Stabilizing the primary emulsion with hydrophobic emulsifiers and salt for encapsulating herbal extracts in a double emulsion

Abstract

In the current study, the effect of hydrophobic emulsifiers (polyglycerol polyricinoleate [PGPR] or soy lecithin) as a surfactant and salt (NaCl) as an electrolyte on the stability of primary water-in-oil emulsion (W 1 /O) of a W 1 /O/W 2 double emulsion was evaluated. Primary emulsion (W 1 /O) was prepared by mixing reverse osmosis (RO) water containing bitter gourd (Momordica charantia) extract (55.2%), salt (3%-5%) and rice bran oil containing varying range of PGPR (2%-4%) or lecithin (4%-6%).Emulsions with different formulations were prepared using full factorial, with optical microscopic images, apparent viscosity and sedimentation stability as the deciding attributes. Emulsions prepared with soy lecithin were unstable and coalesced, leading to phase separation, immediately after preparation. The emulsions prepared with PGPR were significantly (p < 0.05) stable at all the ranges used, when compared to lecithin. Furthermore, the emulsion containing 3% salt and 4% PGPR showed significantly (p < 0.05) higher stability when compared to other combinations used. Practical applicationsMedicinal plant extracts are usually converted into capsules/tablets or as dietary supplements due to their unacceptable sensory characteristics. Bitter gourd is gaining attention as a potential cure for diabetes, thereby increasing its use as a dietary supplement and in foods. Incorporating bitter gourd extract in foods could be a convenient way to combat diabetes mellitus. Utilization of bitter gourd extract needs a medium by which its sensorial aspects can be made acceptable or masked. Double emulsion is one such technique which is used to mask the unacceptable flavour and odour of plant extracts by compartmentalizing it inside an immiscible liquid, which is then protected by layer of another immiscible liquid. This paper discusses the stabilization of the primary emulsion (W1/O) with lipophilic emulsifier and salt for encapsulating the aqueous extract of bitter gourd in a double emulsion (W1/O/W2)

Effect of Selected Stabilizers and Processing Aids on the Stability of a Double Emulsion Encapsulating Bitter Gourd Extract

“…The effect of concentration of the protein-polysaccharide complexes on the apparent viscosity of the double emulsions (W/O/W) was the same as observed by Lutz et al [25]. In addition, apparent viscosity of the primary emulsion (W/O) increased with increasing PGPR concentration [27]. Hence, the increased apparent viscosity of the final double emulsion (W/O/ W) may be due to increased resistance to shearing during secondary emulsification.…”

“…This may have led to a subsequent reduction in rate of coalescence and Ostwald ripening of the water droplets by decreasing the droplet diameter. On the other hand, though with initial increase in NaCl concentration (up to 4%) the apparent viscosity of primary emulsion increased, it reduced at higher NaCl concentration (5%) [27]. This may be because NaCl plays an important role in formation of double emulsion by matching the osmotic and Laplace pressures between the two aqueous phases (W 1 and W 2 ) of the double emulsion.…”

Selection of stabilizers and processing aids to encapsulate bitter gourd extract in a stable double emulsion

“…The effect of concentration of the protein-polysaccharide complexes on the apparent viscosity of the double emulsions (W 1 /O/W 2 ) was the same as observed by Lutz et al (2009a). (Choudhary et al 2018). Hence, the increased apparent viscosity of the final double emulsion (W 1 /O/W 2 ) may be due to increased resistance to shearing during secondary emulsification.…”

Water-in-Oil-in-Water Double Emulsions as Protective Carriers for Sambucus nigra L. Coloring Systems

“…The creaming index was evaluated at different time intervals (0, 5, 10, and 20 days) following the methodology described by Choudhary et al [40] with minor adaptations. Briefly, the emulsions were stored in graduated cylinders of 50 mL at 23 ± 2 • C. The "creaming index" (CI, %) was calculated using Equation (1), where HS and HT were the serum layer and total emulsion height, respectively, expressed in cm.…”