Changes In Moisture Distribution Research Articles

Control on moisture distribution and protein changes of Antarctic krill meat by antifreeze protein during multiple freeze-thaw cycles.

Control on the moisture distribution, protein structure changes, and protein degradation of Antarctic krill meat during freeze-thaw (F-T) cycles by presoaking with antifreeze protein (AFP) was investigated. The results from the thawing loss rate and cooking loss rate indicated that 0.1% was the optimal AFP concentration. Magnetic resonance imaging and low-field nuclear magnetic resonance results showed that AFP inhibited the changes in moisture distribution and maintained the moisture in Antarctic krill meat. The contents of nonprotein nitrogen and trichloroacetic acid-soluble peptides indicated that AFP reduced protein degradation. Further, SDS-PAGE showed that AFP reduced the degradation of actin, troponin T, and myosin light chain. The results of fluorescence spectra, circular dichroism, and chemical bond contents indicated that AFP reduced the damage of the protein tertiary and secondary structures of Antarctic krill meat by holding it in a weak polar environment. This study supplied basic theory for the quality control of Antarctic krill meat. PRACTICAL APPLICATION: Protein degradation, moisture distribution, and protein structure changes occurred to Antarctic krill meat during freeze-thaw cycles due to ice crystal growth and recrystallization, which leads to the decrease in quality. Antifreeze protein has been proven to avoid ice crystals' growth and inhibit ice recrystallization. During freeze-thaw cycles, the moisture distribution of Antarctic krill meat treated with antifreeze protein was more uniform, the degree of protein degradation was lower, and the protein structure was protected. This study demonstrated the potential of antifreeze protein as a water and protein protectant of Antarctic krill meat during freeze-thaw cycles.

Imaging spatial-temporal distribution of moisture in intact maize ear

The moisture distribution in maize ears during the growth period has a major impact on crop quality and post-harvest production costs and is an important indicator for plant breeding. An electrical impedance tomography system with a resilient electrode array was designed to fit around a maize ear, and featured an adjustable diameter that can be adapted to the growth of the ear. We used the system to monitor the dehydration of an intact maize ear in situ over 5 days and observe the changes in moisture distribution. The high-contrast images correlated with the moisture distribution in the maize ear. We also created a 3D model to visualize the distribution of moisture content within the maize ear. Our method provides a novel tool to monitor the spatial-temporal dynamics of the water content within the maize ear in situ.

Effect of Moisture Distribution Changes Induced by Different Cooking Temperature on Cooking Quality and Texture Properties of Noodles Made from Whole Tartary Buckwheat.

While precooking and processing have improved the quality of gluten-free noodles, the effects of different cooking temperatures on their quality—neither gluten-free noodles nor whole Tartary buckwheat noodles—have rarely been clarified. This study investigated the key role of moisture distribution induced by different cooking temperatures in improving the noodle quality of whole Tartary buckwheat. The results showed that cooking temperatures higher than 70 °C led to a sharp increase in cooking loss, flavonoid loss and the rate of broken noodles, as well as a sharp decrease in water absorption. Moreover, the noodles cooked at 70 °C showed the lowest rate of hardness and chewiness and the highest tensile strength of all cooking temperatures from 20 °C to 110 °C. The main positive attribute of noodles cooked at 70 °C might be their high uniform moisture distribution during cooking. Cooking at 70 °C for 12 min was determined as the best condition for the quality improvement of whole Tartary buckwheat noodles. This is the first study to illustrate the importance of cooking temperatures on the quality of Tartary buckwheat noodles. More consideration must also be given to the optimal cooking conditions for different gluten-free noodles made from minor coarse cereals.

Numerical Study to Predict Temperature and Moisture Profiles in Unventilated Grain Silos at Prolonged Time Periods

The experimental acquisition of data for monitoring cereal grain storage in silos for long periods is not practical in most cases; in such situations, mathematical modeling is an excellent alternative to predict temperature and mass transfer behavior. The model was developed in two dimensions using the equations of heat, mass, and momentum transport. The governing equations were solved using discretization of the spatial coordinates by orthogonal collocation with Jacobi polynomials and the resulting algebraic system was solved by employing nonlinear relaxation method that uses less computational resources. For the ambient boundary conditions, it was used as a more accurate equation to represent the diurnal–nocturnal temperature dynamic. This study analyzes the effects of moisture migration and temperature interactions between the interstitial air and the sorghum cereal grain bed defined as a porous medium in a cylindrical cavity, including the variations affected by meteorological conditions over 1 year. The mass–thermal gradients were predicted, and the effects of environmental temperature were analyzed for flow patterns, isotherms and moisture distribution changes, indicating how the environmental fluctuations influence the heat and moisture of the ambient spots in the grain storage. The maximum temperature inside the silo was 42 °C, considering the respiration heat of the grain, and the maximum temperature of the grain without the climatic boundary conditions was reported to be approximately 35 °C in previous studies. The proposed model can be easily extrapolated to be used for other cereal grains or to incorporate additional effects such as solar radiation, shadow sunlight path, wind velocity, equations to predict more precise ambient temperatures, etc. as boundary conditions.

