Effects of plasticizers on thermal properties and heat sealability of sago starch films

Sago starch films were plasticized with sorbitol, glycerol, or a combination of sorbitol/glycerol (1:1, 1:3, and 3:1 ratios) and the effects on the thermal properties and heat sealability of the films were investigated. Films were sealed with an impulse heat sealer at a dwell time of 1 s and temperature of 110 ± 10 °C. Thermal properties of the films (determined using a differential scanning calorimeter) showed that onset temperatures (T_o) of sorbitol-plasticized films were significantly lower than those of glycerol-plasticized films. All films were heat sealable, but sorbitol-plasticized films exhibited better heat sealability than did the glycerol type. The highest seal strength was obtained with a 3:1 combination of sorbitol/glycerol. In summary, the type of plasticizer governed the heat sealability as well as the seal strength of starch films.     

Microstructure and color of starch–gum films: Effect of gum deacetylation and additives. Part 2

Xanthan gum deacetylation, additives (sucrose, soybean oil, sodium phosphate and propylene glycol) and pH modifications influence on cassava starch-based films microstructure and color has been studied. X-ray diffraction and microscopic analysis have demonstrated that sucrose addition influenced (p<0.05) the film crystallinity during 60 days storage (75% RH, 23 °C). Although not enough to prevent sucrose crystallization, deacetylated xanthan gum addition delayed the crystallization process. Comparing to the control, only cassava starch concentration and the additives sucrose and sodium phosphate affected samples total color difference (ΔE). However, all samples presented high lightness and low color values for ‘a’ redness and ‘b’ yellowness, indicating that, independent of the additives or pH modifications, the materials were almost colorless, with a high brilliancy.     

Analysis of water binding in starch plasticized films

The water-binding properties of wheat starch films were studied through the determination of water vapour adsorption isotherms at 20 °C. Starch films were obtained by casting after mixing native starch at 95 °C for 15 min with different ratios of plasticizer (glycerol).     

黄原胶对玉米淀粉糊化性能的影响

将黄原胶引入到淀粉浆料中,采用快速黏度分析法(RVA)研究了黄原胶的加入对玉米淀粉糊化性能和浆液表观黏度的影响,讨论了黄原胶与玉米淀粉分子之间的相互作用.结果表明:黄原胶可促进淀粉糊化,降低淀粉的糊化温度,缩短糊化时间;随着黄原胶质量分数的增加,淀粉的糊化峰值黏度增加,表现了2种高分子的相互作用;黏度衰减值随黄原胶增加...     

Micellar properties of OSA starch and interaction with xanthan gum in aqueous solution

Octenyl succinate (OSA) modified starches are used, as emulsifiers and stabilizers, in many food, cosmetics and pharmaceutical products. The aim of this study was to determine critical micellar concentration (CMC) of two different octenyl succinate modified waxy corn starches at 25 °C, and to examine possibility of their interactions with xanthan gum in aqueous solution. The CMC was determined by viscometry, conductometry, surface tension and dye solubilization. The CMC values for two OSA starches (OS1 and OS2) varied from 0.050 to 0.088 g/100 cm³ and from 0.041 to 0.081 g/100 cm³ respectively, depending on applied technique. The same techniques were used for investigation of the interactions between OSA starch and xanthan gum. The addition of xanthan gum decreases the specific viscosity and increases surface tension and the CMC values compared to the single OSA starch solutions.     

果胶/黄原胶共混膜的制备工艺优化与表征

为了改善果胶膜的性能,拓宽果胶的应用领域,采用果胶与黄原胶共混,制备果胶-黄原胶共混膜。探讨了果胶与黄原胶质量比、甘油添加量、氯化钙浓度因素对共混膜吸水率、溶出率、拉伸强度、水蒸气透过率、吸湿率、保湿率、断裂伸长率等性能的影响,以确定共混膜的最佳制备工艺。并利用红外光谱、X-射线衍射、扫描电镜表征共混膜的结构。结果表明:果胶和黄原胶之间发生了较强的相互作用,黄原胶的加入增强了膜的结晶度。果胶和黄原胶质量比例为9∶1、甘油添加量为0.5 m L、氯化钙添加量为2%是制膜的最优工艺条件,此时膜的吸水率为231.03%,保湿率为84.41%,拉伸强度为59.850 MPa,水蒸气透过率为7.428×10（-3） g·m^-1·K·Pa^-1·d^-1。      

