To investigate the effect of pretreatment methods on the formation of advanced glycation end products(AGEs)in air-fried fish cakes.Fish cakes were prepared from frozen silver carp surimi,and the fish cakes in the experimental group were treated with three pretreatment methods(pre-frying,pre-frying+freezing,and pre-frying with coating)be-fore air frying,and the direct air-fried fish cake was the control group.The AGEs contents,physicochemical indicators and their correlations in the interior,surface and batter layer of air-fried fish cakes were analyzed.Compared with the samples of control group,the pre-frying and pre-frying+freezing significantly increased the oil absorption(83.83％and 203.48％)in the surface layer of fried fish cakes,which accelerated the Maillard and lipid oxidation reactions,leading to an increase of 120％～151％in CML content.On the contrary,the golden crust formed in the pre-frying with coating group reduced the oil absorption(72.63％and 60.00％)and water loss(3.87％and 0.70％)in the interior and surface layer of the samples,and further decreased the generation of AGEs by weakening the lipid oxidation and the degradation of furosine.And the CEL content decreased by 59.32％.Correlation analysis showed that oxidation reaction and Maillard reaction had a positive correlation with the generation of AGEs in fish cake,and the highest correlation coefficient was found between lipid oxidation and AGEs content.In conclusion,the battered pre-frying not only improved the color of fried fish cakes but also decreased their AGEs contents via depressing the lipid oxidation and Maillard reaction.
Fermentation of paocai is a dynamic process of the microbial community structure, and the interaction between community structure and physicochemical factors endows paocai with unique taste and flavor. The study of bacterial and fungal community structure changes and the driving mechanism of physicochemical factors induced changes in community structure, showing that Pseudomonas belonging to Proteobacteria and Lactobacillus belonging to Firmicutes were the dominant bacteria in the process of paocai fermentation. The correlation analysis of physicochemical factors with bacterial community showed that titratable acid was significantly positively correlated with Lactobacillus and negatively correlated with Pseudomonas, while nitrite was the opposite. Redundancy analysis (RDA) showed that pH was positively correlated with the bacterial community in the early fermentation stage, amino acid nitrogen was positively correlated with the bacterial community in the middle fermentation stage, and titratable acid was positively correlated with the bacterial community in the late fermentation stage. Variance partitioning analysis (VPA) showed that environmental factors, pH and metabolites, were the main driving forces of bacterial community diversity, which jointly explained 32.02% of the bacterial community structure variation. To study the glucolysis and nitrogen metabolism in the process of paocai fermentation, we found that in the early stage of the fermentation, the nitrite reductase enzyme of Pseudomonas activity was high, with high nitrite content in the prophase, but by the end of fermentation, lactic acid bacteria rapidly increased, the content of L−lactic acid through the glycolysis pathway, making paocai fermentation environment become acidic, then Pseudomonas decreased. Ascomycota and Basidiomycota were the main phylum fungi in the fermentation process. RDA analysis showed that the fungal community was positively correlated with pH, nitrite, and soluble protein at the early fermentation stage, amino acid nitrogen was positively correlated with the fungal community at the middle fermentation stage, titratable acid and reducing sugar were positively correlated with the fungal community at the late fermentation stage. VPA analysis showed that metabolites were the main driving force of fungal community diversity and accounted for 45.58% of fungal community diversity. These results had a certain guiding significance for the production and preservation of naturally fermented paocai.
通过加热、超声、pH偏移联合改性大豆球蛋白(SG),制备稳定性良好且适于作为Pickering乳液乳化剂的纳米颗粒.通过单因素实验和响应面试验确定最佳改性顺序、加热时间(5～30 min)、超声振幅(0～70%)及超声时间(0～12 min),结果表明,当改性顺序为加热-超声-pH偏移,95℃加热 20 min 19 s,43%振幅超声 5 min 17 s(750 W,20 kHz),pH 12 处理 1 h时,SG纳米颗粒的粒径和Zeta-电位最小,贮藏(4℃)稳定性最强,表面疏水性高达 3 516.16.随着离子强度从 0 mol/L升至0.6 mol/L,粒径显著增大(P<0.05),电位绝对值和溶解度显著降低(P<0.05),0 mol/L 和 0.6 mol/L 样品能够在 4℃稳定 12 d.随着加热温度从 100℃升至 150℃,粒径显著增大(P<0.05),电位绝对值和溶解度呈先升高后降低的趋势,130～150℃样品在 4℃稳定 5 d.pH 2～10 对颗粒稳定性影响较复杂,虽然pH 10 样品的粒径最小、电位和溶解度最高,但pH2 样品在4℃贮藏时间最长,达 20 d.SG纳米颗粒能够经受-80℃冻融循环 1 次.本探究为Pickering乳液乳化剂的开发及在食品中的应用提供理论参考.
