As the demand for “clean label emulsions” and natural emulsifiers is increasing, whey proteins have a big potency to be used as an emulsifier in food emulsions. However, in order to enable their ...application, whey proteins should withstand high temperature processing. Hence, the limited heat stability of whey proteins is a major drawback: they are highly heat labile and thus prone to heat induced protein denaturation and aggregation. As this phenomenon highly impacts their functionality, it is of utmost importance to increase the heat stability of whey proteins to broaden their application in the food industry, which requires a thorough knowledge of the heat stability properties of whey proteins.
To better understand the heat stabilizing activity of whey protein-polysaccharides conjugates, studies on the heat stability of whey proteins and whey protein stabilized emulsions, as well as approaches to improve their heat stability, especially using the dry heat treatment method are reviewed.
Chemical modification by combining whey proteins and polysaccharides has been reported to successfully improve the heat stability of the obtained conjugates. Hence, this new whey protein-polysaccharide material is promising to be used as a natural emulsifier.
•Whey proteins and whey protein stabilized emulsions are heat labile.•Heat stability is crucial for the broader industrial application of whey proteins.•Whey protein-polysaccharide conjugation largely increases the heat stability of whey proteins.•This is attributed to electrosteric stabilization provided by the attached polysaccharides.
Textured vegetable protein (TVP) is gaining popularity as the market for meat analogues grows, but research on processing to improve the texture of TVPs is needed. Heat treatments can change the ...textural properties during the processing of meat and meat analogues. Therefore, this study analyzed the textural characteristics of low‐moisture TVPs following heat treatments using steaming, oven‐cooking, microwaving, and vacuum‐autoclaving, which combines vacuum packaging and autoclaving. The moisture content of the meat analogues had different patterns depending on the treatment used, with the most significant decrease in moisture occurred with microwaving. The morphological analysis of the meat analogues showed that oven‐cooking and microwaving preserved a large air–cell structure and that steaming and vacuum‐autoclaving caused a small air–cell structure to form. The texturization index tended to increase only with microwaving. Disulfide bonds were increased with steaming and vacuum‐autoclaving; this was thought to be related to the increase in tiny air–cell structures. In conclusion, the most helpful cooking method was vacuum‐autoclaving since it allowed the treated meat analogues to trap moisture well, and this led to the formation of a dense structure and a lowering of the texturization index. Therefore, the proposed technique of vacuum‐autoclaving was shown to be significant for its potential as a way of processing meat analogues.
Practical Application
It is expected to improve the quality of plant‐based meat analogue products by controlling the physical properties of low‐moisture textured vegetable protein (TVP) through steaming, oven, microwave, and vacuum autoclave as post‐heat treatments.
This paper investigates the effect of dwell time and heat treatment on the modified friction stir clinched (MFSC) joint of AA2024-T3/AA6061-T6 Al alloys. The precipitation-hardening heat treatment ...method involves the combination of solution heat treatment (at 520 °C for 1 h) and aging (at 165 °C for 18 h) processes. The microstructure, failure load, hardness, and fracture behavior of the as-welded and heat-treated MFSC joints were investigated. TEM images show that re-precipitation of strengthening Al2CuMg and MgZn2 phases, dislocation density, and tangles are more pronounced in the heat-treated MFSC joint. A rise in dwell time increases the average grain sizes (1.39–6.65 μm), tensile-shear strength (101–133 MPa), and cross tension strength (59–88 MPa) of the MFSC welded 2024-T3/6061-T6 joints due to an upsurge in the in-process exposure time-induced heat input and inter-material flow. An increase in dwell time beyond 15 s is undesirable. It induces the formation of nugget cracks and micro-voids in the joints and an impaired joint failure load consequently ensues. Heat treatment processing further causes grain coarsening (2.48–9.15 μm) and improves the hardness (at the weld center), tensile-shear (146 MPa), and cross tension (102 MPa) failure strengths of the MFSC joints due to the re-precipitated strengthening phases.
Recently, γ′ phase has been introduced into the solid-solution strengthening Haynes 230 alloy to improve alloy strength for better satisfying the rigorous service environment. However, previous ...research shows that γ′ phase was not precipitated under the as-fabricated condition and harmful Laves phases with high-W content, which have never been reported, appeared in the novel alloy. Therefore, in this study, Laves phase dissolution mechanisms during solution heat treatments (SHT) and γ′ strengthening mechanism after subsequent aging heat treatment (AHT) of a novel γ′-strengthening superalloy prepared by laser powder bed fusion (LPBF) were first investigated. The results show that Laves phases continue to dissolve with the increment of SHT temperature and finally disappear after SHT-ed at 1200 °C. The higher dissolution difficulty of Laves phases is closely related to the lower diffusion coefficient of W element. The long-range diffusion of solute atoms mainly controls the dissolution of Laves phases in the early homogenization stage. As the holding time increases, the γ/Laves interface widths for the solute atoms diffusion decrease and thus the dissolution process is gradually governed by the interface reaction in the later stage. After AHT, numerous nanosized γ′ particles are precipitated. With increasing SHT temperature, the ultimate tensile strength (UTS) and yield strength (YS) of the AHT-ed samples decrease while the elongation (EL) increases, which is mainly caused by the Laves phases dissolution and grain recrystallization. The 1200+AHT sample presents an excellent combination of strength and ductility with UTS of 1467.7 MPa, YS of 1244.6 MPa and EL of 6.3%. The dominant strengthening contributions in the AHT-ed samples are γ′ strengthening and solution strengthening.
