Kinnari J. Shelat

Milling of Rice Grains. The Degradation on Three Structural Levels of Starch in Rice Flour Can Be Independently Controlled during Grinding

Whole polished rice grains were ground using cryogenic and hammer milling to understand the mechanisms of degradation of starch granule structure, whole (branched) molecular structure, and individual branches of the molecules during particle size reduction (grinding). Hammer milling caused greater degradation to starch granules than cryogenic milling when the grains were ground to a similar volume-median diameter. Molecular degradation of starch was not evident in the cryogenically milled flours, but it was observed in the hammer-milled flours with preferential cleavage of longer (amylose) branches. This can be attributed to the increased grain brittleness and fracturability at cryogenic temperatures, reducing the mechanical energy required to diminish the grain size and thus reducing the probability of chain scission. The results indicate, for the first time, that branching, whole molecule, and granule structures of starch can be independently altered by varying grinding conditions, such as grinding force and temperature.

Separation and purification of soluble polymers and cell wall fractions from wheat, rye and hull less barley endosperm flours for structure-nutrition studies

The nutritional values associated with the cell walls of cereal endosperm flours are due to a combination of solubilized arabinoxylan and (1-3,1-4)-β-d-glucan as well as residual nonsolubilized cell wall material. In order to investigate structure-nutrition relationships, an appropriate method for the complete functional and structural characterization of cell wall polysaccharides in various cereal endosperm flours is described. This involves the separation of soluble polymers and the residual cell wall fraction without using organic solvents, and the fractionation of soluble polymers into arabinoxylan- and (1-3,1-4)-β-d-glucan-rich fractions for subsequent analysis. This methodology is applied to endosperm flours from wheat, hull-less barley and rye, and could be extended to include studies on the effects of food processing with respect to yield and characteristics of the three fractions in order to better understand the structural basis for nutritional functionality.

Kinetic analysis of bile salt passage across a dialysis membrane in the presence of cereal soluble dietary fibre polymers

The kinetics of passage of a model bile salt and complete porcine bile across a dialysis membrane, in the presence and absence of two cereal-derived soluble dietary fibre polysaccharides, were studied as a model for passage across the unstirred water layer that lines the small intestine. A first-order kinetic analysis allowed rate coefficients to be derived which quantified the effectiveness of barley mixed linkage β-glucan and wheat arabinoxylan in retarding the transport of bile. For both, a model bile salt and complete porcine bile, rate coefficients decreased with both concentration and viscosity. A combination of viscosity and molecular interaction effects is suggested to control the effect of the two polysaccharides on the transport of bile.

Interfacial interaction and morphology of EVOH and ionomer blends by scanning thermal microscopy and its correlation with barrier characteristics.

In a blend, the interfacial interaction between the component phases can be effectively utilized to bring about homogeneous mixing and unique performances. While in conventional blends, preserving the morphology of the melt mixed state is unfeasible because of the strong thermodynamic tendency of the components to phase separate, herein, we report the intermolecular interaction of two hydrogen bonded polymers such as a barrier polymer poly(ethylene-co-vinyl alcohol) (EVOH) with an ionic polymer in their blends, which work symbiotically to achieve the desirable characteristics. We demonstrate the creation of a unique ellipsoid microfibrilliar morphology and melt exfoliation of one polymer in the blends through intermolecular interaction and achieve high oxygen barrier characteristics. Scanning thermal microscopy and scanning electron microscopy investigations confirm the presence of such unique morphology. The interfacial interaction and formation of interphase was evident from the local thermal analysis results combined with photoacoustic Fourier transform infrared spectroscopy (PA-FTIR). PA-FTIR confirms the chemical nature of the interaction, while the differential scanning calorimetry results indicate modification of the EVOH phase by the ionomer. The shift of Tg and broadening of the tan delta curve is evident from dynamic mechanical analysis confirming the interaction of the blend components. The blend B(60) with microfibrillar morphology shows fourfold drop in oxygen permeability indicating the role of interfacial interaction and desired morphology.

