Heat Pretreatment Research Articles

Impact of Contact Time, Temperature, and Ethanol Content on Hop Creep-Related Enzymatic Activities in Beer

In the production of hop-forward India Pale Ales (IPA), the “hop creep” phenomenon, resulting from hop enzyme activities (combined with yeast fermentation), is a major issue in breweries worldwide. In order to improve our knowledge of the parameters that can modulate these enzymatic activities, the present work aimed to assess to what extent hop contact time, incubation temperature, and beer ethanol content can affect the enzymatic activities of hops. To this end, various hop varieties were incubated in beer over a three-week period under different conditions of temperature and ethanol content. Samples were periodically collected to monitor changes in fermentable sugar and fermentation ester concentrations over time. A longer contact time favored α-glucosidase and esterase activities, leading to a higher glucose concentration and lower maltose and isoamyl acetate concentrations. An assay at 50 °C allows predicting this phenomenon more quickly. As expected, dry heat pre-treatment of hop was found to delay glucose release and isoamyl acetate hydrolysis. Ethanol at 10% v/v was required to inhibit hop amylolytic enzymes in beer, but had no effect on hop esterases.

Loblolly pine needles processing with deep eutectic solvents to develop porous structure

This work focused on the removal of lignin from pine needles, leaving oriented porous cellulose. Deep eutectic solvent (DES) pretreatment of loblolly pine needles allowed for the removal of lignin from the biomass, leading to the exposure of the desired cellulose structure. Heating under reflux and microwave heating methods were used to pretreat loblolly pine needles with 12:1 lactic acid:choline chloride DES, 2:1 formic acid:choline chloride DES, and 1:2 oxalic acid:choline chloride DES. Characterization of the untreated and pretreated pine needles was done by Brunauer–Emmett–Teller analysis, Fourier-transform infrared spectroscopy, scanning electron microscopy, and ultraviolet–visible spectroscopy. Fiber analysis was also performed on the untreated and pretreated pine needles. The DES pretreated pine needles showed significant enhancements in both specific surface area and pore volume, with microwave pretreatment giving the best results. The oxalic acid:choline chloride DES was the most efficient at eliminating acid-soluble lignin. The optimal duration for conductive heat pretreatment to enhance specific surface area and pore volume was found to be 80 min. For microwave treatment, the formic acid:choline chloride DES was found to be most effective to increase the overall cellulose to lignin ratio.

Investigating the microbial community dynamics in biohydrogen production from palm oil mill effluent (POME) with molasses addition under mesophilic condition

Recently, there has been a surge in global demand for hydrogen as a sustainable and carbon dioxide-free energy carrier. As hydrogen is derived from biological processes, biohydrogen is gaining attention from economic and environmental perspectives because it can be produced from waste, such as palm oil mill effluent (POME). As a country with the largest palm oil industry in the world, Indonesia has the potential to utilize POME as a fermentation substrate for biohydrogen production. This study used local indigenous microorganisms from POME anaerobic pond sludge to produce biohydrogen. The experiment was conducted in an anaerobic batch fermenter under dark fermentation. Screening at initial pH and molasses addition were optimized to obtain the optimal fermentation substrate. A urea addition and heat shock pretreatment were compared to understand the relationship between biohydrogen production, COD reduction representing substrate value, and microbial community dynamics. As in field application, anaerobic process conditions were adjusted at the mesophilic temperature. The importance of comprehending what kind of microorganisms played a role in a consortium was analyzed by the 16S rRNA V3–V4 region using a next-generation sequencing (NGS) approach. Heat pretreatment exhibited the number of bacterial taxa order Thermoanaerobacterales increased significantly in direct proportion to the biohydrogen, up to 24.07% of the total volume gas produced. Notwithstanding, the mesophilic production process altered the microbial community, with Clostridiales as the predominant bacteria group, followed by Lactobacillales, Oscillospirales, and Lachnospirales. Understanding the dynamics and physiochemicals of the microbial community that affect microbial growth is targeted to improve biohydrogen production.

