Freezable Water Content Research Articles

Staling and water dynamics in high-gluten bread

Staling indicators (texture, amylopectin retrogradation, water status and proton molecular mobility) in a high-gluten bread (25% flour substitution and water absorption at 500 Brabender Unit) were compared to a control during 1 week of storage. The contribution of macroscopic crumb to crust water migration on frozen water, molecular mobility and retrograded amylopectin was evaluated in bread loaves and bread crumb stored in NMR tubes. High-gluten bread was softer and had increased volume, cohesiveness, springiness, moisture and frozen water contents than the control, with comparable amylopectin retrogradation. An increased proton molecular mobility was observed in fresh high-gluten bread. In condition of no occurrence of macroscopic water migration, proton molecular mobility indicated reduced changes in breads during storage, suggesting the important role played by migration in the staling process. These changes were further reduced in the high-gluten bread, indicating an influence of the larger moisture content but also a contribution of gluten in regulating molecular changes.

The intraannual variability of land‐atmosphere coupling over North America in the Canadian Regional Climate Model (CRCM5)

AbstractThis study investigates the intraannual variability of soil moisture‐temperature coupling over North America. To this effect, coupled and uncoupled simulations are performed with the fifth‐generation Canadian Regional Climate Model (CRCM5), driven by ERA‐Interim. In coupled simulations, land and atmosphere interact freely; in uncoupled simulations, the interannual variability of soil moisture is suppressed by prescribing climatological values for soil liquid and frozen water contents. The study also explores projected changes to coupling by comparing coupled and uncoupled CRCM5 simulations for current (1981–2010) and future (2071–2100) periods, driven by the Canadian Earth System Model. Coupling differs for the northern and southern parts of North America. Over the southern half, it is persistent throughout the year while for the northern half, strongly coupled regions generally follow the freezing line during the cold months. Detailed analysis of the southern Canadian Prairies reveals seasonal differences in the underlying coupling mechanism. During spring and fall, as opposed to summer, the interactive soil moisture phase impacts the snow depth and surface albedo, which further impacts the surface energy budget and thus the surface air temperature; the air temperature then influences the snow depth in a feedback loop. Projected changes to coupling are also season specific: relatively drier soil conditions strengthen coupling during summer, while changes in soil moisture phase, snow depth, and cloud cover impact coupling during colder months. Furthermore, results demonstrate that soil moisture variability amplifies the frequency of temperature extremes over regions of strong coupling in current and future climates.

Non-Destructive Prediction of Moisture Content and Freezable Water Content of Purple-Fleshed Sweet Potato Slices during Drying Process Using Hyperspectral Imaging Technique

The aim of this study was to investigate the feasibility of hyperspectral imaging in measuring moisture content and freezable water content during drying process. Hyperspectral images were acquired for purple-fleshed sweet potato (PFSP) slices during contact ultrasound assisted hot drying (CUHAD) process, and the corresponding mean reflectance spectra from regions of interest in visible and near infrared (371–1023 nm) regions were extracted. Moving average, Savitzky-Golay smoothing filter (S_G filter) and multiplicative scatter correction (MSC) were investigated to preprocess the raw spectra and partial least square regression (PLSR) calibration model was established to analyze the relationship between the extracted spectral data and measured quality attributes. Comparing the performance of model based on different preprocessing methods, the PLSR model with MSC pre-treatment presented better results with coefficients of determination for prediction ( $$ {R}_P^2 $$ ) of 0.9837 and 0.9323 for moisture content and freezable water content, respectively. Instead of selecting full range spectra data, optimal wavelengths were identified based on the regression coefficients (RC) method. Then two linear calibration algorithms named PLSR and multiple linear regression (MLR), and a non-linear calibration algorithm named backpropagation (BP) neural network were used to establish models to predict quality attributes of samples simultaneously. The results showed that the RC-MLR with $$ {R}_P^2 $$ of 0.9359 and 0.8592 was considered as the best for determining moisture content and freezable water content of PFSP slices. Therefore, the study demonstrates the potential of using hyperspectral imaging in tandem with chemometrics analysis as an objective, fast and non-destructive method for predicting the moisture content and freezable water content at different dehydrated times.

