Effects of NaCl and soy protein isolate on the physicochemical,water distribution,and mobility in frankfurters

In this study, we investigated the effect of gel and rheological properties, microstructure, and water distribution of frankfurters with various amounts of NaCl (1 and 2%) and soy protein isolate (SPI, 3 and 6%). The frankfurter cooking yield, a*value, and hardness significantly increased with the increasing NaCl and SPI content. However, the frankfurter springiness and cohesiveness were lower in the case of 6% SPI and 2% NaCl content than in the case of 3% SPI and 2% NaCl content. The thermal stability of myosin improved with the increasing NaCl and SPI, resulting in more compact and continuous structures. Meanwhile, the initial T_2b, T₂₁, and T₂₂ relaxation times were significantly shorter, and the P₂₁ and P₂₂ peak ratios increased and decreased significantly, respectively, implying the increase of the immobile water content. Overall, the SPI use allowed the production of reduced-salt frankfurter with desirable quality.     

Physicochemical and sensory properties of protein-fortified cookies according to the ratio of isolated soy protein to whey protein

Food Science and Biotechnology - A high-protein diet has a variety of beneficial effects and mixing isolated soybean protein (ISP) with whey protein (WP) reported to increases health and functional...     

Influence of sweet potato flour on the microstructure and nutritional quality of gluten-free fresh noodles

This study investigated the influence of sweet potato flour (SPF) on the microstructure, nutritional and sensory qualities of gluten-free fresh noodles (GFFN). Five kinds of GFFN were produced using SPF (0%–50%) and were compared with cornflour (CF) and wheat flour (WF) noodles. Adding SPF increased springiness and chewiness of the noodles. The β-sheet (amide I, C=O and N–H) and total β-sheet (1704–1683 and 1633–1614 cm⁻¹) protein structures in SPF noodles significantly increased relative to WF. Besides, electron microscopy showed matrix of the filamentous structure in SPF noodles that can mimic a matrix network identical to that of the network in WF. Furthermore, total phenols and antioxidant activity (DPPH and FRAP) were the highest for 40% SPF noodles. This research confirmed that SPF had the potential for improving the microstructure and nutritional value of the noodles, especially for consumers with coeliac disease.     

Effect of gluten content on recrystallisation kinetics and water mobility in wheat starch gels

The effect of gluten on starch retrogradation at 5 °C was studied using ¹H NMR relaxometry. Gels were made from gluten and starch at 27.8 and 38.5% total solids and with gluten comprising either 10, 15 or 20% of the solids. Changes in the transverse relaxation time constant (T₂) were related to water mobility. Mono‐exponential analysis of relaxation curves showed that, in general, gluten retarded starch retrogradation. T₂ values in gluten gels also decreased during storage, but to a much lesser extent. Distributed exponential analysis showed that two distinct regions of T₂ were observed in all samples. During aging, the peak values of both regions shifted to lower values for all gels. Starch gel samples showed the most significant shift, and gluten gels showed the least. The three levels of gluten addition in starch/gluten gels produced similar shifts. For all samples the signal intensity of the less mobile region decreased more dramatically than that of the more mobile region during storage. It was suggested that gluten retards water loss in the granule remnants. Copyright © 2004 Society of Chemical Industry     

Effect of water content on the mobility of solute molecules and of protein side chains in casemate preparations

The effect of water content on the mobility of small solute molecules and of casein side chains was studied by electron spin resonance in caseinate/water systems. The immobilization of nitroxide probes of different sizes and properties were followed during progressive dehydration of concentrated caseinate preparations (3 g H₂O/g dry protein). Above a characteristic minimum moisture content a linear relationship was observed between the rotational diffusivity and water content. The slope of the straight lines depended upon the size of the probe and upon the nature of the interactions with the protein. Nitroxide labels were covalently bound to caseinate and the changes in the flexibility of the side chains as hydration changed were followed. The results are discussed in relation to the solvent properties of water, and to recent suggestions concerning the significance, for stability, of the glass transition phenomenon in such materials.     

Study on the water state,mobility and textural property of Chinese noodles during boiling

The water mobility, state and textural properties of Chinese fresh noodles (CFNs) and Chinese dried noodles (CDNs) made from same wheat cultivar were measured during boiling using low-field nuclear magnetic resonance (LF-NMR), low-field nuclear magnetic Imaging (LF-NMI) and a textural analyser. ‘The oil immersion method’ was applied to gain the clear images from LF-NMI measurement. The distributions of the three water states (T₂₁, T₂₂ and T₂₃) in the noodles were distinguished. The results indicated that water mobility in noodles was closely related to the gelatinisation of noodle starch. Compared with CFNs, CDNs need a longer cooking time for water mobility and starch gelatinisation. The results of the cooked noodle profiles showed that the cooked CDNs (8 min) had an undesirable textural properties compared with the cooked CFNs (2 min). The longer cooking time of CDNs is responsible for its undesirable texture since the textural properties change during the longer cooking time.     

