Immersion Pretreatment Research Articles

Effect of ultrasound immersion pretreatment combined magnetic field assisted freezing on the quality of frozen blueberries

This study investigated the effect of ultrasound combined with static magnetic field freezing on the freezing process and quality changes of blueberries. The aim is to provide a reference for the study of magnetic fields in food. The freezing parameters, quality, and microstructural structure were examined. The results showed that the effect of ultrasound-assisted static magnetic field freezing (U-MF) was better, which significantly shorted the freezing time of the sample. In comparison to −20 °C control frozen (CF), the degree of supercooling increased by 50.08%, freezing time shorted by 16.36%, drip loss decreased by 28.28%, respectively, and the water distribution state was closer to that of fresh fruits. Microstructural analysis indicated that the sample structure of U-MF treated blueberries was better approximated by the fresh sample. Moreover, overall sensory scores for blueberries showed that U-MF treated blueberries presented positive sensory evaluation. In conclusion, ultrasound and static magnetic field play a synergistic effect in assisting freezing, and the combined effect is better than that of ultrasound or static magnetic field alone.

A Microporous Channel Copper Immersion Layer Promotes the Rapid Ni-P Electroless Plating Process on Aluminum Alloys at Medium and Low Temperatures

Electroless plating is a commonly used method to enhance the corrosion resistance, wear resistance, and decorative performance of aluminum alloys. However, in electroless plating processes, it is customary to maintain the solution temperature at levels exceeding 85 °C, a critical condition that ensures a sufficiently rapid deposition rate and thereby fosters the formation of high-performance coatings. Conventional immersion pretreatments with zinc and palladium result in lower deposition rates at low temperatures. This study shows that a copper immersion layer with microporous channels can facilitate the electroless plating process for aluminum alloys at lower temperatures. Through a redox reaction in a Cu2+-containing solution at 70 °C, a copper immersion layer with a microporous structure could be created on an aluminum alloy. The microporous channels between the copper immersion layer and the aluminum alloy create electrochemical corrosion cells in the plating solution, accelerating the electroless plating process. The Ni-P coating obtained after pretreatment by copper immersion has a higher hardness (578 HV) and a lower corrosion current density (0.55 μA cm−2). This work provides a practical method to rapidly fabricate high-performance Ni-P coatings at intermediate temperatures (70 °C–75 °C).

Utilization of Flotation Wastewater for Separation of Chalcopyrite and Molybdenite by Selective Surface Passivation

In the flotation separation process of a Cu-Mo-W polymetallic ore, the wastewater from the scheelite cleaning flowsheet contains large numbers of residual flocculants and metal ions, and the separation of chalcopyrite and molybdenite requires a large number of environmentally harmful depressants. Therefore, it is necessary to find new methods to reduce the environmental and cost pressures of wastewater treatment and the use of depressants. In this work, the flotation wastewater from the scheelite cleaning flowsheet for the separation of chalcopyrite and molybdenite by selective surface passivation was investigated for the first time. Flotations of single minerals and artificially mixed minerals with or without immersion pretreatment in the presence and absence of aeration were performed. The results showed that pulp pH had no effect on the flotation of either mineral, and a molybdenite recovery of 93.22% with a chalcopyrite recovery of 10.77% was achieved under the conditions of 10 days of immersion pretreatment with aeration, 350 mg/L of kerosene, and 100 mg/L of MIBC. By combining the electrochemical cyclic voltammetry analysis and characterization by XRD and SEM, the selective surface passivation mechanism of chalcopyrite was discussed, which could be due to the coverage of the insoluble oxidation products, especially jarosite. This work has simultaneously achieved the depressant-free flotation separation of molybdenite and chalcopyrite and the reuse of scheelite flotation wastewater, which is of great significance for environmental protection and cost saving.

Modification of Al Surface via Acidic Treatment and its Impact on Plating and Stripping.

Amorphous Al2 O3 film that naturally exists on any Al substrate is a critical bottleneck for the cyclic performance of metallic Al in rechargeable Al batteries. The so-called electron/ion insulator Al oxide slows down the anode's activation and hinders Al plating/stripping. The Al2 O3 film induces different surface properties (roughness and microstructure) on the metal. Al foils present two optically different sides (shiny and non-shiny), but their surface properties and influence on plating and stripping have not been studied so far. Compared to the shiny side, the non-shiny one has a higher (~28 %) surface roughness, and its greater concentration of active sites (for Al plating and stripping) yields higher current densities. Immersion pretreatments in Ionic-Liquid/AlCl3 -based electrolyte with various durations modify the surface properties of each side, forming an electrode-electrolyte interphase layer rich in Al, Cl, and N. The created interphase layer provides more tunneling paths for better Al diffusion upon plating and stripping. After 500 cycles, dendritic Al deposition, generated active sites, and the continuous removal of the Al metal and oxide cause accelerated local corrosion and electrode pulverization. We highlight the mechanical surface properties of cycled Al foil, considering the role of immersion pretreatment and the differences between the two sides.

