Freezable Water Content Research Articles

Effects of potato powder on wheat dough properties and fresh noodles quality

ABSTRACT Herein, the mechanism underlying the effect of potato powder on noodle quality is investigated. The pasting, rheological, and thermal properties of dough with different contents (5%, 10%, 15%, 20%, 25%, and 30%) of potato powder and fresh noodle quality were examined. An increase in the potato powder content resulted in the deterioration of the dough pasting properties as well as noodle adhesiveness and springiness, with increases in dough loss and storage modulus. It also decreased the dough freezable water content and water activity and increased the semi-bound dough water content and noodle water absorption. In addition, a broken gluten network could be observed, which became loose with an increase in the noodle cooking loss. Furthermore, a decrease in noodle smoothness and color deterioration were observed, together with an improved taste. Acceptable noodle quality was obtained with the addition of <20% potato powder.

Further interpretation of the strengthening effect of curdlan on frozen cooked noodles quality during frozen storage: Studies on water state and properties

Curdlan has been applied to weaken the quality deterioration of frozen cooked noodles (FCN) during frozen storage. However, the underlying mechanism is still unclear. In this paper, an A/LKB-F probe was used for texture profile analysis and mercury intrusion was firstly used for analyzing ice crystals state in three dimensions. Meanwhile, a systematic study on the water state was conducted, as well as the freeze-thawed stability of FCN under curdlan intervention during frozen storage. The results showed that 0.5% curdlan significantly (P < 0.05) alleviated the decrement in hardness, chewiness and extension, and enhanced the freeze-thawed stability of FCN. This was closely associated with the fact that the addition of curdlan minimized freezable water content, inhibited water mobility and migration, and raised the homogeneity of ice crystals in FCN. This study provides more comprehensive theories for the strengthening effect of curdlan on FCN quality from the perspective of water state.

The effect of γ-[Glu](1≤n≤5)-Gln on the physicochemical characteristics of frozen dough and the quality of baked bread

This study was the first to examine the effects of γ-[Glu](1≤n≤5)-Gln (GGP, a taste enhancer; added at 0.5% or 5.0%) on the breadmaking using frozen dough. γ-[Glu](1≤n≤5)-Gln was produced using the method established in our research center. The addition of GGP at either level increased yeast viability, freezable water content and storage and loss moduli, decreased the free sulfhydryl content of dough during the frozen storage and freeze-thaw cycles, and improved the microstructure of frozen dough and texture of the baked bread. The addition of GGP at 0.5% led to a dough having the highest extensibility, and most complete and uniform starch-gluten network, and a baked bread crumb with the lowest hardness, best texture, and most uniform organization. These results indicated that GGP has great potential as a food-derived cryoprotectant/antifreeze agent for the baking industry.

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

SummaryThe 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 frozen water content and silt fraction on unconfined compressive behavior of fill materials

Characteristics of ice constituent and soil particles primarily determine the mechanical properties of fill materials in extreme regions. The objective of this study is to investigate the unconfined compressive behavior of sand-silt mixed fill materials with various frozen water contents and silt fractions (SFs). Sand-silt mixtures at a relative density of 60% and degrees of saturation of 15% to 25% are prepared at SFs of 0% to 70% in weight. The volumetric water contents are measured at ±5 °C in a freezing mold, and uniaxial compression tests are conducted after freezing. Test results show that the volumetric frozen water content is proportional to the void ratio because these values decrease equivalently when SF < 30% and increase when SF > 30%. The unconfined compressive strength (UCS) and stress at maximum curvature point (MCP), except those of clean sand (SF = 0%), increase with the volumetric frozen water content and void ratio owing to ice-bonding and SF effects. The strength ratio (UCS/MCP) and visualized fracture mode present brittle-to-ductile transitional characteristics according to the SF. This study demonstrates that frozen water content, SF, and fracture mode should be considered when sand-silt mixed materials are used for filling in extreme regions.

