Search

The effects of solid fermentation conditions such as the incubation period, fermentation temperature, initial pH, and inoculum concentration on protease production and in vitro digestibility of flaxseed protein with Aspergillus oryzae 3.951 were reported. From 72h of fermentation at 30 °C, protease activity and protein digestibility were significantly increased. Maximum protease activity was obtained for high temperature-pressed flaxseed meal (HFM) and cold-pressed flaxseed meal (CFM) with initial pH 4.4-5.2, inoculum concentration 0.5×106 spores /mL. The results showed that the melting temperature (Td) increased by 4.8 °C and 7.6 °C for fermented CFM and HFM, respectively. In DSC tests, the enthalpy value is defined as the quantity of heat absorbed by samples during warming process. Results indicate that the enthalpy value of fermented samples significantly reduced from 186.5 J/g to 148.9 J/g (CFM) and from 187.0 J/g to 163.3 J/g (HFM). The result suggests that the lower molecular weight protein was degraded by protease, and the remaining were globulin with greater thermal stability and higher molecular weight. [ABSTRACT FROM AUTHOR]

Abstract: Rheological properties of the extruded pastes of various extrusion conditions were investigated by dynamic oscillation and creep-recovery tests. Temperature sweep test showed that the starch gelatinization of non-extruded pastes took place at about 67°C and no gelatinization was observed for the extruded sample. Frequency sweep tests could be represented by a Power law model and the samples showed gel-like behavior since storage modulus was much larger than loss modulus. The creep-recovery data were modeled by the Burger’s model. With the addition of flaxseed, the viscoelastic modulii of pastes were increased due to the formation of starch–protein–fat network, however, with further increasing the flaxseed content the viscoelastic modulii of pastes were decreased due to excessive fat which lead to network weakening. The water holding capacity results indicated that the viscoelastic properties of pastes were depended on the swelled starch–protein complex granules and the formation of new cross-links in the network. [Copyright &y& Elsevier]

Abstract: Rheological properties of flaxseed mucilage under different extrusion conditions with or without enzyme treatment were studied. The steady-shear tests indicated that the apparent viscosity of flaxseed mucilage fitted well to Power law model and all samples showed a shear-thinning behavior. The consistency index decreased and the flow behavior index increased with an increasing temperature and a decreasing screw speed. The addition of initial moisture content improved the degradation of flaxseed mucilage while further increase affected the action negatively. The empirical equations describing relationships between parameters of rheological models and extrusion factors were obtained. The results showed that extrusion can damage the compact fiber structure which improved the effect of enzyme treatment. The apparent viscosity decreased with the increase in hydrolyzing time and enzyme loading amount. [Copyright &y& Elsevier]

Abstract: Flaxseed gum solutions were extracted and dried by different methods: ethanol precipitation, freeze drying, 105°C oven drying, 80°C oven drying, spray drying, and vacuum drying. The effects of these drying methods on the rheological properties of flaxseed gum were investigated in present study. Ethanol precipitation increased the apparent viscosity of flaxseed gum solution, while all the other methods decreased the apparent viscosity. Most of the drying methods slightly increased the activation energy, except ethanol precipitation. In frequency sweep test, all the drying methods reduced the G′ and G″ values. In creep–recovery tests, the data were modeled by Berger’s model. The E 2 and η 1 values were reduced by all of the drying methods in this study. Some relationships were found between the parameters in the Power Law model of the frequency sweep test and the parameters in Berger’s model. [Copyright &y& Elsevier]

Abstract: Rheological characteristics of potato starch/flaxseed protein concentrate composites were investigated using a rheometer. Effects of starch/protein mass ratio (0.2–1.0) and different cooling rate (2°C/min, 4°C/min and 6°C/min) on rheological behavior of composites were studied. The study showed that G’ and G’’ increased with increase of starch mass ratio in the temperature range of 40–95°C, in both heating and cooling process. The composites exhibited similar and , higher than those of potato starch alone at 60.3°C. The result of frequency sweep of the composites at the end of the cooling at 25°C exhibited an elastic behavior at all test frequency ranges (0.06283–62.83rad/s). Study of cooling rate on rheological characteristic of composites exhibited an increase in the G’ and G’’ values with decrease of cooling rate, probably because of gel network having a stronger structure with more time for dynamic equilibration. [Copyright &y& Elsevier]