Efficient fermentable sugar production from mulberry branch based on a rational design of GH10 xylanase with improved thermal stability

The mulberry branch can be used as a renewable biomass resource for the production of biofuels since it contains a significant amount of lignocellulose. However, the rapid deactivation of enzymes during lignocellulose degradation in a high-temperature environment leads to high costs and low efficiency of enzymatic saccharification. In this study, xylanase was modified by rational design, and xylanase and cellulase were used to synergistically degrade mulberry branches pretreated with seawater. The fermentable sugar yield and degree of synergy (DS) were determined. The dominant mutant S21Y/N318W of Hortaea werneckii xylanase Hwxyl10A was obtained with improved thermostability (T50 increased by 12 °C, t1/2 is 17-fold that of WT). Meanwhile, the specific activity at 75 °C increased from 1470 to 1901 U/mg. Under the condition of seawater immersion pretreatment, the highest yield of fermentable sugar was 313.5 μmol/g, and the highest DS was 1.57 after enzymatic hydrolysis of mulberry branches by cellulase and S21Y/N318W at 50 °C. Therefore, the biotransformation of mulberry branches reducing sugar has been significantly improved, which provides an efficient method of biomass saccharification for biofuel production.

PRE-TREATMENTS AND DRYING METHODS ON THE PHYSICOCHEMICAL AND SENSORY CHARACTERISTICS OF WILD MUSHROOMS (Suillus luteus) FROM APURIMAC-PERU

The objective of this research was to evaluate the effect of pre-treatments and drying methods on the physicochemical and sensory characteristics of edible wild mushrooms, Suillus luteus, collected in the pine forests of the Apurimac region, Peru. Two immersion pre-treatments were used: 5% lemon juice and 6% vinegar. Mushroom caps were cut into 3-cm thick slices, immersed at a ratio of 1:5 (w-v), and subsequently dried by direct solar drying and indirect solar drying using a fitotoldo (shade cover). The proximate composition, rehydration, color, total polyphenol content (TPC), antioxidant capacity (DPPH capacity), and sensory evaluation were determined for each sample. The results showed significant differences (p 0.05) between the treatments. Higher rehydration rates were observed in the samples subjected to direct solar drying and fitotoldo drying without pre-treatment, as well as those treated with vinegar. Regarding color, luminosity (L ) significantly decreased in the dried samples compared to the fresh sample. In the proximate analysis, the untreated samples had protein, crude fiber, and ash contents of 23.67 g 100 g, 11.10 g 100 g, and 5.59 g 100 g, respectively. Free-nitrogen extract (FNE) content increased to 47.13 g 100 g as mushrooms lost water. TPC and antioxidant capacity decreased significantly in the dried samples, but the pre-treated samples with vinegar recorded higher values of 8.38 mg GAE g and 54.13 umol TE g, respectively. In the sensory evaluation, the samples pre-treated with vinegar had higher color, texture, and acceptability scores. Thus, the use of a fitotoldo without pre-treatment and with vinegar pre-treatment is the most efficient method for drying Suillus luteus mushrooms.

Applicability of Immersion Pretreatment to Easy Disassembly of Adhesive Joints

Applicability of Immersion Pretreatment to Easy Disassembly of Adhesive Joints

Evaluation of water contact influence on adsorbents by water immersion pretreatment and serial batch tests

Evaluation of water contact influence on adsorbents by water immersion pretreatment and serial batch tests

Cold Water Immersion Pretreatment of Post-Consuming Particleboards for Wood Chips Recovery by the Hydromechanical Process

In this research work, the effect of 20-day immersion of various types of reclaimed particleboards on thickness swelling and water absorption is investigated. This simple procedure has been chosen as the pretreatment to facilitate the chips’ recovery by the hydromechanical (water jet) method. Maximum swelling was achieved after 20-day immersion but the differences between 10 and 20-day immersion were small, indicating that the time of 10-day immersion can be chosen as the pretreatment time. It was found that the bond between wood chips’ particles was not completely failed since the permanent swelling after immersion and drying was lower than the maximum swelling. Hence, the proposed method needs to be improved by increasing the cross-section areas of particleboard samples after their breaking in order to create irregular pieces and facilitate the water action against the bond of wood particles.

