Effects Of Heating Methods Research Articles

Effect of heating method on some characteristics of chive garlic dumplings

Garlic chive dumplings are one of the most favorable snacks for Thai citizens. Frozen dumplings were now commercially available due to their long shelf and high convenience. However, freezing could induce some quality deterioration. Thus, this research aimed to develop a soy protein coating material for coating the frozen dumplings and investigate the effect of reheating processes on the physical and chemical properties, as well as sensory analysis, compared with uncoated dumplings. The results found that the difference in reheating processes and times showed significant differences in the physical and chemical properties and sensory evaluation (p < 0.05). The coated soy protein on the surface of garlic chive dumplings resulted in lower hardness, drip loss, and reheating loss values by two times. The sensory score revealed that coated garlic chive dumplings heated with microwave for 1.5 min showed the highest acceptability score of 7.2 ± 1.6 than those of uncoated dumplings and reheating process and times. The lipid content and thiobarbituric acid reactive substance (TBARS) levels in uncoated and soy protein-coated garlic chive dumplings slightly increased with increasing the reheating time. However, the TBAR content did not exceed the maximum permissible level (3 mg/kg), indicating the safety of garlic chive dumplings for consumption through the investigation of the reheating process.

Effects of heating method and refrigerating time on nutritional quality and digestive characteristics of refrigerated Chinese steamed bread

Two re-heating methods and different refrigerating time were carried to compare the re-heating stored, refrigerated bread quality. Compared with the natural thawed steamed, sensory properties of re-heating bread were significantly improved, steam method improved moisture content while that re-heated by microwave decreased, the secondary structure of protein was significantly affected by re-heating. Rapidly digestible starch (RDS) content in bread re-heated by steam and by microwave decreased significantly, compared with fresh bread. With the storage time increasing, the sensory quality of bread showed a downward trend after being re-heated by steam; water content increased and then decreased; β-turn decreased gradually, while random coil increased gradually; starch aging showed a trend of gradual enhancement. RDS content and protein digestibility decreased gradually. Nutritional quality of the bread re-heated by steam was better than that by microwave, optimum cold storage time for the bread re-heated by steam should be no more than 24 h.

Effect of heating methods on astringency recurrence, syneresis, and physical properties of persimmon paste.

The soluble tannins in Japanese persimmon gives it an unpleasant astringent taste, which can be removed using certain conventional methods. However, these methods are not very efficient and lead to the recurrence of astringency upon heating. Thus, the use of persimmon in processed food is severely limited. Although the effects of heating time and temperature on astringency recurrence have been explored in detail, the effect of the heating method used has not yet been clarified. Considering this, we subjected an astringency-removed paste to various heat treatments, namely, stir frying, boiling, and pressurization, and examined their effect on astringency recurrence. Soluble tannin contents were also determined, and sensory evaluation was conducted. It was observed that stir frying, which is accompanied by moisture evaporation, is superior with respect to the suppression of astringency recurrence and the prevention of syneresis compared with the other two methods. Moreover, the bright orange color and the gummy texture obtained upon stir frying are favorable for commercial purposes. Therefore, it is expected that these findings will lead to the significant improvement of astringent persimmon processing.

Fast pyrolysis of a SiC-based polymer precursor using a spark plasma sintering apparatus – Effects of heating methods and pyrolysis atmosphere

The effects of heating method on the pyrolysis behavior, crystallinity and ceramic yield of a SiC-based precursor-derived ceramic (PDC) were investigated using commercial allylhydrido-polycarbosilane (AHPCS) precursors, spark plasma sintering (SPS) apparatus and tube furnace. The heating rate of SPS was ten times faster than that of tube furnace. Consequently, the total time of precursor impregnation and pyrolysis (PIP) process decreased distinctly after several PIP cycles. PDCs fabricated by SPS had higher crystallinity than those prepared by tube furnace. The crystallinity of PDCs was 70.4 and 65.1 %, respectively, after the pyrolysis using SPS and tube furnace at 1400℃ for 1h. The highest crystallinity of 82.92 % was achieved after the pyrolysis at 1500℃ for 2h using SPS. The ceramic yield of the precursor was not strongly affected by the heating method. This study provides a promising method for the pyrolysis of ceramic precursors with short processing time and improved thermal stability.

