NaCl Pretreatment Research Articles

Optimization of Microwave-Assisted Inorganic Salt Pretreatment for Production of Fermentable Sugars from Spent Coffee Ground

Spent coffee ground (SCG) is a solid waste that is generated in the coffee brewing process for coffee beverage production. SCG hold a great potential in reducing sugar production as it consists of high amount of carbohydrates. However, SCG is a lignocellulosic biomass (LCB) which requires pretreatment to degrade the lignocellulosic structure and enhance enzyme accessibility during saccharification process. Hence, this research aims to study the performance of microwave-assisted inorganic salt pretreatment for generation of reducing sugars. Different concentrations of NaCl was applied to determine their effects on reducing sugar produced as well as pH, and solid recovery. Pretreatment with 3% NaCl was found to yield the highest reducing sugar concentration of 43.56 mg/mL, hence it was selected for the subsequent optimization study. Process optimization was designed by using the Response Surface Methodology approach (RSM) with Central Composite Design (CCD), based on three pretreatment parameters; solid to liquid ratio (1:50 - 8:50), microwave power (300W – 800W) and irradiation time (1-10 minutes). The optimized conditions were achieved at solid to liquid of 8:50, microwave power of 800 watt and irradiation time of 10 minutes for a maximum response of 40.89 mg/mL. Moreover, it was observed that microwave-assisted NaCl pretreatment had significantly caused surface morphological changes of the SCG and the removal of functional groups in lignin, resulted in increment of the crystallinity value. In conclusion, microwave pretreatment is a promising green technology for fermentable sugar production from SCG.

New insight into enhanced carbon recovery from anaerobic fermentation of waste activated sludge with cation exchange resin coupled with NaCl pretreatment

Carbon recovery from waste activated sludge has been attracting considerable attention. However, the migration and transformation patterns of carbon sources between the phases have rarely been reported. In this study, a novel strategy using cation exchange resin (CER) coupled with sodium chloride (NaCl) to enhance carbon recovery through anaerobic fermentation (AF) was proposed. The results demonstrated that CER coupled with NaCl destroyed OH and CO stretching in amide I while promoting the formation of β-sheet and random coil structures, leading to sludge disintegration. This significantly improved the kinetics of endogenous carbon release, resulting in the release of 1146.33 mg/L of carbon from the solid sludge into the liquid phase. Approximately 75.61 % of the initial carbon source was bio-transformed into short-chain fatty acids. Correspondingly, carbon recovery was significantly increased up to 852.23 mg C/L, 4.57 times that of the control. Mechanism exploration revealed that carbon source recovery was significantly elevated by the synergistic effect of CER and NaCl. CER effectively removed high-valence cations from extracellular polymeric substance (EPS), weakening its bridging and adsorption-electro neutralization capabilities, promoting protein deflocculation, and triggering EPS disruption to release extracellular carbon sources. NaCl disrupted the ionic strength and distribution inside and outside microbial cells, creating an osmotic pressure difference that resulted in cell plasmolysis and lysis, ultimately inducing the release of intracellular carbon sources. Economic and carbon emission reduction benefit analyses verified that the CER coupled with NaCl pretreatment is a cost-effective sludge treatment strategy. This study illustrates the carbon source migration and transformation pathways in the CER coupled with NaCl-assisted AF process, providing guidance for sustainable sludge management.

Chemical Compositions and Characteristics of Biocalcium from Pre-Cooked Tuna Bone as Influenced by Sodium Chloride Pretreatment and Defatting by Asian Seabass Lipase.