A comparative study on stability and flavor of additive-free oat milk obtained by different heat pretreatments (blanching and microwave) of oat kernels

Heat pretreatment of oat kernels is necessary in flavor improvement, but its impact on the stability of so-called “clean label” oat milk has not yet been studied. Therefore, two heat pretreatments, including blanching (BC, 90 °C for 5 min) and microwave (MW, 400 W for 5 min), as well as their combination (BC + MW), were compared in this study. The results showed that after the three treatments, the lipase activity of oat kernels was reduced by 50% or more, and stability of oat milk was significantly improved compared to the control. Furthermore, oat milk with BC treatment exhibited the best stability, accompanied by smallest particle size, surface tension, and fluorescence intensity, as well as highest values of zeta potential, apparent viscosity, surface hydrophobicity, and the total content of α-helix and β-sheet, followed by MW and BC + MW. For the flavor compounds analysis results, BC treatment was sufficient to reduce off-flavor compounds (such as hexanal, nonanal, and 2-pentylfuran etc.) in oat milk, achieving the best sensory quality. This study first confirmed the positive effect of appropriate heat pretreatment (BC) of oat kernels on the stability and overall quality improvement of additive-free oat milk.

Comparative study of different pretreatment methods on peanut oil quality characteristics, anti-oxidation attributes, and phenolic compound compositions

The peanuts heat pretreatment is a crucial step for the following oil extraction, influencing both efficiency and oil quality. The present study investigated the effects of oven roasting (OR, 150 °C, 25 min), infrared ray roasting (IRR, 150 °C, 25 min), and microwave roasting (MR, 700 W, 5 min) on the quality characteristics, anti-oxidation attributes, and phenolic compound compositions of peanut oil. All pretreatment methods changed the physicochemical properties and bioactive compounds of peanut oil. Notably, IRR resulted in the highest oxidation induction index (9.25 h) and enhanced free radical scavenging activity, with increases of 55 % (2,2-diphenyl-1-picrylhydrazyl (DPPH)) and 121 % (2,2′-azinobis-(3-ethylbenzthiazoline-6-sulphonate) (ABTS)) compared with the control. Furthermore, the free phenolics content (Free-P) increased significantly, particularly with IRR, which was increased 6.00 times. Correlation analysis indicated that Free-P was the primary contributor to the anti-oxidation attributes of peanut oil. The results can provide valuable insights for optimizing peanut oil processing technologies.

Efficiency of heat-treated sepiolite in the adsorption of Cd, Zn, and Co from aqueous solutions: A low-cost approach for wastewater treatment

This study investigated the adsorption of Cd, Co, and Zn ions onto unmodified and heat-treated sepiolite, focusing on the effect of contact time, initial pH, and heat pretreatments. Kinetic experiments were conducted in triplicate, and equilibrium experiments indicated that Co2+ had the highest adsorption preference, followed by Zn2+ and Cd2+. The adsorption efficiency for Co2+ significantly increased with higher initial pH, whereas Zn2+ and Cd2+ showed optimal adsorption at lower pH levels. Heat-treated sepiolite at 250 ℃ exhibited a higher surface area and adsorption capacity in comparison with unmodified and 150 ℃-treated sepiolite, which indicated the importance of heat pretreatment. The pseudo-second-order kinetic model better described the adsorption process, and it was confirmed chemisorption as the rate-limiting step. By increasing the contact time, adsorption rates enhanced, with equilibrium achieved within 480 min for all systems. Higher initial solute concentrations led to an increase in adsorption processes, with Co ions consistently showing higher adsorption efficiency in competitive multi-ionic solutions. Adsorption percentages varied with pH and thermal treatment, indicating the importance of these parameters in optimizing sepiolite’s adsorption capacity for heavy metal removal.