Staling of gluten-free breads: physico-chemical properties and 1H NMR mobility

Four gluten-free (GF) breads produced using commercial GF mixes with different formulations were characterized during 1 week of storage and compared to wheat-flour-based bread (STD), in terms of texture (texture profile analysis), amylopectin retrogradation (differential scanning calorimetry) and water status (moisture content, frozen water content by differential scanning calorimetry and 1H nuclear magnetic resonance—NMR mobility by a low-field spectrometer). GF fresh breads were significantly harder, less cohesive and less springy than STD. Water status indicated higher water availability in GF breads, depending on formulation, with higher moisture and frozen water content that was also reflected in a higher molecular mobility (1H spin–spin NMR relaxation time). Furthermore, limited changes in moisture and frozen water contents were observed in GF bread, and therefore, textural changes in these GF products were mostly related to retrograded amylopectin. Statistical analysis with PCA (principal component analysis) allowed to identify the most important factors in the GF bread staling process. The effect of formulation (GFs vs STD) was related to water status descriptors and the effect of storage to textural properties, retrograded amylopectin parameters, as well as the mobility of the more rigid protons.

Investigation of the 2013 Alberta flood from weather and climate perspectives

During 19–21 June 2013 a heavy precipitation event affected southern Alberta and adjoining regions, leading to severe flood damage in numerous communities and resulting in the costliest natural disaster in Canadian history. This flood was caused by a combination of meteorological and hydrological factors, which are investigated from weather and climate perspectives with the fifth generation Canadian Regional Climate Model. Results show that the contribution of orographic ascent to precipitation was important, exceeding 30 % over the foothills of the Rocky Mountains. Another contributing factor was evapotranspiration from the land surface, which is found to have acted as an important moisture source and was likely enhanced by antecedent rainfall that increased soil moisture over the northern Great Plains. Event attribution analysis suggests that human induced greenhouse gas increases may also have contributed by causing evapotranspiration rates to be higher than they would have been under pre-industrial conditions. Frozen and snow-covered soils at high elevations are likely to have played an important role in generating record streamflows. Results point to a doubling of surface runoff due to the frozen conditions, while 25 % of the modelled runoff originated from snowmelt. The estimated return time of the 3-day precipitation event exceeds 50 years over a large region, and an increase in the occurrence of similar extreme precipitation events is projected by the end of the 21st century. Event attribution analysis suggests that greenhouse gas increases may have increased 1-day and 3-day return levels of May–June precipitation with respect to pre-industrial climate conditions. However, no anthropogenic influence can be detected for 1-day and 3-day surface runoff, as increases in extreme precipitation in the present-day climate are offset by decreased snow cover and lower frozen water content in soils during the May–June transition months, compared to pre-industrial climate.

Protein diffusion characteristics in the hydrogels of poly(ethylene glycol) and zwitterionic poly(sulfobetaine methacrylate) (pSBMA)