Pre-cooked bone is a waste product generated during tuna processing and can serve as a potential source of biocalcium (BC). Generally, non-collagenous protein and fat must be removed properly from bone. A NaCl solution can be used to remove such proteins, while fish lipase can be used in a green process, instead of solvent, for fat removal. Thus, this study aimed to investigate the impact of NaCl pretreatment at different concentrations in combination with heat to eliminate non-collagenous proteins, and to implement fish lipase treatments at varying levels for fat removal, for BC production from pre-cooked tuna bone. Optimal NaCl pretreatment of bone was achieved when a 5% NaCl solution at 80 °C was used for 150 min. The lowest lipid content was obtained for bone defatted with crude lipase extract (CLE) at 0.30 Unit/g of bone powder for 2 h. BC powder from bone defatted with CLE (DF-BC) possessed greater contents of ash, calcium, and phosphorus and smaller particle sizes than the control BC powder. X-ray diffractograms suggested that both BC powders consisted of hydroxyapatite as a major compound, which had a crystallinity of 62.92-63.07%. An elemental profile confirmed the presence of organic and inorganic matter. Thus, BC powder could be produced from pre-cooked tuna bone using this 'green process'.

Photosynthetic mechanisms underlying NaCl-induced salinity tolerance in rice (Oryza sativa)

BackgroundSalinity stress is an environmental constraint that normally develops concurrently under field conditions, resulting in drastic limitation of rice plant growth and grain productivity. The objective of this study was to explore the alleviating effects of NaCl pre-treatment on rice seedlings as well as the salt tolerance mechanisms by evaluating morph-physiological traits.ResultsVariety Huanghuazhan, either soaked in distilled water or 25 mg/L Prohexadione calcium (Pro-Ca), were first hardened with varying concentrations of NaCl solutions (0 and 50 mM NaCl), and then subjected to varying degrees of salt stress (0 and 100 mM NaCl), indicated by S0, S1, S2 and S3, respectively. Growth analysis suggested that NaCl-pretreatment improved the root/shoot ratio in water-soaked rice plant at DAP 0. Data related to the reaction center density, photosynthetic electron transport efficiency, trapping efficiency were compared before (CK) using performance Index (PIabs). Compared to S2 (Pro-Ca-S2) treatment, PIabs did not show any difference with plants pre-treated with NaCl (S3 or Pro-Ca-S3). Rather than PIabs, significant difference was found in photosynthetic electron transport efficiency (ΨEo). The ΨEo value in Pro-S2 was significantly lowered as compared to Pro-S3 treatment at DAP 7, and the decrease rate was about 6.5%. Correlation analysis indicated leaf PIabs was weak correlated with plant biomass while the quantum yield for reduction of the PSI end electron acceptors, trapped energy flux per reaction center and PSII antenna size displayed strong positive correlation with biomass. Additional analysis revealed that 100 mM NaCl significantly reduced leaf linear electron flux under low-light conditions, regardless of whether seedlings had been pre-treated with 50 mM NaCl or not.ConclusionsNaCl-induced salt tolerance was related to the robust photosynthetic machinery.

Effect of NaCl Pretreatment on the Relationship between the Color Characteristics and Taste of Cirsium setidens Processed Using a Micro-Oil-Sprayed Thermal Air Technique.

Cirsium setidens is commonly used as a food ingredient, and it is typically stored and distributed in a dried form to prolong its shelf life. In a previous study, a micro-oil-sprayed thermal air (MOTA) technique was developed, which effectively enhanced the rehydration properties and improved the color characteristics of Cirsium setidens after processing. Here, we investigated the relationship between the color characteristics and taste of MOTA-processed C. setidens and the effect of NaCl pretreatment, prior to processing, on the final quality of dried C. setidens. NaCl pretreatment, whether combined with the MOTA technique or not, showed improved color characteristics, in which MOTA-and NaCl+ MOTA-processed C. setidens manifested equal color characteristics. In contrast, NaCl + MOTA-processed C. setidens resulted in significantly higher values of sourness and saltiness than MOTA-processed C. setidens when the taste of the rehydrated C. setidens was examined using an electronic tongue (Astree II; Alpha MOS, Toulouse, France). Pearson correlation coefficient analysis showed that sourness and saltness were negatively correlated with Hunter a* values and positively correlated with Hunter L* and Hunter b* values, indicating that the color characteristics of dried and rehydrated C. setidens could be indicators of taste. Furthermore, the amounts of total phenol and chlorophyll were better preserved in C. setidens processed by the MOTA technique with NaCl than by the MOTA technique alone. Our data revealed that the color characteristics of dried plants are associated with the taste of processed C. setidens, and that the MOTA technique with NaCl pretreatment is a useful method for preserving health-promoting compounds during processing.

