Raw meat products are prone to light-induced oxidation, leading to quality deterioration. Astaxanthin (Asta) exhibits excellent antioxidant capabilities, but it is still unknown if it can inhibit muscle photooxidation. This study established a myoglobin (Mb) mediated water-washed muscle model to exploring the inhibitory ability of Asta. The results indicated that the higher peroxide values (PV) and thiobarbituric acid-reactive substances (TBARs) in Mb-Light group than Mb group confirmed Mb's photosensitivity. Asta significantly reduced OxyMb-to-MetMb conversion, lowered PV/TBARs levels, and demonstrated superior anti-photooxidation efficacy over autooxidation, which was attributed to Asta's pronounced free radical scavenging capacity and singlet oxygen quenching ability. The quenching sites and process was further speculated by Density functional theory. Texture analyzer and GC-MS confirmed that Asta prevented muscle texture degradation, color loss and reduced photosensitive volatile compounds (hexanal/pentanal). These findings provide new insights into the potential of Asta to inhibit lipid oxidation in muscle tissues.

Objective:This study aimed to explore the copigmentation formula of purple corn anthocyanins.Methods:In this study,fructose,tannic acid,and pectin were used as co-pigmentation.The response surface method was used to optimize the co-pigmentation formula of purple corn anthocyanins,and the untreated purple corn was used as a control test.The anthocyanin components,color,texture,taste and antioxidant activity(DPPH free radical scavenging ability,ABTS free radical scavenging ability,and FRAP iron ion reducing ability)of purple corn after different treatments were determined.Results:19％fructose,0.07％tannic acid,and 1.9％pectin had the best copigmentation effect.Compared with the control group,the contents of cyanidin-3-O-glucoside,geranium-3-O-glucoside,and peony-3-O-glucoside in purple corn increased by 77.64％,64.82％,and 54.75％,respectively.The total anthocyanin content increased by 67.98％.The L*value,b*value,and △E value of color decreased,while the a*value increased.Hardness,adhesiveness,and chewing type increased,while elasticity and cohesion decreased.The bitter,astringent,and astringent aftertastes differ slightly,as do the sour,sweet,salty,umami,bitter,and umami aftertastes.In the mass concentration range of 0.02～0.10 mg/mL,the DPPH free radical scavenging ability,ABTS free radical scavenging ability and FRAP iron ion reducing ability of purple corn anthocyanins were 39％～79％,54％～74％and 27％～67％,respectively.Conclusion:The co-pigmentation effect of 19％fructose,0.07％tannic acid,and 1.9％pectin on purple corn anthocyanins was the best.

Hydrogen sulfide (H2S), or dihydrogen sulfane (H2Sn), acts as a signal molecule through the beneficial mechanism of persulfidation, known as the post-translational transformation of cysteine residues to persulfides. We previously reported that Glutathione (GSH) could regulate enzyme activity through S-desulfurization or glutathionylation of residues to generate protein-SG or protein-SSG, releasing H2S. However, little is known about the mechanisms by which H2Sn and GSH affect the disulfide bonds. In this study, we provide direct evidences that H2Sn and GSH modify the sulfhydryl group on Cys272, which forms disulfide bonds in acetylcholinesterase (AChE), to generate Cys-SSH and Cys-SSG, respectively. Glutathionylation of disulfide is a two-step reaction based on nucleophilic substitution, in which the first CS bond is broken, then the SS bond is broken to release H2S. H2Sn and GSH controlled self-breathing motion in enzyme catalysis by disconnecting specific disulfide bonds and modifying cysteine residues, thereby regulating AChE activity. Here, we elucidated H2Sn and GSH mechanisms on disulfide in the AChE system and proposed a self-breathing control theory induced by H2Sn and GSH. These theoretical findings shed light on the biological functions of H2Sn and GSH on sulfhydryl and disulfide bonds and enrich the theory of enzyme activity regulation.