Pressure drop of R134a and R1234ze(E) flow boiling in microchannel arrays with single- and double-side heating

An experimental study was carried out on two-phase pressure drop of R134a and R1234ze(E) flow boiling in glass microchannel arrays containing 50 parallel microchannels. Each channel has a hydraulic diameter of 301.6 μm, an aspect ratio of 2.46 and a length of 50 mm. Experimental conditions, including saturation temperatures of 26.7 °C, 29.1 °C and 31.3 °C, and mass fluxes of 50–250 kg/(m2 s), were taken into account. The effect of refrigerant properties, mass flux and saturation temperature on the flow boiling friction pressure drop were investigated. The two-phase friction pressure drop increases with increasing mass flux and decreasing saturation temperature. Specially, the effect of heating methods, including single-side heating and double-side heating, were experimentally evaluated. The two-phase friction pressure drop in microchannel arrays heated from both sides is higher than that with single-side heating. The experimental data was compared with two-phase friction pressure drop empirical correlations in the literature. The correlation provided by Zhang and Webb gives the best prediction of the experimental data with an average deviation of 34.27% for R134a and 16.88% for R1234ze(E). A new empirical correlation was provided based on the current experimental data, which could predict the current data with 94.5% prediction errors lower than 20%.

Laboratory evaluation of the effect of temperature on skid resistance of different asphalt mixtures

ABSTRACT In this research study, the effect of pavement surface temperature on skid resistance of different asphalt mixtures has been investigated. Four types of asphalt mixtures including Hot Mix Asphalt, Stone Mastic Asphalt, Steel Slag, and Porous asphalt were heated to different temperatures and their respective skid resistance values were measured, using a British Pendulum Tester. In order to evaluate the effect of heating method on skid resistance variations of asphalt mixtures, two heating sources including water bath and oven were used. Results indicate that skid resistance of studied asphalt mixtures decreases as surface temperature increases. Also, type of heating method has no significant effect on the skid resistance variations. In addition, based on experimental results, equations are proposed to describe the relation between skid resistance of different asphalt mixtures and surface temperature.

Extraction of crude gelatin from duck skin: effects of heating methods on gelatin yield

The disposal of by-products of duck production, including duck skin, is a serious concern as it results in environmental pollution. The objectives of this study were to investigate the optimal pretreatment conditions for swelling duck skin and their extraction methods as a novel source. Gelatin was extracted using water bath, sonication, superheated steam, and microwave extraction methods. The gelatin extraction yield and gelatin powder yield were the highest with the superheated steam extraction method. The melting point and gel strength of gelatin extracted using the superheated steam method were the lowest. The viscosity of gelatin extracted with the superheated steam and microwave extraction methods was higher than that of gelatin extracted with the other methods. The sodium dodecyl sulfate-polyacrylamide gel electrophoresis patterns of gelatin extracted using the superheated steam and microwave extraction methods showed more intense bands than those of gelatin extracted using the other methods. Our results showed that gelatin extracted from duck skin using the superheated steam extraction method had optimal physical properties and therefore can be used in meat products.