Mutual transformation of the water binding state and moisture diffusion characteristics of Chinese yams during microwave freeze drying

The moisture distribution changes in Chinese yam slices subjected to microwave freeze drying (MFD) were analyzed using low-field nuclear magnetic resonance (LF-NMR). During this process, the mutual transformation of the water binding state and moisture diffusion characteristics of Chinese yam were analyzed together with changes in the effective water diffusion coefficient, water content, drying rate and pore network structure. Notably, moisture migrated from a high to a low degree of freedom during the MFD process. The effective water diffusion coefficient and water migration velocity increased with increasing microwave power density, and the extent of the conversion of unbound to bound water also gradually increased. During the early stage of drying, moisture diffusion was mainly dominated by liquid phase diffusion. At later stages of drying, moisture diffusion shifted gradually from liquid phase diffusion to gas phase diffusion and was eventually dominated by the latter.

Simulating mixing processes of fresh concrete using the discrete element method (DEM) under consideration of water addition and changes in moisture distribution

The article presents a new model for the use in the framework of the Discrete Element Method to simulate the mixing processes of fresh concrete. The model provides a representation of liquid transfer from fluid entities or moist solid particles to dryer solid particles, including volume adaptation and mass conservation. The parameters and laws of force interactions between two particles are defined locally and depend on the amount and the properties of the liquid phase in the contact area. If two dry particles are in contact, friction and elastic forces are computed based on the Hertz-Mindlin model. If two particles with low moisture content are in contact, additional liquid bridge forces act on the particles. When the suspension state is reached, a Bingham-based model is applied. The simulation enables realistic estimation of the moisture distribution during the mixing processes, the corresponding changes in forces acting on the particles and consequently the effect on the rheological properties of the concrete mixture.

Change of Moisture Distribution in Ribbed Plate with Different Opposite Surface Temperatures

Nowadays to predict hygrothermal performance the methodology of ISO 13788:2012 is widely used. In calculations according to this methodology no material properties are taken into account that leads to overestimate of the risk of interstitial condensation. Therefore in order to provide insight how much results determined according to ISO 13788:2012 can differ from the actual hygrothermal performance the ribbed plywood plate with different opposite surface temperatures was tested. Temperature and relative humidity of the surfaces and internal layers were measured. After data comparison obtained experimentally and by calculation according to ISO 13788:2012 it can be seen that condensation in contrast to the predictions does not occur. Therefore on the basis of this methodology it can be wrongly concluded that analyzed envelope is unsuitable for exploitation. Hence new more accurate calculation methodology is necessary for prediction of hygrothermal performance.

Water Diffusion in Buckwheat Noodles and Wheat Noodles during Boiling and Holding as Determined from MRI and Rectangular Cylinder Diffusion Model

Magnetic resonance imaging (MRI) was employed to observe water diffusion within two kinds of buckwheat noodles (marunuki, sarashina) and one kind of wheat noodle during boiling and holding. The apparent diffusion coefficients for water were statistically estimated with Fick's second law using a rectangular cylinder model, and the changes in moisture distribution in buckwheat and wheat noodles were compared quantitatively. Apparent diffusion coefficients of water in noodles during boiling were 4 to 7 × 10–6 cm2/sec. The diffusion coefficients of water in buckwheat noodles during boiling were higher than those in wheat noodles. For each noodle, the diffusion coefficient during holding after boiling was 2 to 3 × 10–7 cm2/sec and constant through the holding time, from 30 to 120 min. The diffusion coefficients in buckwheat noodles during holding were lower than those in wheat noodles. These results show that, as compared with wheat noodles, buckwheat noodles cooked more rapidly and lost favorable texture during holding.

A mathematical model to describe the change in moisture distribution in maize starch during hydrothermal treatment

SummaryInstantaneous Controlled Pressure Drop, ‘Détente Instantanée Contrôlée’ (DIC) was performed on standard maize starch at residual moisture content (∼12%). Changes in moisture distribution were observed during the treatment and modelled through a phenomenological model based on gravimetric data. The model proposes an exponential variation in the moisture content with processing time at various pressures. The predicted data were found to be in good agreement with experimental data. The values of water activity coefficient (γ) obtained from the model decrease, when processing pressure increases; 5.86, 3.71 and 3.36 (dry basis)−1 for 1, 2 and 3 bar, respectively. The mass transfer coefficient decreases, when the pressure increases. Its value ranged from 5.89 × 10−5 m s−1 for 1 bar down to 0.92 × 10−5 m s−1 for 2 bar and 0.77 × 10−5 m s−1 for 3 bar. This coefficient is not only controlled by a simple resistance to the mass transfer, but also by gelatinisation phenomenon that progresses when temperature increases.