Ammonium ion removal from contaminated water using Cikancra natural zeolite

Abstract Water quality in water bodies is deteriorating due to human activities such as industries, agriculture, and households. These activities have been reported to increase the levels of nitrogen species in water bodies, including ammonium (NH4 +). Various processes have been used to reduce NH4 + concentration in water, including adsorption and ion exchange using zeolite which is renowned as an excellent adsorbent and ion exchange material. In this study, we assessed the ability of Cikancra natural zeolite to reduce the NH4 + concentration in water. Heat pre-treatment was carried out on the zeolite to reveal its effect on the NH4 + removal rate. Furthermore, several factors such as contact time, grain size, and initial NH4 + concentration were evaluated to determine the optimum absorption condition. The experimental results reveal that heat-pretreated natural zeolite can reduce the NH4 + concentration by up to 84% after 60 minutes of contact time. Furthermore, the absorption capacity of the zeolite is reaching 2.37 mg/g at an initial NH4 + concentration of 50 mg/L. The evaluation using Freundlich and Langmuir isotherm models indicates that the process occurs physically due to Van Der Waals interaction between the adsorbate and the adsorbent.

Mechanisms and advancements in microwave-enhanced CO2 mineralization of lightweight porous concrete

Lightweight porous concrete (LPC) typically exhibits low early strength, which can be addressed by enhancing early strength through carbon dioxide (CO2) mineralization curing while achieving permanent CO2 sequestration. The efficacy of this process relies on maintaining optimal moisture levels. This study investigates the influence of moisture content on the performance of solid waste-based lightweight porous concrete blocks (RSFAC) subjected to microwave heating pretreatment. Moisture levels were adjusted to 10%, 20%, 30%, and 40% (initial water-to-cement ratio of 45.4%) before undergoing mineralization curing within an environment set at a temperature of 20 °C, relative humidity 75%, and a CO2 concentration of 40% for a duration of 0.5 h. The impact of moisture content on RSFAC's compressive strength, carbon sequestration rate, mineralization products, and microstructure was evaluated. Results indicate that compared to conventional oven pretreatment methods requiring nearly 10 h, microwave pretreatment technology achieves equivalent water content within just 50 min, significantly reducing the time needed for mineralization pretreatment. RSFAC, when pretreated with microwave heating, outperforms untreated samples (Ref-0 and Ref-1) in terms of compressive strength and carbon sequestration efficiency. Optimal performance was observed at a moisture content level of 30%, with the highest recorded compressive strength achieved at 1, 3, and 7 d respectively. At the curing age of 7 d, the compressive strength reached up to 2.32 MPa while the carbon sequestration rate reached approximately 11.61%. Furthermore, aragonite and calcite (tetrahedral and hexahedral), without poorly crystalline spherulites, were identified as the main crystalline CaCO3 generated by RSFAC under this specific moisture content condition; pores larger than 50 nm served as primary reaction sites for RSFAC mineralization curing, whereas there was a significant increase in pore proportion with sizes less than 20 nm after filling with mineralization products.

Physico-functional properties, structural, and nutritional characterizations of Hodgsonia heteroclita oilseed cakes

The physicochemical and functional properties, structures, and nutritional characterizations of Hodgsonia heteroclita oilseed cake powder (OCP) obtained from oil extraction with no pretreatment (NP), heat pretreatment (HP; drying at 55 °C until reaching 10% moisture content), and the combined heat and enzymatic pretreatment (HEP; 2.98% (w/w) enzyme loading, 48 °C of incubation temperature and 76 min of incubation time) were investigated. HP and HEP caused a decrease in lightness but an increase in the yellow–brown color of OCP. The results showed that HEP-OCP had significantly lower oil and water absorption index, pasting properties and gelatinization enthalpy while higher water solubility index, foaming and emulsifying properties than NP-OCP and HP-OCP. Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction indicated a small change in the protein secondary structure after pretreatment. Moreover, depending on pretreatment method, OCP samples contained a significant difference in nutritional values. However, all OCP samples could be claimed as high protein sources, containing all 9 essential amino acids and 9 non-essential amino acids. Finally, HEP-OCP seemed to have suitable properties to use as a potential ingredient in various food products such as soups, sauces, ice-cream, mousses, chiffon cakes and whipped toppings.

