Effects of modified starch and fat on the rheological characteristics of newly formulated processed cheese: Use of experimental design method

This study aims to investigate the impact of the incorporation of starch (modified and non-modified) on the texture of the processed cheese in order to appreciate a new recipe on one hand and to try to reduce fat content (FC) on the other. The modeling of the experimental results has been performed. An experimental design was used (the variable factors are the amount of starch and FC). The dry extract (DE) of cheese and parameters derived from the modeling of rheological results are the selected responses. The cheese with a concentration of modified starch that is greater than 2% has a high viscosity at rest, while the cheese with non-modified starch has a lower viscosity. When the FC exceeds 15%, the viscosity increases as the concentration of the starch exceeds 2%. Below this concentration, the FC effect is negligible except when the starch concentration is 1%, in this case the viscosity decreases.     

Synthesis and characterization of corn starch based green composites reinforced with Saccharum spontaneum L graft copolymers prepared under micro-wave and their effect on thermal, physio-chemical and mechanical properties

In this paper, green composites of the corn starch were developed by using resorcinol-formaldehyde (Rf) as the cross-linking agent and reinforced with graft copolymers Saccharaum spontaneum L(Ss) and methyl methacrylates (MMA) as principal monomer and its binary mixture with acrylamide (AAm), acrylonitrile(AN), acrylic acid (AA) prepared under micro-wave. The matrix and composites were found to be thermally more stable than the natural corn starch backbone. There was improvement in physico-chemical and mechanical properties of composite were found to exhibit better than matrix. Ss-g-poly(MMA)-MW reinforced composites were found to exhibit better tensile strength, on the other hand Ss-g-poly(MMA + AA)-MW reinforced composites showed maximum compressive strength and wear resistance than other graft copolymers reinforced composite and the basic matrix. Further the matrix and composites were subjected for biodegradation studies through soil composting method. Different stages of biodegradation were evaluated through FT-IR studies and scanning electron microscopic (SEM) techniques.     

Rapid HPLC method for acetyl starch determination in blood

Summary Colloidal plasma substitutes of chemically modified starch are used in surgery and in emergency medicine. Acetyl starch (ACS) is a new plasma substitute based on an amylopectin acetic ester. Metabolic cleavage of the ACS ester substituents leads to improved degradation and elimination of infused polymer. To determine the metabolic fate of ACS a rapid LC-method for ACS quantitiation in blood samples was needed. For this purpose a size-exclusion chromatography (SEC) system with improved sensitivity is outlined using a refractive index detector. The limit of detection is 0.005 mg mL⁻¹. From 0.10–5.00 mg mL⁻¹ a linear relationship (correlation coefficient R=0,9999) between the RI signal and ACS concentration is obtained. Recoveries of ACS from blood plasma range 102.3–107.7% for ACS 200/0.5 (range 0.20–7.94 mg mL⁻¹) and 103.0–111.4% for ACS 200/0.7 (range 0.19–9.33 mg mL⁻¹). Only small differences between runs are obtained. In the inter assay test coeficients of variation of 1.8% and of 2.6% respectively are obtained for ACS 200/0.5 and ACS 200/0.7.     

单模聚焦微波辅助合成1-乙基-3-羧甲基咪唑四氟硼酸盐离子液体

以1-乙基咪唑为原料,采用discover环形单模聚焦微波合成仪合成了1-乙基-3-羧甲基咪唑四氟硼酸盐离子液体,对产品结构进行了表征及热性分析,并测定了粘度、密度、表面张力、电化学窗口等物化性能,同时考察了合成离子液体对淀粉的溶解性能.结果表明,单模聚焦微波辐射合成具有速度快、时间短、反应条件温和等优点,产品产率为88.23％,其密度、粘度、表面张力与温度均呈线性关系,且随温度升高而减小.与水溶剂相比,合成的离子液体对可溶性淀粉具有较高的溶解度,为淀粉及其衍生物的均相衍生化反应提供了理论基础.     

Starch Derived Nanosized Graphene Oxide Functionalized Bioactive Porous Starch Scaffolds

A fully starch‐derived bioactive 3D porous scaffold is developed. The bioactivity is introduced through nanosized graphene oxide (nGO) derived from starch by microwave‐assisted degradation to carbon spheres and further oxidation to GO nanodots. nGO is covalently attached to starch to prepare functionalized starch (SNGO) via an esterification reaction. nGO and SNGO exhibit no cytotoxicity to MG63 at least up to 1000 µg mL⁻¹ under (3‐(4,5‐Dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide) assay. Porous scaffolds consisting of starch and SNGO (S/SNGO) or nGO (S/nGO) are prepared by freeze drying. The porosity and water uptake ability of the scaffolds depend on the concentration of nGO. Moreover, nGO, as a bioactive nanofiller, functions as an effective anchoring site for inducing CaP recrystallization in simulated body fluid. Among all modified starch‐based scaffolds, the S/SNGO scaffold containing the highest concentration of covalently attached SNGO (50%) induces the largest amount of hydroxyapatite, a type of CaP crystal that is closest to bone. The prepared 3D porous nGO functionalized scaffold, thus, exhibits potential promise for bone/cartilage tissue engineering.

