Low-field Nuclear Magnetic Analysis Research Articles

Whey protein isolate regulates the oral processing characteristics of lotus root starch

This study aimed to investigate the influence of different levels of added whey protein isolate (WPI) on the oral processing characteristics of lotus root starch (LRS). The IDDSI test results indicated that WPI-LRS composite gels could be classified as foods suitable for individuals with dysphagia. During in vitro oral digestion process, addition of WPI increased the viscosity of the composite system. When the amount of WPI reached 100% (w/w), the reducing sugar content decreased from 105.23 to 42.35 mg. Inverted fluorescence images revealed that WPI formed a continuous network structure in the starch matrix and served as a barrier against amylase digestion. Different levels of WPI addition had diverse effects on the oral friction characteristics and rheological properties of the composite system. As the protein addition amounts were lower than 45% (w/w), the composite gels had lower lubrication properties and elastic modulus. While as the addition levels were higher than 45% (w/w), the composite gels exhibited higher lubrication properties and elastic modulus. Texture analysis indicated that the hardness value of the composite gel increased from 0.65 N for the individual LRS gel to 4.75 N for the composite gel of LRS+100% WPI. Furthermore, it was found through low-field nuclear magnetic analysis that the addition of WPI restricted the free movement of water molecules and enhanced the water-holding capacity of the composite gels.

Emulsification properties of comb-shaped trimeric nonionic surfactant for high temperature drilling fluids based on water in oil

Novel comb-shaped trimeric nonionic surfactant was synthesized with diethylenetriamine and organic acids, and then the chemical structure of the trimeric nonionic surfactant was characterized by Fourier transform infrared (FTIR) and elemental analysis. The interfacial film strength and critical micelle concentration (CMC) were measured by interface tension method. The emulsification properties was obtained by emulsification rate experiment and low field nuclear magnetic analysis, and the thermal stability of emulsions were also obtained by microscopic analysis and low field nuclear magnetic analysis. And then the comb-shaped trimeric nonionic surfactant showed an excellent emulsification effect with 2.5wt% adding amount in oil based drilling fluid. The performance of drilling fluids with various emulsifier adding amounts were investigated by rheological measurements, thermal stability analysis and filtration experiment. These results shows that the comb-shaped trimeric nonionic surfactant as an emulsifier improved the application performance of oil based drilling fluids, it was also found that the results in our work maybe provided a new research ideas about structure-performance relationships for the new trimeric nonionic surfactant.