发酵方式对馒头在冷藏过程中品质及其货架期的影响

将一次发酵、快速二次发酵和老面发酵的馒头进行冷藏贮存,测定冷藏过程中馒头的pH、水分含量、比容、菌落总数、霉菌的变化趋势,以及将馒头复蒸之后的感官评分变化。结果表明:馒头的水分含量、pH、感官评价均呈现总体下降趋势;馒头的比容在冷藏过程中略有波动比较稳定;三种馒头的菌落总数14 d时未达到10⁶CFU/g,低温有效地抑制了微生物的生长;0~2 d未检测到霉菌,随着贮存时间延长霉菌超出标准范围。老面发酵馒头在0~4 d时稳定性最好,各项指标变化幅度最小,8~14 d时霉菌生长迅速,加快了变质,一次发酵馒头微生物生长最快,水分含量下降最快,二次发酵馒头水分含量变化最为稳定。综合霉菌和感官评分,将冷藏馒头分别划分成三个食用阶段。一次发酵馒头最佳食用阶段为0~4 d,可食用阶段为5~11 d,不可食用阶段为12 d以上;快速二次发酵馒头最佳食用阶段为0~2 d,可食用阶段为3~11 d,不可食用阶段为12 d以上;老面发酵最佳食用阶段为0~4 d,可食用阶段为5~9 d,不可食用阶段为10 d以上。     

乳酸菌协同小麦胚芽油发酵对黑曲霉生长活性的影响

本文通过初筛和复筛考察不同乳酸菌的抗真菌活性,并将小麦胚芽油添加入乳酸菌培养液中进行发酵,旨在明确乳酸菌协同小麦胚芽油发酵对抗黑曲霉活性的影响。研究表明,小麦胚芽油不具有抑制黑曲霉生长的能力,而乳杆菌LF5发酵液抑菌率随着小麦胚芽油浓度的升高明显提升,且该现象具有菌株特异性。通过加热、中和pH、添加蛋白酶及过氧化氢酶发现,乳酸菌协同发酵上清液中的抗真菌活性物质主要由有机酸以及部分具有良好热稳定性的非蛋白类组分组成。此外,采用乳杆菌LF5协同小麦胚芽油发酵制备面包,在第5 d发现肉眼可见霉菌,与空白组(第2~3 d)相较具有显著抑制黑曲霉生长活性的作用,为乳酸菌在发酵米面食品中的应用提供了新的方向。     

利用同相等差感应电压检测面包中的山梨酸钾

采用同相等差感应电压法即45～60 V激励电压及300～500 Hz频率为初级线圈的激励参数,测定并分析次级线圈中山梨酸钾溶液的电信号特性。结果发现,0～200 mg/kg山梨酸钾溶液的瞬时绝对电位不随频率的变化而改变,与激励电压大小呈正相关。当山梨酸钾含量增加时,在不同频率及激励电压作用下,次级线圈中山梨酸钾溶液电势差增大。山梨酸钾含量、激励电压、频率及体系电势差呈线性相关,相关系数R²为0.916。采用同相等差感应电压法与化学法检测5种市售面包样品的山梨酸钾含量,检测结果相对误差均在4%以内。该研究将面包预处理后的料液作为次级线圈,通过同相等差感应电压法测定其电学参数来量化山梨酸钾含量,为面包中山梨酸钾的检测提供了一种新方法。     

基于聚类遗传算法的神经网络规则抽取及应用

提出了一种基于Gabor滤波器和神经网络规则抽取的烘焙面包品质分类方法。滤波器对烘焙面包切片区域灰度图像直接进行小波变换,用能量均值"和均方差!来表示灰度图像的纹理特征,并基于对隐层神经元输出值聚类的遗传算法实现了对面包品质分类的规则抽取。实验结果表明了该方法的实用性和可行性。     

儿茶素对面包贮藏期内氧化性质和感官品质的影响

目的 研究儿茶素对面包贮藏品质的影响。方法 将儿茶素（质量分数为0%、0.025%、0.05%、0.1%、0.2%、0.4%）添加到面团中,研究不同添加量儿茶素对面包的热性质、比容、感官质量、巯基、氧化稳定性、自由基清除能力、色泽、质构特性的影响。结果 随着儿茶素添加量的提高,面包的比容先增大后减小;添加质量分数0.05%儿茶素的面包的比容最大（P<0.05）。在贮藏1～5d内,面包的巯基含量、过氧化值和硫代巴比妥酸值随着儿茶素添加量的增加逐渐降低,DPPH自由基清除率和ABTS自由基清除率总体上逐渐升高。结论 将儿茶素加入面包中起到了抗氧化作用,儿茶素可用于功能型面包的制作。     

