面包焙烤过程中茶褐素含量变化及其检测方法分析

<正>在焙烤普洱茶面包的过程当中,其中的茶褐素会发生一定的变化。本文基于检测茶褐素方法,进行了适当的改进,并且利用新的公式,对面包焙烤的过程当中,茶褐素含量的变化进行了计算。通过具体的实验数据能看出,在面包焙烤的过程中,茶褐素大约能保持60%左右的保留率。因而能看出,在焙烤当中,面包中茶褐素的损失量较小,对于面包营养的增强有着积极的影响。实验步骤材料及设备在具体的检测实验当中,选用了     

普洱茶中多酚与茶褐素的提取工艺研究

通过水浴浸提的方法考察普洱茶多酚和茶褐素的最佳浸提工艺.在单因素实验的基础上,运用正交实验统计分析,确定普洱茶多酚和茶褐素的提取条件为:温度100℃,时间60min,料液比为1:25,茶多酚含量可达到9.04%,茶褐素提取率可达到93.15%.     

普洱茶中多酚与茶褐素的提取工艺研究

通过水浴浸提的方法考察普洱茶多酚和茶褐素的最佳浸提工艺。在单因素实验的基础上,运用正交实验统计分析,确定普洱茶多酚和茶褐素的提取条件为:温度100℃,时间60min,料液比为1∶25,茶多酚含量可达到9·04%,茶褐素提取率可达到93·15%。      

普洱茶与液态发酵普洱茶粉中茶褐素的比较研究

采用有机溶剂萃取法提取液态自然发酵普洱茶粉和固态发酵工艺生产普洱熟茶"7572"的茶褐素,对两种茶褐素的光谱学性质及理化性质进行比较分析。紫外-可见光谱(UV-Vis)表明,液态茶褐素在380 nm左右比固态茶褐素多一个吸收峰;红外光谱(IR)分析结果显示,两种茶褐素所含官能团相似,均为多羟基的酚类化合物,还可能有蛋白质和多糖与其结合;对茶褐素酸性官能团定量分析表明,两种茶褐素均含有羧基和酚羟基,且液态茶褐素中的两种官能团均比固态茶褐素多;膜法分离分级茶褐素结果显示,低聚(M10 ku)部分在固、液态茶褐素中含量分别为26.74%和18.84%;高聚(M100 ku)部分在固态茶褐素中含量56.98%、在液态茶褐素中含量为70.72%;两种茶褐素总还原力均具有剂量依赖性,活性相似;对膜分级后各组分还原力测定表明,两种茶褐素的中聚部分(10 kuM100 ku)、高聚部分的总还原力均明显高于低聚茶褐素。     

普洱茶茶褐素的分离研究

为了了解普洱茶茶褐素的组成,对从普洱茶中提取的茶褐素进行了分离。通过比较不同树脂对茶褐素的吸附与解吸能力,选择AB-8大孔树脂对普洱茶茶褐素进行分离,得到TBs P1和TBs P2两个组分;进一步利用DEAE-52纤维素柱对TBs P1组分进行分离,得到6个组分;对茶褐素组分TBs P1、TBs P2以及TBs P1分离得到的6个组分的总糖、总酚和蛋白质的含量进行了分析,并进一步对各组分的单糖组成进行了分析。结果表明:不同组分的茶褐素其总糖、总酚和蛋白质的含量有一定的区别,TBs P1分离得到的4个主要组分单糖组成相似,含量不同,与从普洱茶生产原料晒青毛茶中提取的水溶性色素的单糖组成和含量有较大的差异。      

普洱茶多酚与茶褐素研究进展

普洱茶是一类具有多种保健功能的后发酵茶,其中多酚和茶褐素都是重要的功能成分。普洱茶茶褐素是一类结构十分复杂的多酚氧化产物,属于天然色素。本文综述了普洱茶多酚和茶褐素的最新研究进展,包括提取分离、功能研究、茶褐素的结构探讨、变化特点、生物活性等。     

