Effects of ultrasound pretreatment on the drying kinetics, water status and distribution in scallop adductors during heat pump drying.

BACKGROUND: A material's physical and chemical properties during drying are influenced by water status and distribution. However, merely overall water removal is reported in many investigations, which hinders clarification of the drying mechanism. Therefore, the effects of ultrasound (US) pretreatment (0 W, CK; 90 W, US-90; 180 W, US-180) on the drying kinetics and quality of heat pump drying (HPD) scallop adductors was performed based on low-field nuclear magnetic resonance (LF-NMR). RESULTS: Compared with CK, effective moisture diffusion coefficient was increased by 12.43% and 23.35% for US-90 and US-180, respectively. The Weibull model satisfactorily described the drying characteristics with a high r2 (> 0.998), low rmse (< 0.0120) and χ2 (< 0.00008). LF-NMR revealed that the immobilized water was predominant in scallop adductors. As drying proceeded, the relaxation time of free and immobilized water was decreased sharply, whereas the relaxation time of bound water scarcely changed. The time required to reduce approximately two-fifths of the original peak area of immobilized water was 720, 630 and 540 min for CK, US-90 and US-180, respectively. The amplitude of immobilized water was decreased and bound water increased significantly, although free water was kept constant (ranging 1-2%). US pretreatment reduced total color difference and hardness, but enhanced the toughness of dried scallop adductors. However, US had no significant influence on the product rehydration rate and shrinkage rate. CONCLUSION: LF-NMR was successfully employed to evaluate the drying degree of scallop adductors. US facilitated the conversion of immobilized water to free water and, consequently, promoted water removal during HPD. © 2021 Society of Chemical Industry.

The states of water in glutinous rice flour characterized by interpreting desorption isotherm.

Water content of glutinous rice flour were determined after equilibrium at water activity (aw) of 0.06-0.98 and temperature of 10, 20 and 30 °C. Distribution of water in different states and its evolution with aw were characterized using four composite models. Interactions of water molecules with solid matrix and themselves were further evaluated. The Park model was a more realistic and mechanism-based approach for describing water desorption of glutinous rice flour. Increased equilibrium water induced by lowering temperature existed mostly as strongly bound water with only a few parts as weakly bound water. The water-polymer thermodynamic incompatibility predominated the water mobility, and resulted in a rapid decrease of diffusion coefficient at aw > ~0.7. Water diffusivity behavior with aw suggested water clustering at high aw levels. The Zimm-Lundberg theory, Park model and Brown analysis all revealed that critical aw of water clustering was of 0.81-0.85, depending on temperature, but gave inconsistent prediction about mean cluster size.

In situ investigation of ice fractions and water states during partial freezing of pork loins and shrimps.

Ice fractions and water states in partially frozen muscle foods greatly affect their quality. In the study, a variable temperature nuclear magnetic resonance (VT-NMR) with a liquid nitrogen temperature control system was employed to in situ investigate the relationship between ice fractions and temperatures and changes in water states during partial freezing and thawing of pork and shrimp. Results indicated that changes in ice fractions ranging from -2 âˆ¼ -20 °C could be divided into 3 stages including slow increase, random leap and remarkable leap. More serious damages to the structures related to immobile water occurred in shrimp than in pork, and partial freezing also caused deterioration in muscle fibres related to free water. Additionally, -2 âˆ¼ -3 °C and - 3.5 °C were the appropriate partial freezing temperatures for pork and shrimp, respectively. Therefore, the VT-NMR method possessed great potential for fundamental studies and applications of partial freezing of muscle foods.

Construction of sodium alginate/trehalose/wheat starch ternary complex and its effects on storage stability of frozen dough system.

In order to improve the quality of frozen dough, a calcium alginate-coated sodium alginate/trehalose/wheat starch ternary complex was designed in this paper. The ternary complex was added to dough, and the dough quality were measured after 0-30 d of frozen storage. The XRD and FT-IR results showed the ternary complex was mainly starchy crystal. The TGA curves showed the starting (To), peak (Tp) and termination temperature (Tc) were increased. The interaction between sodium alginate and trehalose enhanced the thermal performance of ternary complex. As the ternary complex addition to dough increased, the maximum ice crystal formation zone of the frozen dough passed faster, resulting in more uniform and smaller ice crystals. The dough with 0.8% addition contained more bound water and had better hardness, springiness and cohesiveness. In conclusion, the study provides a novel insight and understanding for the development of ternary complex as food additives in frozen food industry.

