Preparation of a Novel Thermoplastic Starch (TPS) Material using Ethylenebisformamide as the Plasticizer

In this paper, ethylenebisformamide was synthesized and used as a novel plasticizer for corn starch to prepare thermoplastic starch (EPTPS). FT‐IR spectra showed that the absorption bands of the C‐O groups of the starch molecules were shifted to lower wavenumbers, which indicated that a strong and stable hydrogen bond had been formed between ethylenebisformamide and starch. By scanning electron microscope (SEM) native individual corn starch granules were proved to transfer to a continuous phase. The crystallinity of native corn starch, GPTPS (glycerol plasticized corn starch) and EPTPS was characterized by X‐ray diffraction (XRD). Water resistance of EPTPS was better than that of GPTPS. It decreased from 50.2% for GPTPS to 37.8% for EPTPS. The mechanical analysis showed that elongation at break increased markedly, being 260% for the EPTPS containing 35% (w/w) ethylenebisformamide. Thermal stability of GPTPSs and EPTPSs was also determined by thermogravimetric analysis (TGA). The glass transition temperature T_g, as measured by dynamic mechanical thermal analysis (DMTA), of EPTPS was higher than that of GPTPS.     

The Effects of Plasticizers Containing Amide Groups on the Properties of Thermoplastic Starch

Several amide groups‐containing plasticizers for thermoplastic starch (TPS), such as formamide, acetamide, and urea, were studied in this paper with glycerol as reference. The hydrogen bond interaction between starch and plasticizers in TPS was tested by Fourier transform infrared (FT‐IR) spectroscopy. Both the oxygen of the C‐O‐H group and the oxygen of the C‐O‐C group in starch could form hydrogen bonds with these plasticizers. The order of the hydrogen bond‐forming abilities is as follows: urea > formamide > acetamide > polyols. The retrogradation of formamide‐plasticized TPS (FPTPS), acetamide‐plasticized TPS (APTPS) and urea‐plasticized TPS (UPTPS) was investigated at three levels of relative humidity (RH=0, 50 and 100%) using X‐ray diffractometry. Urea and formamide could effectively improve the resistance of TPS towards retrogradation. The studied mechanical properties demonstrated that FPTPS had a good breaking strain but poor breaking stress, while UPTPS had opposite characteristics. The properties of TPS mainly relied on the hydrogen bond‐forming abilities between plasticizers and the starch matrix. On the other hand, the water resistance of TPS mainly depended on the plasticizer. The higher the water absorption of the plasticizer was, the better was the water resistance of the TPS.     

N,N‐Bis(2‐hydroxyethyl)formamide as a New Plasticizer for Thermoplastic Starch

N,N‐Bis(2‐hydroxyethyl)formamide (BHF) was synthesized efficiently and used as a new plasticizer for corn starch to prepare thermoplastic starch (TPS). The hydrogen bond interaction between BHF and starch was proven by Fourier‐transform infrared (FT‐IR) spectroscopy. As detected by scanning electron microscopy (SEM), starch granules were completely disrupted and a continuous phase was obtained. The crystallinity of corn starch and BHF‐plasticized TPS (BTPS) was characterized by X‐ray diffraction (XRD). The thermal behavior of glycerol‐plasticized TPS (GTPS) and BTPS was investigated by differential scanning calorimetry (DSC). The water resistance of BTPS was better than that of GTPS. Generally, at low relative humidity (RH), the tensile strength of BTPS was higher than that of GTPS. At high RH, the elongation at break of BTPS was higher than that of GTPS.     

Aliphatic Amidediol and Glycerol as a Mixed Plasticizer for the Preparation of Thermoplastic Starch

The synthesis of 2‐hydroxy‐N‐[2‐(2‐hydroxy‐propionylamino)‐ethyl]propionamide (“aliphatic amidediol”) is described. Aliphatic amidediol and glycerol were used as a novel mixed plasticizer for corn starch to prepare thermoplastic starch. Fourier transform infrared (FT‐IR) spectroscopy proved that the mixture of aliphatic amidediol and glycerol could form more stable and strong hydrogen bonds with starch molecules than glycerol alone. By scanning electron microscopy (SEM) and X‐ray diffraction (XRD) it was proven that native starch granules and crystalline structures were broken and starch was plasticized. Tensile testing revealed that TPS plasticized by aliphatic amidediol and glycerol (AGPTPS) showed a better mechanical properties than TPS plasticized by glycerol (GPTPS). Furthermore, the water resistance of AGPTPS was better than that of GPTPS. In addition, dynamic mechanical thermal analysis (DMTA) showed that both storage modulus and glass transition temperature (T_g) of AGPTPS were higher than those of GPTPS.     

