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 (W1/O) of a W1/O/W2 double emulsion was evaluated. Primary emulsion (W1/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 applications Medicinal 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)