Modelling and Simulation Moisture Transfer in Wheat Stored in a Simulated Sealed Pit

A mathematical model, coupled to another one which was used to calculate the conductive heat transfer, was developed to predict the change of moisture distribution with time in the radial and axial directions in a simulated sealed cylindrical pit storing wheat. The finite difference method was used in the model to calculate the diffusive moisture transfer. The model predicts the grain moisture contents in the pit during the storage period using input data of initial grain temperature, initial grain moisture content, storage time and number of spatial elements in both radial and axial directions. Other input data include the finite difference spatial increment in both directions, the finite time increment, temperatures of soil surrounding the pit and the physical properties of grain, pit wall material and surrounding soil. To validate the model, predicted moisture contents were compared with measured data for wheat of Apollo variety being stored in a simulated sealed pit for a period of 70 days. The wheat was stored in a cylindrical mild steel tank with 0.6 m in both diameter and height. The initial uniform grain temperature was 15 °C and the initial uniform grain moisture content was 12.45% (w.b.). Both measured and predicted moisture contents show that the major change in wheat moisture content took place during the first week of the storage and an establishment of steady state under the storage conditions of the pit is unattainable i.e. moisture diffusion is a very slow process. At the end of the storage period, the grain moisture contents were increased by an average of 1.62% (w.b.) and the grain temperatures were decreased by an average of 2.63°C at the top layer of the pit. For the bottom layer of the pit, the grain moisture contents were decreased by an average of 0.50% (w.b.) and the grain temperatures increased by an average of 7.04°C. The diffusive moisture transfer model predicted the grain moisture contents with a standard error of estimate between measured and predicted of 0.18 -0.75% and of 0.18-0.74% (w.b.) using Chung's equation and modified Henderson's equation, respectively. There was no difference between the two sorption equations (Chung's and modified Henderson's equations) used in predicting grain moisture contents.

Moisture Distribution Changes and Wetwood Behavior in Subalpine Fir Wood during Drying Using High X-Ray Energy Industrial CT Scanner

In some species, such as subalpine fir (Abies lasiocarpa [Hook] Nutt), the water content of the confined zones in heartwood is as high as or greater than that of sapwood. Such wet zones of heartwood are referred to as “wetpocket” or “wetwood.” Wood products from subalpine fir forests are adversely affected by the wetwood-associated problems, particularly during the drying process. The objectives of the study were as follows: (1) to investigate feasibility of a high X-ray energy industrial computed tomography (ICT) scanner for imaging wetwood; and (2) to determine changes of the 2-D and 3-D moisture profiles (from core to shell) at different drying times. Although medical CT scanning has been used for attaining signal intensity profiles of typical wood at different drying times, the technology has not, to date, been used for the study of wetwood phenomenon. This study presents, for the first time, results from the ICT imaging of the wetwood phenomenon. The results indicate that the ICT imaging system provides a powerful technique for imaging wetwood at different drying times. In addition, the results show that during the initial phase of drying, almost flat moisture profiles were observed in all wood types except for the wetwood, which showed a relatively higher moisture profile. A much slower (sluggish) drying development pattern at each increment from core to shell was found within the wetwood zone than normal wood regions along the width, thickness, and length of the board.

Change in the Status of Water in Japanese Noodles During and After Boiling Observed by NMR Micro Imaging

ABSTRACT: A correlation between moisture content (M, g water/ g dry matter) and transverse relaxation time (T2) of water protons in standard wheat gel samples was established by NMR. Changes in moisture distribution in Japanese noodles were estimated from T2 of water protons obtained by NMR micro imaging using the correlation. Penetration of water from the surface to the core during boiling and homogenization of moisture content after boiling were clearly observed in the MR images and moisture profile. A local minimum of T2 of water protons was detected in the moisture profile of noodles boiled in tap water.

The change of moisture distribution in a rice grain during boiling as observed by NMR imaging

The change of moisture distribution in a grain of rice during boiling was observed using the nuclear magnetic resonance (NMR) transverse relaxation time (T 2) imaging method and the factors which governed the cooking process were examined. Partly cooked samples were taken at various intervals and the moisture profile in a slice perpendicular to the long axis of the grain was obtained. Since the change of moisture profile during cooking in a cellulasetreated rice grain showed no remarkable difference from that of a non-treated one, it suggested that the non-cellulase-treated wall of endosperm cells had little effect on suppressing water migration. A one-dimensional moisture profile, which was constructed from an experimentally obtained two-dimensional moisture map, was simulated using a mathematical model in which water percolated through a starch cylinder by diffusion and was limited by gelatinization. Although the calculation successfully simulated the shape of the moisture profile, it showed a delay in the rise of the moisture. The cause of this delay is not yet known.

