Besides that, only steric forces are expected to stabilize this type of emulsions due to the low electrical conductivity of the oil continuous phase. W/O emulsions generally present lower stability than the oil-in-water (O/W) counterparts, due to the high mobility of water droplets, which causes sedimentation, flocculation, or coalescence. However, the kinetic transition to the water/oil separated phases can be so slow that the emulsion may be considered metastable. The main challenge in emulsion technology is their stability, once they are thermodynamically unstable systems. Its structure is suitable for the delivery of hydrophilic compounds, which, in turn, may bring different functions to the emulsified system, such as antimicrobial and antioxidant activities. For example, this type of emulsion can be used for the encapsulation of medicines, immobilizing enzymes, and loading protein drugs. W/O emulsions have high potential for cosmetic, pharmaceutical, agricultural, and food industries. Water-in-oil (W/O) emulsions consist of an aqueous phase dispersed, in the form of small droplets, into a continuous oil phase. The antimicrobial and antioxidant analysis were evidenced, and a sustained behavior compatible with an extract distribution within the two phases, oil and water, in particular for the higher extract concentration, was observed.Įmulsions are colloidal systems consisting of two liquid phases, oil and water, one of which is dispersed into the other. The presence of cinnamon extract leaded to changes in the microstructure as well as in the stability. Among the tested systems, the one using a 54/46 ( v/ v) Span 80/Tween 80 mixture, and subjected to 12 high-pressure homogenizer (HPH) cycles, revealed to be stable up to 6 months, being chosen for the subsequent functionalization tests with cinnamon extract (1.25–5% w/ v water-basis). Firstly, a base W/O emulsion using a high-water content (40/60, v/ v) was developed by testing different mixtures of emulsifiers, namely Tween 80 combined with Span 80 or Span 85 at different contents. In this context, this work aimed to produce stable W/O emulsions from a natural oil, sweet almond oil, to be further tested as vehicles of natural hydrophilic extracts, here exemplified with an aqueous cinnamon extract. In general, they are less studied than oil-in-water (O/W) systems, namely in what concerns the so-called fluid systems, partly due to problems of instability. Water-in-oil (W/O) emulsions have high potential for several industrial areas as delivery systems of hydrophilic compounds.
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