Carotenoids are important lipid-soluble pigments in tea plants， which contributes to various key aromas as precursors. In this study， targeted metabolomics was applied to qualitative absolute content of carotenoids in tea leaves， and it was clear that the total content was （859.98±60.20） μg/g， which lutein contributed the highest ones as （405.06±17.71） μg/g. In made black and green tea， which manufactured by traditional black tea and green tea processing respectively， absolute content of carotenoids remained nearly half inside which decreased more than 50% compared with fresh leaves [（406.17±32.21） μg/g and （433.95±36.21） μg/g respectively]. Interestingly， spraying exogenous methyl jasmonate solution （0.25%） on tea leaves will greatly impact on the constituents of carotenoids. Especially in made green tea which was prepared from tea leaves treated with methyl jasmonate （12 h）， carotenoids greatly remained in made tea as high content of （682.69±46.12） μg/g， however， decreased in made black tea [（433.95±36.21） μg/g ] . Fourteen carotenoid-derived aroma components were identifed with significantly increase in black tea and green tea prepared from fresh leaves induced by methyl jasmoante for 24 h， especially the relative contents of β-damascenone， β-ionone， geranyl acetone and dihydroactinidiolide increased ＞ 2 times. Our results ensured acknowledge of carotenoids constituent and content in tea， promised a clear vision of carotenoids dynamics before， during， and after tea processing. It was confirmed that aroma quality of made teas （green tea and black tea） were greatly improved especially after 12 h and 24 h MeJA treatment time duration， and furthermore maintained a higher content of carotenoids. In conclusion， we have unraveled the mechanism of carotenoids content improvement in tea treated by methyl jasmonate. This will greatly improve our knowledge on taking advantage of exogenous application in tea quality improving.
目的:通过网络药理学及动物实验研究,探讨肉苁蓉总苷对炎症性肠病(IBD)的潜在作用机制.方法:应用Pubchem数据库及文献收集肉苁蓉总苷中 7 种主要活性成分的三维结构.通过PharmMapper,UniProt,GeneCards等数据库获取活性成分相关靶点与IBD相关的基因靶点信息.再将肉苁蓉活性成分靶点和IBD的靶点绘制韦恩图,得到交集靶点,并将交集靶点上传到String数据库进行蛋白质-蛋白质相互作用(PPI)筛选分析.使用DAVID数据库将肉苁蓉总苷活性成分对IBD发挥保护作用的靶点进行基因本体(GO)功能富集、京都基因和基因组百科全书(KEGG)通路富集分析,采用 Cytoscape 3.8.0 软件构建"活性成分-靶点-通路网络",预测肉苁蓉总苷治疗IBD的作用靶点与途径,并构建IBD小鼠模型进一步验证.结果:肉苁蓉总苷活性成分对IBD具有防护作用的靶点有 254 个,PPI分析筛选出核心靶点 30 个.GO功能富集和KEGG通路富集发现肉苁蓉总苷可能主要通过调控癌症通路、mTOR通路、TGF-β通路、JAK-STAT通路、AMPK通路等,进而影响细胞信号传导、增殖、分化、凋亡来发挥作用.动物实验结果表明,肉苁蓉总苷能有效缓解IBD小鼠体质量减轻及粪便出血,降低疾病活动指数,同时有效抑制脾脏中mTOR、TGF-β两个靶点蛋白的表达.通过对小鼠粪便的 16S rDNA扩增子测序进行PICRUSt2 基因功能注释,分析发现肉苁蓉总苷调控IBD疾病与小鼠体内细胞壁/细胞膜/包膜生物生成,脂代谢、糖代谢过程及相关防御信号转导机制有着密切关系,与网络药理学结果相符.结论:肉苁蓉总苷可以通过多成分、多靶点、多途径协同有效防止IBD,这为阐明肉苁蓉治疗IBD的临床应用提供了新方法和新思路.其具体机制及物质基础还需更深入的试验研究加以验证.