Nonfouling materials such as neutral poly(ethylene glycol) (PEG) and zwitterionic poly(sulfobetaine methacrylate) (pSBMA) are ideal biocompatible materials for drug, especially protein drug delivery. The interaction behavior of protein between the nonfouling materials could cause great impact on their future applications, such as controlled release drug delivery systems. In this work, we investigated the diffusion behavior of the fluorescence-labeled model proteins (bovine serum albumin (BSA) and lysozyme (LYZ)) in nonfouling PEG, pSBMA and mixed PEG-SBMA hydrogels (SBMA:PEG 4:1, SBMA:PEG 1:4). It was observed that these four hydrogels showed varied diffusion behavior for either negatively charged BSA or positively charged LYZ due to protein-polymer interaction and the free water content in hydrogel matrix. The relatively stronger interaction between protein-PEG than protein-pSBMA could increase protein loading efficiency and control release rate by changing ratio of PEG to SBMA in the hybrid hydrogel. Moreover, it is further demonstrated the free water (freezable water) content in low cross-linked hydrogel, not the equilibrium water content (EWC), is a more accurate parameter to reflect the diffusion behavior of protein molecules. Thus, these results together provide new insights of the interactions between protein molecules and nonfouling polymers as well as the bio applications of the nonfouling polymeric hydrogels. Statement of SignificanceThis work shows that the relative stronger interaction between protein-PEG than protein-pSBMA could increase protein loading efficiency and control release rate by the change ratio of PEG to SBMA in the hydrogel, while the free water (freezable water) content in low cross-linked hydrogel, not the equilibrium water content (EWC), is a more accurate parameter to reflect the diffusion behavior of protein molecules. The impact of this work (i) gains some new insights of the interactions between protein molecules and nonfouling polymer matrixes for protein drug delivery; (ii) prompts to apply the weak PEG-protein interactions to protein drug loading and release; (iii) provides a new fundamental understanding of free water in hydrogel for protein diffusion.

Hyaluronic acid concentration-mediated changes in structure and function of porous carriers for corneal endothelial cell sheet delivery

In this study, the effects of hyaluronic acid (HA) concentrations (0.05–1.25wt.%) on the properties of porous carriers for corneal endothelial tissue engineering were investigated. The pore size and porosity gradually increased with decreasing solid content. However, at relatively low HA concentration (i.e., 0.05wt.%), the material samples contained small interior pores and a dense surface skin layer, probably due to no gas bubble effect on the stirring processing of porous microstructures of freeze-dried polysaccharide hydrogels. The carriers prepared from 0.25wt.% HA solution had the highest freezable water content and oxygen and glucose permeability among the samples evaluated. Results of cell viability assays and quantitative real-time reverse transcription polymerase chain reaction analyses showed that the HA concentration-related alteration of porous microstructure dictates the compatibility of biopolymer carriers with corneal endothelial cell (CEC) cultures. In vivo studies demonstrated that the CEC sheet/HA carrier construct implants are therapeutically efficacious in the reconstruction of endothelial scrape-wounded corneas. It is concluded that the polysaccharide concentration is the major factor for affecting the processing of carriers and their structure and function. Porous hydrogels prepared from 0.25wt.% HA solution are capable of delivering bioengineered CEC sheets to the posterior surface of cornea.

Investigation of the Changes in Hydrogen Bonds During Low-Temperature Pyrolysis of Lignite by Diffuse Reflectance FT-IR Combined with Forms of Water

The changes in the hydrogen bonds (HBs) of Loy Yang lignite during low-temperature pyrolysis were investigated. The water content of all of the samples was determined by weighing the samples before and after heating in an oven. The changes in the number of the different types of HBs were determined using diffuse reflectance Fourier transform infrared spectroscopy considering the forms of water in lignite. The number of absorption bands, their peak positions, and the area of each peak in each spectrum were determined by curve-fitting analysis with the mixed Gaussian and Lorentzian function. The quantified integrated area of aromatic hydrogen atoms was used to accurately investigate the changes in the HBs. The results showed that the freezable and nonfreezable water contents of the total water weight in raw lignite were 84.8% and 15.2%, respectively. At low temperatures (T ≤ 100 °C), the main removed water was freezable water. The number of OH–lignite interactions decreased compared with raw lignite, which ...