Comparing Efficiency of Green Methods for Surimi Skin and Bone Gelatin Extraction

Globally, the surimi processing industry produces a large amount of by-products in the form of head and viscera, skin, bones, scale, etc. The aim of this study was to assess the combined biomass of pink perch skin and bones obtained from the surimi industry as a potential source of raw material for gelatin production and identify a green method of gelatin extraction by comparing four green processes. Four green gelatin extraction processes were compared for their gelatin extraction efficiency. Among the four processes, process 1 and process 2 comprised of two-step extraction viz pre-treatment with NaCl and extraction with hot water. Process 3 and process 4 comprised of single-step wherein pre-treatment and extraction were done simultaneously with acidic water using acetic acid. The gelatin extraction efficiency was determined based on the yield and L-hydroxyproline content of the extracted gelatin. Further, the extracted gelatin was characterized for their proximate and amino acid composition. The acetic acid based single-step method was found to be more efficient in the extraction of gelatin than the NaCl pretreatment method. The gelatin extracted with this method had a higher yield (4.2%), protein content (79.6%), and imino acid (27.3%) content than the NaCl pretreatment method, which had 1.51% gelatin yield, 48.1% protein content, and 13.1% imino acid content. The results suggested that the single-step extraction method can be effectively utilized for the extraction of gelatin from pink perch skin and bones combined biomass. This study provides a method for the valorization of the surimi industry by-product into a high value product with potential application in various industries.

Evaluation of the Physicochemical and Techno-functional Properties of Gelatin Extracted from Fish Processing Waste

The current research was completed at the Indian Council of Agricultural Research - Central Institute of Fisheries Technology (ICAR-CIFT), Cochin, Kerala, India from August 2021 to August 2022 as a modified thermal extraction protocol for deriving gelatin from processing waste of skipjack tuna (Katsuwonus pelamis) skin. The study evaluated the effect of chemical composition and molecular weight contributing to the techno-functional attributes of the resulting gelatin. In the present study, we followed warm water-coupled NaCl pre-treatment to reduce the lipid content of the extracted gelatin. The extracted gelatin was characterized for Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE). The amount of gelatin extracted from the fish skin was 9.30±0.22%. The protein pattern of extracted gelatin on SDS-PAGE was identical to commercial grade gelatin, which implies the purity of extracted gelatin is comparable to that of commercial one. The physicochemical and functional properties were evaluated and pose remarkable techno-functional properties. Therefore, fish processing skin waste of skipjack tuna could be effectively exploited for the preparation of commercial gelatin. The extraction protocol remains environment friendly and this approach remains optimal for food technological applications. The effective exploration contributed to nutritional benefits, technological, functional, and biological functionalities for a large fraction of applications in the area of food technology, nutraceuticals, pharmaceutics, and numerous others as a future line of research.

Effect of chemical pretreatment on quality attributes of the cashew apple.

