In order to enhance the stability and bioavailability of fat-soluble kaempferol (Kae), the zein-pectin nanoemulsions were synthesized by a novel dual-frequency pulsed ultrasound (DFPU) technology to improve the loading effect of Kae. The effects of ultrasonic operating parameters on the nanoemulsions were examined, along with the influence of DFPU treatment on the structure, stability, digestion, and intracellular uptake of the nanoemulsions in this study. The results indicated that both emulsion encapsulation and DFPU treatment significantly enhanced the protection and delivery of Kae. Compared to the unsonicated emulsion, the emulsifying activity index, stability index, Kae embedding rate, and hydroxyl radical scavenging rate increased by 133.81 %, 4.18 %, 19.20 %, and 19.73 %, respectively, while the particle size decreased by 94.43 % after DFPU treatment. DFPU treatment notably improved the stability of the nanoemulsions during long-term storage, high temperature, and salt concentration conditions, as well as the retention of Kae by 15.59 % in intestinal digestives. Furthermore, DFPU treatment significantly enhanced the Caco-2 intracellular absorption rate, transport rate and bioavailability of Kae by 7.67 %, 9.96 % and 14.67 %, respectively at a dosage of 0.6 mg/mL, which was attributed to the significant downregulation of mRNA expression levels of tight junction protein Occludin and efflux proteins MDR1 and BCRP by 21.27 %, 51.05 %, and 62.26 %, respectively. This downregulation enhanced the intracellular transport capacity of Kae while reducing its exocytosis, thereby improving cellular utilization. The mechanism of improving the intracellular bioavailability of kaempferol was elucidated. This study offers a promising nanoemulsion for the efficient oral delivery of fat-soluble active ingredients, fully facilitating its antioxidant activity. © 2025 Elsevier Ltd

An innovative catalytic infrared (CIR) dry enzyme inactivation method was developed in this study to replace wet-heat methods. The residual activities and structural changes of peroxidase (POD) and polyphenol oxidase (PPO) after heat treatment were assessed experimentally. Molecular dynamics and docking studies were employed to compare the thermal and radiation effects of CIR. The results demonstrated complete inactivation (100 %) of PPO and POD after 65 min at 70 degrees C. This was attributed to both thermal and radiation effects of CIR, which disrupted hydrogen bonds, induced disordered secondary structure, loosened molecular conformation, encapsulated active sites, and reduced binding energy, thereby leading to enzyme inactivation. The thermal effect was more destructive to PPO and POD than the radiation effect, loosening by 1.81 % and 1.21 % of surface area, reducing by 0.87 % and 2.27 %, 2.85 % and 1.32 % of intra- and intermolecular hydrogen bond and 6.71 % and 4.21 % of binding energy, respectively. The mechanism of dry enzyme inactivation by CIR was elucidated. CIR is a promising alternative to wet-heat methods, offering energy savings and enhanced safety. Industry relevance: Enzymatic browning, driven by polyphenol oxidase (PPO) and peroxidase (POD), is a significant concern in global fruit and vegetable processing. Conventional enzyme inactivation methods, such as wet-heat treatments, suffer from high energy and water consumption and contribute to environmental pollution. This increases processing costs and compromises product quality. In contrast, CIR is promising to be a new dry enzyme inactivation technology instead of wet-heat enzyme inactivation methods, which is energy-efficient, environmentally friendly, and capable of achieving optimal enzyme inactivation. This study conveys a better understanding of CIR mechanisms and optimal conditions of dry enzyme inactivation for its effective use in food processing applications on an industrial scale.

