Guggenheim Anderson De Boer Research Articles

Effect of maltodextrin weight fraction on the amorphous state and critical storage conditions of freeze‐dried juices

SummaryDiagrams relating to water activity (aw), equilibrium moisture content (Xw) and glass transition temperature (Tg) are valuable tools for predicting amorphous fruit powders' storage procedure and stability. Thus, Tg–aw–Xw diagrams were constructed to characterise the amorphous state and define the critical values of water content (Xwc) and water activity (awc) of freeze‐dried juices of strawberry, pineapple, kiwi and prickly pear prepared with maltodextrin at the dry mass fraction (WMD) of 0, 0.4 and 0.8. The Tg and sorption data were fitted with a polynomial equation and the Guggenheim–Anderson–de Boer (GAB) model respectively. A Tukey test was performed to evaluate the difference between critical values of the powders (P < 0.05). The awc and Xwc increase with WMD and depend on the chemical composition of the powders. The highest critical values were found in pineapple powders, ranging from 0.174 to 0.632 and 0.029 to 0.142 dry basis (d.b.), and the lowest ones in kiwi juice powders ranging from 0.029 to 0.550 and 0.013 to 0.129 (d.b.). For WMD of 0.8, however, regardless of juice composition, stable powders in an amorphous state were obtained up to an aw of 0.52 at 25°C.

Detection of Neurofilament Light Chain with Label‐Free Electrolyte‐Gated Organic Field‐Effect Transistors

AbstractNeurofilaments are structural scaffolding proteins of the neuronal cytoskeleton. Upon axonal injury, the neurofilament light chain (NF‐L) is released into the interstitial fluid and eventually reaches the cerebrospinal fluid and blood. Therefore, NF‐L is emerging as a biomarker of neurological disorders, including neurodegenerative dementia, Parkinson's disease, and multiple sclerosis. It is challenging to quantify NF‐L in bodily fluids due to its low levels. This work reports the detection of NF‐L in aqueous solutions with an organic electronic device. The biosensor is based on the electrolyte‐gated organic field‐effect transistor (EGOFET) architecture and can quantify NF‐L down to sub‐pM levels; thanks to modification of the device gate with anti‐NF‐L antibodies imparted with potentially controlled orientation. The response is fitted to the Guggenheim–Anderson–De Boer adsorption model to describe NF‐L adsorption at the gate/electrolyte interface, to consider the formation of a strongly adsorbed protein layer bound to the antibody and the formation of weakly bound NF‐L multilayers, an interpretation which is also backed up by morphological characterization via atomic force microscopy. The label‐free, selective, and rapid response makes this EGOFET biosensor a promising tool for the diagnosis and monitoring of neuronal damages through the detection of NF‐L in physio‐pathological ranges.

A new theoretical model for moisture sorption isotherms and its application in deriving a hygroscopicity index for food products

In this paper, a new two-parameter moisture sorption isotherm (MSI) model was developed based on the non-random two-liquid (NRTL) theory. Compared to the most accepted theory of MSI, i.e., the layered adsorption theory, which includes only the effect of water clustering near food surfaces, the NRTL theory considers the effects of both water clustering and food swelling in the description of water adsorption on foods. This new model, referred to as the NRTL-solid-liquid-mixture (NRTL-SLM) model, revealed a rough linearity relationship between the reciprocal of the natural logarithm of water activity (1/ln a w ) and the equilibrium moisture content ( m 1 ). A new index, characterising the magnitude of the slope of the plot of 1/ln a w v. s. m 1 , was constructed for the hygroscopicity assessment of food products. This new index, referred to as the NHI index, was scaled between 0% and 100%, with the bigger value indicating higher hygroscopicity and 100% representing the hygroscopicity of glycerol. In order to evaluate the applicability and reliability of the NRTL-SLM model and NHI index, seven food samples, i.e., grapes, apples, pears, bananas, avocados, potatoes and beef, were selected. Glycerol was chosen as the hygroscopic reference material. The MSI data at 25 °C of all the eight materials, i.e., seven food products and glycerol, were subjected to model evaluation and index calculations. Our results showed that: (a) the NRTL-SLM model could satisfactorily fit the MSI curves of all the eight materials; (b) compared to the existing most successful MSI model, i.e., the Guggenheim-Anderson-deBoer (GAB) model, the NRTL-SLM model provides a slightly lower accuracy but is much simpler and requires fewer parameters; (c) the NHI index could correctly rank the hygroscopicity of the eight materials relative to each other; and (d) the existing most widely used and standardised physical parameter for MSI analyses, i.e., the monolayer moisture content ( M 0 ), which is typically calculated from the GAB model, could not be used as a measure of hygroscopicity for foods. • A new moisture sorption isotherm (MSI) model based on the NRTL theory reveals a linear relationship between 1/ln a w and m 1 . • A new hygroscopicity index was proposed based on the slope of 1/ln a w and m 1 . • MSI of seven food products were investigated by both the conventional and H 2 SO 4 methods. • The proposed model and hygroscopicity index were successfully validated against experimental data. • The monolayer moisture content ( M 0 ) does not correlate with the hygroscopicity level.

