The rheological properties of five gum solutions (Gum Shiraz, Karaya Gum, Ghatti Gum, Arabic Gum and Gum Tragacanth) have been examined. The five mucilage solutions exhibited non-Newtonian, shear-thinning with thixotr...The rheological properties of five gum solutions (Gum Shiraz, Karaya Gum, Ghatti Gum, Arabic Gum and Gum Tragacanth) have been examined. The five mucilage solutions exhibited non-Newtonian, shear-thinning with thixotropy at higher concentrations (0.5% - 1%, m/v). According to the change of viscosity with increasing temperature, all five gums could be defined as three types: gum tragacanth and gum shiraz have a good temperature stability;karaya gum is affected by temperature obviously;the remaining two gums have a general stability. The viscosity of mucilage solutions (Arabic Gum, Ghatti Gum and Karaya Gum) had an apparent dependence on temperature. The parameter n of Shiraz Gum is the minimum, which means it has the best flow properties. The flow activation energy of karaya gum is 2.683 kcal which is the highest than other gums so that it has a great influence on temperature. The gum solutions’ viscosity had different sensitive degree over tested pH range (pH 2 - 10). Shiraz gum and arabic gum possessed better acid-proof and alkali-proof respectively. The addition of salts (NaCl and CaCl2) led to the reduction of viscosity, which was more sensitive to Ca2+ than to Na+. Both storage modulus G’ and loss modulus G” of all five gums had a dependence on temperature and frequency. These results are potentially useful for the application in the field of food processing.展开更多
The rheological properties of six mucilage solutions (Guar Gum, Locust Bean Gum, Tamarind Gum, Flaxseed Gum, Artemisia Sphaerocephala Krasch Gum and Cassia Gum) have been examined. It was found that all six gums could...The rheological properties of six mucilage solutions (Guar Gum, Locust Bean Gum, Tamarind Gum, Flaxseed Gum, Artemisia Sphaerocephala Krasch Gum and Cassia Gum) have been examined. It was found that all six gums could be classified into three different types according to the changes of viscosity with increasing shear rate. Steady shear viscous properties in a range of shear rate from 0.1 to 100 s-1 were investigated in the provision of mucilage concentration, pH, temperature and salts. A non-Newtonian shear-thinning behavior was observed. The data of viscosity-shear successfully correlated Power law model. Apparent viscosity was apparently dependent on mucilage concentration increasing significantly as mass fraction went up. A marked dependence of viscosity on temperature was also observed;as temperature increased, the viscosity decreased sharply. The value n of flaxseed gum is minimum, which means it behaves the greatest shear-thinning properties. Both Guar gum and Tamarind gum possessed better acid-proof and alkali-proof advantages. The flow activation energy of ASKG is 4.3 kcal which is higher than other gums so that the influence of temperature on characteristics of viscosity is stronger. The mechanical spectra in the linear viscoelasticity region were studied in the temperature range from 20°C to 90°C, at a frequency range from 0.1 to 10 Hz. It was observed that Both elastic modulus G' and viscous modulus G" behaviors were found to be dependent on temperature and frequency. What have been investigated in this work could provide guidance for practical application in the field of food industry.展开更多
文摘The rheological properties of five gum solutions (Gum Shiraz, Karaya Gum, Ghatti Gum, Arabic Gum and Gum Tragacanth) have been examined. The five mucilage solutions exhibited non-Newtonian, shear-thinning with thixotropy at higher concentrations (0.5% - 1%, m/v). According to the change of viscosity with increasing temperature, all five gums could be defined as three types: gum tragacanth and gum shiraz have a good temperature stability;karaya gum is affected by temperature obviously;the remaining two gums have a general stability. The viscosity of mucilage solutions (Arabic Gum, Ghatti Gum and Karaya Gum) had an apparent dependence on temperature. The parameter n of Shiraz Gum is the minimum, which means it has the best flow properties. The flow activation energy of karaya gum is 2.683 kcal which is the highest than other gums so that it has a great influence on temperature. The gum solutions’ viscosity had different sensitive degree over tested pH range (pH 2 - 10). Shiraz gum and arabic gum possessed better acid-proof and alkali-proof respectively. The addition of salts (NaCl and CaCl2) led to the reduction of viscosity, which was more sensitive to Ca2+ than to Na+. Both storage modulus G’ and loss modulus G” of all five gums had a dependence on temperature and frequency. These results are potentially useful for the application in the field of food processing.
文摘The rheological properties of six mucilage solutions (Guar Gum, Locust Bean Gum, Tamarind Gum, Flaxseed Gum, Artemisia Sphaerocephala Krasch Gum and Cassia Gum) have been examined. It was found that all six gums could be classified into three different types according to the changes of viscosity with increasing shear rate. Steady shear viscous properties in a range of shear rate from 0.1 to 100 s-1 were investigated in the provision of mucilage concentration, pH, temperature and salts. A non-Newtonian shear-thinning behavior was observed. The data of viscosity-shear successfully correlated Power law model. Apparent viscosity was apparently dependent on mucilage concentration increasing significantly as mass fraction went up. A marked dependence of viscosity on temperature was also observed;as temperature increased, the viscosity decreased sharply. The value n of flaxseed gum is minimum, which means it behaves the greatest shear-thinning properties. Both Guar gum and Tamarind gum possessed better acid-proof and alkali-proof advantages. The flow activation energy of ASKG is 4.3 kcal which is higher than other gums so that the influence of temperature on characteristics of viscosity is stronger. The mechanical spectra in the linear viscoelasticity region were studied in the temperature range from 20°C to 90°C, at a frequency range from 0.1 to 10 Hz. It was observed that Both elastic modulus G' and viscous modulus G" behaviors were found to be dependent on temperature and frequency. What have been investigated in this work could provide guidance for practical application in the field of food industry.