Investigation on in-situ formed Al3V-Al-VC nano composite through conventional, microwave and spark plasma sintering

In the present study, the effect of heating methods has been studied on the microstructure and mechanical properties of in-situ formed Al3V-Al-VC nano-composite. 5 and 15 wt % of VC were added to Al matrix and conventional and microwave sintering processes were performed at 600 °C. While spark plasma sintering process was done at 450 °C with initial and final pressure of 10 and 30 MPa, respectively. The XRD results revealed the formation of Al3V intermetallic compound in microwave sintered sample, while in both spark plasma sintered and conventionally prepared specimens, the only crystalline phases were Al and VC. Microstructure studies, demonstrated a uniform distribution of 5wt% VC reinforcement in Al matrix but the 15wt%VC addition led to form agglomerates in all prepared samples. The highest bending strength (275 ± 13 MPa) and hardness (260 ± 13 Vickers) were obtained in the spark plasma sintered sample with 15wt% of VC content.

Effects of heating method and temperature in combination with hypoxic treatment on γ‐aminobutyric acid, phenolics content and antioxidant activity of germinated rice

SummaryHeat and hypoxic treatments were combined with soaking to enhance γ‐aminobutyric acid (GABA) production in germinated paddy (GP). Effects of heating temperature, heating techniques, that is, impinging stream drying (ISD) and tray drying (TD), and germination time on the GABA content, phenolics content and antioxidant activity were also investigated. Heating temperature had a significant effect on the GABA content; both ISD and TD helped increase the GABA content when the post‐treatment grain temperature was 38–40.5 °C. Within this grain temperature range, soaking in combination with heat and hypoxic treatments (S‐ISD‐H and S‐TD‐H) yielded GP with higher GABA content than soaking (S) and soaking in combination with hypoxic treatment (S‐H). However, ISD was noted to be more suitable than TD. Phenolics content and antioxidant activity of GP prepared by S‐ISD‐H at different heating temperatures and S‐H were not significantly different but were higher than those of the GP prepared by S.

Gelling properties of vacuum-freeze dried surimi powder as influenced by heating method and microbial transglutaminase

Effects of heating method and addition of microbial transglutaminase (MTGase) on properties of gels made from vacuum-freeze dried silver carp surimi were investigated. After vacuum-freeze drying, surface hydrophobicity of surimi proteins obviously increased, Ca2+-ATPase activity slightly decreased, while α-helix percentage significantly decreased, indicating the surimi proteins were partially denaturated. Consequently, the dried surimi formed gels (D gel) with significantly lower breaking force, penetration distance and water holding capacity as compared with those of gels made from frozen surimi (F gel) under all the heating methods. With addition of MTGase, breaking force of the D gels heated at 40 °C/60 min and 90 °C/30 min was not significantly different from those of F gels, while was slightly lower under the heating of 40 °C/60 min + 90 °C/30 min. After adding MTGase, water holding capacity of the D gel under 90 °C heating increased significantly, while the gels under the other heating methods slightly deceased. Heating method obviously influenced color parameters of D gels while MTGase addition did not. Setting (40 °C) and MTGase addition induced covalent cross-linking of myosin heavy chains of D gels. MTGase addition reduced the uniformity of the water distribution in D gels.

Effect of heating method on the microbial levels and acrylamide in corn grits and subsequent use as functional ingredient for bread making

Cereal by-products represent abundant and low-cost resources of nutrients. The study is dedicated to the development of a rapid method for the treatment of corn grits to obtain value added ingredients for breadmaking. The infrared irradiation (IR) at 76°C and 90°C and vacuum microwave (VM) heating at 60°C have been applied for stabilization of corn grits. The corn grit particles were fractionated by size and it was found that the particle size fraction significantly (p<0.05) influenced the moisture and protein contents and the level of microbial population. The highest protein contents were found in particles around 0.5mm in diameter. Considerable reduction of microbial contamination by 5 log cycles, however, an increase in acrylamide formation in IR and VM corn grits up to 75.5% and 91.6%, respectively was detected. A medium strength relationship was found between protein content and acrylamide formation in heated samples (r=0.8537). Thermally stabilized protein-rich corn grits fractions were selected for wheat bread enrichment. Evidently, IR treatment was more effective to alter the physicochemical and functional properties of corn grits components. The bread of best quality and higher acceptability has been obtained by using IR heated rich in protein corn products compared to microwave heated.