A Case Study of Turbulent Free Jet Flows Issuing from Rectangular Slots on Process Performances and Quality of Hot-Air-Dried Apple

This study deals with the improvement in drying process performances and the quality of the final product for industrial equipment in the food industry. Designers need to optimize the design parameters of devices to create synergies between the greater energy efficiency of the process and high-quality dried products. Air impingement drying was carried out on apple cylinders at 323 K and with air velocities ranging between 30 and 60 m s−1. The studied drying process presents a particular setup of jets as they are multiple rectangular slot jets issued from triangular nozzles. The effect of four design jet parameters (slot width, nozzle-to-surface height, nozzle-to-nozzle spacing, and airflow) on the drying process performances and the quality of the final product was analyzed and optimized using response surface methodology (RSM). A minimal influence of design jet parameters on the process performances was shown, while an important impact was observed on the quality of dried apple. The slot width and the nozzle-to-nozzle spacing had a significant effect on the textural and functional properties. Predictive models were established and good agreements were found between predictive and observed values. Sorption isotherms were properly modeled by the Guggenheim–Anderson–de Boer (GAB) model.

Water Uptake as a Crucial Factor on the Properties of Cryogels of Gelatine Cross-Linked by Dextran Dialdehyde.

We investigated the water sorption properties of macroporous cryogels of gelatine (Gel) and dextran dialdehyde (DDA) prepared via cryogelation at 260 K and following the freeze drying processes. Water vapour sorption isotherms for aerogels were studied at 293 K by two independent methods: static-gravimetric and dynamic vapour sorption (DVS) over a water activity range of 0.11–1.0. Experimental data were fitted by use of the Brunauer–Emmett–Teller (BET) and Guggenheim–Anderson–de Boer (GAB) models. The BET model (for a water activity range of 0.1 ≤ p/po ≤ 0.5) was used to calculate the sorption parameters of the studied cryogels (the monolayer capacity, surface area and energy of interaction). In comparison with BET, the GAB model can be applied for the whole range of water activities (0.1 ≤ p/po ≤ 0.95). This model gave an almost perfect correlation between the experimental and calculated sorption isotherms using nonlinear least squares fitting (NLSF). Confocal Laser Scanning Microscopy (CLSM) was used to confirm the structural differences between various DDA:Gel cryogel compositions. Thermogravimetric analysis and DSC data for aerogels DDA:Gel provided information regarding the bonded water loss, relative remaining water content of the material and the temperature of decomposition. Estimation of the amount of bound water in the cryogels after the freeze drying process as well as after the cycle of treatment of cryogels with high humidity and drying was performed using DSC. The results of the DSC determinations showed that cryogels with higher gelatin content had higher levels of bonded water.