Microstructural Characterization of Plasticized Starch‐Based Films

Edible films were developed using different starch sources (corn starch and amylomaize). Starch suspensions were cold gelatinized with NaOH; either glycerol or sorbitol were used as plasticizer. Films were characterized by Differential Scanning Calorimetry (DSC), X‐ray diffraction, Scanning Electron Microscopy (SEM) and gas (CO₂ and O₂) permeabilities. SEM observations showed that plasticizer addition was necessary for film integrity. The evaluation of film formation by DSC indicated that cold gelatinization was the main factor of thermal transitions. Film crystallinity was analyzed by DSC and X‐ray diffraction during storage. For all tested formulations, film crystallinity increased while gas permeability decreased during storage. Films containing glycerol or sorbitol showed a lower crystalline/amorphous ratio by X‐ray diffraction and DSC than unplasticized films. Amylomaize films with higher crystalline/amorphous ratio gave lower gas permeabilities than the corresponding corn starch films; films containing sorbitol showed lower permeability values than those containing glycerol.     

Green Nanocomposites from Renewable Resources: Effect of Plasticizer on the Structure and Material Properties of Clay‐filled Starch

Nanocomposites of starch were prepared via different addition sequences of plasticizer and clay by the solution method. The extent of dispersion of the filler was evaluated by wide angle X‐ray diffractometry (WAXD) in the resulting composites. Thermal stability, mechanical properties and water absorption studies were conducted to measure the material properties whereas FT‐IR spectroscopy was used to study the microdomain structure of composites. The sequence of addition of components (starch /plasticizer (glycerol) / clay) had a significant effect on the nature of composites formed and accordingly properties were altered. Glycerol and starch both have the tendency to penetrate into the silicate layers but penetration of glycerol is favored owing to its smaller molecule size. The filler dispersion becomes highly heterogeneous and the product becomes more brittle when starch was plasticized before filling with clay due to the formation of a bulky structure resulting from electrostatic attractions between starch and plasticizer. It was concluded that best mechanical properties can be obtained if plasticizer is added after mixing of clay in the starch matrix.     

Study of the retrogradation behaviour of rice cake using rapid visco analyser,Fourier transform infrared spectroscopy and X‐ray analysis

Retrogradation of gelatinised starch is the main phenomenon that influences the texture of MiGao (rice cake). The hardness of the MiGao increased during stored at 25 °C for 5 days. Rapid visco analyser (RVA), Fourier transform infrared (FT‐IR) spectroscopy and X‐ray were quantified to analysis the retrogradation behaviour of MiGao. The most significant change in the pasting curve was the increase in peak viscosity over time measured with an RVA. FT‐IR indicated changes in crystallinity of the MiGao crumb. The X‐ray diffraction patterns could be classified as typical of A‐type starch for the fresh MiGao. With aging, the B‐type structure increases, while the A‐type structure remains virtually unchanged. All the results suggested that the main mechanism underlying the changes in properties is suggested to be slow amylopectin crystallisation.     

The Effects of Citric Acid on the Properties of Thermoplastic Starch Plasticized by Glycerol

The effects of citric acid on the properties of glycerol‐plasticized thermoplastic starch (GPTPS) were studied. In the presence of citric acid and glycerol, native cornstarch granules are transferred to a continuous phase as shown by scanning electron microscopy (SEM). As shown by thermogravimetric analysis (TGA), the improvement in thermal stability confirms that the adhesion between citric acid, glycerol, water and starch in TPS was enhanced with the addition of citric acid. It was proven by Fourier transform infrared (FTIR) spectroscopy that citric acid can form stronger hydrogen‐bond interactions with starch than glycerol. Both FTIR spectroscopy and X‐ray diffractometry of citric acid‐modified GPTPS (CATPS) revealed that citric acid can effectively inhibit starch re‐crystallization (i.e. retrogradation), because of the strong hydrogen‐bond interaction between citric acid and starch. Rheology studies revealed that citric acid can obviously decrease the shear viscosity and improve the fluidity of TPS. Citric acid can also improve the elongation of GPTPS and ameliorate the water resistance of GPTPS at high relative humidities, but decreased the tensile stress.     

