The Experts below are selected from a list of 18348 Experts worldwide ranked by ideXlab platform
Craig E. Coleman - One of the best experts on this subject based on the ideXlab platform.
-
The Accumulation of α-Zein in Transgenic Tobacco Endosperm is Stabilized by Co-expression of β-Zein
Plant & cell physiology, 2004Co-Authors: Craig E. Coleman, Paula Randall Yoho, Sonja Escobar, Masahiro OgawaAbstract:;The cysteine-poor α-Zein is the major prolamin storage protein fraction in maize endosperm and is localized in the interior of protein bodies with δ-Zein, whereas the hydrophobic cysteine-rich β- and γ-Zein are found on the exterior of the PB. In transgenic tobacco endosperm expressing Zein genes, α-Zein was unstable unless coexpressed with γ-Zein. Here we showed that α-Zein was also stabilized by β-Zein. Small accretions of α- and β-Zeins, similar in appearance to maize protein bodies, were localized to the endoplasmic reticulum within tobacco endosperm cells. The Zein proteins were also localized to protein storage vacuoles in a more dispersed pattern, suggesting that they were transported there after they were post-translationally sequestered into the ER.
-
The maize gamma-Zein sequesters alpha-Zein and stabilizes its accumulation in protein bodies of transgenic tobacco endosperm.
The Plant Cell, 1996Co-Authors: Craig E. Coleman, Koichi Takasaki, Eliot M Herman, Brian A LarkinsAbstract:Zeins are seed storage proteins that form accretions called protein bodies in the rough endoplasmic reticulum of maize endosperm cells. Four types of Zeins, alpha, beta, gamma, and delta, aggregate in a distinctive spatial pattern within the protein body. We created transgenic tobacco plants expressing alpha-Zein, gamma-Zein, or both to examine the interactions between these proteins leading to the formation of protein bodies in the endosperm. Whereas gamma-Zein accumulated in seeds of these plants, stable accumulation of alpha-Zein required simultaneous synthesis of gamma-Zein. The Zein proteins formed accretions in the endoplasmic reticulum similar to those in maize endosperm. Protein bodies were also found in protein storage vacuoles. The accumulation of both types of Zeins peaked early in development and declined during maturation. Even in the presence of gamma-Zein, there was a turnover of alpha-Zein, suggesting that the interaction between the two proteins might be transitory. We suggest that gamma-Zein plays an important role in protein body formation and demonstrate the utility of tobacco for studying interactions between different Zeins.
Jafar Mohammadzadeh Milani - One of the best experts on this subject based on the ideXlab platform.
-
effect of plasticizing sugars on water vapor permeability surface energy and microstructure properties of Zein films
Lwt - Food Science and Technology, 2007Co-Authors: Babak Ghanbarzadeh, Abdulrasoul Oromiehie, Mohamad Musavi, Elhame Razmi Rad, Keramat Rezayi, Jafar Mohammadzadeh MilaniAbstract:Abstract Sugars are natural plasticizers for food biopolymers and Zein is the most important protein of corn. In this research, sugars (fructose, galactose and glucose) were used as plasticizers and the water vapor permeability (WVP), contact angle and microstructure of the Zein films were studied. The pure Zein film had high WVP and adding of sugars to 0.7 g/g Zein caused to decrease of WVP. Films containing galactose had the lowest WVP. All samples had the lowest contact angle with ethanol and the highest contact angle with water. The Zein films containing galactose had the highest water contact angle within the plasticized films. The pure Zein films and the films containing fructose had higher critical surface tension of wetting (γc) than the films containing glucose and galactose. Adding sugar plasticizer to Zein films increased the surface tension of Zein films. In the unplasticized Zein films, loose structures with a lot of cavities and voids were observed. The films plasticized by fructose had smooth surface and plasticizer particles distributed throughout of the films.