Lipid oxidation significantly contributes to muscle deterioration, with heme protein oxidation playing a crucial role in this process. This study investigated the inhibition of heme protein oxidation by Maillard reaction products (MRPs) using a washed muscle model combining washed carp with myoglobin (Mb). Protein oxidation products, protein texture, and lipid oxidation levels were assessed. Results showed that metmyoglobin (MetMb) is a primary driver of lipid oxidation in meat, likely due to Mb oxidation, exposing hydrophobic groups that bind to lipids. MRPs at concentrations of 0.5% and 1% effectively inhibited Mb oxidation. Specifically, treatment with 1% MRPs reduced MetMb formation by 15.38%, protein carbonyl content by 6.53%, hydroxyl radical content by 20.37%, protein aggregation by 40.81%, and particle size by 36.95% during later storage stages, thereby preserving Mb stability. In the Mb-mediated oxidation model, 1% MRPs inhibited the formation of primary and secondary oxidative metabolites by 59.47% and 68.19%, respectively, while maintaining muscle tissue texture integrity. PRACTICAL APPLICATION: The antioxidation of Maillard reaction products (MRPs) improves the stability of common carp. By inhibiting the autoxidation of myoglobin and lipid, MRPs help preserve the texture and color of fish muscle while extending its shelf life. This study provides a valuable reference for effectively controlling lipid oxidation in refrigerated fish products and enhancing their overall quality.

Numerous secondary metabolites in medicinal food homology plants such as Allium inhibit the activity of acetylcholinesterase (AChE), but the current understanding of the inhibition mechanism is limited. In this study, we employed ultrafiltration, spectroscopic, molecular docking, and matrix-assisted laser desorption ionization time-of-flight tandem mass spectrometry (MALDI-TOF-MS/MS) techniques to investigate the inhibition mechanism of AChE by garlic organic sulfanes, including diallyl sulfide (DAS), diallyl disulfide (DADS), and diallyl trisulfide (DATS). The results of UV-spectrophotometry and ultrafiltration experiments showed the inhibition of AChE activity by DAS and DADS was reversible (competitive inhibition), but inhibition by DATS was irreversible. Molecular fluorescence and molecular docking indicated DAS and DADS changed the positions of key amino acids inside the catalytic cavity through hydrophobic interactions with AChE. By using MALDI-TOF-MS/MS, we found DATS irreversibly inhibited AChE activity by opening disulfide-bond switching of disulfide bond 1 (Cys-69 and Cys-96) and disulfide bond 2 (Cys-257 and Cys-272) in AChE, as well as by covalently modifying Cys-272 in disulfide bond 2 to generate AChE-SSA derivatives (strengthened switch). This study provides a basis for further exploration of natural AChE inhibitors using organic active substances in garlic and presents a hypothesis of U-shaped spring force arm effect based on the disulfide bond-switching reaction of DATS that can be used to evaluate the stability of disulfide bonds in proteins.

为解决葱属硫化物检测方法技术难度大、检测目标单一等局限性,本文以谷胱甘肽(GSH)为标准品,利用还原硫漂白碘铂酸盐的原理建立了一种瞬时检测葱属硫化物的方法,并对6种葱属植物中硫化物的含量进行检测.结果表明,该方法在线性范围(0～30μg/mL)内线性关系良好(R2＞0.9997),最低检出限(LOD)为0.26 μg/mL,最低定量限(LOQ)为0.78 μg/mL,可重复性数据为90.4％,加标回收率均满足80％～120％,变异系数均满足0～5％,试验确定了检测环境为中性或酸性.利用此方法检测出6种葱属植物中硫化物的含量与高效液相色谱-电喷雾电离-质谱联用(HPLC-ESI-MS)法(丹磺酰氯衍生)所测得结果无显著性差异.此比色法的建立为现场快速检测葱属硫化物提供技术参考.

