Cooking and pasteurizing evaluation of barramundi (Lates calcarifer) meats subjected to an emerging microwave-assisted induction heating (MAIH) technology

Microwave-assisted induction heating (MAIH) is a complex heating process characterized by rapid and uniform heating based on a combination of microwave heating (power: 1000 W; frequency: 2450 MHz) applied from above and electromagnetic induction heating (power: 1500 W) applied from below. In this study, we assessed the utility of MAIH in processing the flesh of barramundi (Lates calcarifer), an important aquaculture species in Asian countries. To determine the effects of different heating conditions on the microbial contamination and physicochemical qualities of barramundi meat, fresh barramundi meats (100 g) were sealed in heat-resistant crystallized polyethylene terephthalate containers containing 150 mL of saline solution, and were subsequently heated in MAIH to 90 °C or 70 °C and held to different time. The results revealed that in response to an increase in the duration of heating, there were reductions in the aerobic plate count, psychrotrophic bacteria count, hydrogen sulphide-producing bacteria count, and coliform count, along with lower contents of total volatile basic nitrogen, in treated samples. Conversely, with a prolongation of the time exposed to heat, we detected increases in the L* (lightness),W (whiteness), ΔE(colour difference), and texture (hardness and chewiness) of fish meat, whereas there was a reduction of a* (redness). When the samples were heated for at least 110 s to 90 °C or for at least 130 s to 70 °C, the barramundi meats obtained appeared to be fully cooked with microbial counts below the limits of detection. In addition, under both heating conditions, thermal imaging revealed a uniform distribution of temperature within treated samples. Furthermore, monitoring of temperature profiles at central points in fish samples revealed that maximum temperatures of 97 °C and 79 °C were reached in response to MAIH processing at 90 °C for 110 s and 70 °C for 130 s, respectively. Thus, on the basis of the quality considerations of appearance, microbial count, and texture, the recommended optimal heating conditions for barramundi meats produced using MAIH are 90 °C for 110 s and 70 °C for 130 s.Industrial relevanceThe MAIH equipment is a novel thermal processing technology and allows food to be heated and pasteurized simultaneously after the package is sealed, eliminates issues of secondary contamination due to the need for subsequent packaging, and extends the shelf life. MAIH technology, therefore, serves as a viable future alternative for thermal processing of manufacturing refrigerated ready-to-eat seafood.     

Surfactant-free electrochemical synthesis of fluoridated hydroxyapatite nanorods for biomedical applications

Fluoridated hydroxyapatite (FHA) [Ca₁₀(PO₄)₆F_x(OH)_2−x, x = 0–2] is believed to be a promising calcium phosphate (CaP) to replace pure hydroxyapatite (HA) for next-generation implants, owing to its better biocompatibility, higher antibacterial activity, and lower solubility. Notably, the shape and size of the CaP crystals play key roles in their performance and can influence their applications. One-dimensional (1D) FHA nanorods are important CaP materials which have been widely used in regenerative medicine applications such as restorative dentistry. Unfortunately, the traditional synthesis methods for FHA nanorods either employ surfactants or take a relatively long time. In this study, we aimed to propose a facile synthesis route to fabricate FHA nanorods without any surfactants using an electrochemical deposition method for the first time. This study focused on preparing FHA nanorods without the assistance of any surfactant, unlike the traditional synthesis methods, to avoid chemical impurities. FHA nanorods with lengths of 124–2606 nm, diameters of 28–211 nm, and aspect ratios of 4.4–21.8 were synthesized using the electrochemical method, followed by a heat treatment. For the as-synthesized FHA nanorods, the Ca/P ratio was 1.60 and the atomic concentration of F was 2.06 at.%. An ultrastructure examination revealed that each FHA nanorod possessed long-range order, good crystallinity, and a defect-free lattice with a certain crystallographic plane orientation along the whole rod. In short, we propose a novel, surfactant-free, cost-saving, and more efficient route to synthesize FHA nanorods which can be widely applied in multiple biomedical applications, including drug delivery, bone repair, and restorative dentistry.     