ABPBI-based hollow fiber membranes for forward osmosis (FO) possessing low reverse salt flux

The poly(2,5-Benzimidazole), known for its excellent thermochemical stability, was evaluated as a membrane material for forward osmosis. The dope in methane sulfonic acid was used to make hollow fiber membranes. The availability of bound MSA in HFMs was compared with its neutral form. Aqueous solutions of two common salts reported for FO (NaCl and MgCl2) were used as a draw solution at varying concentrations. The performance was determined in terms of water flux and reverse salt flux. The long-term performance of the membrane was assessed. The heat pretreatment of membranes was beneficial in offering low reverse salt flux, a crucial parameter in FO. The heat treatment at 350 °C exhibited excellent performance of low-RSF, irrespective of the draw solute used. The presence of MSA in the membrane matrix was found to be beneficial. Present HFMs exhibited reverse salt flux as low as 0.003 mol m−2 h−1 using 2 mol L−1 MgCl2 as a draw solution. The water flux of present membranes was lower than that of reported FO-membranes, which is attributable to the larger thickness of the present membranes. The findings will be used to make ABPBI-based membranes in thin form to elevate the fluxes and their practical applicability.

Ingredient Functionality of Soy, Chickpea, and Pea Protein before and after Dry Heat Pretreatment and Low Moisture Extrusion.

This study investigates the impact of dry heat pretreatment on the functionality of soy, chickpea, and pea protein ingredients for use in texturized vegetable protein (TVP) production via low moisture extrusion. The protein powders were heat-treated at temperatures ranging from 80 °C to 160 °C to modulate the extent of protein denaturation and assess their effects on RVA pasting behavior, water absorption capacity (WAC), and color attributes. The results indicate that the pretreatment temperature significantly influenced the proteins' functional properties, with an optimal temperature of 120 °C enhancing pasting properties and maintaining WAC, while a higher pretreatment temperature of 160 °C led to diminished ingredient functionality. Different protein sources exhibited distinct responses to heat pretreatment. The subsequent extrusion processing revealed significant changes in extrudate density and color, with increased density and darkness observed at higher pretreatment temperatures. This research provides insights into the interplay between protein sources, pretreatment conditions, and extrusion outcomes, highlighting the importance of controlled protein denaturation for developing high-quality, plant-based meat analogues. The findings have broad implications for the optimization of meat analogue manufacturing, with the aim of enhancing the sensory experience and sustainability of plant-based foods.

Suppression of crack formation in wafer-scale amorphous SiNx films by residual hydrogen-ligands manipulation

Plasma-Enhanced Chemical Vapor Deposition (PECVD) of amorphous silicon nitride (SiNx) thin films is a critical procedure in microelectronics serving as a surface passivation layer and dielectric barrier. However, intrinsic film stress continuously builds up along with PECVD growth, leading to film cracking. How to achieve crack-free PECVD amorphous SiNx film within a large thickness range remains a critical unresolved challenge in semiconductor industry. In this study, we revealed that high residual NH ligands from the NH3 precursor could induce excessive tensile strain at the SiNx/Si wafer interface and consequently aggravate SiNx film crack formation. With a heating pretreatment on the wafer, residual H ligands were effectively reduced to achieve homogenous chemical composition in SiNx film. As a result, the crack number declined ∼42% and the remaining crack length was substantially shorter in contrast to the original SiNx film. This work demonstrates the crucial role of residual ligands on internal strain regulation and points out a pathway to achieve crack-free PECVD SiNx films in industrial manufacturing.

New insights into controlling rapid combustion synthesis procedure: Shape-tailored Fe3O4 nanoparticles fabrication

This research represents a deliberate choice of larger ligands to regulate agglomeration, resulting in the creation of Fe3O4 nanoparticles with the precise shape control. The reaction environment was controlled by examining the often-overlooked factors, such as the use of surfactants, heat pre-treatment, and degassing. Through the use of cetyltrimethylammonium bromide (CTAB), along with the appropriate heat treatment and degassing, cubic-shaped particles (average length of 55 ± 5 nm) with a single crystalline structure were successfully generated. Substituting CTAB with other surfactants like dodecylammonium iodide (DDAI) and dodecylammonium chloride (DDAC) led to the production of irregular shapes. However, when a combination of CTAB and DDAC (2:1 M ratio) or CTAB and DDAI (4:1 M ratio) was employed, spherical particles with an average diameter of 70 ± 10 nm and rod-shaped particles with an average length of 100 ± 20 nm were obtained, respectively. All IO-B, IO-BC, and IO-BI particles exhibited superparamagnetic properties.