Temperature Dependence of Sorption

Understanding how sorption depends on temperature on a molecular basis has been made difficult by the coexistence of isotherm models, each assuming a different sorption mechanism and the routine application of planar, multilayer sorption models (such as Brunauer-Emmett-Teller (BET) and Guggenheim-Anderson-de Boer (GAB)) beyond their premises. Furthermore, a common observation that adsorption isotherms measured at different temperatures fall onto a single "characteristic curve" when plotted against the adsorption potential has not been given a clear explanation, due to its ambiguous foundation. Extending our recent statistical thermodynamic fluctuation theory of sorption, we have generalized the classical isosteric theory of sorption into a statistical thermodynamic fluctuation theory and clarified how sorption depends on temperature. We have shown that a characteristic curve exists when sorbate number increment contributes purely energetically to the interface, whereas the correlation between sorbate number and entropy drives the temperature dependence of an isotherm. This theory rationalizes the opposite temperature dependence of water vapor sorption on activated carbons with uniform versus broad pore size distributions and can be applied to moisture sorption on starch gels. The adsorption potential is a convenient variable for sorption in its ability to unify sorbate-sorbate fluctuation and the isosteric thermodynamics of sorption.

The Study of Bound Water Status and Pore Size Distribution of Chinese Fir and Poplar Cell Wall by Low-Field NMR

With the increasing shortage of timber resources and the advancement of environmental protection projects, many artificial fast-growing forests are planted and used as raw materials in China. There are significant differences in the properties of natural forest wood and artificial fast-growing forest wood, and the properties of wood mainly depend on the change in the status of bound water in the cell wall. In this study, the fiber saturation point (FSP) and pore size distributions within the cell wall of six species of fast-growing forest wood were studied by low-temperature nuclear magnetic resonance (NMR) technology. The effects of species, growth rings, and extractives on the FSP and pore structure were analyzed. The water vapor sorption experiments were performed, and the adsorption isotherms of the samples were fitted through the Guggenheim-Anderson-de Boer (GAB) equation. According to the least-square regression of the adsorption isotherms and combined with the low-temperature NMR experiments, the content and proportion of the different types of bound water were analyzed. The results showed that the average FSP of each Chinese fir was about 40% and that of each poplar was about 35%. There is about a 10% difference between the FSP measured by NMR technology and the adsorption bound water content obtained by adsorption isothermal. The pore size distribution results show that in all samples, the proportion of pores larger than 10.5 nm is very low, about 10%; the proportion of 1.92-10.5 nm pores is about 30%; and the proportion of pores smaller than 1.92nm is more than 50%. This work will be helpful to the study of the wood moisture status and provide reference data for wood modification.

Influence of physical and chemical modifications on granule size frequency distribution, fourier transform infrared (FTIR) spectra and adsorption isotherms of starch from four yam (Dioscorea spp.) cultivars.

In this work, the effect of the modifications (annealing, acid hydrolysis and citric acid substitution) on starch granule size frequency distribution, Fourier Transform Infrared (FTIR) spectra, and adsorption isotherm of starches of four yam cultivars were studied. The native and modified white yam, water yam, and yellow yam starches had a normal distribution frequency profile for the granule sizes, which were similar among the cultivars. In contrast, the native and modified bitter yam starch granules were not normally distributed. The modifications resulted in a left shift in normal distribution frequency profiles for the granules sizes of the white, water and yellow yam starches due to broadening of the range of granule sizes. The FTIR spectra revealed that additional bands at 1726.95-1729.49cm-1 were introduced due to citric acid modification of the yam starches. The modifications also caused weakening of the FTIR band representing -CH2 and -OH stretching at 2927.85-2932.94cm-1 and 3259.42-3437.33cm-1, respectively. The native, annealed and acid hydrolyzed yam starches all had similar adsorption isotherms at 28°C. On the other hand, the citric acid-substituted yam starches showed a different adsorption isotherm, because they had significantly higher equilibrium moisture content at water activity (a w ) above 0.9. All the adsorption isotherms were type III, J-shaped isotherms. The adsorption isotherms data of the yam starches fitted best to the Guggenheim-Anderson-De Boer (GAB) model. The GAB model monomolecular moisture content ranged between 0.0165 and 0.0597g/g db. Native and modified yam starches' granules size were normally distributed except bitter yam starchFTIR revealed additional bands and molecular rearrangements were introduced due to modificationsAdsorption isotherms revealed type III, GAB-model isotherms with low monomolecular moisture. The online version contains supplementary material available at 10.1007/s13197-021-05200-7.

