A SEMI-EMPIRICAL APPROACH TO OPTIMISE THE QUANTITY OF DRYING AIDS REQUIRED TO SPRAY DRY SUGAR-RICH FOODS

ABSTRACT

A semi-empirical linear equation has been developed to optimise the amount of maltodextrin additive (DE 6) required to successfully spray dry a sugar-rich product on the basis of its composition. Based on spray drying experiments, drying index values for individual sugars (sucrose, glucose, fructose) and citric acid were determined, and using these index values an equation for model mixtures of these components was established. This equation has been tested with two sugar-rich natural products, pineapple juice and honey. The relationship was found to be valid for these products.     

Characterization of purified fungal endoxylanase and its application for production of value added food ingredient from agroresidues

Xylanase from Aspergillus foetidus MTCC 4898 was purified using ammonium sulphate fractionation followed by ion exchange and gel permeation chromatography with 12.26-fold purity and 29.9% recovery. Purified xylanase was found to be 29.9 kDa. Optimum temperature and pH for xylanase activity of purified xylanase were found to be 50 °C and 5.3 respectively. Presence of additives like polyethylene glycol, sodium azide, Tween 80, KCl and NaCl increased the stability of purified xylanase by 35, 29, 28, 32 and 43% respectively at 50 °C after 180 min. Kinetic parameters like K_m and V_max were found to be 4 mg/ml and 7288 μmol/mg/min respectively. The purified xylanase was found to be an endoxylanase as it produced only xylooligosaccharides (XOS) from birchwood xylan. Production of XOS was carried out from xylan extracted from agro-residues using β-xylosidase free xylanase. Maximum yield of XOS was 7.28 ± 0.14 mg/ml and 4.52 ± 0.21 mg/ml from wheat straw xylan and rice straw xylan respectively. XOS mixture was suitable for food industry looking at its high thermal stability at low pH. Prebiotic effect of XOS was evaluated by in vitro fermentation of XOS using known probiotic strains of Bifidobacterium spp.     

Water transport in cellular tissues during thermal processing

Accurate modeling of water transport in food materials requires knowledge of how transport properties depend on the material structure. Water transport in a cellular tissue depends on its pathway (intracellular versus extracellular), which in turn depends on temperature. Using a combination of permeability measurement, pore‐size distribution analysis and bioimpedance analysis, it is shown that water in a cellular tissue (e.g., potatoes) is mostly intracellular at lower temperatures at which cell membranes are intact. During drying at high‐temperatures, cell membranes in potatoes are damaged, and the moisture transport pathway is primarily extracellular (through intercellular spaces and the lacunae created by the killed cells), with a much lower resistance to water transport. The difference in moisture diffusivity in potatoes for the two pathways has been estimated to be three orders of magnitude. Therefore, transport properties measured or predicted at low temperatures cannot be used for high temperatures because they correspond to different moisture migration pathways. © 2010 American Institute of Chemical Engineers AIChE J, 2011     

Transport in deformable food materials: A poromechanics approach

A comprehensive poromechanics-based modeling framework that can be used to model transport and deformation in food materials under a variety of processing conditions and states (rubbery or glassy) has been developed. Simplifications to the model equations have been developed, based on driving forces for deformation (moisture change and gas pressure development) and on the state of food material for transport. The framework is applied to two completely different food processes (contact heating of hamburger patties and drying of potatoes). The modeling framework is implemented using total Lagrangian mesh for solid momentum balance and Eulerian mesh for transport equations, and validated using experimental data. Transport in liquid phase dominates for both the processes, with hamburger patty shrinking with moisture loss for all moisture contents, while shrinkage in potato stops below a critical moisture content.     

Amorphous silicon–carbon based nano-scale thin film anode materials for lithium ion batteries

The buffering effect of carbon on the structural stability of amorphous silicon films, used as an anode for lithium ion rechargeable batteries, has been studied during long term discharge/charge cycles. To this extent, the electrochemical performance of a prototype material consisting of amorphous Si thin film (∼250 nm) deposited by radio frequency magnetron sputtering on amorphous carbon (∼50 nm) thin films, denoted as a-C/Si, has been investigated. In comparison to pure amorphous Si thin film (a-Si) which shows a rapid fade in capacity after 30 cycles, the a-C/Si exhibits excellent capacity retention displaying ∼0.03% fade in capacity up to 50 cycles and ∼0.2% after 50 cycles when cycled at a rate of 100 μA/cm² (∼C/2) suggesting that the presence of thin amorphous C layer deposited between the Cu substrate and a-Si acts as a buffer layer facilitating the release of the volume induced stresses exhibited by pure a-Si during the charge/discharge cycles. This structural integrity combined with microstructural stability of the a-C/Si thin film during the alloying/dealloying process with lithium has been confirmed by scanning electron microscopy (SEM) analysis. The buffering capacity of the thin amorphous carbon layer lends credence to its use as the likely compliant matrix to curtail the volume expansion related cracking of silicon validating its choice as the matrix for bulk and thin film battery systems.     

