Designing excipient emulsions to increase nutraceutical bioavailability: emulsifier type influences curcumin stability and bioaccessibility by altering gastrointestinal fate

Abstract

The influence of emulsifier type on the ability of excipient emulsions to improve the solubility, stability, and bioaccessibility of powdered curcumin was examined. Oil-in-water emulsions prepared using three different emulsifiers (whey protein isolate, caseinate, or Tween 80) were mixed with curcumin powder and then incubated at either 30 °C (to simulate applications of salad dressings) or 100 °C (to simulate applications of cooking sauces). The transfer of curcumin into the excipient emulsions was appreciably higher for excipient emulsions held at 100 °C than those held at 30 °C, and was appreciably higher for surfactant-stabilized emulsions than protein-stabilized emulsions. For example, the amounts of curcumin transferred into emulsions held at 30 and 100 °C were 66 and 280 μg mL(-1) for Tween 80, but only 17 and 208 μg mL(-1) for caseinate. The total curcumin concentration in the digesta and mixed micelle phases collected after excipient emulsions were exposed to a simulated gastrointestinal tract (mouth, stomach, and small intestine) depended on emulsifier type. The total amount of curcumin within the digesta was higher for protein-stabilized emulsions than surfactant-stabilized ones, which was attributed to the ability of the proteins to protect curcumin from chemical degradation. For example, the digesta contained 204 μg mL(-1) curcumin for caseinate emulsions, but only 111 μg mL(-1) for Tween 80 emulsions. This study shows the potential of designing excipient emulsions to increase the oral bioavailability of curcumin for food and pharmaceutical applications.

In vitro bioaccessibility of ergocalciferol in nanoemulsion‐based delivery system: the influence of food‐grade emulsifiers with different stabilising mechanisms

“…As mentioned earlier, the SC‐coated droplets would be expected to be highly positively charged at highly acidic condition (pH 2.5), because this particular pH value was well below the pI of SC. As such, the anionic mucin molecules could adsorb onto the cationic SC‐emulsified droplets in the stomach phase, as has been reported in recent studies (Zou et al ., ; Chang & McClements, ). Consequently, the negatively charged mucin molecules and the positively charged SC‐coated droplets cancelled off each other, leading to the SC‐stabilised nanoemulsions having a ζ‐potential value of near to zero.…”

“…3), suggesting that this emulsion system was highly stable against droplet aggregation under stomach conditions. The reason behind this observation could be related to the fact that the steric repulsion conferred by MO-7S (a nonionic emulsifier) is insensitive to the changes in pH, ionic strength and protease activity (Zou et al, 2015). Conversely, there was an appreciable increase in droplet size for the nanoemulsions stabilised by ML and SC (Fig.…”

“…A previous study has also found that emulsions stabilised by nonionic emulsifiers were more stable towards flocculation and coalescence under gastric condition than those prepared using protein-and phospholipid-based emulsifiers (Chang & McClements, 2016). The instability of nanoemulsions stabilised by ML and SC under gastric phase was correlated with a series of physicochemical phenomenon: (i) the stomach phase reduced the electrostatic repulsion between ML and SC-coated droplets (as will be discussed later), thereby inducing aggregation; (ii) hydrolysis of the adsorbed protein layer by pepsin could possibly have reduced the ability of the protein layer to protect the droplets from growth; and (iii) the biopolymers might have promoted the depletion or bridging flocculation of oil droplets in the protein-stabilised nanoemulsions under acidic condition (Zou et al, 2015). Meanwhile, the nanoemulsions stabilised by the combined emulsifiers (MO7S and ML) were more resistant towards droplet growth as compared to the ML-stabilised ones, suggesting that the physical stability of nanoemulsions stabilised by ML could be improved by the addition of MO7S.…”

The role of the food matrix and gastrointestinal tract in the assessment of biological properties of ingested engineered nanomaterials (iENMs): State of the science and knowledge gaps

“…As discussed above, what is needed is development of in vitro and in vivo methods for studying transformations of iENMs in the GIT, and identifying structure activity relationships that influence absorption and accumulation. Methods such as simulated GIT models that include mouth, stomach, and small intestine phases that mimic the fluid compositions, incubation times, and flow/pressure conditions of the GIT are crucial for assessing ENM transformations and interactions with food matrices (Arroyo-Maya and McClements, 2016; Cho et al , 2014; Lopez-Pena et al , 2016; Mun et al , 2007; Mun et al , 2006; Ozturk et al , 2015; Park et al , 2007; Qiu et al , 2015; Sandra et al , 2008; Yao et al , 2013; Yao et al , 2015a; Yao et al , 2014; Zou et al , 2015a; Zou et al , 2015b). In future work, it may be useful to employ the newly developing “omic” approaches to better understand the potential toxicity of nanoparticles, e.g., metabolomics, proteomics, and transcriptomics.…”

Designing emulsion droplets of foods and beverages to enhance delivery of lipophilic bioactive components – a review of recent advances

“…The interfacial composition affects to a great extent the chemical stability and thus bioaccessibility of the bioactive compound. Similarly, proteins (caseinate and whey protein isolate) were more effective to confer chemical stability to curcumin during in vitro gastric digestion of excipient emulsions than their synthetic counterpart (Tween 80) (Zou et al, 2015). Qian et al (2012b) stated that nanoemulsions stabilised with b-lactoglobulin were less susceptible to b-carotene degradation compared to the ones stabilised with Tween 20.…”