Dehydration of apple slices by sequential drying pretreatments and airborne ultrasound-assisted air drying: Study on mass transfer, profiles of phenolics and organic acids and PPO activity

Pretreatments of either water blanching or NaCl immersion and airborne ultrasound-assisted air drying were combined to dehydrate apple slices. The drying time was found to be reduced by 1.6–69.0% compared with air drying without any pretreatment and sonication. Meanwhile, it was found that sequential water blanching coupled with air drying with sonication gave the shortest drying time. A modified diffusional model incorporating temperature-dependent moisture diffusivity (Deff) could simulate the apple drying process well. Water blanching pretreatment and airborne sonication were found to lower the activation energy required for the enhancement of moisture diffusive ability, and intensify water exchange on apple surface to speed up the drying process. Both water blanching and NaCl immersion significantly increased the amounts of procyanidin B2 in dehydrated apple slices. However, airborne sonication promoted the loss of procyanidin B2 in apple slices with pretreatments during air drying. In addition, sonication had no obvious influences on apple PPO activity and individual organic acids throughout drying. Overall, the sequential NaCl immersion pretreatment (or water blanching pretreatment) and drying with airborne sonication are effective to improve the quality of dried apple slices.

Improved Adhesion of the DLC Coating Using HiPIMS with Positive Pulses and Plasma Immersion Pretreatment

Diamond-like carbon (DLC) coatings are used due to their extraordinary tribomechanical properties, great hardness, high elastic modulus, high wear resistance, low friction coefficient and chemical inertness, which provide them with biocompatibility. Compared to other physical vapor deposition (PVD) coatings of transition nitrides and carbonitrides, DLC has limited adhesion, so it is necessary to develop new techniques to overcome this limitation. This work reports the results of scratch testing for the measurement of adhesion and of tests for wear resistance and nanoindentation in AISI 316L stainless steel coated with a WC:C coating, produced using novel high-power impulse magnetron sputtering (HiPIMS) technology with positive pulses. In addition, the use of a preceding surface modification technique, specifically plasma immersion ion implantation (PIII), was studied with the aim of optimizing the adhesion of the coating. The results show how the coating improved the tribomechanical properties through the use of positive pulse HiPIMS compared to conventional HiPIMS, with an adhesion result that reached critical load values of 48.5 N and a wear coefficient of 3.96 × 10−7 mm3/nm.

The combined impact of calcium lactate with cysteine pretreatment and perforation-mediated modified atmosphere packaging on quality preservation of fresh-cut 'Romaine' lettuce.

The effect of perforation-mediated modified atmosphere packaging (PM-MAP) in combination with calcium lactate (1.5% CaL) and cysteine (0.1, 0.5% Cys) immersion pretreatments on the quality preservation of fresh-cut 'Romaine' lettuce was assessed for 12 days, at 5 and 10 °C. The shredded lettuce was packed in low-density polyethylene films (LDPE, 62µm thickness), including different perforation numbers of 0 (N-MAP), 20 (20-PM-MAP, Diameter = 64µm), and 40 (40-PM-MAP, Diameter = 64µm)per in square meter. Indices of quality maintenance were investigated. The total microbial counts were below the specified limits for ready-to-eat vegetables (< 6 log CFU/g) considering both pretreated 20-PM-MAP and N-MAP samples on day 12. After 8 days, a significant difference (P <0.05) was observed in the browning index (BI), the total color difference (ΔE), and the chlorophyll content between N-MAP and 20-PM-MAP samples with better results in 20-PM-MA packages. At 10 °C, the BI in pretreated 20-PM-MAP samples was 32.44% to 58.35% less than N-MAP samples, on the last day of storage. The 20-PM-MAP samples pretreated with 1.5% CaL/0.5% Cys had the highest (P <0.05) crispness coefficient and water content values. It seems that packaging the pretreated lettuce in 20-PM-MA packages is more effective for maintaining the visual properties (green fresh appearance) of this product, from the 8th to the 12th day of storage. PRACTICAL APPLICATION: The medium to high respiration rate of fresh-cut lettuce causes O2 level drops below its tolerance limit (<1% to 3%) inside the modified atmosphere packaging (MAP). It results in severe browning, off-odors, off-flavor, and growth of anaerobiosis. Perforated-mediated modified atmosphere packaging (PM-MAP) technology can be introduced as an alternative to a nonperforated MAP system (conventional MAP) for fresh-cut lettuce. The application of the PM-MAP system in combination with calcium lactate and cysteine immersion pretreatment (CaL/Cys) may lead to better maintenance of the physicochemical properties of this product.