核桃是世界著名坚果之一,果仁富含不饱和脂肪酸、蛋白质和多酚类抗氧化物质,对心血管疾病、糖尿病等均有较大的益处。目前核桃的干燥方式主要为热风干燥,存在干燥速率低、时间长和能耗高等缺点,严重制约干果质量和产业的发展。催化式红外干燥技术作为一种新型干燥技术,以天然气为主要能源,具有干燥效率高、节能环保等优点,与传统热风干燥（HAD）相比,可以在提升干燥速率的同时兼顾产品品质。低场核磁技术（LF-NMR）因其快速、对物料无损伤性等优点,可应用于干燥过程中水分含量变化以及迁移机制的研究中。因此本论文将滚筒催化红外干燥与传统热风干燥结合,采取恒温与变温干燥模式,优化干燥工艺和计算能耗,并考察其对干燥特性、干燥动力学以及核桃油脂、蛋白、多酚品质的影响;运用LF-NMR技术考察干燥过程中水分迁移机制,建立含水率预测模型;最后考察干燥处理后核桃的贮藏特性,并建立货架期预测模型。主要结论如下:（1）优化获得了一种恒温滚筒催化红外—热风联合干燥（CTDCIR-HAD）方法,其最佳工艺参数为:红外温度450℃、辐射距离30 cm、滚筒转速25 Hz、干燥时间9.5 min,随后转入热风温度43℃、风速3 m/s下干燥16 h,干燥总时间为16.16 h。与HAD（20 h）相比,CTDCIR-HAD处理显著提升了干燥速率,红外干燥阶段去除了10.71%的表壳水分,干燥时间缩短了19.20%,节约了11.60%的能耗,且干制核桃表壳无褐斑和裂缝,呈较好的亮红黄色（L为47.51,a为7.97,b为16.37）。CTDCIR-HAD优于HAD,是一种适宜硬壳坚果类产品干燥的新型高效节能加工方法。（2）优化获得了一种变温滚筒催化红外—热风联合干燥（VTDCIR-HAD）方法,其最佳工艺参数为:红外温度组合300+400℃、辐射距离30 cm、滚筒转速组合25+35+35 Hz、干燥时间22.50 min,随后转入热风温度43℃、风速3 m/s件下干燥14 h,干燥总时间为14.38 h。干制核桃表壳无褐斑和裂缝,呈较好的亮红黄色（L为54.24,a为10.61,b为19.89）,品质良好。与HAD（20 h）相比,VTDCIR-HAD干燥时间缩短了28.10%,节约了25.04%的能耗;与CTDCIR-HAD相比,VTDCIR-HAD干燥时间缩短了11.01%,节约了15.21%的能耗。表明VTDCIR-HAD更加高效节能,更适于硬壳坚果类产品的干燥加工。此外,建立了用于预测VTDCIR-HAD干燥过程的Henderson-Pabis模型,R~2为0.99,RMSE为0.03,拟合效果良好,可以很好地预测核桃在该干燥过程中含水率以及干燥速率的变化。（3）通过基于LF-NMR的水分预测模型揭示VTDCIR-HAD和CTDCIR-HAD过程中水分迁移机理。研究发现,随着干燥时间的延长,自由水峰面积不断下降直至几近消失,弱结合水峰面积亦不断下降,强结合水和油脂峰峰面积无显著变化,说明在干燥过程中散失的主要水分为自由水以及弱结合水,强结合水和油脂含量变化不大;在相似水分比下,CTDCIR-HAD与VTDCIR-HAD处理的核桃弱结合水以及自由水弛豫时间均高于HAD组,表明红外辐射干燥可以加强核桃内部水分子的流动性,加快其从内部向表面扩散,从而提升干燥效率。此外,建立了基于LF-NMR的CTDCIR-HAD与VTDCIR-HAD干燥过程中含水量变化的预测模型,R~2均＞0.92,拟合效果较好,表明LF-NMR技术能够较好地监测核桃在该干燥过程中的水分迁移状态。（4）考察3种干燥方式处理后核桃品质发现:与HAD相比,CTDCIR-HAD与VTDCIR-HAD处理的核桃油酸价分别低了17.31%和28.85%,过氧化值分别低了4%和20%,碘价、油酸、亚油酸和亚麻酸含量无显著变化,其中VTDCIR-HAD处理的核桃油品质最优;VTDCIR-HAD和CTDCIR-HAD处理的核桃蛋白结构更伸展,表现为红外吸收强度增大,α-螺旋结构含量降低了50%和18.75%,荧光强度增强,表面疏水性增加了28.27%和12.51%,游离疏水性氨基酸占比降低了19.24%和9.49%,亲水性氨基酸占比增加了9.84%和4.85%,蛋白表观结构无明显变化;CTDCIR-HAD与VTDCIR-HAD处理核桃的多酚含量分别增加了5.23%和10.92%,IC50（DPPH）与IC50（ABTS）分别降低了24.36%、11.58%和14.72%、10.60%,铁离子还原能力明显提高,其中VTDCIR-HAD处理的核桃多酚含量最高。综上得出,VTDCIR-HAD处理方式最优,可以减缓油脂的氧化酸败速度,改善蛋白质结构,提高多酚含量和抗氧化活性,更有利于保护干制核桃品质。（5）以油脂酸价、过氧化值为评价指标,考察3种干燥方式处理后核桃的贮藏特性发现:随着贮藏时间的延长,酸价与过氧化值均呈升高趋势。与HAD相比,CTDCIR-HAD与VTDCIR-HAD处理核桃的油脂酸价和过氧化值增幅较低,其中VTDCIR-HAD处理的核桃油酸价和过氧化值增幅最小,贮藏性能最好。此外建立了VTDCIR-HAD处理核桃的贮藏货架期模型,R~2均＞0.96,相对误差＜8.93%,表明该预测模型在5～35℃之间可较好地预测该干燥方式处理后核桃货架期。