思想政治教育教学工作应该贯穿高校专业课的全过程.根据食品专业的相关特点,以"食品化学"课程为例,从教师和课堂两个方面入手,阐述了教师如何在讲授专业课的同时也能加强对学生的思想政治教育,即提出了教师应首先提高自身政治素养,扎实掌握自身相关业务能力,还要具备不断更新知识储备的能力.在课堂上,教师应从身边实际存在的例子出发,将思想政治教学内容融入课堂,构建起全员、全程、全方位的"三全育人"体系,形成全方位协同育人效应.

工程教育专业认证是国际通行的工程教育质量保障制度,也是实现工程教育国际互认和工程师资格国际互认的重要基础.以沈阳农业大学食品质量与安全专业工程教育认证为基础,阐述食品化学课程的课程目标以及与毕业要求指标点的对应关系,构建食品化学课程目标达成度评价体系,同时结合2020～2021学年相关教学实践,对食品化学课程达成度的结果进行分析,并在此基础上提出改进教学方法、理论联系实际和完善评价体系等教学改革建议.

从大蒜中提取大蒜油,采用气相色谱-质谱联用仪(GC-MS)对其进行定性分析;采用酶活实时监测技术,揭示大蒜油、二烯丙基二硫醚(DADS)和二烯丙基三硫醚(DATS)对葡萄糖-6-磷酸脱氢酶(Glucose 6 Phosphate Dehydrogenase,G6PD)活性的抑制作用.酶动力学分析表明DADS/DATS对G6PD的抑制作用属于竞争性与非竞争性的混合性抑制.分子荧光技术分析表明DADS/DATS可对G6PD蛋白产生内源荧光淬灭,且为静态淬灭,提示DADS/DATS和G6PD蛋白结合位点数近似为1.热力学分析表明DADS-G6PD体系主要通过疏水作用结合,DATS-G6PD体系主要通过氢键和范德华力结合.利用3D和2D分子对接技术展示DADS/DATS可进入G6PD分子内部,且DADS与G6PD结合性能更好.DADS可与G6PD结合位点周围Ala-377、Val-376、Phe-216、Gly-222、Phe-221、Pro-223等疏水性氨基酸残基形成疏水作用,与Arg-219、Asn-218、Lys-275、Arg-215、Trp-225等极性氨基酸残基形成静电力,且以疏水作用为主.DATS可与G6PD结合位点周围Phe-253、Gly-254、Ala-335、Ile-472、Ile-255、Leu-469、Leu-305等疏水性氨基酸残基形成疏水相互作用,与Arg-175、Lys-476、Arg-257、Thr-334、Thr-333、Glu-473等极性氨基酸残基形成静电吸引.DATS中心位置的S可与Phe235形成氢键,键长为3.2?.疏水作用、静电力和氢键是DADS/DATS对G6PD的主要作用方式.

本实验采用超高效液相色谱-四极杆飞行时间质谱(ultra-performance liquid chromatography-quadrupole time-of-flight mass spectrometry,UPLC-QTOF-MS)和核磁共振(nuclear magnetic resonance spectroscopy,NMR)氢谱、碳谱鉴定从番茄叶中提取并纯化的番茄碱;利用紫外光谱法、分子荧光光谱法和分子对接技术研究番茄碱对乙酰胆碱酯酶(acetylcholinesterase,AChE)活性的影响,同时探究番茄碱与AChE的结合方式,为番茄碱的神经保护机制提供理论依据.结果 表明,纯化产物经UPLC-QTOF-MS和1H NMR、13C NMR分析确定为番茄碱.利用紫外光谱法检测出番茄碱可部分抑制AChE的催化活性,并且番茄碱对AChE的抑制作用为竞争性抑制.分子荧光光谱显示,经番茄碱处理的AChE蛋白在340 nm波长处的发射荧光强度下降,并出现红移现象;Autodock分子对接技术分析结果显示,番茄碱与AChE蛋白中的Ser293、Phe295、Phe338、Phe297、Ser125、Gly121、Ser203、Glu202、Gly120、His447、Gly448、Ile451、Trp86、Tyr124、Tyr337、Tyr341、I1e294形成疏水相互作用并与其中的Trp86形成氢键,表明AChE的微环境发生了变化,竞争性地干扰了底物乙酰胆碱与AChE的结合.因此,番茄碱是通过形成氢键和疏水作用的方式抑制AChE活性.