A Nanoporous Cytochrome c Film with Highly Ordered Porous Structure for Sensing of Toxic Vapors

Creating well-ordered nanoporosity in biomolecules promises stability and activity, offering access to an even wider range of application possibilities. Here, the preparation of nanoporous protein films containing cytochrome c protein molecules is reported through a soft-templating strategy using polystyrene (PS) spheres of different sizes as templates. The stability of the cytochrome c film is demonstrated through electrochemistry studies to show a reusable nature of these films over a long period of time. The size of the PS spheres is varied to tune the pore diameter and the thickness of the cytochrome c films, which are quite stable and highly selective for sensing toxic acidic vapors. The fusion of the templating strategy and the self-assembly of biomolecules may offer various possibilities by generating a new series of porous biomolecules including enzymes with different molecular weights and diameters, peptides, antibodies, and DNA with interesting catalytic, adsorption, sensing, and electronic properties.

Physico-chemical characteristics and fungal profile of four Saudi fresh date (Phoenix dactylifera L.) cultivars

Physico-chemical and microbial analyses of four commercial fresh date cultivars (Sukari, Barhi, Khalas and Rothana) grown in Saudi Arabia were evaluated. Colorimetric assay indicated that Sukari had the highest total sugar content of 13.21g/100gFW while the lowest was in Rothana with 7.96g/100gFW. Total phenolic content (TPC) ranged from 76.74 to 122.20mgGAE/100gFW in Barhi and Rothana respectively, whereas antioxidant activity was highest in Sukari (105.99μgGAE/gFW) and lowest in Khalas (90.81μgGAE/gFW). The dominant fungal genera were Aspergillus sp., Rhizopus sp., Penicillium sp. and Sarocladium sp., occurring at 37, 18, 13 and 12% respectively. The highest fungal occurrence was in Barhi (30%) followed by Sukari (29%), Khalas (26%) and Rothana (15%). The TPC had a negative correlation with fungal occurrence whilst the total sugars had a positive correlation.

Design, Development and Characterization of Synthetic Bruch’s Membranes

Age-related macular degeneration (AMD) is a leading cause of blindness, and dry AMD has no effective treatment. Retinal constructs comprising retinal pigment epithelium (RPE) cells supported by electrospun scaffolds have been investigated to treat dry AMD. However, electrospun scaffolds studied to-date do not mimic the structural microenvironment of human Bruchs membrane (BM), essential for native-like RPE monolayers. The aim of this study was to develop a structurally biomimetic scaffold designed to support a functional RPE monolayer, comprising porous, electrospun nanofibrous membranes (ENMs), coated with laminin, mimicking the inner collagenous layer (ICL) and basal RPE lamina respectively, the cell supporting layers of the BM. In vitro evaluation showed 70nm PLLA ENMs adsorbed high amounts of laminin and supported functional RPE monolayers, exhibiting 3D polygonal-cobblestone morphology, apical microvilli, basal infoldings, high transepithelial resistance (TER), phagocytic activity and expression of signature RPE markers. 70nm PLLA ENMs were successfully implanted into the subretinal space of RCS-rdy+p+/LAV rats, also commonly know as rdy rats. At week 4, in the absence of immunosuppressants, implanted PLLA ENMs were surrounded by a significantly low number of activated microglial cells, compared to week 1, indicating no adverse long-term immune response. In conclusion, we successfully designed and tested ENMs emulating the RPE cell supporting layers of the BM, and found 70nm PLLA ENMs to be best suited as scaffolds for fabricating retinal constructs. STATEMENT OF SIGNIFICANCE Age related macular degeneration (AMD) is a leading cause of vision loss in the developed world, with an increasing number of people suffering from blindness or severe visual impairment. Transplantation of retinal pigment epithelium (RPE) cells supported on a synthetic, biomimetic-like Bruchs membrane (BM) is considered a promising treatment. However, the synthetic scaffolds used do not mimic the microenvironment of the RPE cell supporting layers, required for the development of a functional RPE monolayer. This study indicated that porous, laminin coated, 70nm PLLA ENMs supported functional RPE monolayers, exhibiting 3D polygonal-cobblestone morphology, apical microvilli, basal infoldings, high transepithelial resistance (TER), phagocytic activity and expression of signature RPE markers. These findings indicate the potential clinical use of porous, laminin coated, 70nm PLLA ENMs in fabricating retinal constructs aimed at treating dry AMD.