Studies of mechanical and moisture regain properties of methyl methacrylate grafted silk fibers

The mechanical properties such as the tenacity, breaking extension, initial modulus, elastic and work recovery, and stress relaxation behavior of methyl methacrylate (MMA) grafted silk fibers prepared under different conditions were measured and explained in terms of the relative dominance of the stress concentration, reduction in the interchain cohesion, and fiber matrix stiffening at different grafting percentages. The moisture regain characteristics of fibers grafted in the presence of different solvents were also studied and compared. The grafting of MMA on silk was found to improve the recovery properties significantly without affecting the stress relaxation behavior. The moisture regain studies indicate that moisture regain is reduced with increasing length of the grafted poly(MMA) chains. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 969–974, 2002; DOI 10.1002/app.10202     

Mechanical and dynamic mechanical properties of jute fibers–Novolac–epoxy composite laminates

A study was done of jute composite using a polymer matrix of epoxidized Novolac resin (ENR), diglycidyl ether of bisphenol A (DGEBA)–based epoxy, and their blends with different weight percentages of the resins. It was found that on blending ENR with DGEBA, the storage modulii at room temperature are enhanced by about 100% or more in the case of 30 and 40% ENR‐containing matrices, whereas the enhancement in the case of 20 and 12% ENR‐containing matrices is only 50% that of the pure matrix. It was also observed that the tan δ peak heights of the composites containing 30 and 40% ENR are closer to that of 20% ENR‐containing composite. The probable explanation drawn on the basis of experimental findings of DMA and mechanical analysis is that by blending ENR with DGEBA epoxy it is possible to manufacture jute composites with increased stiffness without sacrificing their ductility. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 2800–2807, 2002     

用QDI稳定轮胎胶料

高里程轮胎要求硫化胶具有较长的使用寿命,胶料的物理性能取决于多种因素,不仅仅是胶料中所用的橡胶、填料以及骨架材料.NR是重型轮胎(例如载重轮胎、航空轮胎和工程机械轮胎)选用的弹性体,它可以提供这些苛刻用途轮胎所需优异的强度和耐疲劳性能,兼有长疲劳寿命和良好的韧性--即抗撕裂性的弹性体需要用硫黄硫化,促进剂的品种和硫黄与促进剂的比例决定了硫交联键的特性.硫的序列,亦即每个交联键中硫原子的平均数基本上决定了所得硫化胶的特性.     

An all-green cellulose acetate/corn cob composite membrane filter: A critical evaluation of its morphology and adsorption characteristics for dyes and heavy metals

Industrial wastewater from various manufacturing sectors poses a significant environmental concern due to the release of dyes, heavy metals, and pollutants into natural water streams. Effective treatment of large volumes of industrial wastewater is crucial to mitigate this issue. Conventional industrial wastewater filtration systems often prove to be inefficient, necessitating the exploration of alternative and cost-effective water filtration methods. In this study, we drew inspiration from the natural adsorption and purification properties of corncob to develop a novel green composite membrane filter. The composite membrane filters, named MCAPCB and MCATPCB, were formulated by incorporating powdered corncob (PCB) and alkali/hydrogen peroxide-treated powdered corncob (TPCB) into cellulose acetate. The adsorption properties of the composite filters were evaluated using UV–Vis spectrophotometry for dye adsorption and inductively coupled plasma optical emission spectroscopy (ICP-OES) and atomic absorption spectroscopy (AAS) for heavy metal adsorption. The results demonstrated that MCATPCB20, incorporating 20 wt% TPCB, exhibited remarkable performance in the removal of methylene blue dye, with an adsorption efficiency of 97.46%. In comparison, MCAPCB20, incorporating 20 wt% PCB, achieved a dye adsorption efficiency of 80.15%. Moreover, MCATPCB20 displayed exceptional heavy metal removal capabilities, effectively rejecting 98% and 95% of cadmium and lead, respectively, from water samples containing 1 ppm of each metal. The composite filter membranes containing 20 wt% TPCB exhibited superior adsorption efficiency, flexibility, and stability. This enhanced performance can be attributed to the higher carboxyl content in TPCB, achieved through alkali treatment, which significantly increased the adsorption capacity of MCATPCB20. Characterization studies employing XRD, SEM, contact angle, BET, ICP-OES, and UV measurements further supported the efficacy of MCATPCB as an effective filter system for water purification.