为研究大蒜油的抗凝血作用,本实验从大蒜中分离提取大蒜油,经气相色谱-质谱联用仪鉴定该大蒜油中主要成分为二烯丙基硫醚(allyl sulfide,DAS)、二烯丙基二硫醚(diallyl disulfide,DADS)和二烯丙基三硫醚(diallyl trisulfide,DATS).体外实验结果表明大蒜油、DAS、DADS、DATS均具有部分抑制凝血酶活性功能,且抑制作用由强到弱依次为DATS>大蒜油>DADS>DAS.利用Lineweaver-Burk双倒数作图法进行酶动力学分析,结果表明大蒜油、DAS、DADS、DATS对凝血酶的抑制作用属于混合性抑制(竞争性和非竞争性抑制).分子荧光光谱分析结果表明大蒜油、DAS、DADS、DATS能与凝血酶蛋白中的发色基团相互作用导致荧光猝灭.三维分子对接分析结果显示出DATS与凝血酶结合性能良好;二维分子对接分析结果显示出DATS与凝血酶蛋白活性位点处Asp189、Gly219和Ala190形成氢键,与酶活性位点的Gly216、Ser195、Trp215形成疏水作用力,体现竞争性抑制作用,与非活性位点Gly226、Asp221A、Tyr225、Glu217、Cys191、Val213形成疏水作用,体现非竞争性抑制作用.体内实验结果表明,大蒜油、DAS、DADS、DATS分别通过正向调控大鼠凝血四项指标而直接展现出抗凝血功能,且抗凝血能力依次为DATS>DADS>DAS>大蒜油.大鼠体内抗氧化实验结果表明大蒜油、DAS、DADS、DATS均只有微弱抗氧化能力,大蒜油、DAS、DADS、DATS具有的抗凝血功能应与其抗氧化能力不相关.

Post-translational transformation of cysteine residues to persulfides, known as protein S-sulfhydration or persulfidation, is a beneficial H2S signaling mechanism. In this paper, we found that GSH is bound to active cysteine sites of protein by S-desulfurization, which is a new covalent modification mechanism of protein, thus regulating catalytic activity. Here, we provide direct evidence that GSH modifies the reactive cysteine residues of four enzymes (alliinase/D-LDH/ADH/G6PD) and generates protein-SG or protein-SSG derivatives by S-desulfurization. S-desulfurization, α-carbon nucleophilic substitution or thiol-disulfide exchange occurs and H2S is released as a by-product. S-desulfurization is the opposite of persulfidation in terms of H2S production/consumption and enzyme inhibition/mitigation. Here, we elucidated the GSH mechanisms and H2S mechanisms in the enzyme-metabolite system and the beneficial roles of persulfidation and S-desulfurization. These theoretical findings are now shedding light on understanding GSH and H2S molecular functions and providing new theoretical basis for them in cell signaling pathways.

[目的]明确农用抗生素对温室白粉虱及其共生菌的影响.[方法]采用饲喂法测定3种农用抗生素对温室白粉虱的生物活性,通过qPCR测定共生菌滴度.通过喷施烟草,测定温室白粉虱的死亡率.[结果]相对于春雷霉素和宁南霉素,嘧肽霉素对温室白粉虱成虫的LC50值最低,对粉虱共生菌Arsenophons和Portiera滴度的抑制效果最明显.3种农用抗生素喷施烟草后,粉虱校正死亡率明显高于对照组.[结论]3种农用抗生素对温室白粉虱的存活和共生菌滴度有抑制作用.