Modeling and Thermodynamic Analysis of the Water Sorption Isotherms of Cottonseed Products

Due to their hygroscopic characteristics, equilibrium moisture contents of agricultural products and byproducts are important factors of their quality. Defatted cottonseed meal (CSM), washed cottonseed meal (WCSM) and cottonseed protein isolate (CSPI) can be used as energy and protein sources of animal feedstuff or industrial raw materials. Information on their moisture adsorption behaviors is needed for their storage conditions and quality control. Thus, this work measured the equilibrium moisture sorption isotherms of CSM, WCSM and CSPI, at 15, 25, 35 and 45 °C. When the moisture contents of the samples were compared at a constant temperature, the general trend of decreasing moisture content was in the order of CSPI < WCSM < CSM for water activity <0.6, but the trend reversed to the order of CSM < WCSM < CSPI for water activity >0.6. Relevant sorption isotherm equations were tested for accurate fit to the moisture adsorption data. Modelling results indicated that the G.A.B. (Guggenheim-Anderson-de Boer) model was a consistently good fit for the data among all sample types and all temperatures. This work provides some insight on designing or selecting appropriate procedures for the handling, aeration, storage and processing of these cottonseed meal products. In particular, it suggests that moisture content should be kept at around 8% for safe storage of these products at room temperature (around 25 °C) but below 5% when they are exposed to higher temperature conditions (e.g., >45 °C).

Influence of gelatinization degree and octenyl succinic anhydride esterification on the water sorption characteristics of corn starch

The effects of gelatinization degree (GD) and octenyl succinic anhydride (OSA) esterification in the sorption-desorption characteristics of normal corn starch (NCS) were studied. NCS was subjected to different GD (53, 70, and 96%) with an extruder and lyophilized. FTIR analysis revealed that GD increased the hydrated (995/1022 ratio) and decreased the short-range ordered (1022/1047 ratio). The equilibrium sorption-desorption curve of starches was obtained for water activities up to 0.95 and fitted with the Guggenheim-Anderson-de Boer (GAB) model. Gelatinization of corn starch decreased its water sorption capacity, increased its sorption hysteresis and decreased its monolayer moisture content. OSA treatment of NCS reduced the water sorption capacity, hysteresis, and monolayer moisture content as reflected by slight variations of these parameters with the GD. A principal component analysis showed that GD and OSA esterification are mutually independent treatments, which can provide different effects on the water sorption characteristics of NCS.

Sorption: A Statistical Thermodynamic Fluctuation Theory.

Can the sorption mechanism be proven by fitting an isotherm model to an experiment? Such a question arises because (i) multiple isotherm models, with different assumptions on sorption mechanisms, often fit an experimental isotherm equally well, (ii) some isotherm models [such as Brunauer–Emmett–Teller (BET) and Guggenheim–Anderson–de Boer (GAB)] fit experimental isotherms that do not satisfy the underlying assumptions of the model, and (iii) some isotherms (such as Oswin and Peleg) are empirical equations that do not have a well-defined basis on sorption mechanisms. To overcome these difficulties, we propose a universal route of elucidating the sorption mechanism directly from an experimental isotherm, without an isotherm model, based on the statistical thermodynamic fluctuation theory. We have shown that how sorbate–sorbate interaction depends on activity is the key to understanding the sorption mechanism. Without assuming adsorption sites and planar layers, an isotherm can be derived, which contains the Langmuir, BET, and GAB models as its special cases. We have constructed a universal approach applicable to adsorption and absorption, solid and liquid sorbents, and vapor and liquid sorbates and demonstrated its efficacy using the humidity sorption isotherm of sucrose from both the solid and liquid sides.

Sorption characteristic of starch-based film

Moisture sorption characteristic is important in determining the stability of bio-based plastic during packaging and storage condition. This study was carried out to investigate the moisture sorption characteristic of starch-based film. Moisture sorption test was conducted at different temperatures (5, 30 and 50°C) and relative humidity (23-75%). The experimental data was fitted using several models. Based on the Peleg model, the maximum rate of absorption and absorption capacity occurred at higher relative humidity. Guggenheim Anderson de Boer (GAB) model was the most suitable model to fit the experimental isotherm data and it is useful to predict the water sorption properties of the film which relate to different relative humidity conditions. In addition, the shelf life of film was reduced when placed under lower temperature due to the higher sorption capacity of moisture. The sorption properties of the starch-based film are important and worth investigation as it will be useful for the final application in food packaging due to its dependency on this behaviour.