Preparation of mullite/B4C composites: A comparative study on the effect of heating methods

The present study investigated preparation of the mullite/B4C composites through microwave and spark plasma sintering processes. A high-energy ball mill was used to mix the nono-sized mullite and B4C powders in ethanol media for 10 min. The mixed nano-sized powders were pelletized and sintered by microwave (MW) and spark plasma sintering (SPS) processes at 1500 and 1300 °C, respectively. The XRD results revealed the reactions between mullite and B4C, and also the formation of SiC, Al2O3, Si phases in SPS sintered sample. The identified crystalline phases in the microwave sintered sample were mullite and B4C. Samples sintered in SPS reached almost full density and showed improved mechanical properties (the hardness of 16.29 ± 0.2 GPa, bending strength of 348 ± 21 MPa and fracture toughness of 3.01 ± 0.18 MPa m−1/2) than those sintered in microwave. The microstructural investigations showed the formation of needle-like mullite at some areas of sample sintered in SPS with a uniform distribution of B4C in mullite matrix alongside pore-free microstructure. The microstructure of microwave sintered sample contained a large number of pores.

HIPed TiO2 dense pellets with improved photocatalytic performance

The effects of heating method and temperature on physical, structural and photocatalytic behaviors of TiO2 pellets prepared by conventional heating and hot isostatic pressing have been evaluated. The pellets of submicron TiO2 powders were heated to 600, 650, 700, 750 and 1000°C using both processing methods in order to compare anatase to rutile phase transformation and densification behaviors. Bulk densities and porosities were calculated using the Archimedes method. XRD analysis were performed to calculate anatase/rutile ratios. Microstructures were characterized using SEM. Photocatalytic experiments have been performed under full spectrum irradiation. Degraded methylene blue samples were periodically monitored through UV–vis spectrophotometer to determine degradation kinetics. Anatase to rutile transformation is slightly faster and densification is better for lower temperatures for conventional heating, however HIPing gives better densification above 750°C as it also retards rutile transformation. Mixed phase structures and HIPed samples showed the best photocatalytic performance which makes this method advantageous.

Effects of different heating methods on the contents of nucleotides and related compounds in minced Pacific white shrimp and Antarctic krill

The effect of heating methods (microwave and water bath, and combined microwave and water bath heating) on 6 nucleotides and related compounds (NRCs) in minced Pacific white shrimp and Antarctic krill was investigated at 25, 40, 55, 65, 75, 85, and 95 °C. In Pacific white shrimp, the main changes of NRCs were in adenosine monophosphate (AMP) and inosine monophosphate (IMP). High temperature (85 and 95 °C) can inhibit the ATP degradation by water bath heating. In Antarctic krill, the main change of NRCs was in inosine (HxR) that decreased in microwave heating treatment at 95 °C. The different methods were compared in terms of IMP content and flavor/bitter ratio, which are related to flavor of aquatic products. The best heating method was pre-heating at 75 °C in water bath followed by microwave heating at 95 °C (IMP content and relatively flavor/bitter ratio were 4.34 μmol/g and 3.00, respectively) for pacific white shrimp and pre-heating at 65 °C in microwave followed by water bath heating at 95 °C (IMP content and relatively flavor/bitter ratio were 0.18 μmol/g and 0.06, respectively) for Antarctic krill, respectively. Chemical analysis, microbiological analysis and sensory evaluation showed that the K value is not suitable for assessing the freshness of Antarctic krill.