Effect of various different pretreatment methods on infrared combined hot air impingement drying behavior and physicochemical properties of strawberry slices.

In current work, the effect of freezing (F), ultrasound (U), and freeze- ultrasound (FU) pretreatment on infrared combined with hot air impingement drying kinetics, cell ultrastructure, enzyme activity, and physicochemical properties of strawberry slices were explored. Results showed that FU pretreatment enhanced cell membrane permeability via forming micropores, altered water status by transforming bound water into free water and thus promoted moisture diffusivity and decreased drying time by 50% compared to the control group. FU pretreatment also extensively decreased pectin methylesterase enzyme activity and maintained quality. The contents of total phenols, anthocyanins, vitamin C, antioxidant activity, and a* value of dried strawberries pretreated by FU were extensively increased compared to the control group. U and FU pretreatments were beneficial for retaining aromatic components and organic sulfides according to e-nose analyses. The findings indicate that FU is a promising pretreatment technique as it enhances drying process and quality of strawberry slices.

A watershed-scale goals approach to assessing and funding wastewater infrastructure.

Capital needs during the next twenty years for public wastewater treatment, piping, combined sewer overflow correction, and storm-water management are estimated to be approximately $300 billion for the USA. Financing these needs is a significant challenge, as Federal funding for the Clean Water Act has been reduced by 70% during the last twenty years. There is an urgent need for new approaches to assist states and other decision makers to prioritize wastewater maintenance and improvements. We present a methodology for performing an integrated quantitative watershed-scale goals assessment for sustaining wastewater infrastructure. We applied this methodology to ten watersheds of the Hudson-Mohawk basin in New York State, USA that together are home to more than 2.7 million people, cover 3.5 million hectares, and contain more than 36,000 km of streams. We assembled data on 183 POTWs treating approximately 1.5 million m(3) of wastewater per day. For each watershed, we analyzed eight metrics: Growth Capacity, Capacity Density, Soil Suitability, Violations, Tributary Length Impacted, Tributary Capital Cost, Volume Capital Cost, and Population Capital Cost. These metrics were integrated into three goals for watershed-scale management: Tributary Protection, Urban Development, and Urban-Rural Integration. Our results demonstrate that the methodology can be implemented using widely available data, although some verification of data is required. Furthermore, we demonstrate substantial differences in character, need, and the appropriateness of different management strategies among the ten watersheds. These results suggest that it is feasible to perform watershed-scale goals assessment to augment existing approaches to wastewater infrastructure analysis and planning.

Buffering capacity of submerged macrophytes against nutrient pulses increase with its coverage in shallow lakes.

Submerged macrophytes can improve water quality and buffer the effects of external nutrient loading, which helps to maintain a clear-water state in shallow lakes. We constructed 12 large enclosures with contrasting coverages (treatments) of submerged macrophytes (SMC) to elucidate their buffering capacity and resilience to nutrient pulses. We found that aquatic ecosystems with high SMC had higher buffering capacity and resilience, vice versa, i. e, the enclosures with high SMC quickly buffered the nutrient pulse and rebounded to clear-water state after a short stay in turbid-water state dominated by algae, while the treatments with low SMC could not fully buffer the pulse and rebound to clear-water state, and they slowly entered the transitional state after staying in turbid-water state. This means that the enclosures with high SMC had a better water quality than those with low SMC, i.e., the levels of nutrients and Chl-a were lower in the treatments with high plant coverage. In addition, plant coverage had a significantly positive buffering effect against nitrogen and phosphorus pulses, i.e., the nutrient concentrations in the treatments with high SMC took shorter time to return to the pre-pulse level. Overall, our results evidenced that the higher that the SMCs is, the better is the water quality and buffering capacity against nutrient pulses, i.e. the more stable is the clear-water state. However, low SMC may not be able to resist the impact of such strong nutrient pulse. Our results provide reference and guidance for water pollution control and water ecological restoration.