Evaluation of storage stability of dried powdered coriander, parsley and celery leaves based on the moisture sorption isotherms and glass transition temperature

The aim of study was to evaluate the storage stability of microwave-vacuum dried (MWVD) and hot air convective dried (HACD) powdered coriander, parsley and celery leaves based on their moisture sorption isotherms and glass transition temperatures (Tg). Dried coriander, parsley and celery leaves were powdered and kept at a storage temperature (TS) of 20 °C for 10 weeks with a water activity ranging from 0 to 0.813 until equilibrium was reached. The values of coefficient of determination (R2 > 0.99) and percentage global relative square error of the approximation (4.9<GRSE<11.3%) indicate that Guggenheim-Anderson-de Boer (GAB), Peleg, Lewicki, Curie and Oswin models well described the relationship between water activity (aw) and the equilibrium moisture content (EMC) of dried materials. The variations in Tg vs. aw or EMC were adequately predicted by linear, square, polynomial, Khalloufi, Gordon-Tylor and Jenckel-Heusch models (R2 > 0.81; 2.95<GRSE<43.5%). For the optimum range of aw (0.2<aw < critical aw), dried powdered coriander, parsley and celery leaves showed the highest stability at EMC from 0.028 to 0.061, 0.022 to 0.074 and 0.027–0.064 g H2O/g DM, respectively. The optimum TS of dried powdered coriander, parsley and celery leaves was from 57.8 to 20.0, 61.3 to 20.0, and 69.8 to 20.0 °C, respectively.

Relationship and Distribution of In-Field Dry-Down and Equilibrium in Maize Grain Moisture Content

The selection of the appropriate harvest time and moisture content (MC) is very important for maize (Zea Mays L.) production, and selection is an essential step that balances the yield and comprehensive benefits. In this study, the process and final MC following a grain dry-down of sixteen maize hybrids was observed in 2017 and 2018. The Guggenheim-Anderson-de Boer (GAB) model, which is commonly used to describe the equilibrium moisture content (Meq) under controlled conditions, was used to evaluate the relationship between the field Meq and the final MC. The results showed that the MC reached a stable level after a long dry-down period in the field, indicating that an equilibrium was present between the grain and the atmosphere. The MC at the equilibrium state represented two characteristics, a “hysteresis effect” and a “convergence effect”, which were as follows: the change in MC always lagged behind the Meq in the atmosphere; and the MC fluctuated continuously with the Meq but could not reach its limit. The time of the “hysteresis effect” was estimated to be approximately 2-4 days. The time to reach equilibrium varied greatly in different maize hybrids, and it was related to the growth period and dry-down characteristics. Moreover, the various climatic types contributed to diverse Meq values, and the humid climate had a higher Meq than the dry-cold climate. The distribution of Meq values and the drying days on which the maize grain moisture content decreased from 30% to 25% (and 20%), guided the threshold for the delayed harvest of maize, as also estimated in various maize ecological areas in China. The optimal harvest time were significantly different in various regions due to different Meq values. Therefore, we suggest that the estimation of the Meq could be an important indicator for predicting the grain dry-down and harvest management strategies for a region.

The Finite Pore Volume GAB Adsorption Isotherm Model as a Simple Tool to Estimate a Diameter of Cylindrical Nanopores.

