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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 electrosteric 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

The generation of novel all‐natural biopolymeric microcapsules fabricated using natural biopolymers, protein (gelatin) and resin (shellac), is reported. These novel microcapsules are generated using a simple extrusion method wherein the gelatin‐shellac mixture is dropped in an acidic medium resulting in an instantaneous solidification of aqueous drops into solid spherical microcapsules that retain their shape on air‐drying. The formation of the microcapsules is basically due to the strong interactions between two oppositely charged polymers (as confirmed from isothermal titration calorimetry and infrared spectroscopy) and the instant precipitation of acid‐resistant shellac. These novel microcapsules prepared without the help of any cross‐linkers or harsh solvent are extensively characterized and several biorelated applications for pharmaceuticals (encapsulation and release of bioactive molecules), foods (loading of colorants and flavors), sensors (encapsulation of pH sensitive dye), and biotechnology (enzyme immobilization) fields are further demonstrated.

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Multilayer plastic foils are important packaging materials that are used to extend the shelf life of food products and drinks. Fourier transform infrared (FT-IR) spectroscopic imaging using attenuated total internal reflection (ATR) can be used for the identification and localization of different layers in multilayer foils. A new type of ATR crystal was used in combination with a linear array detector through which large sample areas (400 x 400 microm(2)) could be imaged with a pixel size of 1.6 microm. The method was tested on laminated plastic packing materials containing 5 to 12 layers. The results of the identification of the different materials using ATR-FT-IR were compared with differential scanning calorimetry (DSC) and the layer thickness of the individual layers measured by ATR-FT-IR was compared with polarized light microscopy (LM) and scanning electron microscopy (SEM). It has been demonstrated that individual layers with a thickness of about 3 microm could be identified in multilayer foils with a total thickness ranging from 100 to 150 microm. The results show a spatial resolution of about 4 microm (measured at wavenumbers ranging from 1000 to 1730 cm(-1)), which is about a factor of two better than can be obtained using transmission FT-IR imaging. An additional advantage of ATR is the ease of sample preparation. A good correspondence was found between visible and FT-IR images. The results of ATR-FT-IR imaging were in agreement with those obtained by LM, SEM, and DSC. ATR-FT-IR is superior to the combination of these techniques because it delivers both spatial and chemical information.

The techniques that are currently available to assess fat crystal networks are compromised with respect to invasive sample preparation and ability to quantify compositional and structural features. Raman confocal hyperspectral imaging coupled to analysis with multivariate curve resolution can address these bottlenecks, as it provides label‐free, noninvasive chemical information in three dimensions (3D). We demonstrate the ability to acquire compositional maps of dispersions of micronized fat crystals (MFC) in oil, which contain local concentrations of liquid oil and solid fat with submicron spatial resolution and with acquisition times in the order of 10 min. From the compositional maps, we can derive quantitative information on the size and porosity of fat crystal flocs, as well as the solid fat content of the embedding continuous phase. Furthermore, the fractal dimension of the fat crystal network could be determined from the compositional maps via the box‐counting method and via the porosities of the crystal flocs. This makes it feasible to assess the validity of the weak‐link network theory under industrial relevant conditions. The confocal imaging mode allows for straightforward acquisition of 3D compositional cubes by recording a stack of two‐dimensional (2D) images. The box‐counting fractal dimension analysis performed on 2D maps can be extended to 3D cubes, which allows for straightforward verification that MFC networks are self‐similar rather than self‐affine.