Cashew apples, tropical pseudo fruit, are rich in bioactive compounds. It is still underutilized due to its high perishability and its astringent flavor. This study aims to extend its shelf life by chemical dip and dry method at the rural level. Inhibition of fruit-spoiling enzymes, such as polyphenol oxidase (PPO), peroxidase (POD), amylase, and cellulase, was a significant response in this method. Enzyme inhibition was carried out using chemicals: NaCl (1-10mM), CaCl2 (1-10mM), and ethylenediamine tetraacetic acid (0.1-1mM). The effect of chemical concentration and dipping time was studied using a full factorial method at three levels (-1, 0, and 1). The dipping time ranged from 60 to 180min, and chemical concentrations from 1 to 10mM were studied. Optimal treatment conditions were obtained as follows: NaCl concentration of 9.45mM, dipping time of 160min, and CaCl2 concentration of 7.8mM, dipping time of 160min. NaCl pretreatment showed maximum inhibition of PPO (>80%) and POD (>80%), whereas CaCl2 pretreatment showed maximum inhibition of amylase (60.58%) and cellulase (80.23%). Hence, to avoid postharvest losses, pretreatment with NaCl and CaCl2 was adequate to preserve the texture and color of cashew apples. PRACTICAL APPLICATION: Chemical pretreatment can prevent the postharvest losses of cashew apples. Inhibition of PPO, POD, amylase, and cellulase is vital in the shelf-life extension of cashew apples. Sodium chloride dip is a cost-effective method for increasing the storability of cashew apples.

Pretreatment of NaCl enhances the drought resistance of cotton by regulating the biosynthesis of carotenoids and abscisic acid

Drought stress is one of the abiotic stresses that limits crop production and greatly affects crop yield. Enhancement of plant stress resistance by NaCl pretreatment has been reported, but the mechanism by which NaCl pretreatment activates cotton stress resistance remains unclear. In this study, upland cotton (Gossypium hirsutum cv H177) was used as the material to conducted the treatments with three replications: 0 Mm NaCl + 0% PEG6000 (Polyethylene glycol), 0 mM NaCl + 15% PEG6000, 50 mM NaCl + 15% PEG6000 to explore the molecular mechanism by which NaCl improves the drought tolerance of cotton. The results showed that pretreatment with 50 mM NaCl could alleviate the adverse effects of PEG on cotton seeds while promoting the elongation of root length. RNA-seq showed that NaCl specifically induced the expression of carotenoid-related genes. By silencing the upstream gene GHLUT2 of lutein synthesis, it was found that the chlorophyll of silenced plants decreased, and leaf wilting was more sensitive to drought. We found that NaCl enhanced the drought resistance of cotton by regulating genes related to the carotenoid and abscisic acid downstream synthesis pathways. This study provides a new reference for the study of drought resistance in cotton and a theoretical basis for the molecular breeding of cotton.

NaCl Pretreatment Enhances the Low Temperature Tolerance of Tomato Through Photosynthetic Acclimation.

Plants often need to withstand multiple types of environmental stresses (e.g., salt and low temperature stress) because of their sessile nature. Although the physiological responses of plants to single stressor have been well-characterized, few studies have evaluated the extent to which pretreatment with non-lethal stressors can maintain the photosynthetic performance of plants in adverse environments (i.e., acclimation-induced cross-tolerance). Here, we studied the effects of sodium chloride (NaCl) pretreatment on the photosynthetic performance of tomato plants exposed to low temperature stress by measuring photosynthetic and chlorophyll fluorescence parameters, stomatal aperture, chloroplast quality, and the expression of stress signaling pathway-related genes. NaCl pretreatment significantly reduced the carbon dioxide assimilation rate, transpiration rate, and stomatal aperture of tomato leaves, but these physiological acclimations could mitigate the adverse effects of subsequent low temperatures compared with non-pretreated tomato plants. The content of photosynthetic pigments decreased and the ultra-microstructure of chloroplasts was damaged under low temperature stress, and the magnitude of these adverse effects was alleviated by NaCl pretreatment. The quantum yield of photosystem I (PSI) and photosystem II (PSII), the quantum yield of regulatory energy dissipation, and non-photochemical energy dissipation owing to donor-side limitation decreased following NaCl treatment; however, the opposite patterns were observed when NaCl-pretreated plants were exposed to low temperature stress. Similar results were obtained for the electron transfer rate of PSI, the electron transfer rate of PSII, and the estimated cyclic electron flow value (CEF). The production of reactive oxygen species induced by low temperature stress was also significantly alleviated by NaCl pretreatment. The expression of ion channel and tubulin-related genes affecting stomatal aperture, chlorophyll synthesis genes, antioxidant enzyme-related genes, and abscisic acid (ABA) and low temperature signaling-related genes was up-regulated in NaCl-pretreated plants under low temperature stress. Our findings indicated that CEF-mediated photoprotection, stomatal movement, the maintenance of chloroplast quality, and ABA and low temperature signaling pathways all play key roles in maintaining the photosynthetic capacity of NaCl-treated tomato plants under low temperature stress.

