Journal Articles

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    Formation of by high power ultrasound aggregated emulsions stabilised with milk protein concentrate (MPC70)
    (Elsevier BV, 2021-12-03) Zhang R; Luo L; Yang Z; Ashokkumar M; Hemar Y
    In this work, oil-in-water emulsions stabilised by milk protein concentrate (MPC70) were investigated. The MPC70 concentration was kept constant at 5% (close to the protein content found in skim milk) and the oil volume fraction was varied from 20 to 65%. Sonication was performed at 20 kHz and at a constant power of 14.4 W for a total emulsion volume of 10 mL. Under certain oil concentration (≥35%) and sonication times (≥3s) the emulsion aggregated and formed high-viscosity pseudo plastic materials. However, the viscosity behaviour of the emulsion made with 35% oil reverted to that of a liquid if sonicated for longer times (≥15 s). Confocal laser scanning microscopy showed clearly that the oil droplets are aggregated under the sonication conditions and oil concentrations indicated above. An attempt to explain this behaviour through a simple model based on the bridging of oil droplets by the MPC70 particles and, taking into account the oil droplet and MPC70 particle sizes as well as the oil volume fraction, was made. The model fails to describe in details the aggregation behaviour of these emulsions, likely due to the inhomogeneous protein layer, where both free caseins and casein micelles are adsorbed, and to the packing of the oil droplets at concentrations ≤55%. Nonetheless, this work demonstrates the potential of ultrasound processing for the formation of dairy emulsions with tailored textures.
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    Cooking of short, medium and long-grain rice in limited and excess water: Effects on microstructural characteristics and gastro-small intestinal starch digestion in vitro
    (Elsevier Ltd, 2021-07) Tamura M; Kumagai C; Kaur L; Ogawa Y; Singh J
    The purpose of present study was to investigate the impact of cooking methods on starch hydrolysis of rice grain using an in vitro digestion model. Three varieties of short, medium and long-grain rice were cooked in two different ways: in limited water method (LWM) using a rice cooker and excess water method (EWM) using a pan. The water absorption of raw rice grain was found to differ among the different rice varieties. The moisture, crude protein, total starch and resistant starch contents of the grain were affected by the cooking method. Starch hydrolysis for medium and long-grain rice at 210 min was higher for rice cooked through LWM (75.1 and 87.5%, respectively) than those cooked using the EWM (65.8 and 64.5%, respectively). Microscopic observations of grain cooked through LWM and EWM showed that the former had bigger voids present throughout the grain and had more cell wall damage than the latter, confirming that the microstructural characteristics were responsible for better enzyme accessibility and higher starch hydrolysis. These results revealed that the starch digestibility of rice grain cooked through different methods was affected by the disruption of the tissue structure that was dependent on the cooking method.
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    Rheological Behavior of High-concentration Sodium Caseinate Dispersions
    (Wiley-Blackwell, 2010) Loveday, SM; Rao, M. A.; Creamer, Lawrence K.; Singh, Harjinder
    Apparent viscosity and frequency sweep (G’, G”) data for sodium caseinate dispersions with concentrations of approximately 18−40% w/w were obtained at 20°C; colloidal glass behavior was exhibited by dispersions with concentration ≥ 23% w/w. The G’−G” crossover seen in temperature scans between 60 and 5°C was thought to indicate gelation (low-temperature crossover). Temperature scans from 5 to 90°C revealed gradual decrease in G’, followed by plateau values. The gelation and end of softening temperatures of the dispersions increased with the concentration of sodium caseinate. From an Eldridge−Ferry plot, the enthalpy of softening was estimated to be 29.6 kJ mol−1.
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    Phase and Rheological Behavior of High-Concentration Colloidal Hard-Sphere and Protein Dispersions
    (Wiley-Blackwell, 2007) Loveday, SM; Creamer, Lawrence K.; Singh, Harjinder; Rao, M. A.
    Colloidal hard-sphere particles of narrow-size distribution exhibit crystalline and glassy states beginning at the particle volume fractions φ=0.494 and φG=0.58, respectively. Dynamic rheological data on the dispersions was strongly modified to solid-like behavior as φ approached φG. In addition, cooperative motion in structural relaxation has been observed microscopically in the colloidal dispersions near the glassy state. Very high viscosities and glassy states were also found in high-concentration dispersions of sodium caseinate, and the globular proteins: bovine serum albumin and β-lactoglobulin. Viscosity models developed for hard-sphere dispersions provided reasonable predictions of relative viscosities of colloidal protein dispersions. Dispersions of food colloidal particles may be employed in studies, in which volume fraction is the thermodynamic variable, for understanding the relaxation and transport processes related to first-order and colloidal glass transitions