Effect of inulin soluble dietary fibre addition on technological, sensory, and structural properties of durum wheat spaghetti

Investigation of two inulins with differing degrees of polymerisation and crystallinity demonstrated different levels of integration with the starch-gluten matrix during pasta preparation. The impact of higher molecular weight inulin incorporation on technological and sensory properties was minimal, with deterioration in properties becoming significant only at 20% incorporation, while lower molecular weight had a greater negative impact on pasta firmness, cooking loss, and sensory acceptability. In vitro starch digestion of pasta was reduced with up to 5% addition of inulin of degree of polymerisation 12-14 (FH-D), but increased with high levels of addition. These effects were not observed in inulin with a degree of polymerisation of 7-8 (LV-100). Microscopy showed the starch granules were apparently encapsulated by a protective coat of inulin FH-D, but at 20% a disruption to the matrix was evident. For inulin FH-D, XRD analysis of digested pasta found a maximum crystallinity which coincided with the maximum reduction in starch hydrolysis, suggesting that a stronger gluten matrix enhanced by added inulin is indeed structurally different at the nanometre level.     

Effect of insoluble dietary fibre addition on technological,sensory, and structural properties of durum wheat spaghetti

Insoluble fibres are important in human health and disease prevention and can be incorporated into food. High fibre pasta prepared with bran is typically inferior quality compared to durum pasta. This study compared spaghetti prepared from durum semolina substituted with various amounts of either durum bran or germ (pollard) dried at high temperature. Pasta was evaluated for cooking properties, texture, sensory, fibre content, antioxidant status (AO) and in vitro starch digestibility to determine the dose producing acceptable quality. Pollard at 10% substitution had minimal impact on quality with higher AO and fibre. Above 30%, pasta had undesirable colour, sensory properties and higher starch digestion. Although bran substituted pasta had undesirable sensory and technological properties, especially at 30% incorporation, it does provide more dietary fibre and antioxidants than regular pasta and does not affect starch digestibility. Interestingly, a significant amount of AO was retained in the cooked pasta. The study illustrates the value of structural analysis to explain observed technological properties of the product with fibre inclusion.     

Evaluation of the technological and sensory properties of durum wheat spaghetti enriched with different dietary fibres

The incorporation of fibres, whether insoluble or soluble, in durum wheat pasta negatively impacts desirable end‐use properties, especially if incorporated in significant amounts. Fibres can disrupt the starch–protein matrix of the dough during pasta preparation and can also often swell more readily with water than starch, competing with the starch for water during dough development. Similar degrees of substitution with different fibres gave markedly different impacts on firmness, stickiness, cooking loss and sensory attributes, suggesting that results obtained for one fibre cannot readily be generalized to other fibres. The in vitro starch digestibility of the pastas was significantly reduced when resistant starch, β‐glucan‐enriched flour, carboxymethyl cellulose or guar gum was incorporated but increased when pollard or inulin was added. In many instances, different sources of the same fibre gave dramatically different impacts on the properties of cooked durum wheat pasta. © 2014 Society of Chemical Industry     

Influence of guar gum addition on physicochemical,microbial, rheological and sensory properties of stirred yoghurt

This study investigated the effects of adding guar gum (0, 0.6 and 0.8 g/100 mL) on the physicochemical, microbial, rheological and sensory properties of stirred yoghurt. Incorporation of guar gum into the yoghurt significantly affected the pH and colour, but did not significantly influence the lactic acid bacteria counts. The magnitudes of apparent viscosity (η_a,100), consistency index (K), yield stress (σ_oc), storage modulus (G′) and loss modulus (G″) for yoghurt samples containing guar gum (0.6–0.8 g/100 mL) were significantly greater than those for the control (without guar gum), indicating that guar gum can improve the steady and dynamic shear rheological properties of yoghurt.     

Effects of guar gum and arabic gum on the physicochemical,sensory and flow behaviour characteristics of frozen yoghurt

This study investigated the effect of guar gum and arabic gum on physicochemical, sensory and flow behaviour properties of frozen yoghurt. The results indicated that gums significantly affected the viscosity, overrun and melting rate of frozen yoghurt. The highest overrun value was observed in sample containing 0.5% arabic gum. Frozen yoghurt containing 0.3% guar gum had the highest viscosity. The longest first dripping time was observed in sample containing 0.5% arabic gum. Flow behaviour of samples showed that all frozen yoghurts exhibited shear thinning behaviour. Guar gum at a concentration of 0.2% and arabic gum at a concentration of 0.5% presented the best total acceptability. The results of this study revealed that the frozen yoghurt produced with arabic gum had the better overall sensory and physicochemical characteristics.     