Effect of Incorporation Nanocrystalline Corn Straw Cellulose and Polyethylene Glycol on Properties of Biodegradable Films

This work aimed to study the effect of nanocrystalline corn straw cellulose (NCSC) and polyethylene glycol (PEG) on the properties of biodegradable corn distarch phosphate (CDP) films. The mechanical properties and barrier properties were investigated. Meanwhile, the compatibility, crystallization, thermal stability, and morphological structure of the films were characterized by Fourier transform infrared spectroscopy (FT‐IR), X‐ray diffraction (X‐RD), thermogravimetric (TGA), and scanning electron microscopy (SEM). In contrast with the CDP films, incorporation of NCSC in the films improved their tensile strength (TS) significantly, and incorporation of PEG improved their elongation at break (EAB) significantly else. PEG, CDP, and NCSC (P‐CDP/NCSC) blend films had the best barrier properties. The thermal stability of the films was increased by the incorporation of NCSC. X‐RD showed that CDP and NCSC (CDP/NCSC) films had higher crystallinity. SEM revealed that all films had smooth surface, while the films presented a uniform network structure through the incorporation of NCSC.     

Preparation and Properties of Octenyl Succinic Anhydride Modified Early Indica Rice Starch

Octenyl succinic anhydride (OSA) modified early indica rice starch was prepared in aqueous slurry systems and the major factors affecting the esterification were investigated systematically. The physicochemical properties of the products were determined by means of Fourier transform infrared (FT‐IR) spectroscopy, scanning electron microscopy (SEM), X‐ray diffraction and Rapid Visco Analyser (RVA). The results indicated that the suitable parameters for the preparation of OSA starch from early indica rice starch in aqueous slurry systems were as follows: concentration of starch slurry 35% (in proportion to water, w/w), reaction period 4 h, pH of reaction system 8.5, reaction temperature 35°C, amount of OSA 3% (in proportion to starch, w/w). The degree of substitution (DS) was 0 018 and the reaction efficiency (RE) was 78%. FT‐IR spectroscopy showed characteristic absorption of the ester carbonyl groups in the OSA starch at 1724 cm^‐1. SEM and X‐ray diffraction revealed that OSA groups acted by first attacking the surface and some pores formed, but OSA modification caused no change in the crystalline pattern of rice starch up to DS 0.046. RVA results indicated that the starch derivatives gelatinized at shorter time to achieve higher viscosities with increased OSA modification.     

Antiretrogradation in Cooked Starch‐Based Product Application of Tea Polyphenols

Retrogradation in cooked starch‐based products is a significant hindrance in extending the shelf life of these products as they become progressively hard to bite over short time periods (say 1 or 2 months). In this study, the effects of tea polyphenols (TPs) on cooked amylopectin‐rich cassava starch have been investigated. Cassava starch was mixed with TPs and then gelatinized to form starch gels. The obtained gels were stored for up to 80 d and characterized by X‐ray diffraction (XRD), hardness test, color analysis, and Fourier transform infrared spectroscopy (FT‐IR). The results of XRD show that the formation of long‐range ordered structure of amylopectin was retarded by the interaction of TPs with amylopectin via hydrogen bond. The results of hardness test show that the accelerating increase in the hardness of cassava starch gel was retarded by the addition of TPs. The increase in hardness versus time can be correlated well using a single‐parameter exponential equation. The increase in hardness, variations in color, and FT‐IR spectrum of the TPs treated samples during storage with TPs were relatively small, suggesting that the retrogradation of starch is inhibited by TPs. This work presents an opportunity of antiretrogradation in the related products.     