Effects of microwave vs. convection oven heating on the formation of oxidation products in canola (Brassica rapa subsp. oleifera) oil

Research on the effects of microwave vs. “conventional” heating of dietary oils on lipid oxidation has been very limited. In this study, canola oil (Brassica rapa subsp. oleifera ) was heated in either convection or microwave oven to compare the effects of heating methods on triacylglycerol (TAG) oxidation. Peroxide and p -anisidine values (PV and p -AV, respectively) were determined and liquid chromatography–mass spectrometric (LC–MS) analysis of non-oxidized and oxidized TAG molecular species was performed. Neither of the heat treatments caused any considerable changes in PV of the oil samples. However, increase in p -AV was observed. The change was higher in the oil heated in microwave oven, demonstrating a higher increase in the amount of secondary oxidation products. The changes were accompanied by a decrease in the polyunsaturated TAG molecular species ACN:DB (acyl carbon number:number of double bonds) 54:7 and 54:6, this change also being higher in the oil heated in microwave oven.

Synthesis of MgAPO-31 nanocrystals via different heating methods and their catalytic performance in the hydroisomerization of n-decane

MgAPO-31 molecular sieves substituted by different magnesium contents were synthesized using microwave irradiation (MW) and conventional electrical heating method, respectively. The bifunctional catalysts Pd/MgAPO-31 were prepared by the incipient wetness impregnation technique. The structure and acidity of MgAPO-31 were characterized by XRD, SEM, N2 physical adsorption, FT-IR, and Py-IR. The catalytic performance of Pd/MgAPO-31 were tested in the hydroisomerization of n-decane, which was used as the probe-reaction, and the effect of heating method on acidity of MgAPO-31 and the catalytic performance of Pd/MgAPO-31 were investigated. The results showed that all of the MgAPO-31 samples with ATO topology structure were pure phase and high crystalline materials. The Mg(II) heteroatoms were confirmed to isomorphously substitute for the framework atoms of AlPO4-31 molecular sieve. These Pd/MgAPO-31catalysts showed good catalytic performance for the hydroisomerization in the temperature range of 330–370 °C. The activity of Pd/MgAPO-31 in the hydroisomerization of n-decane and the selectivity for i-decanes were considered to depend on the crystal size and acidity of MgAPO-31.The highest selectivity for i-decanes was obtained over the catalyst Pd/0.05MgA31-MW prepared using the MW method.

Effects of lipophilic continuous phases and heating methods on thermal degradation and isomerization of β-carotene.

Rates of thermal degradation and isomerization of all-trans-β-carotenes in air and in triacylglycerols were determined. Degradation of carotenes in triacylglycerols was faster than that in air. The 13-cis-β-carotene level in triacylglycerols was higher than in air. Oxidized materials of triacylglycerols probably facilitated isomerization of carotenes and, thus, degradation. Amounts of all-trans-β-carotenes and all-trans-α-carotenes in pumpkin decreased with an increase in heating time. The proportion of 13-cis-β-carotene increased after heat treatment started, probably due to thermal isomerization of all-trans-β-carotenes to cis-isomers, and to decreases in amounts of all-trans-β-carotenes and all-trans-α-carotenes in pumpkin. Effects of heating methods on proportions of isomers; however, were not different.

Solution Chemistry, Substrate, and Processing Effects on Chemical Homogeneity in Lead Zirconate Titanate Thin Films

The effects of chemistry, substrate, and processing conditions on through‐thickness cation distributions are explored in solution‐derived morphotropic composition lead zirconate titanate (PZT) films. Films prepared from chelate‐based and conventional sol–gel chemistries were spin cast onto Pt/ZnO/SiO2/Si and Pt/Ti/SiO2/Si substrates and pyrolyzed at 300°C, 350°C, and 400°C prior to crystallization at 700°C either in a preheated furnace or via rapid thermal processing. For films crystallized within a conventional furnace on Pt/ZnO/SiO2/Si substrates no chemical gradients were observed. All films prepared on Pt/Ti/SiO2/Si substrates had increased titanium concentrations near the PZT/Pt interfaces, and the source is shown to be titanium diffusing from the substrate metallization stack. The effect of heating method and rate was explored in films prepared on Pt/ZnO/SiO2/Si substrates with 15°C, 50°C, and 100°C/s heating rates within a rapid thermal annealer. Only one solution chemistry‐heating rate combination resulted in the formation of a chemical gradient: a conventional sol–gel chemistry and a 50°C/s heating rate. Infrared spectroscopy of pyrolyzed gel films showed absorption spectra differences in the bonding structure between the two chemistries with the conventional sol–gel‐derived films exhibiting a signature more similar to that of a PbTiO3 gel, suggestive of a gel‐structure source of gradient formation during crystallization.