The finite pore volume Guggenheim–Anderson–de Boer (fpv-GAB) adsorption isotherm model has been considered as a simple tool which not only enables us to analyze the shape of isotherms theoretically, but also provides information about pore diameter. The proposed methodology is based on the geometrical considerations and the division of the adsorption space into two parts: the monolayer and the multilayer space. The ratio of the volumes of these two spaces is unambiguously related to the pore diameter. This ratio can be simply determined from the N2 adsorption isotherm by its fitting with the use of fpv-GAB model. The volume ratio is equal to the ratio of the adsorption capacities in the monolayer and the multilayer—two of the best-fit parameters. The suggested approach has been verified using a series of isotherms simulated inside ideal carbon nanotubes. The adsorption data for some real adsorbents has also been used during tests. The studies performed have proven that diameters estimated with the use of the proposed method are comparable with the geometrical sizes or diameters published by others and based on the application of more sophisticated methods. For pores wider than 3 nm, the relative error does not exceed a few percent. The approach based on the fpv-GAB model reflects well the differences in pore sizes for the series of materials. Therefore, it can be treated as a convenient tool to compare various samples.

Changes in cell wall components and hygroscopic properties of Pinus radiata caused by heat treatment

After thermal modification at 210 °C using the Thermowood method, changes in Pinus radiata D. Don wood cell wall components and hygroscopicity were studied for subsequent comparison with recently felled wood of the same species in samples from the same region of provenance (Basque Country, Spain). To this end, samples were characterised by sorption isotherms at 15, 35 and 50 °C fitted to the Guggenheim–Anderson–de Boer (GAB) model, the chemical composition was obtained by high performance liquid chromatography (HPLC) and infrared spectroscopy (FTIR), and crystallinity and structural organisation of cellulose (crystal orientation) were determined using powder and 2D X-ray diffraction (XRD). Heat treatment caused the following changes in the wood: a decrease in the equilibrium moisture content (EMC); a smaller hysteresis area and therefore more hygroscopically stable wood; a decrease in the hemicellulose content; an increase in the relative percentage of cellulose, lignin and extractives; and a higher degree of crystallinity and crystal orientation of the cellulose. The reorganisation of cellulose could be explained by epitaxial growth of cellulose starting from the highly oriented crystalline regions during the recrystallisation process. All these chemical and structural changes induced by heating could explain the reduction in hygroscopic properties of wood, as well as its stability.

Determination and Modeling Desorption Isotherms of Okra (Abelmoschus esculentus L. Moench) and Sweet Green Pepper (Capsicum annum L. Moench)

The aim of this study was to determine the experimental moisture sorption isotherm of green pepper and okra, assess the performance of literature sorption models describing their behavior, and specify bound water properties. Isotherms were determined through the static gravimetric method at 30, 40, 50, and 60 °C. Twenty models were studied and fittings were done through nonlinear regression using MATLAB R2015b. GAB and Caurie models were used to determine energy constants and bound water properties respectively. Structural parameters were determined according to Kelvin and Halsey equations. All the experimental isotherm were of sigmoid shape. For both samples, Peleg, Enderby, and Guggenheim Anderson de Boer (GAB) models gave the best validation statistic criteria. R-squared (R2) values were all greater than 0.926 and root-mean-square error (RMSE) values less than 0.04 for both substrates. The GAB energy constants varied with temperature between 6.00 to 51.75 and 34.23 to 176.78 for Cg constants, and 0.70–0.99 and 0.75–0.93 for Kg constants, respectively, for okra and green pepper. The Cg energy constant globally decreased with increasing temperature. The monolayer moisture content Wm, varied with temperature between (0.0740–0.1044) kg kg−1 and (0.0760–0.1522) kg kg−1 respectively for okra and green pepper. Green pepper bound water property values were globally higher than those of okra and both were successfully modeled according to the equilibrium moisture content and according to the temperature. Analysis based on the IUPAC classification revealed a macroporous structure of the two materials. The hygroscopic equilibriums, physicochemical and microbiological stability conditions of green pepper and okra, were determined, for given environmental temperature values. The results obtained from the present study would serve in understanding the water state and mechanism of water sorption, defining drying and storage conditions of the tested vegetables, as well as designing corresponding dryers and packaging.