Enhanced gelling properties of myofibrillar protein by ultrasound-assisted thermal-induced gelation process: Give an insight into the mechanism.

Effects of the incorporation of ultrasound with varied intensities (0-800 W) into the thermal-induced gelation process on the gelling properties of myofibrillar protein (MP) were explored. In comparison with single heating, ultrasound-assisted heating (<600 W) led to significant increases in gel strength (up to 17.9%) and water holding capacity (up to 32.7%). Moreover, moderate ultrasound treatment was conducive to the fabrication of compact and homogenous gel networks with small pores, which could effectively impair the fluidity of water and allow redundant water to be entrapped within the gel network. Electrophoresis revealed that the incorporation of ultrasound into the gelation process facilitated more proteins to get involved in the development of gel network. With the intensified ultrasound power, α-helix in the gels lowered pronouncedly with a simultaneous increment of ß-sheet, ß-turn, and random coil. Furthermore, hydrophobic interactions and disulfide bonds were reinforced by the ultrasound treatment, which was in support of the construction of preeminent MP gels.

The Effect of Terminal Freezing and Thawing on the Quality of Frozen Dough: From the View of Water, Starch, and Protein Properties.

Frozen dough is suitable for industrial cold chain transportation, but usually experiences temperature fluctuations through the cold chain to the store after being refrigerated in a factory, seriously damaging the product yield. In order to analyze the influence mechanism of temperature fluctuation during the terminal cold chain on frozen dough, the effects of terminal freezing and thawing (TFT) on the quality (texture and rheology) and component (water, starch, protein) behaviors of dough were investigated. Results showed that the TFT treatment significantly increased the hardness and decreased the springiness of dough and that the storage modules were also reduced. Furthermore, TFT increased the content of freezable water and reduced the bound water with increased migration. Additionally, the peak viscosity and breakdown value after TFT with the increased number of cycles were also increased. Moreover, the protein characteristics showed that the low-molecular-weight region and the ß-sheet in the gluten secondary structure after the TFT treatment were increased, which was confirmed by the increased number of free sulfhydryl groups. Microstructure results showed that pores and loose connection were observed during the TFT treatment. In conclusion, the theoretical support was provided for understanding and eliminating the influence of the terminal nodes in a cold chain.

Peeling mechanism of tomato induced by HHAIB: Microscopic, ultrastructure, chemical, physical and mechanical properties perspectives.

In order to better manage the peeling degree and avoid unnecessary losses, the current work aimed to explore the peeling mechanism of a novel peeling technology, high-humidity hot air impingement blanching (HHAIB). The relationships between HHAIB peeling performance and the changes in skin temperature, skin structure, water state, pectin fractions content, and skin mechanical properties of tomatoes were analyzed. Results showed, after HHAIB treatment, the epicuticular wax was disrupted, the skin exhibited more and longer random cracks, the degradation of inner skin tissue was observed by transmission electron microscopy, the free water percentage increased resulting in water loss in the whole tomato, the water-soluble pectin contents decreased in tomato fleshes, while the contents of chelate-soluble pectin and sodium-carbonate-soluble pectin increased. HHAIB heating reduced the elongation at break, and increased Young's Modulus of tomato peel. This study revealed the HHAIB peeling mechanism and provided new insights for developing HHAIB peeling technology.

Effect of ultrasound-assisted osmotic dehydration on the drying kinetics, water state, and physicochemical properties of microwave vacuum-dried potato slices.