Investigation of the State of Water in Energy Trees in the Process of Drying by Differential Scanning Calorimetry

This paper presents the results of investigation of the state of water in young sprouts of energy trees (willow, poplar, and alder) in the process of drying to the limiting moisture content by differential scanning calorimetry. The content of freezing (free) and nonfreezing (bound) water in samples with various moisture contents has been determined. It has been shown that the specific content of bound water (referred to dry substance) Wb.w in the above trees in the process of their drying in the range from natural moisture to the limiting moisture content is not a constant quantity. In these trees in the state of natural moisture the Wb.w value exceeds their hygroscopicity limit, and in the process of dehydration the Wb.w value decreases. For instance, Wb.w varies from 0.419 to 0.254 g/g of dry substance for poplar, from 0.425 to 0.248 g/g of dry substance for willow, and from 0.354 g/g of dry substance for alder.

Investigation of Overrun-Processed Porous Hyaluronic Acid Carriers in Corneal Endothelial Tissue Engineering.

Hyaluronic acid (HA) is a linear polysaccharide naturally found in the eye and therefore is one of the most promising biomaterials for corneal endothelial regenerative medicine. This study reports, for the first time, the development of overrun-processed porous HA hydrogels for corneal endothelial cell (CEC) sheet transplantation and tissue engineering applications. The hydrogel carriers were characterized to examine their structures and functions. Evaluations of carbodiimide cross-linked air-dried and freeze-dried HA samples were conducted simultaneously for comparison. The results indicated that during the fabrication of freeze-dried HA discs, a technique of introducing gas bubbles in the aqueous biopolymer solutions can be used to enlarge pore structure and prevent dense surface skin formation. Among all the groups studied, the overrun-processed porous HA carriers show the greatest biological stability, the highest freezable water content and glucose permeability, and the minimized adverse effects on ionic pump function of rabbit CECs. After transfer and attachment of bioengineered CEC sheets to the overrun-processed HA hydrogel carriers, the therapeutic efficacy of cell/biopolymer constructs was tested using a rabbit model with corneal endothelial dysfunction. Clinical observations including slit-lamp biomicroscopy, specular microscopy, and corneal thickness measurements showed that the construct implants can regenerate corneal endothelium and restore corneal transparency at 4 weeks postoperatively. Our findings suggest that cell sheet transplantation using overrun-processed porous HA hydrogels offers a new way to reconstruct the posterior corneal surface and improve endothelial tissue function.

Extraction of Oat (Avena sativa L.) Antifreeze Proteins and Evaluation of Their Effects on Frozen Dough and Steamed Bread

In this study, vacuum infiltration-centrifugation of cold-induced oats at −18 °C was adopted in the extraction of oat antifreeze proteins (AFPs), and the effects of the oat AFPs on the physicochemical, rheological, and fermentation properties of frozen dough and the textural characteristics of steamed bread were investigated. Supplementation with oat AFPs lowered the freezable water content of the dough, resulting in some beneficial effects on final steamed bread. The rheological properties of the oat AFP group showed a greater fermentation capacity than did the control group (without oat AFP). A scanning electron microscopic analysis showed that supplementation with oat AFPs could protect the gluten matrix from disruption, thus resulting in superior textural properties in the steamed bread. In conclusion, oat AFPs could be used as a beneficial additive to frozen dough.

Effect of bran on bread staling: Physico-chemical characterization and molecular mobility

High fibre breads were produced with the addition of durum wheat bran fractions (regular bran and a fraction extracted from the most internal bran layer) and their physico-chemical properties and water status were characterised during storage. Bran enriched breads exhibited similar properties during storage, they were harder, less springy and less cohesive than the control. Water status was strongly affected by bran addition, independently of bran composition: water activity, moisture and frozen water content (measured by Differential Scanning Calorimetry) were generally higher in the bran samples than in the control bread during storage. Amylopectin retrogradation was significantly larger in the presence of bran fractions. 1H NMR mobility (T2 number of populations and relaxation times) was different in the high fibre breads as compared to the control sample. The changes in protons mobility observed upon storage indicated an influence of bran on water/gluten/starch molecular domains and their dynamics, that may have affected the development of the gluten network resulting in different textural properties.