Stabilization of Pb, Cd, and Zn in soil by modified-zeolite: Mechanisms and evaluation of effectiveness

As a type of soil stabilization material, zeolite has good cation exchange ability and synchronous stabilization potential for multiple active heavy metal cations in soil. However, natural zeolite contains relatively high amounts of impurities, and has a single heavy metal stabilization mechanism, which limits its capacity to stabilize heavy metals in soil. To develop a stabilization material that could efficiently stabilize several heavy metals simultaneously, in the present study, modified zeolite (MZEO) was prepared via NaCl pretreatment, chitosan modification, modified chitosan loading, and CaSiO3 modification to enable Pb, Cd, and Zn stabilization in soil. The aim of the present study was to explore zeolite modification technologies, reveal the stabilization mechanism of polymetallic contaminated soil and evaluate the stabilization effects of MZEO. According to the results, the modification treatment increased the cation exchange capacity of MZEO nearly 8-fold, the specific surface area 3.4-fold, and its internal pore structure was richer, with more adsorption sites. The appearance of a -NH2 absorption bands confirmed the loading of chitosan successfully, and the modification enhanced the heavy metal stabilization mechanism. Upon the addition of MZEO to Baiyin soil, the chemical morphologies of heavy metals changed, which reduced the weak acid extracted forms of Pb, Cd, and Zn in the soil by 21%, 10%, and 19%, respectively. The potential mechanisms of free heavy metal reduction were ion exchange with Na in MZEO, heavy metal mineral formation by Al replacement in the crystal lattice, and bonding with SiO32− formed by the hydrolysis of MZEO-loaded synaptic CaSiO3 particles, to form silicate precipitation. MZEO application minimized heavy metal leaching risk in the soil and heavy metal biological/plant accessibility, with potential economic benefits. MZEO has promising applications in polluted soil remediation.

Assessing the Performance of Environmentally Friendly-Produced Zerovalent Iron Nanoparticles to Remove Pharmaceuticals from Water

Nano zerovalent iron (nZVI), produced from green tea extracts, was incorporated in a cation exchange resin (R-nFe) to investigate its performance regarding the removal of four non-steroidal anti-inflammatory drugs (NSAIDs): ibuprofen (IBU), naproxen (NPX), ketoprofen (KTP) and diclofenac (DCF). The effect of contact time, NaCl pretreatment, pH, R-nFe dose, the role of the supporting material, the initial concentration of pollutants, and the combined effect of nZVI with oxidative reagents was assessed through a series of batch experiments. According to the results, the best removal efficiencies obtained for DCF and KTP were 86% and 73%, respectively, at 48 h of contact time with NaCl pretreated R-nFe at a dose of 15 g L−1 and a pH of 4. The maximum removal efficiency for NPX was 90% for a contact time of 60 min with PS 1 mM and a pH of 3, which was quite similar to the experiment with a greater contact time of 48 h without PS addition. The maximum IBU removal was 70%; this was reached at pH 3, with a contact time of 30 min and R-nFe 15 g L−1. To the authors’ best knowledge, this is the first study investigating the utilization of nZVI, produced from leaf extracts and incorporated into a cationic exchange resin, to remove NSAIDs from water.

