Browsing by Subject "Viscoelasticity"

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  • Tanner, Timo; Antikainen, Osmo; Ehlers, Henrik; Yliruusi, Jouko (2017)
    With modern tableting machines large amounts of tablets are produced with high output. Consequently, methods to examine powder compression in a high-velocity setting are in demand. In the present study, a novel gravitation-based method was developed to examine powder compression. A steel bar is dropped on a punch to compress microcrystalline cellulose and starch samples inside the die. The distance of the bar is being read by a high-accuracy laser displacement sensor which provides a reliable distance-time plot for the bar movement. In-die height and density of the compact can be seen directly from this data, which can be examined further to obtain information on velocity, acceleration and energy distribution during compression. The energy consumed in compact formation could also be seen. Despite the high vertical compression speed, the method was proven to be cost-efficient, accurate and reproducible. (C) 2017 Elsevier B.V. All rights reserved.
  • Wang, Hang; Luo, Yongkang; Ertbjerg, Per (2017)
    Minced beef was stored for 8 days and myofibrillar protein (MP) was extracted to investigate the effect of oxygen concentration (0, 20, 40, 60, and 80%) in modified atmosphere packaging (MAP) on heat-induced gel properties. Compression force of gels was lower when prepared from beef packaged in 0% oxygen, intermediate in 20 to 60% oxygen and greater in 80% oxygen. Total water loss of gels prepared from beef packaged with oxygen (20-80%) was higher and rheology measurements presented higher G' and G '' values. Additionally, gels from beef packaged without oxygen exhibited higher J (t) values during creep and recovery tests, demonstrating that oxygen exposure of meat during storage in MAP affect MP in such a way that heat-induced protein gels alter their characteristics. Generally, storage with oxygen in MAP resulted in stronger and more elastic MP gels, which was observed already at a relative low oxygen concentration of 20%. (C) 2017 Elsevier Ltd. All rights reserved.
  • Oleyaei, Seyed Amir; Razavi, Seyed Mohammad Ali; Mikkonen, Kirsi Susanna (2018)
    In this study, the physico-chemical and rheo-mechanical properties of sage seed gum hydrogel, reinforced by various ratios (0-25 wt.%) of Laponite, were investigated. Particles size measurements indicated the formation of large SSG-Laponite microstructures upon nanoparticle adding, due to the interactions generated between the anionic SSG and the charged surfaces of clay platelets. Laponite affected the surface tension and density of the SSG-based systems significantly, but only influenced the-potential above 20 wt.%. The dynamic rheological behavior of SSG-based nanocomposites reflected the reinforcing effect of secondary structures and percolated three-dimensional network, suggested a structural modification of the hydrogels with the Laponite loading. An improvement in texture profile analysis parameters was observed in Laponite content 5 wt.%, whereas for nanoparticles > 5 wt.%, a significant decrease was obtained. In conclusion, Laponite improved the rheological and physico-chemical properties of SSG-based hydrogel and extended its potential as promising future bio-products for industrial applications.