The objective is to study the partial coalescence process in calcium‐fortified double (W1/O/W2) and simple (O/W2) emulsions prepared with soybean flour dispersion as continuous aqueous (W2) phase and vegetable fat plus polyglycerol polyricinoleate (PGPR) as lipophilic emulsifier (at varied concentration) in lipid phase. Calcium chloride is included in the dispersed aqueous (W1) phase and the W2 phase of W1/O/W2 and O/W2 emulsions, respectively. No partial coalescence is observed in the O/W2 emulsion without PGPR and calcium, while the inclusion of the emulsifier and/or divalent cation promotes the phenomenon. The presence of PGPR in lipid phase or calcium in W2 phase can enhance capture efficiency because of the decrease of electrostatic and steric repulsions between fat globules, the modification of fat crystals, and/or the increased size of individual globules. W1/O/W2 emulsions show a lower partial coalescence degree in comparison to O/W2 emulsions prepared with the same components, attributed to the isolation of a fraction of added calcium in the W1 phase of the former systems. PGPR produces microstructural and rheological changes over time in emulsions subjected to prolonged cold storage; but its effect is reduced in the presence of calcium, probably because of the formation of stronger globule aggregates. Practical applications: This article deals with two parallel phenomena occurring in W1/O/W2 and O/W2 emulsions prepared with soybean flour dispersion as W2 phase and vegetable fat in lipid phase: the promotion of partial coalescence by the lipophilic emulsifier, PGPR; and the aggregation of proteins and fat globules due to the presence of calcium in W2 phase. In this way, the effects of PGPR and/or calcium on partial coalescence are studied in these systems, analyzing their microstructure and rheology. The encapsulation of calcium within the W1 phase of W1/O/W2 emulsions and its impact on partial coalescence is also analyzed. The results obtained in this work can be relevant for the formulation of calcium‐fortified, vegetable food emulsions, showing a texture similar to whipped dairy cream, where PGPR concentration or calcium release can be controlled to adjust the rheological characteristics of the system.

The flow of solutions of poly(ethylene oxide) (PEO), hydrolyzed polyacrylamide (HPAA), and their blends through opposed jets is investigated. Measurements of pressure drop across the jets as a function of strain rate were used to characterize the elongational flow behavior. In deionized water, solutions of PEO/HPAA mixtures exhibit a synergistic increase in flow resistance with respect to the parent polymer solutions. The addition of amounts of HPAA as low as 2 ppm to a 500 ppm PEO solution cause sizeable increases in pressure drops. Such increases have been interpreted as arising from the formation of interpolymer transient entanglement networks that become mechanically active at time scales equivalent to the lowest strain rates available. In the case of excess salt environment, the flow resistance of the mixtures seems to be dominated by the PEO in the concentration range explored.

ABSTRACT:The flow of solutions of poly(ethylene oxide) (PEO), hydrolyzed polyacrylamide (HPAA), and their blends through opposed jets is investigated. Measurements of pressure drop across the jets as a function of strain rate were used to characterize the elongational flow behavior. In deionized water, solutions of PEO/HPAA mixtures exhibit a synergistic increase in flow resistance with respect to the parent polymer solutions. The addition of amounts of HPAA as low as 2 ppm to a 500 ppm PEO solution cause sizeable increases in pressure drops. Such increases have been interpreted as arising from the formation of interpolymer transient entanglement networks that become mechanically active at time scales equivalent to the lowest strain rates available. In the case of excess salt environment, the flow resistance of the mixtures seems to be dominated by the PEO in the concentration range explored.