Effect of water and gluten on physico-chemical properties and stability of ready to eat shelf-stable pasta

A multi-analytical and multi-dimensional approach was used to investigate the effect of moisture and gluten on physico-chemical properties of shelf-stable ready to eat (RTE) pasta.Moisture and frozen water contents were not affected by formulation nor storage time. Hardness and retrograded amylopectin significantly increased during storage in all samples, more markedly in pasta with the lowest moisture content. Higher amounts of water and gluten reduced pasta hardening and contributed to control RTE pasta quality. 1H FID became steeper in all samples during storage, but no effect of high moisture and gluten levels was observed on the mobility of these protons. Three proton T2 populations were observed (population C, population D and population E). Population C and D were not resolved during all storage. 1H T2 relaxation time of the most abundant population (population E) shifted to shorter times and the amount of protons increased during storage, more importantly in the samples with lower moisture and gluten content.

The use of potato fibre to improve bread physico-chemical properties during storage

Bread staling reduction is a very important issue for the food industry. A fibre with high water holding capacity, extracted from potato peel, was studied for its ability to reduce bread staling even if employed at low level (0.4g fibre/100g flour). Physico-chemical properties (water activity, moisture content, frozen water content, amylopectin retrogradation) and 1H Nuclear Magnetic Resonance molecular mobility were characterised in potato fibre added bread over 7days of storage. Potato fibre addition in bread slightly affected water activity and moisture content, while increased frozen water content and resulted in a softer bread crumb, more importantly when the optimal amount of water was used in the formulation. Potato fibre also reduced 1H NMR molecular mobility changes in bread crumb during storage. Potato fibre addition in bread contributed to reduce bread staling.

Effect of barley antifreeze protein on thermal properties and water state of dough during freezing and freeze-thaw cycles

This study examined the effects of barley antifreeze protein (BaAFP-1) on the thermal properties and water state of dough during freezing and freeze-thaw cycles. The thermal properties of treated and untreated fresh dough, including the apparent specific heat, freezing temperature, melting temperature, freezable water content and glass transition temperature were determined and compared. For frozen dough samples, the change in melting performance, freezable water content, pasting properties, moisture content, water mobility and water distribution during freezing and freeze-thaw cycles were analysed. The results demonstrated that the addition of BaAFP-1 increased the apparent specific heat of dough after freezing, increased the freezing temperature and the temperature range of the melting and glass transition temperatures, and decreased the melting enthalpy and freezable water content of fresh dough. The addition of BaAFP-1 also influenced the melting performance and gelation property of frozen dough after freeze-thaw cycles. It slowed the decrease in moisture content, weakened the influence of the freeze-thaw treatment on water mobility and influenced the water distribution in frozen dough.

Influence of Ultrasound-Assisted Osmotic Dehydration and Freezing on the Water State, Cell Structure, and Quality of Radish (Raphanus sativus L.) Cylinders

Ultrasound-assisted osmodehydrofreezing technique is a partial dehydration technique prior to freezing to diminish the tissue damage and preserve the quality by quickly removing part of the water from vegetable tissues. In this study, radish cylinders with three different water contents (85%, 80% and 75%, w/w) were dehydrated by osmotic dehydration (OD) and ultrasound-assisted osmotic dehydration (UOD). The effects of OD and UOD pretreatment on the characteristics (e.g., latent heat of fusion of ice, freezable water and microstructure) of dehydrated products and quality attributes (e.g., freezing time, firmness, drip loss and ascorbic acid content) of osmodehydrofrozen products were investigated. Ultrasound application significantly shortened the time of dehydration and subsequent freezing. Compared to OD products with equal water content, UOD products exhibited less freezable water content and better preservation on firmness and microstructure. After freezing/thawing, frozen products of UOD also displayed less drip and ascorbic acid losses and better firmness than that of OD.