Moisture adsorption isotherms of guar (Cyamposis tetragonoloba) grain and guar gum splits

Moisture adsorption isotherms of guar grain and guar gum splits were determined at 10, 20, 30 and 40 °C and 23-96% relative humidities using gravimetric method. The sorption data were fitted to six well-known sorption isotherm models (modified Chung-Pfost, modified Halsey, modified Henderson, modified Oswin, Chen-Clayton, and GAB models) using non-linear least square method. The GAB model was found the most satisfactory for representation of the equilibrium moisture content data for guar grain and guar gum splits. The equilibrium moisture content of guar gum splits was found to be significantly higher (p < 0.05) than that of guar grain. The isosteric heat of sorption was determined from the equilibrium moisture adsorption data using Clausius-Clapeyron type equation. Exponential relationship described well the dependence of isosteric heat of sorption on the equilibrium moisture content. The enthalpy-entropy compensation theory applied to sorption isotherms indicated enthalpy controlled sorption process.     

Comparison of the viscosity of trehalose and sucrose solutions at various temperatures: Effect of guar gum addition

The viscosity of trehalose and sucrose solutions was measured and compared as well as the effect of adding guar gum. Viscosity measurements of trehalose and sucrose solutions were performed in the range 20-45 g/100 g; 0.1 g guar gum/100 g was added in mixed systems. Viscosity of trehalose or sucrose solutions was measured at 20, 27 and 34 °C. Trehalose solutions had always a higher viscosity than sucrose, with the biggest difference (p < 0.001) in the range 30-45 g/100 g. Addition of guar gum revealed a synergistic effect with both disaccharides, particularly for trehalose. Viscosity dependence on temperature was also analyzed by calculating activation energies for all systems studied.     

Influence of pumpkin puree and guar gum on the bioactive,rheological, thermal and sensory properties of ice cream

The effects of pumpkin puree and guar gum on the bioactive, rheological, thermal and sensory properties of ice cream were investigated. The addition of pumpkin puree increased total phenolic content, dietary fibre, and antioxidant activity. Appropriate models described shear thinning and thixotropic behaviours of all mixes. By either adding pumpkin puree or by increasing guar gum concentration, all rheological properties increased except the flow behaviour index. Adding pumpkin puree reduced the freezing point temperature, ice content, frozen water and glass transition temperature but it increased unfreezable water. Increasing guar gum concentration did not alter colour and firmness, whereas the pumpkin puree increased colour, intensity of fruit flavours and firmness.     

Role of initial apparent viscosity and moisture content on post irradiation rheological properties of guar gum

Guar gum is a polygalactomannan used in various industries. Previous studies on radiation processing of guar gum showed a decrease in its viscosity during irradiation. Present work reports rheological properties and magnitude of depolymerization as affected by initial apparent viscosity (AV) and moisture contents of guar gum during irradiation processing. Rate of degradation was found to be dependent on the initial moisture content of guar gum during irradiation. D₅₀ values for oven dried gum was 490 Gy and it increased to 1250, 2600 and 2420 Gy in samples having 10%, 25% and 30% initial moisture respectively. EPR spectroscopy showed disappearance of anisotropic signals with increasing moisture content indicating crosslinking of polymer. FTIR spectroscopy results suggested that there were no major chemical functional group transformations during irradiation.     

The effects of date syrup and guar gum on physical,rheological and sensory properties of low fat frozen yoghurt dessert

The effect of adding date syrup (0%, 25% and 50% as sugar replacement) and guar gum (0%, 0.1%, 0.2% and 0.3% as fat replacement) was examined in respect of physicochemical, rheological and sensory properties of low fat frozen yoghurt. Increasing date syrup and guar gum concentration increased the mixture viscosity and acidity. Guar gum softened the frozen yoghurt whereas date syrup increased the hardness of the product. The control yoghurt was less sticky than samples containing the gum, but date syrup had no significant effect on the samples stickiness. Melt‐down stability of the samples also increased with increase in gum and date syrup concentration. The low fat orange flavoured frozen yoghurt dessert prepared in this study also had good sensory properties.     