The effects of pre-treatments on the drying characteristics, water state, thermal properties, and bulk shrinkage of potato slices during microwave vacuum drying (MVD) were investigated. The pre-treatment included ultrasound in distilled water (USOD-0%), and ultrasound-assisted osmotic dehydration in a 60% sucrose solution (USOD-60%). Results showed that the drying time of potato slices was reduced and the drying rate was increased when USOD-0% was used as a pretreatment, whereas USOD-60% had a negative effect on the drying rate of the samples. The Weibull model was effective in predicting the water changes in potato slices during the drying process. NMR analysis revealed that the relative content of immovable water (M22) increased initially, then decreased for drying, while the transverse relaxation time (T2) and the relative content of free water (M23) decreased consistently. The DSC results indicated that the glass transition temperature (Tg) had an inverse relationship with the water content of the samples, yet had virtually no influence on the volume shrinkage. The sample volumes decreased linearly with the decrease in water content during the initial drying stages. USOD pre-treatment lessened the volume shrinkage of MVD potato slices. Static gravimetry was used to determine the moisture sorption isotherms of MVD potato slices at 30 °C within the aw range of 0.113-0.923. The GAB model accurately fitted the experimental sorption data, which showed sigmoid shape curves for the MVD samples. When aw values exceeded 0.7, the USOD-60% treatment significantly reduce the water sorption capacity of MVD potato slices, while USOD-0% treatment was observed to increase the hygroscopic properties of MVD samples. Compared with the control, USOD-0% pretreatment significantly increased the monolayer water content (X0), sorption surface area (S0), the thickness of sorbed water multilayer (tm), and density of sorbed water (Ds) values of MVD potato slices, while USOD-60% decreased these values.

Effect of carboxymethyl chitosan on the storage stability of frozen dough: State of water, protein structures and quality attributes.

Carboxymethyl chitosan (CMCh), an ampholetic chitosan derivative, has found broad applications in the food industry. However, its cryo-protective properties remained less explored compared to other viscous polysaccharides, such as carboxymethyl cellulose, carrageenan etc., which have been widely utilized as frozen food additives. In this study, we investigated the effect of CMCh addition to frozen dough in terms of water state, protein structure, and the textural properties of prepared frozen dumpling wrappers. Results indicated that CMCh restricted the water migration in dough and delayed protein deterioration during frozen storage. Specifically, the content of freezable water in dough was reduced and the water distribution became more uniform as reflected by DCS and LF-NMR analysis. CMCh also stabilized disulfide bond and secondary structures of the protein, leading to inhibition of dough rheology changes. Accordingly, the obtained frozen dumplings wrappers demonstrated decreased cracking rate and water loss, and improved textural properties. Moreover, CMCh with higher degree of carboxymethyl substitution (DS: 1.2, CMCh-B) exhibited better cryo-protective effects compared to CMCh of lower DS (DS: 0.8, CMCh-A). Our study provides novel insights and scientific basis for the development of ampholetic polysaccharides as high-performance food additives.

Effect of acetylated distarch adipate on the physicochemical characteristics and structure of shrimp (Penaeus vannamei) myofibrillar protein.

To investigate the effect of acetylated distarch adipate (ADA) on the physicochemical properties and structure of shrimp myofibrillar protein (MP), the changes in chemical bonds, secondary structure and protein composition of shrimp MP and MP gel (MPG) were analyzed. Besides, the microstructure, water state, texture properties and water holding capacity (WHC) of MPG with different ADA additions were compared. The results showed that the shrimp MPG with 1% ADA addition had the highest breaking force and gel strength, WHC, and the densest three-dimensional network structure. The ADA had little significant effect on the secondary structure of MP and MPG. In addition, hydrogen and ionic bonds were the main chemical bonds of MP, while MPG is mainly dominated by hydrophobic and disulfide bonds. The correlation analysis of gel properties and water state of MPG showed that bound water and immobilized water had a positive effect on the gel strength.

Water quality profits by the submerged macrophyte community consisting of multi-functional species-rich groups.

The re-establishment of submerged macrophytes facilitates the formation of a clear-water state in shallow eutrophic lakes. But most restorations of submerged macrophytes are often unstable and cannot maintain a stable clear-water state, probably because the species and functional diversity have not been fully taken into account. In this study, we try to explore submerged macrophyte communities and water quality changes under different submerged macrophyte combinations through mesocosm experiments. We hypothesized that communities with high species and functional diversity would be more conducive to improving water quality. The results showed that the mean community biomass of single-species and 8-species were higher than 5-species. And the stability and mean relative growth rate of the 8-species community were higher than the 5-species community. With the same configuration of three functional groups, the 8-species community was more stable and had better water quality than the 5-species community. The path analysis revealed that different functional groups of submerged macrophytes play different roles. The erect and canopy-producing submerged macrophytes were conducive to reducing total suspended solids (TSS) concentrations in the water column during community construction. In contrast, bottom-dwelling submerged macrophytes were conducive to reducing total nitrogen, total phosphorus, and TSS concentrations during the stage of disturbances. Our results also suggested that canopy-producing groups may have a competitive advantage for light over bottom-dwelling species. Based on the above results and biodiversity insurance hypothesis, we conclude that the community consisting of multi-functional species-rich groups is conducive to building stable submerged macrophyte communities and obtaining a stable clear-water state. Our findings will improve water quality management and pollution control for eutrophic shallow lakes.