Construction of an Interfacial Layer of Aramid Fibers Grafted with Glycidyl POSS Assisted by Heat Treatment and Evaluation of Interfacial Adhesion Properties with Epoxy Resin.

The surface of para-aramid fibers (AFs) was modified via air-assisted heat pretreatment and solution impregnation by varying the glycidyl polyhedral oligomeric silsesquioxane (POSS) content. Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy showed an ester group, confirming the graft reaction between glycidyl POSS and oxidized AFs. The mechanical properties of AFs could be altered by varying the glycidyl POSS content. The modified AFs exhibited an optimal tensile strength after embedding 5 wt % glycidyl POSS on the fiber surface. The thermal stability of the modified fibers decreased; however, no obvious changes in crystallinity were observed by varying the glycidyl POSS content. Moreover, the tensile strength of monofilament increased from 23.8 to 25.8 cN·dtex-1, the thickness of the grafted layer on the fiber surface was above 30-40 nm after the graft modification with 5 wt % glycidyl POSS, and the interfacial shear strength (IFSS) increased by 62.55% to 26.22 MPa. Thus, the modified glycidyl AFs can be used for the reinforcement of composite materials.

Unveiling a 72.5 GPa peak hardness in sustainable nanodiamond composite hard coatings via discharge energy control: A nanoindentation-Raman approach

Sustainable nanodiamond composite (NDC) films hold promise for high-performance hard coatings thanks to coaxial arc plasma deposition (CAPD). This eco-friendly technique eliminates the need for external heating, chemical reactions, or Co substrate pre-treatment. CAPD boasts lower energy consumption and faster deposition rates, making it a sustainable solution for the growing demand for high-quality, environmentally friendly coatings. This study investigates the influence of discharge energy on the nanostructure and mechanical properties of these NDC films. Optimal discharge energy, ranging from 2.3 to 12 J/pulse, was meticulously explored. A combined nanoindentation-Raman approach reveals a significant correlation between discharge energy and film properties. Remarkably, at 7 J/pulse, a peak hardness of 72.5 GPa is achieved, surpassing other energy levels. Raman spectroscopy confirms maximum nanodiamond content at this energy level (evidenced by maximized Adia/AG ratio, indicating a higher diamond-to-graphite ratio), along with minimal graphitization. Additionally, the presence of trans-polyacetylene (t-PA) peaks (denoted as At-PA) revealed the existence of maximum grain boundaries ratio (At-PA/AG), contributing to enhanced mechanical properties. Optimizing discharge energy tailors NDC film nanostructure, enhancing mechanical performance for advanced hard coatings.

Impact of Ohmic Heating and Ultrasound Pretreatments on Oil Absorption and Other Quality Parameters of Fried Potato

Impact of Ohmic Heating and Ultrasound Pretreatments on Oil Absorption and Other Quality Parameters of Fried Potato

Effect of different pretreatment techniques on quality characteristics, chemical composition, antioxidant capacity and flavor of cold-pressed rapeseed oil

This study investigated the effects of different pretreatment techniques (microwave heating, infrared heating, oven heating and enzymatic methods) on the quality of cold-pressed rapeseed oil (CPRO) with commercially available first-grade pressed rapeseed oil (CFO) as a control. The results showed that CPRO is more nutritionally valuable than CFO while meeting the quality standard without refining. Microwave heating pretreatment's cold-pressed rapeseed oil (MHO) exhibited a higher oil yield (70.83 ± 0.40 %), a higher trace active ingredient content (tocopherol 53.79 ± 0.19 mg/100 g, phytosterol 726.98 ± 4.14 mg/100 g, and polyphenol 87.09 ± 0.08 mg GAE/100 g), and a stronger antioxidant capacity. Correlation analysis and multiple linear regression analysis indicated that antioxidant capacity was mainly related to the content of α-tocopherol and polyphenols. Microwave heating promoted the degradation of the Maillard reaction and glucosinolates, significantly improving the flavor of CPRO. Therefore, microwave heating is a promising pretreatment technology for the production of high-quality CPRO.