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.

Use of ultrasound as a pre-treatment for vacuum cooling process of cooked broiler breasts

In this study, ultrasound application at two different frequencies (37 or 80 kHz) and durations (15 or 30 min) was used as a pre-treatment for raw broiler breasts, and its effect on cooling, color, textural and sensory characteristics of cooked broiler breasts during vacuum cooling process was determined. The anterior and posterior parts of broiler breast halves were carefully removed, and these parts with a 20 mm width were named as the regions A and B, respectively. Both regions were vacuum-packed and pre-treated by ultrasound, followed by oven-cooking in aluminum foils, and cooling time, weight loss and temperature distribution characteristics were determined. Besides sensory and textural properties, the effect of the ultrasound pre-treatment on the pH, dry matter and ash contents and color (CIELAB) values of cooked breasts was determined. During vacuum cooling, ultrasound pre-treatment significantly reduced cooling time required to cool cooked broiler breasts from 85 °C to 12.5 °C, and the lowest values for the regions A and B were obtained for the 30 min ultrasound pre-treatment at 37 kHz as 12.72 and 14.61 min, respectively (p < 0.05). The cooling losses of breasts from the regions A and B were 12.64 and 11.61%, respectively. In comparison to immersion pre-treatment, increasing the frequency and duration of ultrasound pre-treatment generally decreased cooking loss values for both A and B regions while cooling loss increased. Instrumental hardness values of breast samples for the 15 min ultrasound pre-treatment decreased while they increased with the 30 min pre-treatment (p < 0.05) at both frequencies. The redness values (a*) increased by ultrasound pre-treatment while the highest value was found for a 30 min pre-treatment at 80 kHz for both regions. Sensory hardness (on a 14.5 cm scale) results indicated that the highest value (9.33) was determined for a 30 min ultrasound pre-treatment at 37 kHz while the ultrasound pre-treatment at 37 kHz for 15 min had no negative effect on hardness compared to control samples (p > 0.05). In conclusion, ultrasound pre-treatment can be successfully used for the vacuum cooling process of broiler breasts for the reduction of cooling time, and a 30 min ultrasound pre-treatment at 37 kHz can provide relatively superior cooling characteristics.

Effects of hot water immersion pretreatment on biogas production from Eupatorium adenophorum Spreng

ABSTRACT Eupatorium adenophorum Spreng is an invasive weed and an abundant carbon resource threatening the safety of ecosystems and humans. We evaluated hot water immersion (HWI) pre-treatment of E. adenophorum to produce biogas by anaerobic digestion. Chemical components (hemicellulose, cellulose, and lignin) did not change significantly between treated and untreated samples. The cumulative methane yield of HWI-pre-treated versus untreated samples significantly decreased by 62.59%. However, the anaerobic digestion period was shortened by 42.86% after pre-treatment compared with 35 d before HWI pre-treatment. Furthermore, kinetic analysis shows that cumulative methane production data fitted well to the modified Gompertz model.

Production and characterization of freeze-dried banana slices pretreated with ascorbic acid and quince seed mucilage: Physical and functional properties.

The objective of this investigation was to illustrate the effects of quince seed mucilage (QSM) and ascorbic acid pretreatments to prevent the quality of freeze‐dried banana slices. The studied parameters were moisture content, antioxidant activity, total phenol, color properties, structural properties, and sensory evaluation. Both treatments were effective in protecting total phenolic content and antioxidant activity in dried banana slices (P ˂ .05). The control slices showed greater increase in browning index (BI) and greater decrease in lightness (L*) than pretreated dried samples. Ascorbic acid and QSM treatments can be effective in the control of the enzymatic browning along with maintaining the quality properties of banana chips. Therefore, using of immersion pretreatment with 0.25% QSM and 0.05% ascorbic acid is recommended to prevent enzymatic browning as well as maintain the quality of banana chips before the drying process.