普洱茶茶褐素对高脂血症大鼠的治疗作用

本文探讨了不同分子量普洱茶茶褐素对高脂血症SD大鼠的治疗作用。通过45 d的治疗,饲喂TB1和RTB的大鼠血清TCTG和LDL均显著低于高脂模型组(p0.01),HDL显著高于高脂模型组(p0.01),且TG与HDL与正常对照组无显著性差异。TB1和RTB对肝脏组织中HSL酶活性影响不显著,但在附睾组织和肠系膜组织中HSL活性极显著高于高脂模型组(p0.01),与正常对照组差异不显著(p0.01)。同时,TB1和RTB可显著抑制高脂血症大鼠脂肪组织ACC酶活性(p0.01)和FAS酶活性(p0.05)。说明TB1和RTB可通过提高HSL活性来加速脂质代谢,同时通过抑制ACC和FAS活性来减少脂肪酸合成。Western Blot检测发现,TB1和RTB有上调HSL蛋白表达、下调ACC1蛋白表达的作用。肝脏病理切片显示,TB1和RTB能有效减缓和降低高脂血症大鼠肝脏脂肪变性的速度和程度。研究结果表明,TB1是RTB的主要活性成分,对高脂血症大鼠有一定的治疗作用。     

普洱茶茶褐素对高脂血症大鼠血脂代谢的影响

为探讨普洱茶荼褐素对高脂SD大鼠的降血脂作用,采用生化试剂盒分析普洱茶茶褐素对实验大鼠血清中TC、TG、LD-C、HDL-C的动态影响.结果显示:饲喂高脂饲料4周后,模型组大鼠血清TC、LDL-C极显著升高(P＜0.01),TG显著升高(P＜0.05),说明高脂血症大鼠模型建立成功.与高脂模型组相比,饲喂茶褐素的降脂组高脂血症大鼠血清TC、LDL-C水平极显著降低(P＜0.01),TG显著降低(P＜0.05),而HDL-C水平明显升高;与正常对照组相比,无显著性差异,说明普洱茶茶褐素具有降血脂作用.预防组高脂饮食大鼠因同时饲喂茶褐素,故其血清中TC、TG、LDL-C水平升高以及HDL-C水平降低均受到抑制,与正常对照组没有显著性差异(P＞0.05),说明茶褐素能减少肝脏脂肪沉积,具有预防实验大鼠脂肪肝形成的作用.正常试物组(饲喂基础饲料和茶褐素)大鼠虽然被饲喂茶褐素,但其血清TC、TG、HDL-C、LDL-C水平与正常对照组无显著性差异(P＞0.05),说明茶褐素对正常大鼠血脂代谢影响不大.     

大孔树脂法纯化六堡茶中茶褐素的研究

选取5种型号的大孔树脂D900、DM-301、ADS-17、S-8、D101对广西六堡茶中的茶褐素进行纯化,通过对影响大孔树脂的因素:茶褐素溶液浓度、溶液p H、洗脱剂、洗脱剂浓度以及上样流速和洗脱流速进行试验,找出了溶液浓度0.1 mg/m L,p H为5时,吸附效果较好,且50%乙醇为洗脱剂时的解析效果较好,动态试验中确定了上样流速为1 m L/min,洗脱流速为4 m L/min。     

普洱茶茶褐素对代谢综合征大鼠生长过程中肝脏差异表达基因的影响

为探讨普洱茶茶褐素对代谢综合征大鼠生长过程中的差异表达基因信息的影响,研究基于前期已获得的高质量代谢综合征大鼠肝脏转录组数据,用Short Time-series Expression Miner(STEM)软件,先对差异基因(DEGs)进行趋势分析,然后对显著上调和下调趋势包含的DEGs进行GO和KEGG富集分析.趋...     

Modelling the browning of bread during baking

In this work, we study the development of browning at bread surface during baking. Computer vision is applied to follow the progress of browning at surface, while the variations of temperature and water activity are obtained by numerical simulation of a mathematical model previously validated. The formation of the bread crust is a complex process where temperature and water content change continuously during baking, making browning a non-isothermal process occurring in a non-ideal system. Minimum requirements for initiation of colour formation are temperature greater than 120 °C and water activity less than 0.6. We apply a non-isothermal kinetics approach to model the browning development at bread surface during baking, where the variation of local temperature and water activity is taken into account. The methodology presented here is suitable for modelling and predicting browning during baking; model parameters can be estimated by using a non-ideal system closer to real processing conditions.     

应用快速烘焙法测试面包烘焙品质

介绍了一种用于实验室测试面包烘焙品质的快速烘焙法.其发酵和醒发分别只需要20 min和40 min,经实验验证表明其适用于我国小麦粉的面包烘焙品质测试.该方法可以大大缩短实验时间,提高工作效率,用该方法烘焙的面包整体效果较好.     

