Synergistic effect of high-intensity ultrasound and β-cyclodextrin treatments on browning control in apple juice

This work evaluated the synergistic effects of combined high-intensity ultrasound (HIU) with β-cyclodextrin (β-CD) treatments on inhibiting browning of apple juice and explored the mechanism through simulation system. The combined treatment of 300 W HIU with 0.006 g mL⁻¹ β-CD had a synergistic impact on maintaining juice colour, resulting in a 39.06% reduction in browning degree, only a 36.64% decrease in total phenolic content, and a 17.82% reduction in PPO activity. The inhibition of enzymatic browning in simulated system revealed that HIU suppressed the enzyme (Polyphenol oxidase, PPO) and β-CD inhibited enzyme (PPO) and embedded substrate (polyphenol). The results of spectroscopic analysis showed that the particle-size distribution of PPO narrowed, the content of α-helix in the secondary structure increased, the fluorescence intensity increased, and the maximum wavelength was red-shifted after HIU and β-CD treatment. Changes in structure could further result in PPO activity loss. Hence, the combined treatment could synthetically alleviate the browning of apple juice.     

Ir(III) and Ru(II) Complexes in Photoredox Catalysis and Photodynamic Therapy: A New Paradigm towards Anticancer Applications

Individually, photoredox catalysis (PC) and photodynamic therapy (PDT) are well-established concepts that have experienced a remarkable resurgence in recent years, leading to significant progress in organic synthesis for PC and clinical approval of anticancer drugs for PDT. But, very recently, new photoredox catalyst systems based on Ir(III) and Ru(II) complexes have garnered significant interest because they can simultaneously be used as PDT agents apart from their demonstrated PC activity. This highlight discusses the unique PC behavior of emerging Ir(III)- and Ru(II)-based systems while also examining their potential PDT activity in cancer treatment.     

微波辅助孵育法富集麦胚多肽的工艺优化

目的 麦胚孵育过程中蛋白酶将蛋白质水解成肽和氨基酸，多肽具有明确的生理活性和营养调节作用。本研究以麦胚为试验原料，采用微波辅助预处理的方法，研究孵育的温度、时间、pH及料液比4种因素对孵育后的蛋白酶活力及多肽含量的影响。 方法 通过单因素和响应曲面试验进行工艺条件优化。 结果 与未进行微波辅助预处理的样品相比，微波辅助处理（600 W, 10 s）能显著提高孵育后样品中的蛋白酶酶活力（约9.4倍）和肽含量（约3.1倍）。经过微波辅助处理后，孵育温度为51.5℃、pH为4.0、时间为6.33 h、料液比为1:7时，蛋白酶活力达最高为3826.24 U/g；孵育温度为45.0 ℃、pH为4.8、时间为8 h、料液比为1:7时，肽含量达最高为262.63 mg/g。 结论 微波辅助处理能有效的激活麦胚孵育液中的内源性蛋白酶活性，促进蛋白水解反应，显著提高孵育后的肽含量。该研究结果为麦胚多肽的制备新工艺开发提供了研究基础。     

Brönsted方程动力学模型研究ZSM-5催化乙烯齐聚及芳构化活性和酸强度分布之间的定量关系

乙烯催化齐聚和芳构化是烯烃高值化和合成液体燃料的关键过程，采用NH₃-TPD谱图分析计算方法得到的探针分子脱附活化能作为催化剂的酸位点强度分布的参数，结合线性自由能理论在Br?nsted方程中引入酸强度对反应的影响因子γ作为动力学方程参数关联探针分子脱附活化能与反应活化能，明确固体酸酸强度的基准在催化动力学方程中的物理意义。建立同为MFI拓扑结构 Si /Al摩尔比为12.5、19、25、60、70的ZSM-5分子筛催化剂上不同酸强度位和乙烯齐聚及芳构化中氢转移、齐聚、芳构化各单元步骤以及对应的烷烃、低碳烯烃和芳烃产物分布的定量关系。根据拟合得到动力学参数γ可以发现不同强度的酸位点对乙烯齐聚及芳构化具有不同的作用系数。氨脱附活化能(DAE)为90 kJ·mol^-1的酸位点是氢转移反应的主要活性位点，而对于乙烯齐聚反应中主要的活性酸位点为DAE 90 kJ·mol^-1和124 kJ·mol^-1，DAE为150 kJ·mol^-1的酸位点是芳构化反应的主要活性位点。     

Angiotensin I‐converting enzyme inhibitory and Ca‐binding activities of peptides prepared from tuna cooking juice and spleen proteases

Tuna cooking juice is a by‐product from the tuna canning industry. In this study, tuna cooking juice was hydrolysed by proteases extracted from the spleen. Tuna cooking juice showed the highest ACE inhibitory and Ca‐binding activities after hydrolysis for 270 and 180 min, respectively. The hydrolysate was further fractionated by ultrafiltration. The permeate exhibited highest ACE inhibitory and Ca‐binding activities when passed through 1 and 5 kDa cut‐off membranes, respectively. Gel filtration chromatography was used to determine the MW of bioactive peptides that exhibited highest ACE inhibitory and Ca‐binding activities. Those peptides that exhibited highest ACE inhibitory and Ca‐binding activities were the MW range of 238–829 Da and 1355–1880 Da, respectively. These results suggest that the tuna cooking juice and the spleen protease extract are a potential source of bioactive peptides that can be utilised as bioactive ingredients in functional food and nutraceuticals.