Whey protein microgel particles as stabilizers of waxy corn starch + locust bean gum water-in-water emulsions

Food-grade whey protein isolate (WPI) microgel particles were investigated as a particle stabilizer of water-in-water (W/W) emulsions. The microgel particles were produced via the novel method of forcing coarse particles of a pre-formed thermally processed WPI protein gel through a jet homogenizer. The Z-average particle size was 149 ± 89 nm but the particles showed a strong tendency for aggregation when the pH was lowered from pH 7 to 4, when the zeta potential also switched from -17 to +12 mV. The viscoelasticity of suspensions of the particles, measured between 1 and 15 vol.% (0.02 and 3 wt.%) increased with concentration and was also higher at pH 4 than pH 7. However, all the suspensions were only weakly shear thinning, suggesting that they did not form very strong networks. The particles were added (at 1-15 vol.%) to a model W/W system consisting of waxy corn starch (S) + locust bean gum (LBG) that normally shows phase separation when the components are mixed at 90 °C then cooled to room temperature (22-25 °C). At 10 to 15 vol.% particles and pH 4, visual observation showed striking inhibition of phase separation, for a period of up to 1 year. Confocal laser scanning microscopy suggested that under these conditions extensive aggregation of the microparticles occurred within the starch phase but also possibly at the W/W interface between the starch-rich and gum-rich regions, supporting a Pickering-type mechanism as responsible for the enhanced stabilization of the W/W emulsion by the microgel particles

Electricity Tracing in Systems With and Without Circulating Flows: Physical Insights and Mathematical Proofs

This paper provides new insights into the electricity tracing methodology, by representing the inverted tracing upstream and downstream distribution matrices in the form of matrix power series and by applying linear algebra analysis. The n th matrix power represents the contribution of each node to power flows in the other nodes through paths of length exactly n in the digraph of flows. Such a representation proves the link between graph-based and linear equation-based approaches for electricity tracing. It also makes it possible to explain an earlier observation that circulating flows, which result in a cyclic directed graph of flows, can be detected by appearance of elements greater than one on the leading diagonal of the inverted tracing distribution matrices. Most importantly, for the first time a rigorous mathematical proof of the invertibility of the tracing distribution matrices is given, along with a proof of convergence for the matrix power series used in the paper; these proofs also allow an analysis of the conditioning of the tracing distribution matrices. Theoretical results are illustrated throughout using simple network examples

Rheological properties of starches from grain amaranth and their relationship to starch structure

Amaranth starch (Amaranthus cruentus L. and Amaranthus hypochondriacus L.) in this investigation possessed a relatively small and uniform granule size of a type ¿A¿ pattern obtained by X-ray diffraction, with the degree of crystallinity ranging from 24.5 to 27.9%. This was followed by work on steady and dynamic rheological properties on shear of seven native amaranth starches. Aqueous pastes (5% solids) exhibited shear-thinning behavior, and the flow behavior was fitted with the Herschel¿Bulkley equation (regression coefficients were over 0.99). Cultivar V69 showed much higher G? (storage modulus) and G? (loss modulus) than the other samples and produced a solid-like gel, which could be attributed to the high amylose content of its network. Correlation analysis revealed that amylose content was positively correlated with G? and negatively with the loss tangent (tan delta) of the material