Effect of Power Ultrasound and Pulsed Vacuum Treatments on the Dehydration Kinetics, Distribution, and Status of Water in Osmotically Dehydrated Strawberry: a Combined NMR and DSC Study

The effect of power ultrasound and pulsed vacuum (PV) treatments on the dehydration kinetics and the status of water during osmotic dehydration of strawberries was investigated. Low-field nuclear magnetic resonance (LF-NMR) and magnetic resonance imaging (MRI) were used to determine the spatial distribution and status of water within the cellular and intercellular spaces. Differential scanning calorimetry (DSC) was used to determine the freezing point depression and the amount of frozen water. Osmotic treatment was performed by immersing the samples in 25 and 50 % (w/w) sucrose solutions at 40 °C for 3 h. Water loss and solid gain of strawberry samples were measured and the data were fitted by Peleg’s model. The Peleg’s model fitted the experimental water loss and solid gain kinetics data well (R 2 > 0.98). At a given sucrose concentration, the highest water loss and the highest decrease in firmness occurred while using ultrasound treatment, while the highest solid gain and the highest firmness values were achieved by pulsed vacuum treatment. LF-NMR signals were able to quantify the effect of water-osmotic solute exchange on the cell compartments (vacuole, cytoplasm plus intercellular space, and cell wall). The LF-NMR data showed that the relative space occupied by the vacuole decreased and the relative space occupied by the cytoplasm and intercellular space were increased due to these osmotic treatments. MRI results indicated that a bright “water strip” appeared in the periphery of all the osmotically dehydrated samples. DSC results showed that the decrease in water content and the increase in the osmotic solutes depressed the initial freezing point and the freezable water content in osmotically dehydrated strawberry.

Bread staling: Effect of gluten on physico-chemical properties and molecular mobility

Three gluten enriched breads were produced (5% and 15% gluten samples where water was adjusted with farinograph determination, and a 15% sample with the same water amount of the control). The effect of gluten on bread staling (7 days) was evaluated, focussing on texture, amylopectin retrogradation, water status and 1H molecular mobility.The addition of gluten at higher levels (15%) resulted in breads, that retained higher softness, springiness and cohesiveness upon storage. Crumb moisture content was not affected by gluten but at a macromolecular level (DSC) 15% samples showed higher frozen water content. NMR measurements showed a significant effect of gluten on proton T2 relaxation time distributions, revealing a larger presence of protons strongly interacting with water and a more pronounced proton exchange with increasing storage time. The results suggested that, in the presence of gluten, a larger amount of water might be available to plasticize the crumb structure, resulting in a softer product.

Effect of ripening stage and infusion with calcium lactate and sucrose on the quality and microstructure of frozen mango

SummaryThe effect of the ripening stage and infusion with calcium lactate and sucrose on the quality and microstructure of frozen mango was investigated. Partially ripe and ripe mangoes cubes were infused in 1% calcium lactate solution or a combination of 1% calcium lactate and 50% sucrose solution for 1 h before freezing at −20 °C and stored for 14 days. After thawing, both the partially ripe and ripe mangoes treated with the combination of calcium lactate and sucrose exhibited the highest firmness value, sensory firmness score and lowest drip loss. Light microscope images also illustrated less damage to the cell wall of mango pretreated with calcium and sucrose. The calcium‐reinforced structure of the fruit and osmotic dehydration with sucrose reduced the freezable water content and consequently limited ice crystal damage. Furthermore, partially ripe mango was more suitable for freezing than ripe mango due to its stronger cell wall structure.

Influence of acetylated potato starch on the properties of dumpling wrapper

Physicochemical properties of dumpling wrappers with different levels of acetylated potato starch (APS) were measured. Differential scanning calorimetry (DSC) indicated that the presence of APS significantly reduced the freezable water content (FWC) of the system. For the systems, the mobility of the water which was measured by pulse nuclear magnetic resonance (NMR) demonstrated that the existence of APS reduced the relaxation time. Whereas, the centrifugation measurement indicated that the water holding capacity (WHC) values of wheat flour with APS were higher than the control. Scanning electron microscope (SEM) was used to examine the micromorphology of dumpling wrappers.