Effect of Emulsifier Diacetyl Tartaric Acid Ester of Mono- and Diglycerides (DATEM) and Enzyme Transglutaminase on Quality Characteristics of Rice Bran Croissants

Rice bran (RB) is a good source of dietary fibre. Addition of rice bran into croissant interferes with the gluten formation of dough and hence affect the physicochemical properties of croissant. The effect of RB addition on physicochemical properties of croissant were determined by using 0%, 10% and 15% RB. Besides, additives such as emulsifiers and enzymes can be used in pastry to enhance the physicochemical properties of croissant. Diacetyl tartaric acid ester of mono-diglycerides (DATEM) and transglutaminase (TGase) were used respectively on 0%, 10% and 15% RB to investigate the effect of such additives on physicochemical properties of croissant. Increased % RB and DATEM, produced a significant decrease in specific volume, together with a significant increase in colour, hardness and chewiness. With increased % RB, TGase caused significant increase in colour, hardness and chewiness but significant decrease in specic volume. The overall moisture sorption isotherm curves of the croissant belong to the Type III isotherm, also known as Flory-Huggins Isotherm (J-shaped). The critical aw obtained from the Guggenheim-Anderson-de Boer (GAB) equation showed that the shelf life of croissants were not positively impacted by the addition of DATEM and TGase and the addition of RB did not cause any significant positive effects on quality characteristics of croissants.

Moss-dominated biocrusts enhance water vapor sorption capacity of surface soil and increase non-rainfall water deposition in drylands

Surface soil vapor sorption and non-rainfall water (NRW) deposition are important sources, and can be highly influential in soil water dynamics and biochemical processes in drylands. As an important living skin, biocrusts have great impacts on soil water balance and play a vital role in water transport at near surface soil, while it remains unclear how biocrusts affect soil water vapor sorption and NRW deposition. In this study, we analyzed and modeled the water vapor sorption isotherms (WSIs) of moss-dominated biocrusts and uncrusted surfaces on loess soil and aeolian sand in the Chinese Loess Plateau. Furthermore, the actual NRW deposition amount of the biocrusts and uncrused soil in field was continuously measured across ~4 months in summer. Our results showed that the vapor sorption amount of the biocrusts was increased by up to 130.5% on the loess and 157.1% on the aeolian sand, and soil vapor sorption capacity of the biocrusts was mostly attributed to their higher contents of fine particles (clay and silt) and organic matter, and the moss morphology in comparison to the uncrusted soil. The Guggenheim-Anderson-de Boer (GAB) model performed well (R2 > 0.97, RMSE < 0.0005 g g−1, E < 13.2%) in simulating WSIs of each treatment. Moreover, the biocrusts enlarged the hysteresis effects by > 23.1%-200.0% as compared with the uncrusted soil at 0–10 cm depth. Additionally, the daily NRW amount of the biocrusts was increased by 19.2% on loess soil and 22.0% on aeolian sand, respectively, which means that the biocrusts significantly increased the NRW deposition capacity at 0–10 cm depth (F ≥ 11.12, P < 0.001). Lastly, the surface soil temperature of the biocrust layer was averagely 1.0–2.3 °C higher than that of the uncrusted soil during daytime, indicating that the biocrust layer enlarged the daily soil temperature differences between the crusted and uncrusted soils, and consequently increased the hourly NRW amount. In conclusion, this study demonstrates the important effects of biocrusts in improving vapor sorption capacity and NRW deposition of surface soil, and these properties in return would further generate feedback impacts on surface soil water and heat balances, enhancing microbial activity within the soil profile and nutrient adsorption from NRW in drylands.

Development of powder based ginger drink: analysis of dehydration kinetics and moisture sorption isotherm

The perishable herb ginger (Zingiber officinale) possesses natural aroma and different biologically active components which are beneficial for our health. This can be dried for preservation in pick season for shelf-life increment. This study studied the analysis of the chemical composition, moisture sorption isotherm, dehydration kinetics of ginger for preservation. Air drying was carried out using a cabinet dryer at different temperatures and thickness. According to the sorption isotherm study, monolayer moisture content (MMC) is higher as per Guggenheim-Anderson-DeBoer (GAB) equation compared to the Brunauer-Emmett-Teller (BET) equation. Drying rate increased with the increase in temperature at constant thickness while the adverse result was found with the increase in thickness at a constant temperature. Then, powder-based drinks were prepared by using five different percentages of ginger. The preferences of consumers were measured by statistical analysis of the scores obtained from the response of organoleptic taste panel. The sample containing 1.84% ginger powder was considered the best in overall acceptability