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)
Emblicanin rich water‐soluble extract of Emblica officinalis (EEO) is encapsulated in the inner phase of double emulsion (DE) by using emulsifiers in different phases at different concentrations. The effects of other variables like homogenization speed, salt and herbal concentration are also investigated on various phases of DE to obtain a stable matrix. Finally, optimized EEO encapsulated DE has 2% w/w NaCl and 50% w/w EEO in inner (W1) phase, 4% w/w polyglycerol polyricinoleate (PGPR) in middle oil‐phase and 2% w/w low‐methoxy‐pectin and reverse osmosis water in outer (W2) phase. Ultra‐Turrax high shear homogenizer is employed to prepare primary emulsion (W1/O) at 20 000 rpm and DE (W1/O in W2) at 12 000 rpm. The EEO encapsulated DE has been characterized for encapsulation efficiency (>90%), viscosity (0.715 ± 0.18 Pa s), sedimentation stability, zeta potential (−32.17 ±1.17 mV), and particle size. Light and confocal laser microscopy are used for elaborating the microscopic structure of EEO encapsulated DEs. DE has shown storage stability up to 42 days and protect antioxidant activities as compared to control (herbal extract was not encapsulated in the inner phase). The present study demonstrates that the optimized DE matrix can be used to protect the bioactive properties of EEO for its use in functional food formulation.
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