面包烘焙直接发酵法与中种发酵法对比研究

对直接发酵法和中种发酵法进行了比较。结果表明,直接法更能够反映样品之间的差异,而中种法则能改善强筋力小麦的面包加工性能。而C—CELL分析结果则表明中种发酵法烘焙的面包内部结构细腻。此外,对两种方法的适用性进行了讨论。     

Computational fluid dynamics modeling of bread baking process

A computational fluid dynamic (CFD) model was developed to study the temperature and browning profile of bread. This study differs from previous work of CFD modeling reported in literature in that phase change during evaporation as well as evaporation-condensation mechanism during baking process was incorporated in this model. Simulation results were validated with experimental measurements of bread temperature at three different positions. In this study crumb temperature does not cross 100 °C due to incorporation of evaporation-condensation mechanism in this model. Baking process completes within 25 min of processing time once the temperature of crumb becomes stable at 98 °C. Formation of crust and browning of bread surface were studied using earlier reported kinetic model and it predicted more browning at bread edges than the surfaces. However, predicted browning index was well within the range (< 52).     

Effect of crust temperature and water content on acrylamide formation during baking of white bread: Steam and falling temperature baking

The effect of crust temperature and water content on acrylamide formation was studied during the baking of white bread. To assess the effect of over-baking, we used a full factorial experimental design in which the baking time was increased by 5 and 10 min at each baking temperature. Additional experiments were performed with steam baking and falling temperature baking. Immediately after baking, the crust was divided into the outer and inner crust fractions, and the water content and acrylamide concentration of each fraction was measured. The outer crust had a significantly lower water content and higher acrylamide concentration than the inner crust did. Crust temperature in combination with water content had a significant effect on acrylamide formation, higher temperatures resulting in higher acrylamide concentrations. However, at very high temperatures and lower water contents, acrylamide concentration was observed to decrease, though the bread colour was then unacceptable for consumption. Steam and falling temperature baking, on the other hand, decreased the acrylamide content while producing bread crust with an acceptable colour. The lowest acrylamide values and an acceptable crust colour were produced by steam baking.     

Two-dimensional CFD modeling and simulation of crustless bread baking process

A special type of baking oven was developed where crustless bread was made by gently baking the dough at controlled temperature by spraying water at prefixed intervals on the surface of the dough. In this study, a two-dimensional (2D) CFD model for crustless bread during baking has been developed to facilitate a better understanding of the baking process. Simultaneous heat and mass transfer from the bread during baking was successfully simulated. It was found that core temperature of the bread reached at 95 °C at the end of baking where as moisture of the bread satisfies the normal bread quality. The model can be successively applied to study the unsteady heat and mass transfer from the crustless bread during baking.     

Thermal degradation of deoxynivalenol during maize bread baking

The thermal degradation of deoxynivalenol (DON) was determined at isothermal baking conditions within the temperature range of 100–250°C, using a crust-like model, which was prepared with naturally contaminated maize flour. No degradation was observed at 100°C. For the temperatures of 150, 200 and 250°C, thermal degradation rate constants (k) were calculated and temperature dependence of DON degradation was observed by using Arrhenius equation. The degradation of DON obeyed Arrhenius law with a regression coefficient of 0.95. A classical bread baking operation was also performed at 250°C for 70?min and the rate of DON degradation in the bread was estimated by using the kinetic data derived from the model study. The crust and crumb temperatures recorded during bread baking were used to calculate the thermal degradation rate constants (k) and partial DON degradations at certain time intervals. Using these data, total degradation at the end of the entire baking process was predicted for both crust and crumb. This DON degradation was consistent with the experimental degradation data, confirming the accuracy of kinetic constants determined by means of the crust-like model.     

Thermal degradation of deoxynivalenol during maize bread baking

The thermal degradation of deoxynivalenol (DON) was determined at isothermal baking conditions within the temperature range of 100-250°C, using a crust-like model, which was prepared with naturally contaminated maize flour. No degradation was observed at 100°C. For the temperatures of 150, 200 and 250°C, thermal degradation rate constants (k) were calculated and temperature dependence of DON degradation was observed by using Arrhenius equation. The degradation of DON obeyed Arrhenius law with a regression coefficient of 0.95. A classical bread baking operation was also performed at 250°C for 70?min and the rate of DON degradation in the bread was estimated by using the kinetic data derived from the model study. The crust and crumb temperatures recorded during bread baking were used to calculate the thermal degradation rate constants (k) and partial DON degradations at certain time intervals. Using these data, total degradation at the end of the entire baking process was predicted for both crust and crumb. This DON degradation was consistent with the experimental degradation data, confirming the accuracy of kinetic constants determined by means of the crust-like model.