•Laves phase dissolution is mainly controlled by the long-range diffusion of solute atoms in the early stage and gradually governed by the interface reaction in the later stage.•The 1200+AHT sample presents an excellent combination of strength and ductility with UTS of 1467.7 MPa, YS of 1244.6 MPa and EL of 6.3%.•The dominant strengthening mechanisms are γ′ strengthening and solution strengthening.
As a crucial branch for titanium industry, high-strength titanium alloys (HS-TAs, with UTS ≥ 1100 MPa) are indispensable structural materials for advanced engineering applications such as aerospace ...and marine fields. Along with the expansion of HS-TAs’ market, achieving satisfying synergies of high strength, high ductility (elongation ≥ 6%) and high toughness (KIC≥ 50 MPa⋅m1/2) has been identified as the uppermost technical bottleneck for their research and development. To overcome the challenge, two primary strategies have been initiated by the titanium community, developing novel alloys and innovating processing technologies. For the former, a dozen of newly-developed alloys were reported to exhibit excellent strength-ductility-toughness combinations, including Ti-5553, BT22, TC21 and Ti-1300, for which the ideal mechanical performances were based on specific microstructures realized by low impurity rate (e.g. oxygen content ≤ 0.15 wt%), complicated processing and complex heat treatment. For the latter, several innovatory forging and heat treatment technologies were originated for the mature alloys to optimize their balanced property by extraordinary microstructural characteristics. In this review, we provide a comprehensive overview over the research status, processing and heat treatment technologies, phase transformation, processing-microstructure-property correlation and strengthening-toughening mechanism of HS-TAs for aerospace engineering applications manufactured via melting-forging process. Finally, the prospects and recommendations for further investigation and development are proposed based on this review.
Fabrication of nuclear reactor components using additive manufacturing (AM) methods is now a practical option since the AM technologies have advanced to allow for building of complex parts with high ...quality materials. To assess the mechanical performance of printed components in reactor-relevant conditions and to build a property database for the AM 316L stainless steel (SS), mechanical testing and characterization were performed before and after neutron irradiation. Miniature tensile specimens were irradiated at the High Flux Isotope Reactor (HFIR) to 0.2 and 2 displacements per atom (dpa) at 300 and 600°C. The AM 316L SS was tested in the as-built, stress-relieved, and solution-annealed conditions, and the wrought (WT) 316L SS in solution-annealed condition as a reference alloy. The baseline test result showed that the AM 316L SS, regardless of the post-build heat treatment, had higher strength than the WT 316L SS, but similar ductility. Post-irradiation tensile testing was conducted at RT, 300°C, and 500°C for selected irradiation conditions. Neutron irradiation induced significant changes in the mechanical behavior of the AM stainless steels, including both hardening and softening. Although the as-built 316L steel after 300°C irradiation showed necking just after yielding, the overall property changes of the as-printed alloy became less significant after 600°C irradiation. Irradiation-induced ductilization was also observed after the higher temperature irradiation. In general, the strength change was smaller in the relatively stronger as-built and stress-relieved AM SSs than in the solution-annealed AM and WT SSs. These relatively lower strength 316L SSs overall retained higher ductility in the irradiation conditions tested, but the stronger 316L SSs demonstrated a similar level of ductility after the higher temperature (600°C) irradiation. It is a positive assessment for the AM 316L materials that no embrittlement was observed within the test and irradiation conditions of the experiment.
Crystallographic texture in metals influences material properties, e.g., r-value. In this work, a moderately strong texture is obtained in AA5182-O through continuous-bending-under-tension processing ...followed by a recovery heat treatment from the initial weak cube texture. EBSD scans confirm that the texture is retained after heat treating. The processed material exhibits increased strength and reduced planar anisotropy, providing benefits to subsequent forming operations, compared to the as-received material. Crystal plasticity simulations confirm the texture change during deformation and predict the flow stress response. Such simulations can be used for stress superposition process design to intentionally manipulate material properties.
Atomically dispersed transition metal sites have been extensively studied for CO2 electroreduction reaction (CO2RR) to CO due to their robust CO2 activation ability. However, the strong hybridization ...between directionally localized d orbits and CO vastly limits CO desorption and thus the activities of atomically dispersed transition metal sites. In contrast, s‐block metal sites possess nondirectionally delocalized 3s orbits and hence weak CO adsorption ability, providing a promising way to solve the suffered CO desorption issue. Herein, we constructed atomically dispersed magnesium atoms embedded in graphitic carbon nitride (Mg‐C3N4) through a facile heat treatment for CO2RR. Theoretical calculations show that the CO desorption on Mg sites is easier than that on Fe and Co sites. This theoretical prediction is demonstrated by experimental CO temperature program desorption and in situ attenuated total reflection infrared spectroscopy. As a result, Mg‐C3N4 exhibits a high turnover frequency of ≈18 000 per hour in H‐cell and a large current density of −300 mA cm−2 in flow cell, under a high CO Faradaic efficiency ≥90 % in KHCO3 electrolyte. This work sheds a new light on s‐block metal sites for efficient CO2RR to CO.
Atomically dispersed magnesium atoms embedded in graphitized C3N4 (Mg‐C3N4) show weak CO adsorption because of nondirectionally delocalized Mg 3 s orbit. Mg‐C3N4 exhibits a high turnover frequency (TOF) of ≈18 000 hour−1 under a CO Faradaic efficiency ≥90 %. Furthermore, the flow cell fabricated with Mg‐C3N4 reaches a large current density of −300 mA cm−2 under a CO Faradaic efficiency ≥90 %.
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