Exchange Counterion in Polycationic Hydrogels: Tunability of Hydrophobicity, Water State, and Floating Capability for a Floating pH Device.

Smart gel materials are capable of controlling and switching swelling, water state, and wettability properties triggered by external stimuli. In this study, we fabricated a series of polyelectrolyte hydrogels bearing a 3-trimethylammoniumpropyl pendant to a methacrylamide-based backbone and examined the switchability with hydrophobic-like counteranions. The exchange between the initial chloride and camphor sulfate (CaS), dodecyl sulfate (DS), and perfluorooctanoate (PFO) counterions was investigated. The kinetics of the exchange showed that the fast exchange (within 4 h) of PFO allowed for a favorable coordination for ion pairing, resulting in a decrease in hydration. The reversibility of the exchange to the Cl- ion was only enabled for the CaS ion due to its bulkiness, while the PFO and DS hydrogels were unable to exchange, even by using tetrabutylammonium chloride, which is a structurally similar reagent, due to aggregation or the coagulates in the collapsed state of the linear tails of the counterions. The hydrogels exhibited a modulable water state and water swelling. Moreover, the hydrogels containing DS and PFO, as counterions, showed surface hydrophobic (contact angle 90°) and high hydrophobic (110°) behavior, respectively. The Raman spectrometry fluorescence with a pyrene probe indicated an increase in strong hydrogen-bonded water molecules, water confinement, and hydrophobic domains in the PFO hydrogel. Moreover, the PFO-modified hydrogel demonstrated a free-floating ability on the water surface, with a strong water repellency, showing that it has the potential to be applied in a floating pH detection device to distinguish between volatile and nonvolatile bases in a controlled manner.

Effect of hydration on water state, glass transition dynamics and crystalline structure in chitosan films.

The influence of water uptake on water state, glass transition dynamics and crystalline structure in chitosan films was investigated by differential scanning calorimetry (DSC), X-ray diffraction and infrared spectroscopy (FTIR) techniques. DSC result indicated that two types of water, i.e., non-freezable water and freezable water, appeared in turn with the gradual increase of water content. Only the non-freezable water was responsible for the reduction of glass transition temperature (Tg), which leveled off at higher hydration levels. Structural analysis revealed that moisture could bring about a slight increase in the crystallinity of polymer due to alignment of hydrated and relaxed chitosan chains in the amorphous region. FTIR result showed that the hydrogen bonds and electrostatic forces existing in chitosan films varied slightly with water content. These observations suggest that changing the water content in such systems offers the possibility to control the microstructure as well as properties of polymers.

Changes of water state and gel characteristics of Hairtail (Trichiurus lepturus) surimi during thermal processing.