Physical and Mechanical Properties of Durum Wheat (Triticum durum) Starch Films Prepared with A‐ and B‐type Granules

The use of starch for the production of biodegradable materials has been increasing. Wheat is an important source, however, durum wheat starch and its separated granular components had not been evaluated for this purpose. The aim of this study was to evaluate the physical and mechanical properties of durum wheat starch films when prepared with a distribution of different granular‐sized starches (A‐ and B‐type). Starch was isolated, and the A and B populations of granules were separated. Films were prepared by casting. Glycerol (G) was used as a plasticizer in concentrations of 25% and 40%, respectively. Starch films were evaluated using scanning electron microscopy (SEM), mechanical properties (tensile strength, TS, elongation at break, E, elastic modulus, EM), solubility, and X‐ray diffraction (XRD). Durum wheat starch films were transparent, flexible, and, according to SEM, highly homogeneous. Films prepared with 25% G showed brittle material behavior (TS = 42–50 MPa, E = 1.4–2.7%, and EM = 31–34 MPa), whereas those prepared with 40% G had ductile material characteristics (TS = 11–17 MPa, E = 4–41%, and EM = 4–11.3 MPa). These mechanical properties of the films were significantly affected by the glycerol concentration and the starch granule type used. The film solubility was low when compared to those reported in other studies. It increased with increasing plasticizer concentration. According to the XRD, the films showed a semi‐crystalline structure.     

Synthesis and evaluation of physicochemical properties of cross‐linked Phaseolus aconitifolius starch

Highly substituted moth bean starch (MBS) phosphate ester was synthesized using POCl₃ as cross‐linking reagent. Titrimetric and FT‐IR spectral analysis was used to characterize the substitution. The physicochemical properties of cross‐linked moth bean starch (CLMBS) were done by using X‐ray powder diffractometer (XRD), thermogravimetric analysis (TGA) and swelling study at various temperatures. The change in starch morphology was done using scanning electron micrograph (SEM), and found that it lost its crystallinity after cross‐linking. The results revealed that crystalline nature of native MBS was transformed into amorphous after cross‐linking. TGA report exhibited higher thermal stability, which make it suitable for various industrial applications. Swelling behavior showed high swelling at low temperatures (30 and 60°C) as compared to at high temperature (90°C).     

Mechanical and Thermal Characteristics of Pea Starch Films Plasticized with Monosaccharides and Polyols

Edible starch films were produced from pea starch and various plasticizers (mannose, glucose, fructose, and glycerol and sorbitol) at the ratio of 4.34, 6.50, 8.69, and 10.87 mmol plasticizer per gram of starch. After film specimens were conditioned at 50% relative humidity, mechanical properties (tensile strength, elongation, and modulus of elasticity), water vapor permeability (WVP), moisture content, and thermomechanical properties (G’ and tan8) were determined as a function of plasticizer concentration. At all concentration levels, monosaccharides (mannose, glucose, and fructose) made the starch films stronger (higher tensile strength) and more stretchable than polyols (glycerol and sorbitol), while WVP of monosaccharide‐plasticized starch films were lower than those of polyol‐plasticized starch films, especially at higher plasticizer concentration levels. Except for 4.34 mmol/g of mannose‐plasticized film, all the other films showed similar modulus of elasticity at the same plasticizer concentration. Polyol‐plasticized films had lower T than the monosaccharide‐plasticized films. Glucose‐ and sorbitol‐plasticized films needed more activation energy to go through glass transition than others. After all, research results showed that not only the polyols but also the monosaccharides were effective in plasticizing starch films. It is concluded that molecular size, configuration, total number of functional hydroxyl group of the plasticizer as well as its compatibility of the plasticizers with the polymer could affect the interactions between the plasticizers and starch molecules, and consequently the effectiveness of plasticization.     

Phosphorylation of Corn Starch in an Ionic Liquid

Corn starch was phosphorylated by reaction with sodium dihydrogenphosphate or disodium hydrogenphosphate using 1‐butyl‐3‐methylimidazolium chloride (BMIMCl) as reaction medium. The parameters varied included the molar ratio of reactant, reaction time and temperature and were investigated regarding the degree of substitution for the phosphorylated starch. The degree of substitution of starch phosphates prepared ranged from 0.03 to 0.55. The product was characterized by Fourier‐transform infrared (FT‐IR) spectroscopy, scanning electron microscopy (SEM) and X‐ray diffraction (XRD) techniques. It was found that the native crystallinity of corn starch was largely distroyed during the dissolution and functionalization process in the ionic liquid system under the reaction conditions.     