Synergistic impact of heat and salicylic acid pretreatment on gluten films: Characterization and functional properties

This study investigates how wheat gluten (WG) films in the presence of salicylic acid are influenced by thermal pretreatment. Unlike previous methods conducted at low moisture content, our procedure involves pretreating WG at different temperatures (65 °C, 75 °C, and 85 °C), in a solution with salicylic acid. This pretreatment aims to enhance protein unfolding, thus providing more opportunities for protein-protein interactions during the subsequent solvent casting into films. A significant increase in β-sheet structures was observed in FTIR spectra of samples pretreated at 75 °C and 85 °C, showing a prominent peak in the range of 1630–1640 cm−1. The pretreatment at 85 °C was found to be effective in improving the water resistivity of the films by up to 247 %. Moreover, it led to a significant enhancement of 151 % in tensile strength and a 45 % increase in the elastic modulus. The reduced solubility observed in films derived from pretreated WG suggests the development of an intricate protein network arising from protein-protein interactions during the pretreatment and film formation. Thermal pretreatment at 85 °C significantly enhances the structural and mechanical properties of WG films, including improved water resistivity, tensile strength, and intricate protein network formation.

Effects of pretreatments involving ohmic heating and infrared radiation on the drying process of bananas using hot air

AbstractNowadays, the hot air drying process is the most widely used method for producing dried food and agricultural products due to its suitable investment and low operational costs. However, one of the disadvantages of drying with hot air is the prolonged drying time, which sometimes leads to serious damage to the quality characteristics of the resulting products, especially at high temperatures. Therefore, there is a need to find the most suitable conditions for producing high‐quality dried products. To conduct this experiment, after determining the desired number of samples, infrared preheating and ohmic heating were performed sequentially. In the first stage of preheating, the samples were placed in the ohmic heating device, and in the second stage, they were exposed to infrared radiation. Then, the samples were transferred to a hot air dryer for complete drying. The results showed that the antioxidant content increased with the increase in the thickness of the banana slices. Moreover, an increase in the drying temperature and the number of infrared lamps led to a reduction in the antioxidant content. The slices with less thickness and higher drying temperatures had the minimum phenol content. The maximum and minimum measured values of the total phenol content were 34.51 and 37.32, respectively. The range of variation in the solid soluble content was between 11.708% and 19.5437% Brix. In addition, at the same temperature values, an increase in the thickness of the banana slices resulted in a decrease in the solid soluble content of the samples. Furthermore, with an increase in the temperature for slices of the same thickness, the solid soluble content of the samples increased.Practical applicationsThe purpose of this research is to evaluate the effect of the thickness factors of the sample pieces, the temperature of the hot air dryer along with ohmic heating pretreatments, and the infrared lamps in the hot air dryer on the quality indicators of banana.

Preparation of soy protein isolate-naringin-chitosan protein gel: Synergistic effect of ohmic heating pre-treatment and chitosan addition

Soybean protein isolate (SPI)-Naringin (Nar) complex pre-aggregates were prepared by ohmic heating (OH) and protein gels were formed by adding chitosan (CS). The properties of the pre-aggregate, gel rheological properties, texture, and water holding capacity (WHC) were evaluated. For the properties of the SPI-Nar pre-aggregate, under an OH treatment of 6 V/cm, the α-helix and β-turn structures of the SPI-Nar pre-aggregate were found to be 17.72% and 15.30%, respectively, with a uniform particle size distribution. The surface hydrophobicity, total free sulfhydryl, and turbidity were measured to be 794, 6.54 μmol SH/g, and 0.364, respectively. Atomic force microscopy images showed an Rq value of 3.63 and a height of 14.5 nm. Regarding the properties of the SPI-Nar-CS protein gel, when the CS addition level was 3%, the gel (SPI-Nar-CS 3) exhibited the best rheological properties, with hardness, springiness, and cohesiveness values of 10.17 g, 0.79 mm, and 0.31, respectively. The WHC and LF-NMR analysis of the protein gel revealed that SPI-Nar-CS 3 exhibited a WHC of 90.67% and optimal LF-NMR imaging and apparent state. SEM images showed the best microstructure at this CS addition level. In addition, the synergistic mechanism between the OH treatment and CS addition in protein gel formation was discussed, providing a theoretical foundation for future applications in the food industry.