Release properties of gel-type W/O/W encapsulation system prepared using enzymatically-modified starch

• Gel-type W/O/W emulsion was prepared using 4αGTase-treated starch.
• The longer sonication and the higher W/O fraction, the more stable W/O/W emulsion.
• Embedding W/O/W within 4αGTase-treated starch gel prolonged dye release even at 90 °C.

A gel-based encapsulation system was developed by incorporating W/O/W emulsions and 4-α-glucanotransferase (4αGTase) treated starch capable of thermoreversible gel formation, and its physical and release characteristics were investigated as functions of preparation conditions and temperature. Release properties of the W/O/W gels were affected by stability and encapsulation efficiency (EE) of W/O/W emulsions embedded within. Lower EE caused by longer sonication time increased fast release dye portion, which resulted in higher dye release rate, even though emulsion stability improved at longer sonication time. Lower dye release rate of W/O/W gels prepared with relatively higher W/O volume fractions slightly increased as temperature increased from room temperature to 90 °C. However, samples prepared with relatively lower W/O volume fractions showed higher dye release rate and a larger increase at 90 °C. The 4αGTase-treated starch gel improved W/O/W emulsion stability and thus retarded dye release even at 90 °C.