利用固定化酶改善酸法大豆浓缩蛋白持水性和吸油性的研究

利用固定化谷氨酰胺转胺酶(MTG)对酸法大豆浓缩蛋白(SPC)进行改性,并对改性SPC进行红外光谱分析。通过单因素和正交实验研究了MTG改性对SPC持水性和吸油性的影响。结果表明,当固定化MTG添加量1U/g,pH6.0,50℃下反应2h时,改性后大豆浓缩蛋白的持水性和吸油性分别比对照提高了24.8%和64.5%;与大豆分离蛋白相比,其凝胶性和吸油性分别高出58.3%和27.0%,持水性则低8.0%。     

大豆分离蛋白与小麦粉复配对面制食品品质影响的研究进展

综述了添加大豆分离蛋白对面条、面包、馒头等面制品食用品质的影响,得出在小麦粉中添加适量的大豆分离蛋白后,能够使其蛋白质含量增加,有效地改善面制品的食用品质、面筋强度、流变学性质、营养价值,延长其货架期。     

Microwave irradiation of guar seed flour: Effect on anti-nutritional factors,phytochemicals, in vitro protein digestibility,thermo-pasting,structural, and functional attributes

Guar seed flour (GSF) has a high amount of carbohydrates, proteins, phytochemicals, and anti-nutritional factors (ANFs), which limits its use. To address this issue, the current study was undertaken to understand the effect of microwave (MW) irradiation on ANFs, phytochemicals, in vitro protein digestibility (IVPD), and functional attributes of GSF at varying power density (P_d: 1–3 W/g) and duration (3–9 min). The ANFs were determined using a colorimetric assay and a Fourier transform infrared spectrum. At 3 P_d-9 min, the maximum reduction in ANFs (tannin, phytic acid, saponin, and trypsin inhibitor activity) was observed. Higher P_d and treatment duration increased antioxidant activity and total phenolic content, except for total flavonoid content. Furthermore, compared to the control sample (78.38%), the IVPD of the GSF samples increased to 3.28% (3 P_d-9 min). An increase in P_d and duration of MW treatment improved the thermal and pasting properties of GSF samples up to 2 P_d-9 min. Due to inter- and intramolecular hydrogen bonding degradation, the relative crystallinity of the 3 P_d-9 min treated GSF sample was 30.58%, which was lower than that of the control (40.08%). In MW-treated samples, SEM images revealed smaller clusters with rough and porous structures. However, no noticeable color (ΔE) changes were observed in MW-treated samples. Aside from water absorption capacity and water solubility index, MW treatment reduced oil absorption capacity, foaming capacity, and emulsifying capacity. As demonstrated by principal component analysis, MW irradiation with moderate P_d (2–3) was more effective in reducing ANFs, retaining nutritional contents, and improving the digestible properties of GSF, which could be a potential ingredient for developing gluten-free products.     

Influence of wheat flour substitution with potato pulp on dough rheology,microstructure and noodle quality

The effects of potato pulp (0–40%) on dough rheology and microstructures, as well as noodle quality, were investigated in this study. Substitution of wheat flour with potato pulp led to a decrease in β-sheet content, an increase in α-helix and unordered content for protein in dough, as well as a drop of the storage and loss modulus, which was mainly caused by the weakening of dough gluten strength. Scanning electron microscopy confirmed that the gluten–starch network could no longer to be observed for the formulated dough containing 30–40% potato pulp. Structural damage of dough induced the increases in optimal cooking time, cooking loss and adhesiveness, and a decrease in cohesiveness of cooked noodles. However, the samples with 20% potato pulp addition showed higher values in water absorption, hardness, springiness and chewiness, indicating that noodles with potato pulp content below 20% were acceptable.     

Effect of turanose on the rheology and oil uptake of instant fried noodles

Effects of turanose on the functional properties of instant fried noodles were assessed mainly in terms of rheology- and oil uptake-related characteristics. The Mixolab results showed that the water absorption of dough decreased as the turanose level increased, whereas the gel stability and starch retrogradation increased. Also, the use of turanose lowered the storage and loss moduli of the dough, showing a more viscous nature. These viscoelastic characteristics were correlated with the decreased resistance to extension and increased extensibility. NMR spin–spin relaxation analysis showed three distinct water populations in the turanose noodle doughs whose relaxation times were varied depending on the level of turanose. After frying, the noodles with turanose exhibited a continuous and smooth surface as well as a less porous structure. These microstructural characteristics were correlated with the reduced oil uptake by 20.8%, the enhanced oxidative stability and furthermore the improved breaking stress.     

