Recent years have seen the problematic global trend countries of an increasing aging society. Chewing ability and intake functionality decrease with increase in age, and this can induce aspiration pneumonia. Thus, appropriate food texture, such as viscosity, is needed for easy swallowing by the elderly to prevent aspiration. Use of unsaturated lipid in food for the elderly is limited due to its high lipophilicity and low oxidative stability. A hydrosol, where liposoluble components are dispersed in the water phase, is useful as a utility form of lipid for the elderly food. However, the hydrosol with the droplets of lipid is a thermodynamically metastable dispersed system, and it leads to phase separation after flocculation, coalescence, and creaming due to high interfacial tension between the aqueous and oil phases. Therefore, stably concentrated hydrosol is required for the production of food with functional lipid for the elderly. In this study, the effect of the viscosity on the oxidative and the dispersion stabilities of concentrated hydrosol with the droplets of unsaturated lipid was examined, and a comprehensive stability including lipid oxidation and collapse was evaluated based on the viscosity.<br/>First, a 90-mL aqueous solution containing pectin (6%–8%, w/v) and decaglycerol monolaurate (1%, w/v) was prepared and was added to 10 mL of soybean, olive, or fish oil. Then, the mixture was emulsified using a rotor/stator homogenizer for 15 min at 15,000 rpm in a tube immersed in ice water. The prepared hydrosol was stored at 37°C in a dark container. The viscosity of the hydrosol was measured at 20±2°C using a rotating cylinder viscometer. Moreover, the particle size distribution of oil droplets in the hydrosol and the peroxide values of the hydrosol was periodically measured.<br/>The rate constant for the oxidation of the hydrosol decreased with increasing the initial median diameter of oil droplets. The particle sizes for all the tested hydrosol were almost constant for storage period. The tendency that the floating velocity of oil droplets in the hydrosol decreased with increasing the rate constant for the oxidation was observed. The index, whose low value showed comprehensively high stability of the hydrosol, was estimated from rate constant for the oxidation and he floating velocity of oil droplets. Its dependency on the viscosity of the hydrosol was downwardly convex. This indicates that the viscosity strongly contributes to the stability the hydrosol.

Evaluation of stability of concentrated hydrosol with the droplets of unsaturated lipid

2019 Fall National Meeting

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