Understanding the structural, pasting and digestion properties of starch isolated from frozen wheat dough

The multi-scale structure and physicochemical properties (e.g., pasting and digestion features) of starch isolated from native and frozen dough (storage at −18 °C for 10, 20 and 30 days, respectively) were investigated with combined analytical methods. Differential scanning calorimetry revealed increased freezable water contents as the extension of frozen storage time. Results showed that frozen storage treatment disrupted the granular structure but increased the particle size and ordered degree of semi-crystalline lamellae system involving lamellar structure, crystalline structure, short-rang ordered molecular structure and helical structures. And these multi-scale structural alterations were more obvious with the storage time increasing. As for gelatinization and pasting properties of frozen starches, it reflected an improved thermal-stability (e.g., increased Tc and pasting temperature) and decreased viscosity parameters such as peak and final viscosity, which may be due to the rearrangement and ordered packing of starch molecular chains during frozen storage. However, the frozen storage treatment caused increased digestibility of wheat starch by promoting the access and binding of enzymes to starch. Therefore, these results extended the knowledge of starch microstructures and technological properties during frozen storage, which may be beneficial to promote better preservation of frozen foods.

Performance of digital patternless freeze-casting sand mould

Digital patternless freeze-casting technology is a new approach for obtaining frozen sand moulds using digital milling technology. The change law of tensile strength and air permeability of frozen sand moulds (100-mesh and 200-mesh silica sand, and zircon sand moulds) under different freezing temperatures and water contents was studied. Results show that with the decrease of freezing temperature and the increase of water contents, the tensile strength and air permeability of the sand moulds are gradually improved. Meanwhile, computed tomography technology was used to characterize the shape and size of the water film between the sand particles mixed with 4wt.% water. The results show that in silica sand moulds, the form of water film is lumpy, and 200-mesh silica sand moulds have more water films and higher proportion of small-sized water films than 100-mesh silica sand moulds, while in zircon sand moulds, the form of water film is membranous. At the same freezing temperature and water content, the tensile strength of zircon sand mould is the highest, and 100-mesh silica sand mould is the lowest. A comparative solidification experiment of A356 aluminum alloy was carried out in frozen sand mould and resin sand mould. The results show that the primary α-Al phase appears in the form of equiaxed and eutectic silicon phase is needle-like in freezing sand mould casting, but the primary α-Al phase grows in the form of dendrites, and the eutectic silicon phase is coarse needle-like in the resin sand mould casting. The difference of microstructure is caused by the different cooling rate. The cooling rate of A356 aluminum alloy in frozen sand mould is higher than that in resin sand mould.

Thermal, rheological properties and microstructure of hydrated gluten as influenced by antifreeze protein from oat (Avena sativa L.)

This study examined the thermal, rheological properties and microstructure of hydrated gluten as influenced by oat antifreeze protein (AsAFP). The thermal properties of fresh hydrated gluten, including the melting temperature, freezing temperature, freezable water content and glass transition temperature, were determined. For hydrated gluten samples after freeze-thaw treatment, the change in melting performance and freezable water content were analyzed. The results showed that the addition of AsAFP increased the glass transition temperature and decrease the melting enthalpy and freezable water content of fresh hydrated gluten. The supplementation of AsAFP also influenced the melting performance of hydrated gluten after freeze-thaw treatment. The rheological properties showed that the addition of AsAFP inhibited the deterioration of the rheological properties of hydrated gluten. The secondary structure of the gluten proteins changed significantly, α-helix decreased and β-sheet increased. The microstructure of the hydrated gluten demonstrated that supplementation with AsAFP may protect the gluten matrix from disruption during freeze-thaw cycles.

Grey poplar explant acclimation to improvethe dehydration tolerance and cryopreservation

Cryostorage techniques have been developed to preserve the most valuable genotype from an endangered native population of Populus × canescens Aiton Sm. (grey poplar), which is located in the floodplain forest in the South Moravia region of the Czech Republic and which is difficult to propagate using cuttings. The prevailing genotype with valuable traits was selected by the simple sequence repeats method. This genotype was used to determine the most effective pre-cultivation conditions (cold hardening, and cold hardening combine with osmotic treatment) on dehydration tolerance and post-thaw recovery of the grey poplar shoot tips. The pre-cultivation and application of a modified plant vitrification solution 3 (PVS3) considerable reduced the freezable water content in shoot tips. Evaluation after eight weeks of regrowth revealed that simultaneous effect of cold and osmotic pre-treatments and application of PVS3 for 120 min enabled 93.3 ± 5.8 % recovery. The results emphasize the importance of the pre-cultivation conditions, which significantly improved the post-thaw recovery of the grey poplar explants.