-
Effect of plasticizing sugars on rheological and thermal properties of Zein resins and mechanical properties of Zein films
Food Research International, 2006Co-Authors: Babak Ghanbarzadeh, Abdulrasoul Oromiehie, Mohamad Musavi, Zahra Emam Djomeh, Elhame Razmi Rad, Jafar Mohammadzadeh MilaniAbstract:Abstract Zein is the most important protein in corn. Zein has good film forming properties. One of the film forming methods is production of Zein resin and then thermomolding by hot press. Pure Zein film is very brittle. Plasticizers can improve mechanical and film making properties of Zein. In this research, sugars (fructose, galactose and glucose) were used as plasticizers and rheological properties of Zein resin were studied by dynamic oscillatory tests for determination of plasticization effectiveness. Effect of plasticizers on thermal properties of resins was investigated by DSC at −100 to 150 °C. No crystallization and melting peaks related to Zein and plasticizers were observed. As well as there was not significant difference at glass transition temperature between Zein resins containing various sugars. Zein films were prepared from Zein resins by rolling and hot press and then mechanical properties of films were measured. Films containing galactose had better tensile properties than other films and showed higher tensile strength, strain at break, and Young modulus than films containing fructose and glucose.
Graciela Wild Padua - One of the best experts on this subject based on the ideXlab platform.
-
Effect of pH and ethanol content of solvent on rheology of Zein solutions
Journal of Cereal Science, 2013Co-Authors: Panadda Nonthanum, Youngsoo Lee, Graciela Wild PaduaAbstract:Abstract Zein, a corn protein, is a mixture of the polypeptides α-, γ-, β-, and δ-Zein. α-Zein and γ-Zein comprise 70–85% and 10–20% of total Zein mass, respectively. Both peptides have similar amino acid composition, except γ-Zein is rich in cysteine. The presence of cysteine has been associated with gelation of Zein solutions. A common solvent for Zein is aqueous ethanol. Preliminary results suggested that pH and ethanol content affect the rheology of Zein solutions. Our objective was to investigate the effect of ethanol content (65–90%) and pH of the solvent (2, 6, and 12) on rheological properties of Zein solutions (20% w/w) containing γ-Zein. Steady shear tests and oscillatory time sweeps were performed to determine flow behavior and gelation time of Zein solutions. Results indicated that α-Zein solutions were nearly Newtonian while those containing γ-Zein showed shear thinning behavior. At high pH, γ-Zein increased the consistency index (K) and shortened gelation time. Results were attributed to the cysteine in γ-Zein. High pH promoted formation of disulfide bonds leading to higher K values and shorter gelation times. Results of this work are expected to be useful in the design of Zein extraction processes and the development of new Zein applications.
-
Formation of Zein spheres by evaporation-induced self-assembly
Colloid and Polymer Science, 2012Co-Authors: Yi Wang, Graciela Wild PaduaAbstract:Zein is an amphiphilic protein capable of self-assembly into microspheres. Zein microspheres may form by evaporation-induced self-assembly (EISA) of Zein solutions in ethanol/water. The formation of microspheres is of particular interest for the development of delivery systems. Zein solutions in ethanol/water 75 % (v/v) were slowly evaporated to promote self-assembly of microspheres. The ethanol content of the solvent decreased during EISA changing solvent polarity which induced self-assembly of Zein particles. The growth of Zein spheres was modeled from the hydrophobic and hydrophilic contributions to the interfacial free energy (R2 = 0.92). The good fit indicated that during EISA Zein microspheres increased in size due to hydrophobic interactions between Zein molecules. The model may allow the prediction of evaporation time and thus control over microsphere size.
-
Effect of γ-Zein on the rheological behavior of concentrated Zein solutions.