Characterization of edible gum cordia film: Effects of plasticizers

Gum Cordia based edible films were fabricated as a function of plasticizer type and concentration and their thermal, mechanical and gas permeation were investigated. Solution casting method was adopted for film fabrication. Glycerol, sorbitol, PEG 200 and PEG 400 in the range of 0.1–0.3 g g⁻¹ dry polymer weight basis were used as plasticizer. Film properties were found to be dependent on the plasticizer type and concentration. Fourier transform infrared (FTIR) spectroscopy revealed some interaction between plasticizers and the polymer. Differential scanning calorimetry (DSC) supported that plasticizers were miscible with the polymer. The glass transition temperature was found to be between −66 and −11 °C. Mechanically, gum Cordia films were found to have good tensile strength (>10 MPa) and elongation at break (>10%). The most pronounced change in tensile property was exerted by glycerol followed by sorbitol, PEG 200 and PEG 400 respectively. Water vapor permeability was found to be in the range 0.91–5.5 × 10⁻¹⁰ g m⁻¹ s⁻¹ Pa⁻¹. Oxygen permeability was found to be between 0.16 and 5.31 × 10⁻¹⁵ g m⁻¹ s⁻¹ Pa⁻¹.     

瓜尔胶和黄原胶对马铃薯淀粉糊化特性影响的比较研究

将马铃薯淀粉分别与瓜尔胶和黄原胶以一定的比例复配,探讨两种胶体对马铃薯淀粉黏度、热稳定性、凝沉性、冻融稳定性和质构特性等糊化特性的影响。结果表明:瓜尔胶提高了淀粉糊的黏度和冻融稳定性,降低了淀粉糊的热稳定性、凝沉性、硬度、黏附性、胶黏性和咀嚼性;而黄原胶增加了淀粉糊的热稳定性和冻融稳定性,但降低了糊的黏度、凝沉性、硬度、黏附性、胶黏性和咀嚼性;且随着两种胶体含量的不同淀粉糊化特性也不同。      

Thermal and rheological properties of tapioca starch gels with and without xanthan gum under cold storage

Changes in the thermal and rheological properties of tapioca starch (TS) with and without xanthan gum (Xan) (total polysaccharide concentration = 25% w/w) were investigated using a differential scanning calorimeter, Rheolograph Gel and Texture Analyser. The gelatinization temperatures of TS shifted to higher values with the Xan concentration. Xan enhanced the retrogradation of TS during the initial stage of storage but retarded the process for a further storage time at 5 °C. The onset temperature of all reheated TS/Xan gels decreased with increasing storage time indicating thermally unstable structure formation after a longer storage time. Storage Young’s moduli (E′) of the TS and TS/Xan gels stored at 5 °C increased with increasing storage time. The E′ values became more temperature dependent with storage time due to the weak cross-linkage of amylopectin molecules in the gels but became less dependent in the system containing Xan. TS/Xan gels kept for 14 days showed lower Young’s moduli than TS gels from the compression test confirming retardation of the retrogradation process by Xan. The results suggested that Xan could retard the retrogradation of TS gels for longer storage times.     

Simultaneous estimation of amylose,resistant, and digestible starch in pea flour by visible and near-infrared reflectance spectroscopy

Due to its health benefits, resistant starch (RS) has received increasing attention from the public, and there is a need to develop methods to measure the amylose and RS concentration in pea (Pisum sativum L.) flour. The aim of this study was to develop a visible and near-infrared reflectance (vis–NIR) model for the simultaneous determination of amylose, RS, and digestible starch (DS) in pea flour. A total of 123 dry pea samples consisting of different pea varieties grown in different environments were collected, and ground to flour, and then the vis–NIR spectra were scanned. The amylose, RS, and DS contents of the pea flours were also measured by an enzymatic colorimetric assay. The spectra data were calibrated with the enzymatic colorimetric-assayed values. Results showed that amylose, RS, and DS in the pea flours can be simultaneously estimated using the vis–NIR spectra. Instead of using the full spectrum (300–2300 nm), we found the most efficient wave bands lying in the visible region between 370 and 560 nm and the NIR spectra in the range of 1600–1800 nm. Using the stepwise regression with backward elimination method, the multiple linear regression (MLR) models were developed from the most efficient wavelengths. The MLR models had the determination coefficients R² of 0.95, 0.76, 0.80, and 0.88 for amylose, RS, DS, and total starch, respectively. The correlation coefficients between model estimated and the enzymatic colorimetric assayed values were 0.97, 0.80, 0.85, and 0.93 for amylose, RS, DS, and total starch, respectively.     