A novel method of osmotic-dehydrofreezing with ultrasound enhancement to improve water status and physicochemical properties of kiwifruit

Abstract A novel method of osmotic-dehydrofreezing with ultrasound enhancement to improve water status and physicochemical properties of kiwifruit was investigated. Kiwifruit were subjected to osmotic dehydration with different ultrasound power (20 kHz, 0–300 W) at 30 °C for 30 min, and then frozen as well as stored at −18 °C. The results showed that osmotic dehydration with ultrasound enhancement increased water loss and solid gain, and maintained the cell structure. Osmotic dehydration with ultrasound enhancement also reduced freezable water content and decreased water mobility in comparison to osmotic dehydration alone. Osmotic dehydration with ultrasound application prior to freezing shortened the freezing time, decreased drip loss, maintained ascorbic acid content and firmness, preserved the flavor and improved the taste for kiwifruit after freezing and thawing compared to control. Therefore, these results demonstrated that the osmotic-dehydrofreezing with ultrasound application can effectively increase freezing rate and improve the physicochemical properties of kiwifruit in freezing and thawing processes.

Effects of potato starch on the properties of wheat dough and the quality of fresh noodles

ABSTRACT The effects of potato starch on the pasting, rheological, and thermal properties of the dough, and the quality of the noodles were analyzed. The results showed that the addition of potato starch increased the pasting properties parameters of the dough, and increased the adhesiveness and hardness of the noodles; reduced the elastic and viscous modulus of the dough, and increased the springiness of the noodles; increased the freezable water content of the dough, decreased the semi-bound water content, and increased the water absorption of the noodles. The gluten network structure of the dough was destroyed, and the cooking loss and breaking rake of the noodles increased. The color and smoothness of the noodles were improved, the taste was worse. The quality of the noodles was acceptable when no more than 20% potato starch was added.

Characterization of the dough rheological and steamed bread fortified with extruded purple sweet potato flour

ABSTRACT Addition of purple sweet potato flour has a negative effect on the technological characteristics of steamed bread. The present study researches the potential of extruded purple sweet potato flour (EP) in improving the quality of composite dough and steamed bread. Compared to unextruded purple sweet potato flour (UP), addition of EP significantly increased dough thermal temperatures and decreased the freezable water content, indicating that it enhanced the binding of dough components with water molecules. The rheological properties of dough height, extensibility, configuration ratio, and deformation energy of EP added dough were similar to wheat dough. Moreover, steamed bread made from EP had higher specific volume, lower hardness, and chewiness than their elaborated from UP. Furthermore, the total polyphenol content and antioxidant activity of EP were significantly improved in comparison with the UP and wheat steamed bread. In conclusion, results mightily suggest that the addition of extruded purple sweet potato flour could be an effective way of enhancing the technological and nutritional of composite steamed bread.

Analysis of freezable water content by DSC for apple dormant bud cryopreservation

Dormant bud cryopreservation is a valuable tool for the germplasm of temperate trees preservation. Freezable water content, as an important cryopreservation characteristic, was analysed by DSC. Scions of modern apple tree varieties (Malus domestica) were collected during the winter season from orchards, freeze-dehydrated to 26–32% of water content at –5°C and cryopreserved by the two-step procedure. Samples were rehydrated in moist peat after 4 months of cryopreservation and grafted on rootstocks in a field. Regeneration by sprouting buds on rootstocks was evaluated. The varieties were divided into three groups according to their water content and percentage of crystallized water. The regeneration in the three groups decreased with decreasing bud water content. Regeneration was higher than 80% in most of the varieties and reached 100% in almost 1/3 of the tested varieties. In only one variety, was regeneration lower than 40%, which is still a high regeneration rate for considering apple genotypes as successfully cryopreserved. According to this study, the two-step cryoprotocol was successfully optimized for Central European conditions.