Journal of agricultural and food chemistry, 2012Co-Authors: Panadda Nonthanum, Youngsoo Lee, Graciela Wild PaduaAbstract:Zein, the prolamin of corn, is attractive to the food and pharmaceutical industries because of its ability to form edible films. It has also been investigated for its application in encapsulation, as a drug delivery base, and in tissue scaffolding. Zein is actually a mixture of proteins, which can be separated by SDS-PAGE into α-, β-, γ-, and δ-Zein. The two major fractions are α-Zein, which accounts for 70–85% of the total Zein, and γ-Zein (10–20%). γ-Zein has a high cysteine content relative to α-Zein and is believed to affect Zein rheological properties. The aim of this study was to investigate the effect of γ-Zein on the often observed phenomena of Zein gelation. Gelation affects the structural stability of Zein solutions, which affects process design for Zein extraction operations and development of applications. The rheological parameters, storage modulus (G′) and loss modulus (G″), were measured for Zein solutions (27% w/w solids in 70% ethanol). β-Mercaptoethanol (BME) was added to the solvent to ...
-
Water sorption properties of extruded Zein films.
Journal of agricultural and food chemistry, 2004Co-Authors: Ying Wang, Graciela Wild PaduaAbstract:Water interactions in extruded Zein films were investigated through moisture sorption isotherms. Sorption isotherms of Zein products were affected by composition and structure morphology. Zein powder showed moisture sorption hysteresis, which was not observed in extruded samples. Extruded samples held less moisture than Zein powder, while films containing oleic acid showed further reduction in moisture uptake. Brunauer, Emmett, and Teller (BET) and Guggenheim, Anderson, and De Boer (GAB) models fitted well the moisture sorption isotherms of Zein products. Monolayer values estimated by BET and GAB models were consistent with predictions based on Zein structural models. Water vapor permeability (WVP) of Zein films was affected by the relative humidity of testing environment. Higher relative humidity resulted in higher WVP.
-
Thermal behavior of Zein sheets plasticized with oleic acid
Cereal Chemistry, 2000Co-Authors: F. X. Budi Santosa, Graciela Wild PaduaAbstract:ABSTRACT Zein, extracted from underutilized corn gluten meal may serve as an alternative starting material for fabrication of biodegradable packaging. Zein plasticized with oleic acid may be formed into flexible and water-resistant sheets. Our objective was to investigate the effect of plasticization on thermal behavior of Zein sheets employing differential scanning calorimetry (DSC). Zein sheets were rolled from a resin prepared by dispersing Zein and oleic acid in aqueous alcohol followed by the recovery of the formed moldable compound by precipitation with water. Sheets were later replasticized with additional oleic acid to increase ductility. DSC thermograms were used to investigate Zein-oleic acid interactions in Zein sheets. DSC endotherms were attributed to melting of free oleic acid or to the dissociation of Zein-oleic acid bonds. Plasticized sheets contained bound and free oleic acid. Further heat-treatment of plasticized sheets apparently resulted in Zein absorption of free oleic acid. However, ...
Masahiro Ogawa - One of the best experts on this subject based on the ideXlab platform.
-
The Accumulation of α-Zein in Transgenic Tobacco Endosperm is Stabilized by Co-expression of β-Zein
Plant & cell physiology, 2004Co-Authors: Craig E. Coleman, Paula Randall Yoho, Sonja Escobar, Masahiro OgawaAbstract:;The cysteine-poor α-Zein is the major prolamin storage protein fraction in maize endosperm and is localized in the interior of protein bodies with δ-Zein, whereas the hydrophobic cysteine-rich β- and γ-Zein are found on the exterior of the PB. In transgenic tobacco endosperm expressing Zein genes, α-Zein was unstable unless coexpressed with γ-Zein. Here we showed that α-Zein was also stabilized by β-Zein. Small accretions of α- and β-Zeins, similar in appearance to maize protein bodies, were localized to the endoplasmic reticulum within tobacco endosperm cells. The Zein proteins were also localized to protein storage vacuoles in a more dispersed pattern, suggesting that they were transported there after they were post-translationally sequestered into the ER.
Elisângela Corradini - One of the best experts on this subject based on the ideXlab platform.