Cell wall-degrading enzymes' activities under infrared treatment are vital for peeling; it is critical to elucidate the mechanisms of the novel infrared peeling in relation to its impact on cell wall-degrading enzymes. In this study, the activities, and gene expressions of eight degrading enzymes closely related to pectin, cellulose and hemicellulose were determined. The most influential enzyme was selected from them, and then the mechanism of its changes was revealed by molecular dynamics simulation and molecular docking. The results demonstrated that infrared had the most significant effect on β-glucosidase among the tested enzymes (increased activity and up-regulated gene expression of 195.65 % and 7.08, respectively). It is suggested infrared crucially promotes cell wall degradation by affecting β-glucosidase. After infrared treatment, β-glucosidase's structure moderately transformed to a more open one and became flexible, increasing the affinity between β-glucosidase and substrate (increasing 75 % H-bonds and shortening 15.89 % average length), thereby improving β-glucosidase's activity. It contributed to cell wall degradation. The conclusion is that the effect of infrared on the activity, gene expression and molecular structure of β-glucosidase causes damage to the peel, thus broadening the applicability of the new infrared dry-peeling technique, which has the potential to replace traditional wet-peeling methods. © 2023 Elsevier B.V.

The peelability of fruit is influenced by numerous factors; thus, it is critical to identify key factors to anticipate peelability. This study aimed to examine variations in peelability and key indices of tomatoes at various infrared (IR) parameters, and their quantitative relationships, using Pearson's correlation and multiple linear regression (MLR) statistical tools. Results showed that the peelability during IR treatment could be quantitatively reflected by content, esterification degree (DE), intrinsic viscosity of pectin, surface temperature, intracellular and extracellular resistance, and relative electrolyte leakage (REL). Among them, contributions of REL, pectin content, DE of pectin, and surface temperature to peelability were more significant. This is because as IR's time and temperature increased, tomatoes' surface temperature increased, leading to the degradation of pectin, and changes in DE of pectin and REL. This contributed to thermal softening of peel and decreased adhesions of cells, leading to skin loosening. Skin loosening along with accumulated pressure improved skin rupture, improving peelability. This peeling model was statistically significant (Adjust R2 = 0.971, Sig. of F-test© 2023 The Authors

Food quality is greatly impacted by traditional heat methods for polygalacturonase (PG) inactivation; therefore, it's imperative to develop a novel infrared (IR) inactivation approach and identify its mechanism. Utilizing molecular dynamics (MD) simulation, this study verified the PG's activity, structure, active sites, and substrate channel under the single thermal and non-thermal effects of IR. PG activity was significantly reduced by IR, and structure was unfolded by increasing random coils (65.62 %) and decreasing β-sheets (29.11 %). MD data indicated that the relative locations of PG's active sites were altered by both IR effects, and the enzyme-substrate channel was shortened (10.53 % at 18 μm and 15.79 % at 80 °C). The thermal effect of IR on the inactivation of PG was significantly more pronounced than its non-thermal effect. This study unveiled the mechanism by which the infrared disrupted PG's activity, active sites, and substrate channels; thus, it expanded the infrared technique's efficacy in enzyme control. © 2023 Elsevier Ltd