Effects of ultrasound-assisted freezing on the water migration of dough and the structural characteristics of gluten components

The effects of ultrasound-assisted freezing on the freezing time and water migration of dough, and the structural characteristics of gluten components were investigated. The effects of ultrasound-assisted freezing in the whole immersion freezing process (UWF) on the freezing time were better than those of ultrasound-assisted freezing in the maximum ice crystal generation zone. The shortest freezing time was obtained at 80 W/L, and was 577 s shorter than that with traditional immersion freezing. The UWF treatment at 80 W/L significantly (p < 0.05) affected the absorption enthalpy, freezable water content and water migration of frozen dough. In UWF compared with traditional immersion freezing, the SH content of gluten, glutenin and gliadin was significantly (p < 0.05) higher, by 12.06%, 27.55% and 21.65%, respectively. The surface hydrophobicity of gluten, glutenin and gliadin in UWF treated samples significantly (p < 0.05) decreased, by 19.67%, 13.21% and 9.17%, respectively. The secondary structure of gluten components was also significantly changed by UWF. The network of gluten, the chain structure of glutenin and the gliadin particles were all changed by UWF treatment. These findings indicated that UWF is an effective method to improve the moisture distribution in dough and reduce the damage to protein molecular structure caused by freezing.

Cryoprotective effect of silver carp muscle hydrolysate on baker's yeast Saccharomyces cerevisiae and its underlying mechanism.

Cryoprotective effect of silver carp muscle hydrolysate (SCMH) on baker's yeast (Saccharomyces cerevisiae) was examined by analyzing the growth and survival of the yeast during freeze–thaw cycles, and the physicochemical properties [ultrastructure, intracellular proteins and fatty acids, external ice formation (EIF) and internal ice formation (IIF), freezable water content] of yeast cells with or without SCMH through transmission electron microscopy, SDS‐PAGE, GC‐MS, and differential scanning calorimetry. The 4% of SCMH treatment exhibited good yeast cryoprotective activity and increased the yeast survival rate from 0.71% to 90.95% after 1 freeze–thaw cycle as compared to the control. The results demonstrated that the addition of SCMH could attenuate the freeze damage of yeast cells, prevent the degradation or loss of soluble proteins, and increase the composition and absolute content of fatty acids. Besides, the addition of 4% SCMH caused a drop in the EIF peak temperature (from −17.95℃ to −25.14℃) and a decrease in the IIF and freezable water content of yeast cells.

Effect of Pregelatinization and Retrogradation on Some Physicochemical Changes of Wheat-Potato Starches

The freezable (FW) and unfreezable water (UFW) contents of wheat and potato starches and their physically modified forms [pregelatinized (PGS) and retrograded (RS)] were analyzed by Differential Scanning Calorimetry (DSC) at various hydration levels (25, 35, 45, 55, 65, 75 and 85%). In all the starch samples, the UFW content increased with increasing hydration level. Potato starch samples (native, pregelatinized and retrograded) had higher UFW contents than wheat starch samples at all hydration levels. Similarly, with the increase of hydration level in all starch samples, onset (To), peak (Tp) and endset (Te) temperatures of the peaks also increased. It was obtained that physical modifications in starches had significant effects (P<0.05) on water absorption index (WAI) and water solubility index (WSI) of starch samples. The highest WAI (10.51) and WSI (2.31) values were determined in pregelatinized potato starches. Rapid Visco Analyzer (RVA) profiles revealed that physically modified starches had higher viscosity values than native starches. The results clearly showed that pregelatinization and retrogradation had positive effects on the physicochemical properties studied.

Functional group configuration influences salt transport in desalination membrane materials

Five methacrylate-based co-polymers, which have different ratios of 2-hydroxyethyl methacrylate (HEMA) and glycerol methacrylate (GMAOH) co-monomers, were prepared to investigate the influence of functional group configuration on salt transport properties. The HEMA and GMAOH co-monomers were selected because of the differences in position and number of hydroxyl groups in the two molecules. Co-polymer composition was varied systematically from a vicinal diol-rich (GMAOH-rich) configuration to a distributed hydroxyl group (HEMA-rich) configuration. To decouple the impact of functional group configuration and of changing water content on transport properties, all of the materials were prepared to have statistically equivalent water content. Salt sorption was lower and salt diffusion was slower in the HEMA-rich configuration compared to the GMAOH-rich configuration. Microwave dielectric relaxation spectroscopy revealed lower relative permittivity (i.e., dielectric constant) for the HEMA-rich co-polymers, which is consistent with suppressed salt sorption in those materials compared to the GMAOH-rich co-polymers. This observation was complemented by state of water analysis that suggested freezable (i.e., bulk-like) water content decreased as HEMA content increased. Both results suggest that stronger interactions between water molecules and the polymer are favored when hydrophilic functional groups are distributed more evenly throughout the material. These results suggest that functional group position in hydrated polymers influences salt transport properties, and engineering polymers that have a distributed functional group configuration may suppress salt transport properties, which could result in favorable materials for desalination membranes.