近年来,由于微生物及有毒有害物质污染而引起的食品安全事件频发,不仅给人们的健康带来了严重的危害,也给国民经济造成了巨大的损失.随着国家对食品安全监管力度的不断加大,以及感官数字化技术在食品检测中的日益普及,使得食品质量监测更加快捷、简便、准确.此外,结合虚拟现实技术的应急演练活动,打破了食品安全监管中时间、空间等多方面的限制,显示出感官数字化技术的极大优势.主要针对电子鼻、电子舌、电子眼、虚拟现实技术等感官数字化技术在应急演练中的应用进行详细的阐述.

为了筛选出对温室白粉虱Trialeurodes vaporariorum具有增效作用的农药复配组合,室内采用玻璃管饲喂法测定了辣椒碱与吡虫啉、溴氰虫酰胺、苦参碱复配对温室白粉虱初羽化成虫的联合毒力,并以共毒因子法与共毒系数法对各复配组合的联合毒力进行评价.试验结果表明,共毒因子大于20的配比共6组,进一步细化配比后筛选出共毒系数大于120的复配组合,其中14组具有增效作用,辣椒碱分别与吡虫啉、溴氰虫酰胺、苦参碱按287∶1、1 558∶1、423∶1复配时增效作用最显著,其共毒系数分别为257.89、255.65、248.80,LC50分别为31.83、128.07、98.87 mg/L.辣椒碱与吡虫啉按287∶1复配为最佳复配组合.

采用顶空固相微萃取-气相质谱联用(SPME-GC-MS)技术检测西兰花挥发性成分,应用自动质谱退卷积定性系统(AMDIS)进行数据分析,并结合保留指数进行定性.首先对SPME萃取头进行筛选,然后通过剪切、常温研磨、低温研磨和灭酶研磨4种样品制备方式,考察西兰花内源酶对其主要挥发性物质形成的影响.结果显示:65μm PDMS/DVB在萃取西兰花挥发性成分的数量及种类上优于75μm CAR/PDMS和100μm PDMS.剪切组主要成分为酯类、醇类和硫化物,分别占检出成分的42.11％,41.22％,3.53％;常温研磨组为醇类、硫化物和酯类,分别占51.58％,27.21％,16.19％;低温研磨组为醛类、醇类和硫化物,分别占79.81％,3.5％,3.44％;灭酶研磨组为醛类、呋喃,分别占19.91％和6.96％,结果表明由于内源酶充分作用,所以常温研磨下形成醛、醇、酯及硫化物等西兰花主要成分种类最多,其次是剪切组;低温和加热抑制了酶的作用,使低温研磨和灭酶研磨组的挥发性成分种类受限,特别是灭酶过程挥发性损失较大.此外,二甲基二硫含量,常温研磨>低温研磨>剪切>灭酶研磨;二甲基三硫含量,常温研磨>低温研磨,剪切组和灭酶研磨未检出(均P<0.01),说明西兰花中二甲基二硫/三硫主要是含硫氨基酸等前体物质通过酶催化作用产生.

The contents of glucose, N-epsilon-(carboxymethyl)lysine (CML), and two main intermediate products, glyoxal (GO) and fructoselysine (FL), were determined, and the corresponding mathematical models were established to investigate the formation and kinetics of CML in a glucose-lysine model heated at 80 degrees C for 50 h. The effects of oleic acid (OA), temperature, and energy on CML formation were considered in the kinetic models. The mathematical modeling results suggested that glucose consumption was incomplete at 50 h and 80 degrees C. Although OA contributed to the formation of GO, CML was primarily formed from FL via the Maillard reaction, not from GO. The Arrhenius model was used to deduce that FL is the main pathway in the glucose-lysine-OA system because 88.39 kJ/mol of activation energy via the GO pathway was significantly higher than the 73.97 kJ/mol of activation energy via the FL pathway, and because the rate constant k(4) was higher than k(3) at different temperatures. OA (50 mmol/L) acted as a catalyst as well as a reactant in CML formation. This is the first study in which CML formation has been determined by both multi-response modeling and kinetic models based on glycation and lipid oxidation.