The effect of genotype and environmental conditions on grain physiochemical properties of Syrian durum wheat cultivars

The physical and chemical characteristics of five Syrian durum wheat cultivars grown under varying environmental conditions were investigated. Two cultivars were grown under irrigated conditions whilst two were grown under rainfed conditions in five different locations. A known cultivar (Sham‐1) was grown alongside the samples in all locations as a control. Test weight, 1000‐kernel weight, the degree of vitreousness, protein content, starch content, amylose content and starch pasting properties were determined for the samples. The effect of the environmental factors and their interaction (site × irrigation) showed that the irrigation factor was more responsible for physical quality variations than the site factor (for instance, site variation of the irrigated conditions was responsible for 61% of the total quality variation and 34% of total quality variations in the rainfed conditions). Starch composition was influenced more by site variations than irrigation, whereas cultivar factor mainly influenced starch quantity, chemical composition and pasting properties (for instance, variations were mostly affected by cultivar (63%) more than site (15%) in the irrigated lands). The interaction of cultivar and site demonstrated significant effects on the degree of vitreousness, amylose content and starch pasting properties.     

Synthesis and application of reactive stiffening agent based on the methlyolated products of (poly-acrylamide) guar gum polyblends

Polyacrylamid-guar gum polyblends have been prepared via graft copolymerization of acrylamide onto guar gum using KBrO₃/thiourea redox system as initiators. In order to obtain polyblends with suitable viscosity and full total conversion the prepared polyblends were subjected to further treatment with K₂S₂O₈. The amide groups in the polyblends are converted to reactive groups through methylolation with formaldehyde, with a view to obtain reactive polyblends. The feasibility of utilization of the obtained reactive polyblends as permanent stiffening agents for cotton fabrics was studied. The reactive polyblends (i.e. methylolated polyblends) was then applied to cotton fabrics using the conventional pad-dry-cure method under various conditions. The influence of curing temperature, duration and type of catalysts (i.e., ammonium sulphate (NH₄)₂SO₄ and ammonium chloride (NH₄Cl) on the cross-linking reactions between the reactive polyblends in question and the cotton cellulose was investigated. The efficiency of the cross-linking reaction was monitored via determining nitrogen percentages. Evaluation tests on tensile properties (i.e., tensile strength (TS), and elongation at break (EAB), crease recovery angle (CRA), and stiffness were made. The results obtained indicate that reactive polyblends, the cotton fabrics under the optimum pad-cure conditions arrived at (3%Nmethylol-PAam-GG, 0.5% (NH₄)₂SO₄; curing temperature 140°C, and curing time, 5 min) produces fabric having excellent permanent stiffness, superior tensile strength as compared with that of untreated fabric. Tentative mechanisms, including different chemical events that can occur through the whole course of polymerization, methylolation and cross-linking processes, are reported.     

Physicochemical,thermal, rheological,and morphological properties of flour from different guar seed (Cyamopsis tetragonoloba) cultivars

In the present study, physicochemical, thermal, rheological, and morphological properties of flours from guar seed cultivars (G80, Ageta 112, and HG365) were assessed. Ageta 112 flours showed the highest protein content (26.78%) and varied significantly from G80 and HG365. The fiber, ash, and carbohydrate displayed significant differences in all three guar cultivars. Maximum gum content was extracted from G80 (41.19%), followed by HG365 and Ageta 112. Assessment of thermal properties revealed G80 flours with highest onset, peak, and endset temperature. Flours from cultivar Ageta 112 were recorded with highest paste temperature and peak viscosity and G80 flours showed lowest setback viscosities. Scanning electron microscopy was used to observe the morphological structure of different guar seed flour. Scanning electron micrographs presented the internal structure containing the galactomannans. Several significant correlations between physicochemical, gum yield, and thermal properties were revealed by Pearson correlation.     

刺槐豆胶/瓜尔豆胶复合体系的流变学性质研究

研究刺槐豆胶(LBG)/瓜尔豆胶(GG)复合体系的流变学性质,并采用流变学的模型进行拟合分析。实验表明:BG/GG复合体系为非牛顿流体,流动曲线服从Carreau模型,随着LBG比例的增大,其粘度越小,非牛顿性越不明显,触变性越低。LBG与GG复配对粘度的影响可产生协同作用,LBG/GG=1∶9时,复合体系粘度最大。在频率扫描范围内,LBG/GG复合体系同时具有粘性和弹性,随不同的角频率处理展现不同的动态粘弹性行为,LBG/GG=1∶9时,复合体系的动弹粘弹性最大。      