     

羧甲基淀粉与烷基二甲基苄基氯化铵的相互作用研究

通过电导法、荧光法、粒度法等方法研究了羧甲基淀粉与3种不同碳数烷基二甲基苄基氯化铵之间的相互作用。结果表明,羧甲基淀粉与长链烷基二甲基苄基氯化铵在小于单纯表面活性剂临界胶束浓度（cmc）1～2个数量级的浓度下发生复合,并产生沉淀。当表面活性剂烷基链增加且浓度增大时,表面活性剂长碳链间的疏水作用及与羧甲基淀粉间的疏水作用...     

Preparation and properties of water‐absorbent composites of chloroprene rubber,starch, and sodium acrylate

The effects of the amounts of starch, sodium acrylate (NaAA) and dicumyl peroxide (DCP) on the properties of chloroprene rubber (CR)/starch/NaAA composites prepared by melting method were investigated. The results showed that the addition of starch improved the mechanical properties, but decreased the water‐absorbing capacity of the composite, most likely due to the decrease in the local concentration of the main water‐absorbing material sodium polyacrylate and the increase in crosslinking density of the composite resulting from the reaction between starch and CR. This reaction was verified by the vulcanized curves, DSC curves, and the cut surface morphology. The as‐prepared composite demonstrated higher water‐absorbing capacity, resulting from the incorporation of NaAA. The mechanical properties decreased with increasing the DCP loading, and the water‐absorbing ratio is the maximum at 1.0 phr DCP. The tensile strength of the composite decreased significantly after water immersion, due to the absorbed water acting as a plasticizer. The extracted component from composites after water immersion is mainly sodium polyacrylate according to Fourier transform infrared (FT‐IR) spectroscopy analysis. The morphology of the composites before and after water immersion was observed by optical transmission microscopy (OTM). The results indicated that the starch exhibits a good dispersion state, and the water‐absorbing capacity results primarily from sodium polyacrylate. Copyright © 2010 John Wiley & Sons, Ltd.     

Reactive compatibilization of PA12/plasticized starch blends: Towards improved mechanical properties

Glycerol-plasticized starch (TPS)/polyamide 12 (PA12) blends were processed by melt mixing using two types of interfacial agent, i.e. diglycidyl ether of bisphenol A and a poly(ethylene-co-butyl acrylate-co-maleic anhydride) copolymer. Morphologies of the blends were tailored from the nature and amount of the interfacial agents. The average size of the dispersed phase was shown to decrease with the incorporation of the reactive agents and was proved to respect models, usually employed for conventional blends, for size predictions of the dispersed phase. By means of rheological experiments, it has been investigated whether the size reduction of the dispersed phase was coming from the compatibilization of the blend or from the viscosity changes due to chain extension in the matrix. The influence of the coupling agents on the viscoelastic behavior of the blend was characterized. Both interfacial agents led to increase the absolute complex viscosity but in the case of diepoxy reactive agent, the Newtonian flow behavior of complex viscosity totally disappeared in the low-frequency region. Mechanical properties of the TPS/PA12 blends were characterized and were proved to be strongly impacted by the use of interfacial agents. Elongation at break was enhanced as a consequence of a better adhesion between the matrix and the dispersed phase, whereas a decrease of the Young’s modulus was observed with increasing DGEBA content. Polyamide 12 crystallization in TPS/PA12 blends was found to be strongly dependent on DGEBA content while the introduction of maleic anhydride-grafted copolymer had no influence.     

Effect of 300 and 500 MPa pressure treatments on starch–water adsorption/desorption isotherms and hysteresis

Pressure treatments of 300 and 500?MPa during 15?min were found to change starch–water sorption (adsorption and desorption) isotherms and the hysteresis effect, particularly the 500?MPa. This last treatment shifted the adsorption/desorption isotherms downward, compared with non-treated starch and starch treated at 300?MPa. The observed hysteresis effect decreased with the increase in pressure level in the whole a_w range, indicating that adsorption and desorption isotherms became closer. Guggenheim–Anderson–De Boer and Brunauer–Emmett–Teller model parameters Cb, Cg, K and Mm also showed changes caused by pressure, the latter being lower in the pressure-processed samples, thus indicating possible changes on microbial and (bio)chemical stabilities of pressure-processed food products containing starch.     

Transient entanglements and clusters in dilute polymer solutions

A convenient method to monitor polymer dissolution is to measure the pressure drop created by passing a polymer solution through a capillary constriction rheometer. In this work, we studied the dissolution of polyethylene oxide (PEO) and cationic starch (C‐starch). We found that for freshly dissolved and entangled PEO, the main contribution to the overall pressure drop is due to the contraction and expansion of PEO entanglements at the entrance and exit of the capillary, and that the friction in the capillary plays a minor role. On the other hand, for well‐dissolved PEO, because of the absence of PEO entanglements, the loss of pressure is mainly due to friction. At high velocities the contraction and expansion coefficient for freshly dissolved PEO was more than 20 times higher than for well‐dissolved PEO, resulting in a three times higher overall pressure drop. C‐starch consists of amylopectin (～ 85%) and amylose and is known to contain clusters when freshly dissolved, likely formed from the globular amylopectin molecules. For C‐starch, the main contribution to the overall pressure drop is due to friction. Entrance and exit effects contribute only 10% to the overall pressure drop, which might be due to the linear amylose molecules in C‐starch. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 253–262, 2008