玉米淀粉与黄原胶复配体系糊化及回生特性的研究

本文研究了玉米淀粉与黄原胶复配体系的糊化和回生特性。RVA糊化实验表明黄原胶降低了玉米淀粉的成糊温度,并随着黄原胶在复配体系中的比例逐渐增加,其复配体系的峰值黏度和终值黏度均显著增加(p<0.05),崩解值和回生值降低(p<0.05)。热稳定性实验表明加入黄原胶后的复配体系在95℃之后的高温下可以较长时间维持体系的黏度,具有良好的热稳定性。凝沉性实验表明黄原胶可以降低玉米淀粉的凝沉作用,当m(玉米淀粉)∶m(黄原胶)为9∶1时复配体系凝沉作用最小,在120h后仍无明显上清液析出。冻融稳定性实验表明黄原胶能抑制复配体系的回生,提高其冻融稳定性。      

Influence of sucrose on thermal and pasting properties of tapioca starch and xanthan gum mixtures

Sugars and hydrocolloids are used in starch-based product formulations during processing for improving the final quality of foods. Effect of sucrose (0–30%) on thermal and pasting properties of 5% w/w tapioca starch (TS) – xanthan gum (Xan) mixtures was investigated using differential scanning calorimeter (DSC), rapid visco-analyser (RVA) and rheometer. Sucrose increased gelatinization temperatures and enthalpies of TS and TS/Xan dispersions. RVA pasting temperatures, peak viscosity, final viscosity, breakdown and setback values of TS/Xan mixtures increased with increasing sucrose concentration (p < 0.05). Addition of sucrose in all TS/Xan pastes increased the rate of viscosity breakdown during RVA heating under constant shear and temperature. Setback values of TS/Xan pastes increased with sucrose addition but decreased significantly with increasing Xan content. Xan enhanced thermal stability of steady shear viscosities to TS pastes with and without sucrose. Linear regression from pasting profile revealed a good relationship for predicting final viscosity. These results could facilitate the development of TS-based products with improved thermal and pasting properties.     

Effect of extrusion cooking on structure and functional properties of pea and kidney bean proteins

Pea (Pisum sativum L cv Ballet) and kidney bean (Phaseolus vulgaris L cv Pinto) seeds were extruded at 148 and 156 °C respectively. Protein solubility at various pH values and in various solvents was determined and analysis of protein fractions was carried out by SDS‐PAGE. Also, sulphhydryl and disulphide groups, water‐holding capacity (WHC), water solubility index (WSI) and oil absorption capacity (OAC) were determined. No changes in total nitrogen content of pea and kidney bean seeds occurred as a result of thermal treatment. Protein solubility from raw and extruded legumes was significantly higher in saline solutions than in water in the pH range 2–10. The solubility of proteins from extruded pea and kidney bean flours was greatly decreased with respect to native flours when extraction was in buffer (pH 7.0) alone. Extraction with buffer containing 2‐mercaptoethanol (2‐ME) or sodium dodecyl sulphate (SDS), alone or in combination, greatly increased protein extractability. As a result, the relative solubility was nearly 100% in buffer with SDS and 2‐ME for both raw and extruded samples. Total and free sulphhydryl group and disulphide contents decreased significantly (P < 0.05) after extrusion cooking. Moreover, extrusion treatment caused major changes in the band patterns of the albumin and globulin fractions obtained by SDS‐PAGE. WHC and WSI of extrudates increased significantly in both peas and kidney beans. A significant reduction in OAC was observed in extruded kidney bean flour. © 2000 Society of Chemical Industry     

Functional properties of air-classified yellow pea (Pisum sativum)fractions

The objective of the present investigation was the characterisation of yellow pea (Pisum sativum L) fractions obtained on a commercial scale by air classification of the milled peas. Some analytical aspects of the process were investigated including particle size distribution of fractions and their functional properties.     