An application of magnetic resonance imaging to the real time measurement of the change of moisture profile in a rice grain during boiling

The change of moisture distribution in a rice grain during boiling was observed in real-time by NMR T 2 imaging. A series of one-dimensional proton images along a lateral line (through the cross section) perpendicular to the long axis of the grain was obtained every two minutes using a CPMG multi-spin-echo method. The series of images was analyzed to give the apparent T 2 profile, which was then converted into the moisture content profile. The rise in moisture profile during boiling obtained by real-time observation was found to be unexpectedly rapid when it was compared with that reported previously using a non-real-time method for samples which were quenched after boiling for selected periods of minutes. The error in the NMR imaging method caused by the effect of diffusion on the apparent T 2 was fully analyzed using the pictorial phase diagram method.

Moisture distribution changes during drying

Changes of the moisture profiles were determined during drying by measurements of board density using a CT-scanner.

Moisture distribution changes during drying

Moisture distribution changes during drying

NONDESTRUCTIVE MEASUREMENT OF MOISTURE DIFFUSION COEFFICIENT IN WOOD DRYING

ABSTRACT The computer tomography(CT image of wood was analyzed to estimate the moisture content from CT number. Comparing moisture contents, densities and CT numbers, moisture distributions were nondestructively determined by CT numbers detected with the scanner. By periodically measuring CT images of the same cross section of specimens in drying, change of moisture distribution was computed. The coefficients of moisture movement at given positions inside the specimen were directly calculated from Fick's Law with known values of moisture content change, distance and drying time. The diffiion coeficient was described as a function of various driving forces of moisture content, partial vapor pressure and chemical potential of moisture in wood. The results were comparable to data in the literature. Furthermore, it is shown that diffusion coefficients based on moisture content varies as a curve with the maximum value at about 15% m.c. during drying, and that the moisture content is actually adaptable to the driving force for moisture movement in wood because of capability over wide moisture content range.

Change of Moisture Distribution in Clay Bed During Electroosmotic Dewatering Process.

An experimental study of electroosinotic dewatering was carried out, using a kneaded clay bed. By investigating the experimental results, the following conclusions were obtained. (1) After a long time, a final moisture distribution is formed in the clay bed where the electric current flows but electroosinotic flow does not occur. (2) The gradient of the final moisture distribution curve increases with increasing voltage applied to the clay bed. (3) The minimum moisture content on the final moisture distribution curve can reach a lower value than either experimental data published in the literature or the critical moisture content for dewatering shrinkage of the clay bed.

針葉樹材中への水の自然縦浸透 軟Ｘ線デンシトメトリによる解析

Natural penetration of water into wood specimens was investigated by using soft X-ray densitometry. This method makes it possible to obtain the continuos moisture distribution within the specimen during water penetration without destruction.Specimens were taken from the sap- and heartwood of Hinoki (Chamaecyparis obtusa Endl.) and the sapwood of Akamatsu (Pinus densiflora Sieb. et Zucc.), and trimmed to the dimension of 10mm (R)×10mm(T)×180mm(L) and 10mm(R)×2mm(T)×180mm(L). One end of each specimen was dipped in distilled water and the water uptake was measured continuously by a load cell. At given time intervals, the specimens were taken out to weigh water uptake and for soft X-ray irradiation. After these measurements, the specimens were put back to continue the water penetration. The X-ray film obtained was scanned both in L- and R-direction of the specimens by a densitometer. Moisture increase within the specimen was calculated from the difference of film densities before and after penetration. As a result, the changes in moisture distribution in L- and R-directions of the specimen and penetration height during the process were clarified. With the aim to make clear the path of water penetration, wood specimens were stained with 1% aqueous solution of acid fuchsine, and the split radial surface was observed under a stereoscopic microscope.It was concluded that the moisture distribution in each direction of the specimen was characteristic of the wood species. This characteristic was considered to be caused by the difference in penetration mechanism due to wood structure.

Changes in moisture distribution caused by partial reworking of butter shortly after churning

SummarySamples of butter were reworked at various times after removal from the churn, either in a laboratory mixer or by pressing between a microscope slide and cover glass. Moisture distribution was studied by microscopic examination and by indicator papers.Reworking within 30 min of completion of the original working caused no change in moisture distribution but delayed reworking caused aggregation of water droplets. The further the setting of the butter had proceeded before reworking, the greater was the extent of aggregation.Cream-cooling treatments which resulted in a softer butter delayed or decreased the aggregation of droplets caused by reworking.A theory is suggested relating changes on reworking with the formation of a crystal structure on setting.