为研究萃取头及样品制备方式对碰碰香茎、 叶挥发性成分的影响,采用顶空固相微萃取-气相质谱联用(solid-phase microextraction gas chromatography-mass spectrometry,SPME-GC-MS)技术,并运用自动质谱退卷积定性系统(automated mass spectral deconvolution and identification system,AMDIS)对数据进行了分析.结果表明:65μm PDMS/DVB在萃取碰碰香挥发性成分的数量及种类上优于75μm CAR/PDMS和100μm PDMS;茎、茎浆、叶及叶浆中分别鉴定出40,43,41,44种挥发性成分,主要为单萜烯、倍半萜烯及单萜醇、酯等含氧衍生物,其中茎中含量较高的成分分别是α-古巴烯18.6％、柠檬烯13.2％、乙酸龙脑酯12.1％;茎浆中分别为芳樟醇22.4％、乙酸龙脑酯19.2％、α-古巴烯8.4％;叶中分别为芳樟醇13.4％、柠檬烯10.1％、α-古巴烯9.5％;叶浆中分别为芳樟醇15.9％、β-石竹烯10.5％、萜品油烯10.1％.经研磨,茎中挥发性成分单萜烯、倍半萜烯含量极显著减少(p<0.01),单萜含氧衍生物含量极显著增加(p<0.01),叶中单萜烯含量变化不显著(p>0.05),单萜含氧衍生物含量极显著增加(p<0.01),倍半萜烯含量显著减少(p<0.05).可见,研磨处理增加了碰碰香挥发性成分中单萜含氧衍生物的种类和数量.

Three types of main pigments, lycopene, Lutein, and beta-carotene were extracted from tomato and analyzed by chromatography-tandem mass spectrometry (UPLC-MS). The inhibitory effects of the three types of pigments on the formation of advanced glycation end-products (AGEs) in a heated model system at 65 degrees C were then studied by determining glyoxal, N-epsilon-(carboxymethyl)lysine (CML), pentosidine, and fluorescent AGE assays. Three pigments showed good inhibition to glycation products. SDS electrophoresis images also proved that pigments can significantly inhibit cross-linked AGE formation in a time-dependent manner. Lutein and lycopene displayed the better inhibition activity on CML and fluorescent AGE than beta-carotene (p < .05), especially lycopene showed almost twofolds stronger inhibitory activity on pentosidine and CML than beta-carotene, this results were attributed to its efficient inhibition to active oxygen and open-loop structure of thermal resistance. Many studies reported that plant-derived antioxidants are currently attracting greater research interest given their relative safety and comparable efficacy. Carotenoids are important natural pigments that contain a large number of conjugated double bonds, which give them good resistance to oxidation. Our results demonstrated that some important components of carotenoids could significantly inhibit cross-linked AGEs formation in a time-dependent manner. Using them, we successfully reduced the generation rate of AGEs in baked cookies, the inhibition rate of tomato pigment (2.74 mg/g) on CML and fluorescence-AGEs were 26.89% and 45.86%, respectively, in homemade cookies. Thus, tomato pigments or carotenoids as additives in food processing can effectively reduce the formation of AGEs and control the quality of products without affecting the value of commodities. Practical applications

The qualities and aroma of fresh tomato juice treated b≥a high pressure treatment (25℃ and 400 MPa for 30 min) and a thermal treatment (100℃ for 5 min) were compared after 3 months storage. The total number of colonies, mold and≥east of fresh tomato juice treated with the high pressure treatment met the National Food Safet≥ Criteria after two month storage. During the two months storage, the pH value, PPO activit≥, and POD activit≥ of high pressure treated fresh tomato juice decreased while the vitamin C content decreased b≥ about 24% . However, the vitamin C content of fresh tomato juice treated b≥ the thermal treatment was reduced b≥ about 96% . After the high pressure treatment, the aroma of the fresh tomato juice was similar to that of the original tomato aroma, while that was deteriorated after the thermal treatment. Therefore, the high pressure treatment maintained the qualities and aroma of the fresh tomato juice after 2 months storage.