Deposition of mirror-like surface finish ultrananocrystalline diamond films on tungsten carbide by optimizing the substrate pretreatment

In this study, we successfully fabricated ultrananocrystalline diamond (UNCD) films on tungsten carbide with mirror-like surface finish (Ra < 40 nm), strong adhesion, and exceptional tribological performance by adopting the optimized two-step pretreatment process. It was found that the ultrasonication in Murakami reagent will substantially increase the substrate surface roughness even with short duration, which is less controllable compared with that of immersion in Murakami reagent. Besides, the surface roughness is strongly affected by acid etching when the substrate is firstly ultrasonicated in Murakami reagent. However, it is much less influenced for the immersion pretreatment. With the UNCD film, a decrease in the surface roughness up to 72% can be realized compared with the as-pretreated substrate. The Rockwell indentation tests demonstrate that the adhesive strength of the UNCD film deposited with the optimized pretreatment is comparable to that of MCD and NCD films as reported in other studies. Ball-on-plate tribotests with Si3N4 counterpart balls reveal that the coefficient of friction (COF) of the UNCD film is 0.07–0.12, which is 76.6% and 41.6% lower compared with that of the MCD and NCD film. The wear rate of the UCND film is 0.708–1.844 × 10−7 mm3/(N·m), close to that of the MCD and NCD film. The results reported in study provide significant insights into the scientific and industrial research of diamond-coated WC-Co cutting tools.

Application of sodium chloride and quince seed gum pretreatments to prevent enzymatic browning, loss of texture and antioxidant activity of freeze dried pear slices.

In the study the effect of sodium chloride and quince seed gum solutions as immersion pretreatment to prevent enzymatic browning reaction in pear slices before freeze drying was evaluated. Four levels of gum concentrations (0%, 0.25%, 0.5% and 1%) and three concentrations of salt (0%, 0.25% and 0.5%) were used. Subsequently, freeze drying method was used to dry the pear slices and the qualitative, structural and sensory characteristics of dried pear slices were investigated. The moisture content of the dried pear slices decreased significantly with increasing sodium chloride concentration, while increasing the concentration of the gum significantly increased the moisture content (P < 0.05). Use of both immersion pretreatments were effective in maintaining the antioxidant activity and reducing browning index of the slides and with increasing concentration of the immersion solutions, the antioxidant activity loss decreased in the slices (P < 0.05). Electron microscopy study revealed that the microstructural changes of the drying process on the slices are very slight, although gum pre-treatment at the high levels made a layer on the surface of the pear slices which slowed down the transfer of water vapor molecules. By considering the results of qualitative, structural and sensory evaluations, using of immersion pretreatment with 0.25% gum and 0.25% salt solution to prevent enzymatic browning along with preserving the quality properties of pear slices prior to the drying process is recommended. SEM of cross section of dried pear slices after processing.

Experimental and numerical analysis of a multilayer composite ocean current turbine blade

Ocean environmental corrosion and mechanical load vibration introduce considerable negative effects caused by the fluid-structure-environment interaction. A new design scheme for a blade with salinity corrosion resistance and mechanical fatigue resistance is proposed, based on numerical simulation and fatigue tests. The one-way fluid-structure interaction (FSI) model for an ocean current turbine blade was established and calculated by a computational fluid dynamics (CFD) solver and finite element method (FEM) solver. According to the FSI results, the maximum equivalent stress and deformation in extreme operating conditions are found to be within material and structural limits. On this basis, an aluminum alloy/nano particles reinforced polypropylene multilayer composite blade was designed and fatigue tested. The results show that an obvious crack-resistance effect exists within a certain stress range, and there is basically no change in the fatigue crack growth rates of NPRP in the four environmental fatigue tests. The multilayer composite blades with immersion pretreatment can stand 1 × 107 cycles of fatigue tensile loads and torque loads without failure. The results provide specific theoretical guidance for the optimization of the structural design of ocean current turbine blade in ocean environment.

Olive semidrying process: oleuropein degradation in relation to sensory bitterness.

Today, treatment with brine or NaOH is the most common debittering procedures for olive industry. Although these debittering procedures are used widely, they have serious disadvantages such as high salt content of the final product, time consuming process (6-8 months required), degradation of other phenolic compounds, nutrient losses and formation of high amounts of waste water. Semidrying method has been recently introduced as a new debittering method. The aim of the present study was to evaluate the degradation of oleuropein and the sensory bitterness during semidrying of olives in a dryer at 40oC and 60oC with 1.5 m/s air flow rate. In this research, oleuropein, hydroxytyrosol and tyrosol content and sensory bitterness of olives have been determined for the first time during semi drying. An acceptable bitterness level and 88.76-91.29% oleuropein reduction was reached while 31.03-38.24% weight loss of olive was determined after semi drying process. Debittered olives were obtained with 22.41-28.61% water content. Results suggest that semi drying with piercing in combination with immersion pre-treatments could be used as an environmentally friendly olive debittering method for the production of higher nutritional value and low or free of salt table olives.