New insight into enhanced short-chain fatty acids production from waste activated sludge through pretreatment of cation exchange resin coupled NaCl addition

In this study, a novel pretreatment of cation exchange resin (CER) coupled NaCl addition was proposed to enhance waste activated sludge (WAS) hydrolysis and promote short-chain fatty acids (SCFAs) production in the anaerobic fermentation process. At the optimal pretreatment condition of 3 g/g SS CER and 15 g/L NaCl, considerable SCOD (i.e. 5107 mg/L, 35.4% of TCOD) was released after 2-day coupled treatment, which provided sufficient organic substance for the subsequent SCFAs production. The sludge hydrolysis mechanism was illustrated, i.e. CER triggered extracellular polymeric substances (EPS) disruption and NaCl induced microbial cells lysis. The synergistic interaction between CER and NaCl pretreatment was investigated and application potential of fermentative liquid was evaluated after the coupled pretreatment-enhanced anaerobic fermentation. In the presence of abundant biodegradable substrates in the fermentative liquid, 4742 mg COD/L (i.e. 388 mg COD/g VSS) of SCFAs production was achieved within 6-day anaerobic fermentation, mainly composed of acetic and propionic acids (70.4% of total SCFAs).

The Programming of Antioxidant Capacity, Immunity, and Lipid Metabolism in Dojo Loach (Misgurnus anguillicaudatus) Larvae Linked to Sodium Chloride and Hydrogen Peroxide Pre-treatment During Egg Hatching.

Non-nutritional stress during early life period has been reported to promote the metabolic programming in fish induced by nutritional stimulus. Sodium chloride (NaCl) and hydrogen peroxide (H2O2) have been widely applied during fish egg hatching, but the influences on health and metabolism of fish in their later life remain unknown. In the present study, H2O2 treatment at 400mg/L but not 200mg/L significantly increased the loach hatchability and decreased the egg mortality, while NaCl treatment at 1,000 and 3,000mg/L showed no significant influences on the loach hatchability nor egg mortality. Further studies indicated that 400mg/L H2O2 pre-treatment significantly enhanced the antioxidant capacity and the mRNA expression of genes involved in immune response of loach larvae, accompanied by the increased expression of genes involved in fish early development. However, the expression of most genes involved in lipid metabolism, including catabolism and anabolism of loach larvae, was significantly upregulated after 200mg/L H2O2 pre-treatment. NaCl pre-treatment also increased the expression of antioxidant enzymes; however, only the expression of C1q within the detected immune-related genes was upregulated in loach larvae. One thousand milligram per liter NaCl pre-treatment significantly increased the expression of LPL and genes involved in fish early development. Thus, our results suggested the programming roles of 400mg/L H2O2 pre-treatment during egg hatching in enhancing antioxidant capacity and immune response of fish larvae via promoting fish early development.

Salt-induced growth promotion in rice varieties during nursery

Climate change will increase the occurrence of salinity in agricultural land along with the coastal areas. One of the technologies to reduce salinity is NaCl pretreatment. This study aimed to evaluate salinity treatment's effect during nurseries on the growth of lowland rice seedlings. There were three separate experiments, and all the experiments used Randomized Complete Block Design. In the first experiment, local black rice seeds (var. Jelitheng) was used. The nursery was carried out at three salinity levels, i.e. 0.2, 3 and 5 dS/m. The second experiment was conducted using salt-resistant rice seeds (var. Dendang) and salt susceptible rice seeds (var. IR 64). The salinity levels applied were non-saline (0.2 dS/m) and saline (5 dS/m). The third experiment used rice seedling var. IR 64, with the first factor being the salinity level (0.2 and 5 dS/m) and the second factor was a wet nursery and dry nursery. In general, the results from the three experiments showed that giving salinity levels of 3-5 dS/m in several rice varieties improved seedling performance. Although salinity during nursery could increase the concentration of Na+ and decrease the concentration of K+ in leaves, salinity during nursery increased the seedlings fresh weight, and dry weight increased the number of seedlings leaves and increased the concentration of leaf chlorophyll. The better seedlings growth variable in the saline nursery will help the plants cope with salinity in the later growth stage in the field.