-
Recent Advances in Food-Packing, Pharmaceutical and Biomedical Applications of Zein and Zein-Based Materials
International journal of molecular sciences, 2014Co-Authors: Elisângela Corradini, Priscila Schroeder Curti, Adriano B. Meniqueti, Alessandro F. Martins, Adley F. Rubira, Edvani C. MunizAbstract:Zein is a biodegradable and biocompatible material extracted from renewable resources; it comprises almost 80% of the whole protein content in corn. This review highlights and describes some Zein and Zein-based materials, focusing on biomedical applications. It was demonstrated in this review that the biodegradation and biocompatibility of Zein are key parameters for its uses in the food-packing, biomedical and pharmaceutical fields. Furthermore, it was pointed out that the presence of hydrophilic-hydrophobic groups in Zein chains is a very important aspect for obtaining material with different hydrophobicities by mixing with other moieties (polymeric or not), but also for obtaining derivatives with different properties. The physical and chemical characteristics and special structure (at the molecular, nano and micro scales) make Zein molecules inherently superior to many other polymers from natural sources and synthetic ones. The film-forming property of Zein and Zein-based materials is important for several applications. The good electrospinnability of Zein is important for producing Zein and Zein-based nanofibers for applications in tissue engineering and drug delivery. The use of Zein’s hydrolysate peptides for reducing blood pressure is another important issue related to the application of derivatives of Zein in the biomedical field. It is pointed out that the biodegradability and biocompatibility of Zein and other inherent properties associated with Zein’s structure allow a myriad of applications of such materials with great potential in the near future.
-
preparation and characterization of thermoplastic starch Zein blends
Materials Research-ibero-american Journal of Materials, 2007Co-Authors: Elisângela Corradini, Antônio José Felix Carvalho, José Augusto Marcondes Agnelli, Antonio Aprigio Da Silva Curvelo, Luiz Henrique Capparelli MattosoAbstract:Blends of starch and Zein plasticized with glycerol were prepared by melting processing in an intensive batch mixer connected to a torque rheometer at 160 °C. The resulting mixtures were compression molded and then characterized by scanning electron microscopy, differential scanning calorimetry, wide-angle X ray diffraction and water-absorption experiments. The blends were immiscible, showing two distinct phases of starch and Zein. The water uptake at equilibrium and its diffusion coefficient were determined. The water uptake at equilibrium decreased with increasing Zein content. The diffusion coefficient fell sharply on addition of 20% Zein and remained constant as Zein content was increased. No appreciable effect of Zein on starch crystallization was observed by X ray diffraction. The use of Zein in thermoplastic starch compositions causes a decrease in the water sensitivity of these materials and lower its melt viscosity during processing making Zein a suitable and very promising component in TPS compositions.
-
Preparation and characterization of thermoplastic starch/Zein blends
Materials Research, 2007Co-Authors: Elisângela Corradini, Antônio José Felix Carvalho, A.a.s. Curvelo, José Augusto Marcondes Agnelli, Luiz Henrique Capparelli MattosoAbstract:Blends of starch and Zein plasticized with glycerol were prepared by melting processing in an intensive batch mixer connected to a torque rheometer at 160 °C. The resulting mixtures were compression molded and then characterized by scanning electron microscopy, differential scanning calorimetry, wide-angle X ray diffraction and water-absorption experiments. The blends were immiscible, showing two distinct phases of starch and Zein. The water uptake at equilibrium and its diffusion coefficient were determined. The water uptake at equilibrium decreased with increasing Zein content. The diffusion coefficient fell sharply on addition of 20% Zein and remained constant as Zein content was increased. No appreciable effect of Zein on starch crystallization was observed by X ray diffraction. The use of Zein in thermoplastic starch compositions causes a decrease in the water sensitivity of these materials and lower its melt viscosity during processing making Zein a suitable and very promising component in TPS compositions.