1-甲基环丙烯结合不同保鲜袋对叶用甘薯茎尖冷藏保鲜效果的影响

目的探究1-甲基环丙烯(1-methylcyclopropylene,1-MCP)结合不同保鲜袋对叶用甘薯茎尖贮藏品质的影响,筛选最适的保鲜方式。方法以叶用甘薯茎尖为材料,经0.91μL/L1-MCP处理24h后结合聚乙烯(PE)或微孔膜(WK)保鲜袋包装,在5℃下进行贮藏,分别于0、3、6、9、12 d时对其失重率、色差、黄化率、呼吸强度、乙烯释放量、多酚氧化酶活性等指标进行测定。结果贮藏12 d后, 1-MCP+PE, 1-MCP+WK处理组的失重率分别为3.43%,2.72%,显著低于未经1-MCP处理组(P0.05),说明1-MCP处理能够有效抑制叶用甘薯茎尖失水; 1-MCP+WK处理下的L值为33.9,高于其余3种处理,表明该处理能够更好的保持叶用甘薯茎尖的亮度和新鲜感。此外,1-MCP结合保鲜袋处理能够减弱呼吸作用,降低乙烯释放量及多酚氧化酶活性。结论1-MCP处理并结合PE膜或者微孔膜包装对叶用甘薯茎尖具有良好的保鲜效果,可以有效延长其贮藏期。     

破囊壶菌发酵生产DHA的研究进展

二十二碳六烯酸（DHA）是一种非常重要的多不饱和脂肪酸，能参与人及动物体内多个生理过程。破囊壶菌具有生长迅速、细胞内DHA含量高的特点，是工业化生产DHA的潜力菌。本文主要介绍破囊壶菌DHA代谢通路、影响破囊壶菌生产DHA的因素以及破囊壶菌中试发酵的研究现状。首先，对破囊壶菌合成DHA的两个代谢途径，即脂肪酸合成酶（fatty acid synthesis pathway，FAS）途径和聚酮合酶（polyketide synthesis pathway，PKS）途径进行总结和描述；其次，对影响破囊壶菌发酵生产DHA的三个主要因素（碳氮源、溶氧和温度）进行综述；随后，阐述了破囊壶菌发酵生产DHA的中试放大工艺的研究现状；最后，提出破囊壶菌发酵生产DHA过程中存在的问题，并指出进一步分离获得优质的破囊壶菌菌株、对其代谢途径和关键酶的研究以及中试放大工艺的研究是下一步研究的重点。通过对上述一系列问题进行综述，旨在为利用破囊壶菌工业化生产DHA提供一定的参考。     

A novel utilized method of tar derived from biomass gasification for fabricating binder-free all-solid-state hybrid supercapacitors

As an industrial pollutant, tar derived from biomass gasification is used as the precursor for fabricating a novel carbon-metal hydroxides composite electrode. A slurry (the mixture of tar, KOH and melamine) is daubed uniformly onto the nickel foam, which is directly carbonized to form NPC@LDH electrode material. This electrode is further coated with NiCo-LDH nanosheets using an electrodeposition method to form NF@NPC@LDH. The newly made NF@NPC@LDH electrode exhibits a high specific capacity of 9.6 F cm⁻² at a current density of 2 mA cm⁻² and good rate performance (55.3% retention). Furthermore, a hybrid NF@NPC@LDH//NF@PC all-solid-state supercapacitor is fabricated, and the device exhibits high energy density of 1.28 mWh cm⁻³ at a power density of 8.04 mW cm⁻³, low resistance and good cycling stability.     

Determination of Metastable Zone Width and Nucleation Induction Period of Palm Oil and its Olein/Stearin in Melting Layer Crystallization

Measurement methods of metastable zone width (MZW) and nucleation induction time for melting layer crystallization of palm oil (PO) and its olein/stearin (POL/PST) were established, and the effects of cooling rate (corresponding to various supercoolings) on MZWs and induction time for melting layer crystallization of PO, POL, and PST were determined. The results indicated that the MZW coherently rose with increasing cooling rates with respect to PO and POL, while it declined with higher cooling rates for PST. The induction period results demonstrated that the nucleation induction periods of PO, PST, and POL decreased with increasing supercoolings, and the lag time for nucleation negatively correlated to the melting point of oils at the same supercooling. These data could offer significant instruction in designing and controlling the melting layer crystallization process for palm oil.     