Effect of high pressure treatment on aggregation and structural properties of soy protein isolate

The aggregation and structural properties of soy protein isolate (SPI), induced by high pressure (HP) treatment at 200-600 MPa were investigated by size-exclusion chromatography combined with multi-angle laser scattering (SEC-MALLS) and fourier transform infrared (FTIR) spectroscopy. HP treatment at lower pressure level (e.g., 200 MPa) resulted in formation of marked insoluble aggregate of SPI, while the treatment at higher pressure level (e.g., 600 MPa) led to transformation of insoluble aggregate to soluble one. The soluble aggregate formed at 400 or 600 MPa had much less mean molecular weight (MW) (about 5.2 × 10⁶ g/mol) than that at 200 MPa (about 1.6 × 10⁷ g/mol), and was also much more homogenous in MW distribution. FTIR analyses confirmed changes in secondary and tertiary structures, induced by HP treatment. These results can provide direct evidence or explanation for HP-induced modification of soy proteins.     

Impact of arabinoxylan with different molecular weight on the thermo‐mechanical,rheological, water mobility and microstructural characteristics of wheat dough

The aim of this study was to investigate the effects of arabinoxylan with different molecular weight on the wheat dough thermo‐mechanical, rheological, microstructural and water mobility properties. Arabinoxylan was extracted from wheat bran and hydrolysed by endo‐1,4‐β‐xylanase (EC 3.2.1.8 from Trichoderma reesei, 10 000 U g^?1) for 2 min (AX_M) and 10 min (AX_L), respectively. The addition of hydrolysed arabinoxylan AX_L increased the stability time, decreased the setback value of wheat dough and enhanced the values of storage modulus (G′) and loss modulus (G″), while unhydrolysed arabinoxylan (AX_H) reduced these values. Meanwhile, unhydrolysed arabinoxylan increased T₂ relaxation time while hydrolysed arabinoxylan AX_L decreased T₂₁ and T₂₂. Confocal laser scanning microscope (CLSM) results showed that the addition of hydrolysed arabinoxylan AX_L promoted the formation of a more compact and continuous protein network in wheat dough. These results revealed that compared with high molecular weight arabinoxylan, hydrolysed arabinoxylan could improve the rheological properties and processing properties of wheat dough by enhancing the interaction among water molecules, starch and gluten in wheat dough.     

Glutathione affects rheology and water distribution of wheat dough by changing gluten conformation and protein depolymerisation

The effects of reduced glutathione (GSH) on dough rheology, water state and distribution, gluten conformation, and protein molecular weight distribution were investigated. Addition of GSH (0.02−0.04%) resulted in a more viscous and less elastic dough with decreased G′ and increased tanδ values, which suggested decreased cross-links in gluten network and a weakened dough structure. The molecular weight of proteins was reduced by the GSH-induced cleavage of intermolecular disulphide bonds. Fourier transform infrared spectroscopy showed a high fraction of β-sheet formation at the expense of α-helix and β-turns, indicating a destabilised secondary structure and protein depolymerisation. GSH increased water release from the gluten network in dough resulting in an increase in freezable water content and caused water redistributed from bound water to weakly bound water. This study provided insights into correlation between wheat dough rheological properties and gluten structure influenced by GSH.     

Effects of protein oxidation on the rheological behaviour of different wheat flour

Wheat flour proteins are subject to oxidation reactions during production, processing and storage. The quality of protein and the rheological properties of wheat are crucial for the flour industry. However, the impact and mechanism of protein oxidised on wheat flour quality remain unclear. In this study, ozone was used to oxidise wheat grains, the secondary structure of protein in flour and the rheological properties of dough were analysed by FTIR and Mixolab. The proportion of α-helix and β-folding of protein were decreased significantly, as were the development time (DDT), stability time (DST) and protein weakening (C2) value of dough. Meanwhile, starch gelatinisation (C3), amylase activity (C4) and retrogradation (C5) were increased significantly, along with the elastic modulus (G′) and viscous modulus (G″). Microstructure analysis indicated that protein oxidation destroyed the gluten network structure in the dough. In addition, the L* value of dough was decreased and a* and b* values were increased significantly. The results showed that the oxidation of protein reduced the stability of protein secondary structure, weakened the structure and stability of the gluten network in dough, and changed the viscoelasticity and colour of dough. Overall, these findings provide a better understanding of rheological behaviour in wheat flour.     

Effects of partially replacing skimmed milk powder with dairy ingredients on rheology, sensory profiling, and microstructure of probiotic stirred-type yogurt during cold storage

This study aimed to evaluate the quality of stirred-type skim milk probiotic yogurt fortified by partially replacing skim milk powder (SMP) with whey protein concentrate (WPC) and sodium caseinate (Na-CN) during cold storage for 28 d compared with nonfortified yogurt. The rheological properties (as measured using dynamic oscillation) and sensory profiles of probiotic yogurts were greatly enhanced when SMP (i.e., 45%) was replaced with WPC and Na-CN. Higher values of mechanical parameters related to storage and loss modulus and consistent microstructure were found in the fortified yogurts. The acidification profile was not affected by supplementation of the solids in the milk base, and the viable counts of probiotic microbiota were high and satisfactory. These positive characteristics of probiotic yogurts were maintained until the end of the storage period. The microstructure of the fortified yogurt showed some differences compared with the nonfortified product, which were due to changes in chemical composition of the milk base in addition to the colloidal characteristics of the product.