Application of box–behnken design–based response surface methodology optimization for predicting lignin residue following microwave-assisted inorganic salt (NaCl) pretreatment of Napier grass

ABSTRACT Microwave irradiation is an effective pretreatment method for lignocellulosic biomass. Microwave-assisted inorganic salt (MAIS) pretreatment was employed to treat Napier grass (Pakchong 1) (Pennisetum purpureum) under different conditions to break down lignin from cellulose and hemicellulose in plant cell walls. Lignin and hemicellulose content were investigated under different NaCl concentrations (0.0, 1.0, and 2.0 M), and microwave irradiation was performed at 300, 450, and 800 W at three treatment times (2, 5, and 8 min). The results indicate that under pretreatment conditions of 1.0 M NaCl and 300 W for 2 min, hemicellulose content decreased by 7.93%, cellulose increased from 32.96% to 39.69% (untreated and pretreated, respectively), and lignin content decreased to 20.56%. The predicted lignin residue from the model was 13.85%, and 2 M of NaCl at 600 W for 8 min were determined to be the optimal conditions. Sample morphology following pretreatment was analyzed using scanning electron microscopy. MAIS was found to be effective and efficient for removing hemicellulose and lignin residue.

Characteristics of Reconstituted Collagen Fibers from Chicken Keel Cartilage Depends on Salt Type for Removal of Proteoglycans

The aim of the presented research was to obtain reconstituted atelocollagen fibers after extraction from poultry cartilage using the pepsin-acidic method in order to remove telopeptides from the tropocollagen. Firstly, we examined the extraction of collagen from the cartilage extracellular matrix (ECM) after proteoglycans (PG) had been removed by the action of salts, i.e., NaCl or chaotropic MgCl2. Additionally, the effects of the salt type used for PG and hyaluronic acid removal on the properties of self-assembled fibers in solutions at pH 7.4 and freeze-dried matrices were investigated. The basic features of the obtained fibers were characterized, including thermal properties using scanning calorimetry, rheological properties using dynamic oscillatory rheometry, and the structure by scanning electron microscopy. The fibers obtained after PG removal with both analyzed types of salts had similar thermal denaturation characteristics. However, the fibers after PG removal with NaCl, in contrast to those obtained after MgCl2 treatment, showed different rheological properties during gelatinization and smaller diameter size. Moreover, the degree of fibrillogenesis of collagens after NaCl treatment was complete compared to that with MgCl2, which was only partial (70%). The structures of fibers after lyophilization were fundamentally different. The matrices obtained after NaCl pretreatment form regular scaffolds in contrast to the thin, surface structures of the cartilage matrix after proteoglycans removal using MgCl2.

Application of immersion pre-treatments and drying temperatures to improve the comprehensive quality of pineapple (Ananas comosus) slices

Drying of pineapple slices combined with different pre-treatments was done to reduce various adverse changes by adding satisfactory value. Process optimization was done by dipping the pineapple slices in four different solutions (1% trehalose, 2% NaCl, 10% sucrose, and 10% fructose) before drying. The effects of different pre-treatments and drying temperatures of 50, 55, and 60 °C with a constant 30% relative humidity (RH) were optimized based on the quality attributes, drying time and microbial load of dried pineapple slices. The optimal drying temperature was 55 °C using 1% trehalose pre-treatments based on the physical and biochemical properties. The reconstituted dried pineapples implied at this condition, contributed to the better structure preservation as indicated by the lower shrinkage (0.21) and the higher Coefficient of Rehydration (0.941), and rehydration ratio (6.840). On the other hand, the retention of color, vitamin C, B vitamins, and antioxidant activity of the samples were decreased by increasing drying time and temperatures. The highest Total Phenolic Content (121.02 mg GAE/100g), Total Flavonoid Content (8.72 mg QE/100g), and DPPH radical scavenging activity (7.22 EC50 g/100g) were found at 60 °C drying temperature with 10% fructose pretreatment's samples. The lowest drying time required was 7.64 h using 2% NaCl pre-treatment at 60 °C, considering the time required to reach 20% moisture content in the dried product at 30% RH. Based on the reported results, it is concluded that 1% trehalose at 50 °C can be used to develop high quality pineapple snacks, which maintained the maximum desired physicochemical and nutritious properties. This study could play an essential role in meeting the emerging demand of developing good quality nutritious dried pineapple snacks.