淀粉的塑化及其生物降解餐具性能研究

研究了3种增塑剂对淀粉的增塑效果，并采用正交实验确定了它们之间协同作用最佳配比，通过红外及X－衍射对淀粉塑化本质进行表征，进一步探讨了以塑化淀粉制备的一次性餐具的物理性能、卫生指标及其生物降解特性。     

ISOLATION AND PHYSICOCHEMICAL CHARACTERIZATION OF STARCHES FROM DIFFERENT BANANA VARIETIES

The physicochemical properties of the starches extracted from three varieties of banana indigenous to Thailand were investigated. The Thai names of these varieties are Hak Muk, Nam Wa Kom, and Ta Nee. Starch from all three varieties were found to contain 30.9% to 32.0% amylose. Other components were moisture (11.47 to 11.76%), protein (0.22 to 0.93% dry weight basis dwb), lipid (0.07to 0.11 % dwb) and ash (0.07to 0.17% dwb). X‐ray diflraction patterns showed Hak Muk and Nam Wa Kom were of B type whereas Ta Nee was of C type. All three varieties showed strong paste stability to both thermal heating and mechanical shearing but high retrogradation. The banana starch paste stability in digerent pH slurries pH 7 to 4.5) indicated that they are suitable for food application that require high amylose and high retrogradation afer processing.     

Effect of Plasticizers on Mechanical and Barrier Properties of Rice Starch Film

The effect of plasticizers, glycerol, sorbitol and poly(ethylene glycol) 400 (PEG 400), on mechanical and barrier properties of rice starch film has been investigated. Sorbitol‐ and glycerol‐plasticized starch films appeared homogeneous, clear, smooth, and contained less insoluble particles compared to unplasticized rice starch films. PEG 400 did not form plasticized films of suitable characteristics. The softness and stickiness of films improved with increasing concentrations of glycerol and sorbitol. In general, films plasticized with glycerol and sorbitol displayed a better solubility in water than unplasticized films, i.e. 35% (w/w) glycerol and 45% w/w (sorbitol) (optimum solubility). The tensile strength of films decreased especially in the high concentration regime of plasticizers, between 20–45% (w/w) of plasticizer/rice starch film. Through the entire concentration regime, the tensile strength of glycerol‐plasticized films was significantly lower than that of sorbitol‐plasticized films, but their elongation was larger. The water vapor transmission rate (WVTR) through plasticized films and the oxygen transmission rate (OTR) increased with glycerol and sorbitol concentrations, however, glycerol was revealed to be significantly more effective in reducing the tensile strength as well as increasing the WVTR and the OTR compared to sorbitol. With the higher tensile strength and the smaller OTR and WVTR, the 30% sorbitol‐plasticized film reveals an improved coating performance in terms of a reduction of coating failures.     

淀粉老化对微波膨化影响及机理的研究

通过控制淀粉物料的静置冷藏时间来调节淀粉老化程度,采用X－衍射方法确定了淀粉物料的老化度,研究了淀粉的老化对其微波膨化的影响,实验结果表明：随着淀粉物料的静置冷藏时间增加,淀粉的老化度增加,而淀粉物料的微波膨化产品的膨化率下降,淀粉物料的老化对其微波膨化不利。从X－衍射图谱出发分析淀粉老化造成淀粉物料的物性状态及分子结构的变化,结合微波加热特性从理论的角度分析探讨了淀粉老化对微波膨影响的机理。     

The influence of flaxseed gum on the retrogradation of maize starch

The influence of flaxseed gum (FG) on the retrogradation of maize starch (MS) was investigated in this study. Based on the results of rapid visco‐analyzer (RVA), differential scanning calorimetry (DSC), X‐ray diffraction (XRD), Low field nuclear magnetic resonance (LF‐NMR) and scanning electron microscopy (SEM), FG has a retardation effect on the retrogradation of MS. With the addition increasing, the more significant the retardation effect was observed (P < 0.05). However, when the concentration of FG was up to 0.4%, the change of retrogradation ratio showed no significant difference (P > 0.05). FG could wrap around starch granules, suppress the recrystallisation of amylose and amylopectin, increase the water mobility and decrease the water loss. In summary, the overall results suggested that FG could be used as a natural inhibitor of the retrogradation of starch in food industry.