This study examined the changes of water state and gel characteristics of Hairtail surimi during thermal processing including two steps. The results showed that there were four content of water in Hairtail surimi gels. Water-holding capacity (WHC) and T23 relaxation time of water and gel strength increased from 47.01 to 78.97% and from 64.23 to 51.52 ms, respectively, and whiteness decreased from 63.87 to 55.22 during the entire thermal processing. Meanwhile, the texture properties including hardness, gumminess, and chewiness declined from 402.42 to 130.41 g, from 294.39 to103.70 g, and from 233.68 to 43.60 g, respectively, during the first step, and then increased markedly during the second step from 130.41 to 2,301.87 g, from 103.70 to 1,250.99 g, and from 43.60 to 978.51 g, respectively. Furthermore, the WHC and textural profile had positive correlation, and changes in protein secondary structure were interesting, with the α-helices decreasing significantly from 26.40 to 14.12%, while the ß-sheet and the random coil structure increasing significantly from 36.28 to 44.03%, and from 10.89 to 14.31%, respectively, and ß-turn structure increasing form 26.44 to 27.98% during the first step and then declining markedly during the second step, moreover ß-sheet had a fine positive correlation with WHC hardness and chewiness. Overall, dense, porous and compact three-dimensional network gel structure gradually formed. In a word, during thermal processing. WHC of Hairtail surimi increased, and protein secondary structure of protein became orderly, and a fine, dense gel formed during thermal processing. Water is considered as the highest and most important chemical constituent in surimi products. During surimi gelation, water molecules exist as bulk water and motionally restricted water on the protein surface. In order to gain more insights into the surimi heating-induced gelation processing, and improve the surimi gel properties, and give same advice to manufacturing enterprise, this work was conducted to study the structural changes of protein and water state during surimi gelation processing and performed along with the monitoring of the texture, WHC and other physical characteristics of surimi gel, as well as the microstructure of surimi gel.

Water state and sugars in cranberry fruits subjected to combined treatments: Cutting, blanching and sonication.

To ease the mass exchange in fruit tissues, cutting and blanching are traditionally performed. However, recently, unconventional methods such as sonication are becoming more popular, which cause several alterations of physical and chemical properties as well as microstructure changes. The aim of this work was to evaluate the distribution of water inside the cranberry fruits, microstructural changes and sugars content, following traditional and sonication pre-treatments in osmotic solutions. TD-NMR spectroscopy was used to measure the transverse relaxation time (T2) and intensity of proton pools in different cellular compartments. The microstructure of the samples was evaluated by SEM microscopy, sugars content by HPLC and sucrose melting temperature and enthalpy by DSC. Different pre-treatments appeared to promote microstructure alterations and loss of water from vacuole and cytoplasm/extracellular space, more pronounced in cut and blanched samples. Cutting and blanching followed by osmotic dehydration with assisted sonication eased sucrose penetration into the tissue.

Investigation of water state during induced crystallization of honey.

This work studied water state of honey during crystallization, obtained statically and dynamically, by differential scanning calorimetry (DSC), water activity (aw) assessment and time domain nuclear magnetic resonance (TD-NMR). Crystallization was induced by adding 5% of crystallized honey to three honey samples with different fructose/glucose ratio, the key characteristic for honey crystallization. Samples were stored at 14 °C. Dynamic crystallization was obtained by using an impeller. DSC showed that the dynamic crystallization was faster than the static one, the latter characterized by two phases, showing different rates. The crystallization rate did not affect aw, that remained below 0.600. TD-NMR allowed to separately observe two kinds of protons, both pertaining to liquid sugars, one chemically exchanging with water and one not exchanging with it. The combination of techniques allowed speculating that the two crystallization methods led to crystals of different size and shape.

Insight into hydrogen bonds and characterization of interlayer spacing of hydrated graphene oxide.

The number of hydrogen bonds and detailed information on the interlayer spacing of graphene oxide (GO) confined water molecules were calculated through experiments and molecular dynamics simulations. Experiments play a crucial role in the modeling strategy and verification of the simulation results. The binding of GO and water molecules is essentially controlled by hydrogen bond networks involving functional groups and water molecules confined in the GO layers. With the increase in the water content, the clusters of water molecules are more evident. The water molecules bounding to GO layers are transformed to a free state, making the removal of water molecules from the system difficult at low water contents. The diffuse behaviors of the water molecules are more evident at high water contents. With an increase in the water content, the functional groups are surrounded by fewer water molecules, and the distance between the functional groups and water molecules increases. As a result, the water molecules adsorbed into the GO interlamination will enlarge the interlayer spacing. The interlayer spacing is also affected by the number of GO layers. These results were confirmed by the calculations of number of hydrogen bonds, water state, mean square displacement, radial distribution function, and interlayer spacing of hydrated GO. Graphical Abstract This work research the interaction between GO functional groups and confined water molecules. The state of water molecules and interlayer spacing of graphene oxide were proved to be related to the number of hydrogen bonds.