Sterilization of solid food has always been a key technical problem in food industry. In order to ensure an energy-saving, efficient, and safe sterilization process, in recent years, a series of emerging physical sterilization technologies have emerged in reference to two physical phenomena from the space extreme environment, electromagnetic wave and plasma. These include thermal physical sterilization technologies represented by catalytic infrared radiation, microwave, radio frequency, and non-thermal physical sterilization technologies represented by photodynamic, pulsed light, cold plasma activated water/ice, and in-package cold plasma. These emerging technologies could adapt to the surface or overall sterilization of solid foods with different forms and component characteristics. This article focused on the core issues and latest application research of relevant technologies, and proposed the main tasks for future development of physical sterilization of solid foods from four aspects. 1) Deepen the mechanism research of physical sterilization technology. Based on different solid food matrix environments, explore the response mechanisms of different food-borne microorganisms under different physical field stress. 2) Promote the key technology research of multi-physical field coupling sterilization. According to the characteristics of different solid food materials, coordinate various emerging physical sterilization technologies with their respective characteristics to establish a balance between sterilization effectiveness and food quality reduction. 3) Break through the manufacturing bottleneck of physical sterilization key equipment. Based on interdisciplinary research, overcome the technical difficulties in development of key equipment for physical sterilization, and minimize manufacturing cost. 4) Promote the development and application of in-package physical sterilization technology. According to the real production scenarios of solid food, promote the development of in-package physical sterilization technology to avoid secondary pollution after sterilization. © 2023 Beijing Technology and Business University, Department of Science and Technology. All rights reserved.

To protect the pulp quality, the effect of infrared peeling on the physicochemical, structural, rheological, and gelling properties of tomato pectin was investigated using newly developed catalytic infrared peeling equipment and compared with manual, hot-water and lye peeling. Compared to manually peeled pectin, the results showed that hot-water peeling reduced the pectin yield by 13.19% but significantly increased the pectin's Z-average radius of gyration (Rg) and hydrodynamic radius (RH). And the pectin gel had excessive hardness. Lye peeling reduced the pectin yield by 30.43%, the degree of esterification (DE) by 25.97%, RH by 7.8 nm and Rg by 2.9 nm. And the pectin gel had the worst water-holding capacity and texture. The yield and DE of pectin (IPP) after infrared peeling only decreased by 3.88% and 0.9%. IPP exhibited moderate physicochemical, structural, rheological, and gelling properties, which was the closest to manually peeled pectin. IPP gel showed steady viscoelasticity and high water-holding capacity (96.71%). Conclusively, the infrared peeling technique can provide better pulp quality and is sustainable. © 2023 Elsevier Ltd

To protect tomato pulp quality, this study investigated the effect of the infrared peeling method (using our newly developed catalytic infrared peeling equipment) on pectin's chemical, structural and functional properties and their correlation compared with manual, hot-water, and lye peeling methods. Infrared peeling significantly improved pectin's emulsifying and antioxidant capacity compared to manual peeling by increasing branching degree. Hot water peeling significantly improved pectin's viscosity, emulsifying and antioxidant capacity. However, the pectin chains had low flexibility. The effect of lye peeling on pectin was the greatest, causing the lowest linearity and the largest degree of branching. In comparison, infrared peeling had the least impact on pectin. It was further confirmed that pectin’ viscosity, emulsifying, and antioxidant capacity were highly correlated with its chemical and structural properties. In summary, the infrared peeling method provides better pulp quality and is more sustainable because no water and chemicals are used. © 2022 Elsevier Ltd

This paper investigated the effect of catalytic infrared radiation (CIR) only and CIR coupled with holding time (CIRH) on decontamination of damp-returning dried shiitake mushrooms contaminated with Aspergillus niger (A. niger). The effect of initial moisture content (IMC) of the samples on CIR/CIRH operation layout was also investigated. Analysis of surface color, observations of electron microscopy and evaluation of quality (retention rate of total sugar, crude protein and total phenolics) directly manifested that CIRH treatment had the outstanding potential to maintain the original appearance and microstructure compared to CIR (p 2 = 0.9790–0.9977, which can well predict the changes in A. niger of dried shiitake mushrooms with different IMCs in the holding process. Therefore, the present work could pave the way for future production of good quality dried shiitake mushrooms using CIRH. © The Authors