Effect of temperature and cross-linking density on rheology of chemical cross-linked guar gum at the gel point

The evolution of viscoelasticity within a solution of guar gum (GG) in the presence of an excess of cross-linker (glutaraldehyde, Ga) has been monitored, at different temperatures (7, 15, 25 and 37 °C), evaluating the sol–gel transition by means of dynamic mechanical experiments. Furthermore, at 25 °C, the samples were characterized as a function of the different amounts of cross-linker. The gelation time of the systems, evaluated with the loss tangent, decreased with increasing temperature and, at a fixed temperature (25 °C), decreased with increasing cross-linker concentration. At the gel point a power-law frequency dependence of the dynamic storage modulus (G′≈ωⁿ) and loss modulus (G″≈ωⁿ) was observed. The value of n, evaluated according to three different methods (n_slope, considering the parallelism of the two moduli, n_tan, from the frequency-independence of tan δ, and from the crossing point between the apparent exponents of G′ and G″, n_app), decreases with increasing cross-linking densities and with increasing temperature. The fractal dimension (d_f) was determined for the incipient GG/Ga hydrogels. The value of d_f increases with increasing cross-linker concentration and decreases with increasing temperature. This trend of d_f suggests a more “tight” structure of the network at higher cross-linking densities and at lower temperatures. The activation energy (E_a) of the chemical reaction between GG and Ga was estimated: the experimental value was close to those obtained in the case of similar chemical reactions among polymers and different kinds of cross-linkers.     

Effects of particle size on physiochemical and in vitro digestion properties of durum wheat bran

In order to promote the potential health benefits of high fibre products, wheat bran is the main focus of the food industry. The physiochemical and in vitro digestion properties of wheat bran containing different particle size were investigated and compared against raw bran samples. Firstly, the bran sample containing superfine particles (11.63 μm) was hydrolyzed by the α-amylase, pepsin, and pancreatin enzymes separately using a single factor and orthogonal test. Secondly, optimized hydrolysis parameters of superfine particles were employed to measure in vitro digestibility of macronutrients in raw, coarse, medium, and superfine bran particles. The maximum degree of hydrolysis obtained via α-Amylase (concentration 10 mg mL⁻¹, pH 6.6, and time 12.5 min) was 55.71%; pepsin (concentration 50 mg mL⁻¹, pH 1.2, and time 9 h) was 82.10%; and pancreatin (concentration 100 mg mL⁻¹, pH 7.0 and time 12 h) was 84.71%, respectively. The highest in vitro digestibility rate of reducing sugar, protein, fat, and soluble fibre content was observed in superfine bran samples to 33.4%, 82.55%, 91.53%, and 21.66%, respectively.     

The influence of inulin addition on the morphological and structural properties of durum wheat pasta

The effect of the addition of different concentration of inulin fibre to durum wheat pasta was evaluated in terms of structure, texture and morphological characteristics. Inulin fibre fraction was incorporated into pasta at 5%, 10% and 15% inclusion rates. Changes to pasta quality were observed with inulin fibre fraction addition by scanning electron microscopy, X-ray diffraction and Raman spectroscopy methods. Investigation of pasta microstructure indicate a lowering in crystallinity increasing the inulin content and characterisation of starch gelatinisation events indicated that a combination of changes to the starch–protein matrix and the high water-binding capacity of inulin alters the physico-chemical properties and then the digestibility of the pastas.     

Isolation and partial characterisation of two low molecular weight durum wheat (Triticum durum) glutenins

Two low molecular weight durum wheat (Triticum durum Desf) glutenins, DSG-1 and DSG-2 (durum-wheat sulphur-rich glutenin fractions) were isolated from two cultivars, Mondur of good technological quality and Kidur of poor technological quality. The glutenin fraction, composed mostly of DSG protein, was extracted using a low concentration of NA-tetradecanoate and then fractionted by by using molecular sieve chromatography (Bio-Gel P 30). The amino acid compositions and the N-terminal sequences of the pure DSG proteins were determined, and their hydrophobic characteristics, calculated on the basis of these data, showed that DSG-2 is more hydrophobic than DSG-1. The amino acid compositions of DSG-1 and DSG-2 were different. The N-terminal amino acids of DSG-1 and DSG-2 were also different but were identical for each of the two cultivars. In the case of DSG-1, in addition to the main chain a minor chain was found in which the first three amino acids of the main chain were missing. The minor chain represented about 30% int he DSG-1 of mondur and almost 50% in Kidur.