Search

The reasons for the increased world-wide incidence of obesity, type-2 diabetes, and cardiovascular disease include sedentary lifestyles and poor food choices. Regulatory agencies in several countries now require companies to add unattractive front of package labels to their products where salt, sugar and fat (or saturated fat) levels are prominently displayed. After the demise of partially hydrogenated fats, saturated fat has become the new target. Consumption of saturated fat over polyunsaturated oil has been clearly shown to increase cholesterol levels in humans. However, saturated fats provide the functionality required in many food products. To complicate matters, concerns over sustainability, veganism, genetically modified organisms, animal welfare, as well as religious beliefs, severely limit our sources of saturated fat. In this review we will discuss recent advances in our understanding of the nano and mesoscale structure of fats, responsible for their physical functionality and contrast it to that of fat mimetics. Fat mimetics include polymeric networks of ethylcellulose, emulsion-templated networks of proteins and polysaccharides, colloidal and self-assembled fibrillar networks of polar lipid crystals, as well as solid o/w emulsions of oil trapped within crystallized lamellar mesophases. Clean label and economic considerations will also be touched upon.

Natural polyphenolic compounds show interesting complexation behavior with various macromolecules due to their unique structural characteristics that enables molecular transition such as electronic delocalization and conjugation and intra- and intermolecular hydrogen bonding. Here, we report on the preparation and characterization of novel colloidal complexes (size range of 56–116 nm) based on the spontaneous interactions of a small molecular weight polyphenol (tannic acid) with an industrially relevant macromolecule (methylcellulose). The binding stoichiometry obtained from isothermal titration calorimetry suggested that 33 molecules of tannic acid were bound to one molecule of polymer. The values of ΔH (−11.4 kJ mol−1) and ΔS (−35.5 J K−1 mol−1) suggested that the interaction was enthalpy driven and the relatively low value of ΔH further indicated the non-covalent nature (i.e. hydrophobic interaction and hydrogen bonding) of the interaction. Effects of this complexation on the functionalities of methylcellulose were investigated in terms of the loss of thermoreversible gelling (due to the irreversible association of colloidal complexes at high temperature), improvement of the emulsifying property (because of the interfacial localization of hydrophobic colloidal complexes further contributing to the gelling of the interfacial film) and enhancement of the foam stabilizing property (based on the absorption of colloidal complexes on the air–water interface and resulting enhancement of the interfacial stiffness due to surface gelation invoked by the colloidal complexes). These findings will be of wide interest to researchers and industrial scientists working in the field of polymer chemistry and material science, especially because methylcellulose is one of the most commonly used polymers for a range of industrial applications.

We report generation of temperature responsive colloidal particles based on the spontaneous interactions of two small molecular weight actives of natural origins. This finding is an important step towards the development of controlled colloidal structures from natural and sustainable materials for food and drug delivery applications.

Orally administered bioactive compounds have to survive acidic environs (pH 1.2) of the stomach and reach the small intestine (pH 6.8–7.4), which is the main site of absorption in the gastrointestinal tract. Hence, it is desired to have a delivery system which can protect the active molecules from degradation in acidic pH but release them in the small intestine. This objective was achieved in the present work by formulating stable shellac colloidal particles that showed pH dependent release. Colloidal particles were prepared using a simple anti-solvent method, wherein shellac was precipitated spontaneously by adding ethanolic shellac solution to aqueous polymer (xanthan gum) solution, which acts as electro-steric stabiliser. The average particle size could be controlled from around 150 nm to 300 nm depending on the initial concentration of shellac in the stock solution. High negative surface charge (−64.8 to −81.7 mV) and spherical shape of the particles were confirmed using zeta-sizer and transmission electron microscopy. To evaluate the suitability of the colloidal particles for delivery of bioactive compounds, silibinin (a flavonolignan) was loaded up to 10% w/w into the shellac particles and characterised for pH stability and in vitro release. X-Ray diffraction studies indicated amorphous nature of the entrapped silibinin in the colloidal particles. The release of silibinin was followed under gastric (pH 1.2) and intestinal conditions (pH 7.4) and the amount was detected in terms of antioxidant activity (Ferric Reducing Antioxidant Power). Due to the pH dependent solubility of shellac, silibinin entrapped in the colloidal particles was found to be stable to acidic pH and showed more than 90% release in the intestinal pH.

Novel structures with controllable morphology made from natural materials hold promise for several applications in pharmaceuticals, foods and biotechnology field. In this paper, we utilized the strong interactions between epigallocatechin gallate (EGCG), a polyphenol obtained from green tea, and water soluble cellulose ethers like methyl cellulose (MCE) and hydroxyl propyl methylcellulose (HPMC) to fabricate novel beads with controllable core–shell morphology. The novel polymer–polyphenol beads were prepared by simply adding polymer solution dropwise into an aqueous solution of polyphenol. Effect of process variables like concentration and viscosity grades of polymer, reaction time and concentration of EGCG on bead formation was evaluated. Spherical milky white beads with average diameters ranging from 600–2500 µm were obtained that retained shape after freeze drying. Internal structure of beads was studied using automated light microscopy and cold stage scanning electron microscopy (Cryo-SEM). Percent loading of EGCG in the beads was above 25% w/w in all the cases. The release study in simulated intestinal fluid revealed burst release of EGCG (20% in first 5 minutes) followed by sustained release with more than 90% release at the end of 300 minutes. The antioxidant power of EGCG in the beads was effectively maintained in the alkaline conditions with 5–6 fold activity as compared to free EGCG. Further, the temperature triggered release characteristic of beads was explored by encapsulating eucalyptus oil and studying the release of oil using hot stage microscopy. Enzyme immobilisation application of beads was demonstrated by immobilising α-amylase onto the beads and studying its enzyme activity after several washings.

Zein–curcumin composite colloidal particles were synthesized using an antisolvent precipitation method. The average particle size could be controlled down to 100–150 nm, depending on the solvent system and the ratio of zein and curcumin used in the synthesis. In all cases, spherical particles were obtained, as confirmed by transmission electron microscopy. Depending on the preparation conditions, curcumin load and encapsulation efficiency varied from 1.6 to 4.1% and 71.1 to 86.8%, respectively. Solid state characterization by differential scanning calorimetry and X-ray diffraction indicated the amorphous nature of entrapped curcumin. An UV irradiation study confirmed enhanced photostability of curcumin due to the entrapment of curcumin in the biopolymeric matrix. The particles were also found to have good colloidal stability at a broad range of physiologically relevant pH (1.2, 4.5, 6.7 and 7.4) and in simulated gastro-intestinal conditions. Results from an in vitro mucoadhesion study showed retention of more than 60% curcumin for 150 minutes. The mucoadhesion property was further confirmed from a mucin association study carried out on Caco-2 cells.