Preparation of steppogenin and ascorbic acid, vitamin E, butylated hydroxytoluene oil-in-water microemulsions: Characterization, stability, and antibrowning effects for fresh apple juice

- Various MEs including four SMEs were developed and characterized.
- ME greatly helped to improve steppogenin solubility compared with that in water.
- Various MEs were stable after acceleration and long-term storage.
- Various SMEs exhibited strong antibrowning effects for apple juice.
- S + VCME showed the strongest antibrowning effect among various SMEs.

Oil-in-water microemulsions (O/W MEs) allow the preparation of insoluble compounds into liquid. In this study, we prepared O/W MEs to improve the solubility and stability of steppogenin (S) in aqueous liquid, and studied their ability to inhibit fresh apple juice browning. The ME technique greatly increased steppogenin solubility up to 3000-fold higher than that in water. All SMEs demonstrated good stability after acceleration and long-term storage. In particular, 0.01% SME was associated with dramatic inhibition of fresh apple juice browning after 24 h at room temperature and 7 days at 4 °C, and its antibrowning effects were further improved when combined with 0.05% ascorbic acid. On the other hand, simultaneous encapsulation of steppogenin with vitamin E or butylated hydroxytoluene into ME did not greatly improve SME antibrowning effects. Taken together, these results suggested that steppogenin might serve as a potential antibrowning agent to preserve fresh apple juice.