Abstract
Hydrogel beads composed of methylcellulose (MC) and polyvinylalcohol (PVA) were prepared using the reverse dispersion, in which the corn oil was used as the continuous phase. A few edible pigments were encapsulated as a core material, which have responsibility to such a stimulus from the outside as pH change, in this experiment. The water phase dissolving MC, PVA and the edible pigment were poured into the oil phase to form the w/o dispersion. Then, the water phase dissolving the gelation agents was poured into the dispersion. Two kinds of aqueous droplets were coalesced each other to prepare the hydrogel beads in which pigment was encapsulated. And the purpose of application is to give the beads the function as the alarm for the rotten condition in the aqueous foods, because pH of food changes for acidity when it rots off. In this procedure, the concentrations of MC and PVA, the addition method of the cross-linking or the gelation agents, the kinds of the edible pigments, and the agitation velocity, were mainly changed stepwise. Then, the influences of their conditions on the characteristics of beads were evaluated. In the concrete, the diameter, the swelling behavior in water, the encapsulation efficiency and the leak rate of edible pigments when the beads are keeping in water, and the behavior of color change while the beads are keeping in an acidic water or distilled water, were observed.