Rapid Liquefaction of Wood in Polyhydric Alcohols Under Microwave Heating and its Liquefied Products for Preparation of Rigid Polyurethane Foam

Comparing to the conventional bath heating, the effects of liquefaction parameters on the degree of liquefaction of wood in polyhydric alcohols by using microwave as an energy source were evaluated. Polyurethane foams were successfully prepared from the liquefied biomass-based polyols. The effects of heating methods (conventional bath heating and microwave) and liquefaction reaction time on the properties of liquefied biomass-based polyols were investigated. The influences of isocyanate index on the properties of rigid polyurethane foams were also discussed, and feasible formulations for preparing liquefied biomass-based polyurethane foams were proposed. The results indicated that rapid liquefaction of wood in polyhydric alcohols under microwave heating could be achieved. The foams prepared from liquefied biomass-based polyols obtained by microwave-assistant liquefaction exhibited excellent mechanical properties. Polyurethane foams (PU Foams) are used widely in many fields as heat-insulating, packaging, structural, flotation and load bearing materials, due to their ease of processing and unique combination of excellent thermal insulation and mechanical properties. Traditional PU foams are prepared by the polymerization of polyol with isocyanate simultaneously occurring with gas generation resulting from the chemical reaction of water of blowing agent evaporation by the exothermic reaction itself. However, the raw materials for preparing PU foams, based on polyol (polyether of polyester polyols) and isocyanate, are obtained mainly from fossil resources. With increasing concern of the shortages of fossil resources and the impetus for reducing costs of polyurethane, preparation of polyols from renewable biomass resources has been an interesting subject in the polyurethane industry. Biomass as natural polymer contains more than one hydroxyl group in the molecular chains, and can be used as polyol for preparing polyurethane materials. By the hydroxyalkylation reaction, polyols with desirable hydroxyl values and viscosities have been prepared from many hydroxyl-containing biomass substances such as sorbitol (1), sucrose (2), methyl glucoside (3), lignins (4, 5), and so forth. These polyols have become important ingredients for rigid polyurethane foams because of the great functionalities of the starting materials.

Investigation on the effects of microwave and conventional heating methods on the phytochemicals of pomegranate (Punica granatum L.) and black mulberry juices

Black mulberry and pomegranate juices were concentrated by conventional and microwave heating at different operational pressures (7.3, 12, 38.5, and 100kPa). The effects of each heating method on the phytochemical changes (total anthocyanin content and antioxidant activity) of juices were investigated. The effect of various heating methods on the profile of the pomegranate anthocyanins were conducted using high-performance liquid chromatography–mass spectrometry (HPLC–MS). The main anthocyanins of pomegranate quantified by HPLC–MS were cyanidin, delphidin, pelargonidin, 3-glucoside, and 3, 5-diglucoside. In black mulberry juice, the final juice concentration of 42° Brix was achieved in 140, 120, and 95min at 100, 38.5, and 7.3kPa respectively and the final pomegranate juice concentration of 40° Brix was achieved in 140, 127, and 109min at 100, 38.5, and 12kPa respectively by using a rotary evaporator. Applying microwave energy decreased the required times to 115, 95, and 60min for black mulberry juice and to 118, 95, and 75min for pomegranate juice. Results showed that anthocyanin degradation and consequently decrease in antioxidant activity were more pronounced in rotary evaporation compared to microwave heating method.