Effects of glucose oxidase and organic acids on the properties of a model low sodium dough prepared from Harvest and Pembina CWRS wheat

This research investigates the impact of glucose oxidase (GO) addition in the presence of organic acids (acetic, ascorbic, citric, fumaric, lactic, or succinic) on several parameters of a reduced salt dough system (1.0% NaCl). These parameters include dough rheology, stickiness, freezable water content (FWC), and percentage of glutenin macropolymer (%GMP). Two cultivars were used: Harvest and Pembina which are known for their weak and strong dough characteristics, respectively. It was found that the inclusion of most of the acids at 1.2 mmol/100 g flour increased stickiness and reduced dough strength, but had no effects on %GMP and little increase in FWC. As expected, ascorbic acid defied the trends for rheology and stickiness since it has use as a dough strengthening agent; however, no synergistic effects were observed between it and GO. The inclusion of GO (0.001%/flour wt.) was able to mitigate some of the effects on rheology and stickiness, but GO had no effect on the freezable water content and %GMP. The mechanism of the interactions of these acids within the dough remains to be elucidated and GO still appears to have potential as a low sodium bread improver, but it requires testing in complete dough systems and final bread products.

Effect of Degree of Konjac Glucomannan Enzymatic Hydrolysis on the Physicochemical Characteristic of Gluten and Dough.

Influences of different enzymatic hydrolysis degrees of konjac glucomannan (KGM) with various addition proportions on the structural characteristic of gluten protein and dough properties were evaluated. Results revealed that addition of KGM decreases the free sulfhydryl and freezable water content of dough, and KGM with different enzymatic hydrolysis degrees had more beneficial effects on strengthening the gluten structure by the raised molecular weight of gluten proteins and the increased disulfide bonds and β-sheet content, especially KGM with 15 min enzymatic hydrolysis treatment (KGM II). Besides, microstructure observation and thermal analysis results illustrated that addition of KGM promotes gluten cross-linking and improves the thermal stability of the gluten network structure. Dough possessed better elasticity, as well as tensile and texture properties with the addition of KGM than the control sample. And the KGM with 15 min enzymatic hydrolysis showed the most positive effect on dough quality than others, and 2.0% addition proportion is the most acceptable.

Evaluation of the antifreeze effects and its related mechanism of sericin peptides on the frozen dough of steamed potato bread

This study investigated the effects of sericin peptides (SPs) on frozen potato dough with trehalose as a reference. The results found that SPs decreased freezable water content in frozen dough and increased yeast survival ratio significantly after 4-week frozen storage. Additionally, compared with control group and frozen dough containing 5% of trehalose, frozen dough with 5% of SPs showed less starch granule separation and more complete gluten membrane during 8-week storage. Specific volume of the frozen dough with 5% of SPs decreased by 6.3%, significantly lower than the control and reference groups. Furthermore, compared with trehalose, SPs effectively decreased the hardness and gumminess of steamed potato breads, as well as enhanced their resilience. The quality improvement of frozen potato dough with SPs could be attributed to ideal structural matching, hydrogen bonds, and non-bond interactions between sericin peptides and ice surface, as well as the inhibition of the formation and recrystallization of ice crystals. Practical applications Frozen dough method is widely used in baked flour products, providing fresh, safe, consistent quality products and simplifies the manufacturing process. However, the overall quality of frozen dough decreased gradually during frozen storage. Traditional antifreezes (trehalose and sorbitol) have high calories, which are not conducive to diabetics and obese patients. Therefore, it is essentially important to find a new and efficient antifreeze to replace traditional antifreezes. SPs, the hydrolysate of sericin, exhibited a strong cryoprotection and antifreeze activity according to this study. We can expect a potential application of SPs in cell protection and food preservation.