Effect of modified tapioca starch and xanthan gum on low temperature texture stability and dough viscoelasticity of a starch-based food gel

This work investigated the effect of modified tapioca starch and xanthan gum on dough viscoelasticity and texture stability during storage at 4 °C of starch sheets for Chinese shrimp dumplings. Hydroxypropylated starch and hydroxypropylated-crosslinked starch were used to substitute for tapioca starch in the control formulation, and xanthan gum was added to adjust the formulation. During storage, texture of the control became firmer due to amylopectin retrogradation confirmed by differential scanning calorimetry and X-ray diffraction. Conversely, gel sheets containing modified starches showed less texture change. Dough viscoelasticity of the formulations substituted by hydroxypropylated starch were much softer and easier to deform than that of the control one. Dough with hydroxypropylated-crosslinked starch was, however, stiffer and more strain-resistant. Moreover, the formulation comprising the mixture of both types of modified starches and xanthan gum gave dough viscoelasticity similar to that of the control, and provided gel sheet the least texture change. Consequently, this modified formulation could be beneficial for the application of frozen/chilled dumpling wrappers.     

Phytate content and phytate degradation by endogenous phytase in pea (Pisum sativum)

In order to rapidly reduce the content of inositol tri–hexaphosphates in pea flour by action of the endogenous phytase, raw materials as well as incubation conditions have been evaluated. The phytate (inositol hexaphosphate) content was analysed in 27 pea varieties; the influence of storage time and the difference in phytate content between the germ and the cotyledon were determined. Furthermore, degradation of inositol phosphates by the endogenous phytase enzyme was studied in pea flour, germ and cotyledon. To find the maximum phytate degradation, the effects of temperature and pH during pea flour incubation were investigated. The most efficient phytate degradation in pea flour incubation was achieved at pH 7.5 and 45 °C. At this condition an almost complete degradation of phytate and a 66% reduction in the sum of inositol hexa‐, penta‐, tetra‐ and triphosphates were reached in 10 h. The storage time of pea seeds or removal of the germ did not have a major effect on the phytate content. Since several inositol pentaphosphate isomers were produced during phytate degradation, it can be concluded that peas contain several phytate‐degrading enzymes, or one phytate‐degrading enzyme with unspecific initial hydrolysation pattern. © 2001 Society of Chemical Industry.     

The effect of electrostatic interactions on pasting properties of potato starch/xanthan gum combinations

The effects of electrostatic interactions on pasting properties of potato starch (PS)/xanthan gum (XG) combinations were investigated. The RVA peak viscosity of combinations was decreased firstly and then increased with the adding of XG. The analysis and regression model performance of RVA measurement showed that there was the relationship between pasting properties of combinations and XG concentrations. Electrostatic repulsions between native potato starch or anionic modified potato starches (AP) and XG could be present by decreasing peak viscosity, but the pasting temperatures showed increasing trend. However, electrostatic attractions between cationic modified potato starch (CP) and XG showed the opposite effect. Negative zeta potential determination for combinations (− 54.6 mv) was higher than PS (− 35.2 mv) illustrated that combinations had more electronegativity and stability, in addition a phase-separated microstructure was exhibited in the combinations determined by Zeta potential results. SEM micrographs presented that XG film attached to the surface of PS granules, which inhibited the starch granules destruction and leaching of amylase. The electrostatic repulsion leaded to more stability of the three dimensional network structures of combinations. The strong electrostatic interactions between PS and XG were found to play an important role on the pasting properties of the combinations.     

Determination of protein in pea flour by near infrared analysis

Equations were derived for predicting crude protein content (total nitrogen × 6.25 or Kjeldahl nitrogen × 6.25) of pea varieties from near infrared data measured on a filter instrument (Technicon Infra Analyzer 400). The accuracy of the predictions were tested against different data sets and found to be better than ±1.5% (P=0.95), and adequate for use in a plant breeding programme.