.) were determined using a water vapour sorption microbalance. Contrary to porosity, addition of fat decreased equilibrium moisture contents. The effective moisture diffusivity (Deff) was identified from a numerical solution of Fick’s second law, taking into account an external mass transfer coefficient and the swelling of the solid matrix. Deff increased from 1.61 to 8.67 × 10−10 m2/s with moisture content, reached a threshold at moisture content 0.15 g/g d.b. and then decreased until water saturation. Deff decreased from 8.67 to 2.97 × 10−10 m2/s with decreasing porosity. This effect was attributed to a change of water diffusion mechanism, from predominant vapour to liquid. Deff decreased from 8.67 to 2.12 × 10−10 m2/s with increasing fat content. Addition of fat had an effect on the water diffusion in two ways, decreasing porosity (sagging of the foam) and increasing tortuosity.  相似文献   

18.
This study aims to develop edible films using agrifood by-products (pumpkin seeds, broken rice and orange pectin) and wastes (quince peel, potato peel, potato pulp, orange peel, pumpkin peel). The physicochemical characteristics of the films were investigated, including their mechanical and barrier properties. Higher amounts of plasticizer induced poorer mechanical and barrier properties in the films. The most promising ones were obtained with orange pectin, broken rice and pumpkin peel, with water contact angles (WCA) between 48° and 57°, maximum water vapor transmission rate and water vapor permeability of 575 g.m−2.d−1 and 108 × 10−12 g.Pa−1.s−1.m−1, respectively, Young's modulus between 350 and 800 MPa, maximum tensile strength between 9.0 and 26.25 MPa, and elongation at break between 2.28 and 9.3%. Orange pectin and broken rice are promising raw materials since they led to higher WCA, better barrier and mechanical properties. Broken rice and quince peel can be good substitutes for commercial starch and glycerol, respectively. Agro-industrial by-products and wastes revealed potential for the production of sustainable edible films.  相似文献   

19.
Seven strains of Beauveria bassiana were evaluated for their effects on the eggs of Lasioderma serricorne under laboratory conditions. Strains were applied at a single dose of 0.03 g conidia kg−1 of grain = 2 × 109 conidia g−1 of kaolin kg−1 of grain. All strains were pathogenic on the eggs of L. serricorne. Two strains, MS-8, and 7284, caused the highest levels of egg mortality. These two strains were then formulated at a fixed dose of 0.03 g conidia, with kaolin as an active carrier, at doses of 0.0, 0.5 g, 1 g, 2 g and 3 g of kaolin kg−1 of grain. These powder formulations were evaluated for their effects on adult mortality, larval mortality, number of adults emerged, level of grain damaged and level of weight loss on rice grains. The highest levels of adult mortality and larval mortality were caused by Strain MS-8 at a kaolin dose of 3 g kg−1. It also caused the lowest levels of adult emerged (10%), grain damaged (1.07%) and weight loss (0.55%). When unformulated, the same dose of conidia performed poorly for the same parameters (64%; 20.2%; 3.37%). The highest levels of grain damaged (27%) and weight loss (6.04%) were observed in the untreated control (UTC). Observations made with a scanning electron microscope (SEM) showed that unformulated conidia clumped together whereas conidia formulated in kaolin remained as discrete conidia.  相似文献   

20.
《LWT》2005,38(4):393-398
A mathematical model is employed to describe sulfur dioxide (SO2) diffusion and reaction during steeping of dent corn. Experiments are performed to measure change of SO2 content of grain during process. A computer-aided nonlinear optimization technique is used to estimate the effective diffusion coefficients and rate constants in the temperature range 25–55 °C. The effective diffusion coefficient for SO2 varied between 2.27×10−11 and 6.24×10−11 m2/s and had an Arrhenius activation energy of 24.3 kJ/mol. The reaction rate of SO2 in dent corn followed first-order kinetics, with rate constants in the range of 0.80×10−6–5.38×10−6 s−1 and activation energy of 49.16 kJ/mol.  相似文献   

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