Abstract: Flaxseed oil is the main component of the flaxseed and has many beneficial functions to human health. In this paper, the ultrasound-assisted extraction of oil from flaxseed is reported. The effects of some operating parameters such as ultrasonic power, extraction time, extraction temperature and solvent to solid ratio on the yield of flaxseed oil have been investigated and some of the results have been compared with that of conventional method. It has been found that ultrasound-assisted extraction requires a shorter extraction time and a reduced solvent consumption. The yield of flaxseed oil has been found to increase with the increase of the ultrasonic power and to decrease as the temperature is increased. Scanning electronic microscopy analysis was carried out on the flaxseed powder after the extraction. The images are powerful evidences to show the effect of ultrasound. The fatty acid compositions of the oils extracted by the ultrasound-assisted method and the conventional method have been analyzed using gas chromatography. It has been shown that the compositions of the flaxseed oils were not affected significantly by the application of ultrasound (p >0.05). The ultrasound-assisted extraction may be an effective method for lipid production. [Copyright &y& Elsevier]

Abstract: In this study, the extrusion detoxification technique on flaxseed was investigated by uniform design optimization. The effect of the temperature (°C), the feeding rate (kgh−1), the screw speed (rpm) and the moisture content (%) on the response value (the removal rate, %) of hydrocyanic acid (HCN) in flaxseed has been investigated. U12 (123 ×4) mixed-level uniform design was selected and the equation of extrusion detoxification model was obtained after 12 experimentations. The content of cyanide in flaxseed was determined by Association of Official Analytical Chemists (AOAC) method. The extrusion detoxification technique was optimized with stepwise non-linear regression analysis and response surface method (RSM). DPS Professional V.3.01 and MATLAB (Version 6.5.1) were used for data analysis. The optimized results, including the temperature, the feeding rate, the screw speed, the moisture content of flaxseed, the optimized value and the relative error of the model, were 146.0°C, 32.7kgh−1, 152.5rpm, 12.5, 93.23 and 1.76%, respectively. In order to improve the productivity, the feeding rate can be increased to 60kgh−1on condition that it can reach the demanding value of detoxification. At this feeding rate, the model value of the removal rate of HCN in flaxseed is 84.38%; the experimental value is 83.32%; the relative error of the model is 1.27%. [Copyright &y& Elsevier]

Abstract: Flaxseed is a good source of plant protein for both human diet and animal feed. Extrusion process effectively improves the digestion of flaxseed. In the present work, the effects of extrusion parameters such as screw speed, moisture content, temperature and feed rate on the IVPD of the extruded flaxseeds were investigated. A central composite design was used with four controlled variables: screw speed (70, 120, 170, 220 and 270r/min); moisture content (4%, 10%, 16%, 22% and 28%); temperature (84, 108, 132, 156 and 180°C); and feed rate (25.4, 47.4, 69.4, 91.4 and 113.4kg/h). The experimental values of IVPD measured from 69.46% to 77.43%. A second-order model was obtained to predict the IVPD. It has been found that moisture content and feed rate affect the IVPD more significantly compared with the temperature and screw speed. In the present study, the maximum digestibility was obtained when the screw speed, moisture content, temperature and feed rate were 120r/min, 10%, 120°C and 91.4kg/h, respectively. The application of this analysis method for optimizing the extrusion process of flaxseeds is discussed. [Copyright &y& Elsevier]

Abstract: The optimal conditions for the extraction of lignans from flaxseed were determined. A second-order regression for rotation-orthogonal composite design was used to investigate the effects of three independent variables, namely ethanol concentration (%), extraction temperature (°C), and extraction time (h) on the response, the acquired ratio of lignans. The independent variables were coded at five levels and their actual values selected on the basis of results of single-factor experiment. The second-order regression for rotation-orthogonal composite design consisted of 23 experimental points and 9 replications at the central point. Data were analyzed using MATLAB software. The results indicated that acquired ratio of lignans might be beyond 8% at a probability of 95% in the range of ethanol concentration: 56.6–83.4%, extraction time: 26.7–27.9h, extraction temperature: 38.7–40.1°C. And the optimal extraction conditions were ethanol concentration of 70%, extraction time of 28h and extraction temperature of 40°C according to the analysis of response surface. In this condition, the experimental acquired ratio of lignans was 8.975% (w/w; lignans/defatted flaxseed powder), which is close to the predicted value (9.316%). [Copyright &y& Elsevier]