麦麸细粉营养成分分析及在面包烘焙中的应用

采用喷雾调质、研磨和筛选分离出小麦麸皮中的麦麸细粉,分析其营养成分,并通过流变特性测试及烘焙应用试验,研究其对面粉营养成分及面团烘焙特性的影响。结果表明,分离所得麦麸细粉的蛋白质和膳食纤维含量高达15.8%和33.6%,且富含钾、钙、铁等多种矿物质。随着麦麸细粉在面包专用粉中添加比例的增加,面包专用粉的灰分和湿面筋含量呈递增趋势;面筋指数、糊化黏度逐渐降低,面团吸水率、弱化度逐渐增加;稳定时间、延展性呈减小趋势;面包的搅拌时间、发酵时间延长,比容和品质评分降低。添加10%麦麸细粉的面包烘焙性能和感官品质较好,且营养价值得到了显著改善。     

The polypeptide composition,structural properties and antioxidant capacity of gluten proteins of diverse bread and durum wheat varieties,and their relationship to the rheological performance of dough

The aim of this study was to compare five bread and five durum wheat genotypes for gliadins and glutenins profiles, the concentration of free sulphhydryl groups and disulphide bonds, antioxidant capacity of gluten proteins and their bread‐making performance. On average, bread wheat had significantly higher concentration of total sulphur‐rich (S‐rich) and sulphur‐poor (S‐poor) subunits of gliadins, as well as total low molecular weight (LMW) and high molecular weight (HMW) subunits of glutenins than durum wheat. However, durum wheat had higher concentration of S‐rich γ‐gliadins and S‐poor D‐LMW‐glutenins, but did not possess S‐poor ω‐gliadins. The concentration of disulphide bonds and total cysteine was higher in the durum gluten than that in the bread gluten, as well as antioxidant capacity (on average 90.6 vs. 85.9 mmol Trolox Eq kg^?1, respectively). In contrast to the bread wheat, the concentration of HMW‐glutenins was negatively associated with extensibility, as well as resistance to extension in durum wheat flour dough.     

Arabinoxylan content and characterisation throughout the bread‐baking process

End‐use quality of wheat (Triticum aestivum L.) is influenced in a variety of ways by nonstarch polysaccharides, especially arabinoxylan (AX). The objective of this study was to track total and water‐extractable AX (TAX and WEAX, respectively) throughout the bread‐baking process, using wholemeal and refined flour. The TAX and WEAX content and the ratio of arabinose: xylose were assessed in flour, mixed dough, proofed dough and the bread loaf, which was separated into crumb, upper crust and bottom crust. Changes in TAX during the baking process differed between the refined flour and wholemeal samples, suggesting a change in the TAX availability which we ascribe to molecular interactions and heat treatment. WEAX content dramatically decreased during baking, suggesting that oxidative cross‐linkages rendered it unextractable. Higher levels of WEAX and lower levels of arabinose substitution were correlated with higher loaf volumes for refined flour among the hard wheat varieties. Having a better understanding of the importance of both WEAX content and arabinose substitution allows for directed breeding efforts towards improved hard wheat varieties for optimum bread baking.     

杜仲叶超微粉馒头制备工艺及品质特性分析

目的 优化杜仲叶超微粉馒头制备工艺,并对其品质特性进行分析。方法 以馒头感官评分及质构特性为考量指标,以杜仲叶超微粉添加量、酵母粉添加量、水添加量为影响因素进行单因素试验;在此基础上,采用响应面试验优化杜仲叶超微粉馒头的制备工艺。结果 最优工艺条件:杜仲叶超微粉添加量1.3%、酵母粉添加量1.6%、水添加量49%。按此工艺制备得到的杜仲叶超微粉馒头的感官评分为95.33±0.83分。各因素对杜仲叶超微粉馒头品质的影响顺序为:杜仲叶超微粉添加量>酵母粉添加量>水添加量。馒头的质构特性表明:添加杜仲叶超微粉后馒头硬度、胶黏性、咀嚼性及黏度均显著优于对照组(P<0.05)。结论 优化后杜仲叶超微粉馒头营养丰富,且具有杜仲叶独特的风味,有较大的应用潜力。