Effect of Tween 20, emulsification temperature and ultrasonication intensity on structured emulsions with monoglycerides

Abstract

Structured emulsions are regarded as an innovative way to replace saturated fat in food products. Monoglycerides (MGs) as lipid-based surfactants could form mainly water-in-oil emulsions, which tend to phase separate. The aim of this study was to investigate the interaction of Tween 20 (0–6% w/w) in 3% (w/w) MGs-based emulsions, under various emulsification temperatures (−3–70 °C) and various ultrasonication intensities. Several analytical methods such as differential scanning calorimetry, confocal and polarized optical microscopy and rheometry were employed to characterize the structured systems. The presence of Tween 20 promoted the formation of oil-in-water structured emulsions and prevented the droplet coalescence and phase separation. The emulsification at low temperatures accelerated the secondary crystallization of the MGs to the coagel state, promoted the preference of the crystals to be located at the interface of the oil droplets and act as Pickering particles. The formed free-standing emulsion gels showed improved stability under freeze-thaw cycling. High ultrasonication intensities during emulsification formed firmer gels with fast crystallization rates, while at low intensities the coagel crystallization was delayed. The MGs/Tween 20 formed needle-like crystals in water, which were employed as Pickering type emulsifiers to form oil-in-water structured emulsions. The MGs/Tween 20 structured emulsions showed improved stability than the conventional emulsions, indicating that they could be utilized as animal fat substitute systems in plant-based alternative food products, as well as in cosmetic and pharmaceutical applications.