Synchronous fluorescence and multivariate classification analysis as a screening tool for determining Sudan I dye in culinary spices

Spices are a globally traded commodity which has been found to be adulterated with forbidden Sudan dyes. This work proposes a screening method for determining the adulteration of paprika varieties (mild, hot and smoked) with Sudan I dye, based on constant-wavelength synchronous fluorescence spectroscopy with multivariate classification. Different wavelength-intervals (Δλ) were evaluated. Classification models were built with Partial Least Squares-Discriminant Analysis (PLS-DA) at two Sudan I dye concentration levels (1 and 5 mg L⁻¹) and they were tested with samples at a lower level (0.5 mg L⁻¹). Classification results were quite satisfactory when a strategy based on first-derivative spectra was used for improving classification results. Δλ = 60 nm was chosen as the optimum wavelength interval giving a 100% of sensitivity and specificity. These results are promising because the risk of assigning adulterated samples as safe to be consumed is highly minimized. The proposed method is feasible, rapid and simple taking advantage of Sudan I fluorescence phenomena in a direct way.     

Modeling surface water-groundwater interaction in arid and semi-arid regions with intensive agriculture

In semi-arid and arid areas with intensive agriculture, surface water-groundwater (SW-GW) interaction and agricultural water use are two critical and closely interrelated hydrological processes. However, the impact of agricultural water use on the hydrologic cycle has been rarely explored by integrated SW-GW modeling, especially in large basins. This study coupled the Storm Water Management Model (SWMM), which is able to simulate highly engineered flow systems, with the Coupled Ground-Water and Surface-Water Flow Model (GSFLOW). The new model was applied to study the hydrologic cycle of the Zhangye Basin, northwest China, a typical arid to semi-arid area with significant irrigation. After the successful calibration, the model produced a holistic view of the hydrological cycle impact by the agricultural water use, and generated insights into the spatial and temporal patterns of the SW-GW interaction in the study area. Different water resources management scenarios were also evaluated via the modeling. The results showed that if the irrigation demand continuous to increase, the current management strategy would lead to acceleration of the groundwater depletion, and therefore introduce ecological problems to this basin. Overall, this study demonstrated the applicability of the new model and its value to the water resources management in arid and semi-arid areas.     

Evaluation of anaerobic co-digestion of spent brewery grains and an azo dye

Anaerobic batch biodegradation of spent brewery grains (SBG) was investigated in the presence of co-substrates and a monoazo dye (Acid Orange 7 – AO7) under mesophilic and thermophilic regimes. The highest values for the yield coefficient of biogas (STP) on substrate (Y_bs) were obtained under mesophilic conditions (0.381–0.516 Lbiogas/g COD_removed and 0.147 to 0.475 L_biogas/g COD_removed for mesophilic and thermophilic regimes, respectively). A stimulation of the degradation of SBG associated with microbial growth was observed in the presence of co-substrates (glucose and acetate). Supplemented co-substrates also lowered the residual COD leading to an increase in the COD removal efficiency, particularly under thermophilic regime (from 41% to 70%). Although biogas yield (Y_bs) indicates a decrease in the presence of the dye, suggesting that it has inhibitory effects, the overall COD removal was not significantly altered. An increase of colour removal was observed when the temperature of the operation was increased (87 ± 2% and 93 ± 1% for mesophilic and thermophilic reactors, respectively), which could be explained by both faster adsorption and biotic reductive cleavage of azo dye bond mechanisms. These results indicate that raw SBG is more prone to biodegradation under an anaerobic mesophilic regime; hence its bio-energetic valorisation is possible.     

BE-ACGAN: Photo-realistic residual bit-depth enhancement by advanced conditional GAN

Since more demands for high quality visualization have been raised in various fields, monitors with higher bit-depth (HBD) become popular in recent years. However, most digital images are at low bit-depth (LBD) and usually of low visual quality with annoying false contours when displayed on HBD monitors directly. To reconstruct visually pleasant HBD images, many bit-depth enhancement (BE) algorithms have been proposed from various aspects, but the recovered HBD images are usually unsatisfactory with conspicuous false contours or over-blurred textures. Inspired by discriminative learning, we propose a residual BE algorithm based on advanced conditional generative adversarial network (BE-ACGAN), in which the discriminator adversarially helps assess image quality and train the generator to achieve more photo-realistic recovery performance. Besides, since it is hard to distinguish between the reconstructed and real HBD images with similar structures, the discriminator takes residual images as input and further takes LBD images as conditions to achieve more reliable performance. In addition, we present a novel loss function to deal with the difficulty of unstable adversarial training. The proposed algorithm outperforms the state-of-the-art methods on large-scale benchmark datasets. Source codes are available at https://github.com/TJUMMG/BE- ACGAN/.