Na+ accumulation alleviates drought stress induced photosynthesis inhibition of PSII and PSI in leaves of Medicago sativa

ABSTRACT To probe the mechanism of action of NaCl in regulating drought adaptation in Medicago sativa, we pretreated M. sativa with different concentrations (0, 50, 100 and 200 mM) of NaCl, then studied the effects of NaCl pretreatment on water content, chlorophyll content, photosynthetic function, and membrane peroxidation of M. sativa plants subjected to drought stress. Although pretreatment with different concentrations of NaCl significantly increased the Na+ content in the aboveground of M. sativa, it had no significant effect on the activity of PSII and PSI. However, different concentrations of NaCl pretreatment significantly increased the water content of the aboveground of M. sativa under drought stress, alleviated the degree of photoinhibition of PSII and PSI, and maintained the flow and stability of donor and acceptor electrons in PSII. NaCl pretreatment promotes the increase of non-photochemical quenching (NPQ), which relieves oxidative damage in the leaves of M. sativa under drought stress, playing an important role in maintaining the activity of PSII and PSI. In conclusion, pretreatment with a certain concentration of NaCl can help M. sativa leaves maintain relatively high-water content and alleviate the photosynthesis inhibition of PSII and PSI under drought stress, thereby improving the drought resistance of M. sativa.

Cotton seedling drought tolerance is improved via salt preconditioning.

In this study, 12 upland cotton seedlings were used as the material, and four treatments were designed (15% PEG for 6 h, 250 mM NaCl for 3 h, 15% PEG for 6 h after 250 mM NaCl pretreatment, and blank control). Various physiological indicators, including the malondialdehyde (MDA) and proline (Pro) contents and superoxide dismutase (SOD) and peroxidase (POD) activities, and the relative electrolyte leakage (REL), were measured during exposure to the aforementioned stresses, and three stress-related transcription factors (GhHsfA, GhbZIP, and GhNAC) were used to assess the differences in the drought resistance of cotton during exposure to PEG stress and NaCl/PEG combined stress. The analyses of the physiological and biochemical indicators revealed that the cotton seedlings exposed to NaCl/PEG combined stress exhibited the highest relative changes in the SOD and POD enzyme activities, while the relative changes in the MDA content and REL were relatively small. The cluster analysis showed that the treatments could be ranked as follows based on degree of damage exhibited by the exposed cotton seedlings: PEG > NaCl > NaCl/PEG. The exposure of cotton to NaCl/PEG combined stress resulted in a lower degree of damage than that obtained after exposure to PEG alone, which indicated that an appropriate amount of NaCl could partially relieve the adverse effects of drought on cotton seedlings. In addition, the relative expression levels of GhHsfA, GhbZIP, and GhNAC were significantly correlated with multiple physiological and biochemical indicators under different stresses, and the principal component analysis identified these transcription factors as important indicators. Based on these findings, these three transcription factors can be used as molecular indicators for the identification of drought resistance. A comprehensive D value cluster analysis ranked the 12 cotton varieties based on their drought resistance, and the most drought-resistant variety was ND359-5. This study provides new methods and materials for research on drought resistance in cotton.