醒面温度对高水分面团流变学性质的影响

为了研究不同醒面温度对高水分面团流变学性质影响,就面团的拉伸特性、湿面筋品质、面筋蛋白二级结构、水分分布以及动态流变特性等指标进行比较分析。结果表明:随着醒面温度的升高,面团的抗拉伸力逐渐下降,拉伸距离先升高后下降。醒面温度超过35℃后,湿面筋含量和面筋指数显著下降。在20~30℃,面筋蛋白二级结构中β-折叠、无规则卷曲、α-螺旋、β-转角无显著变化。在30~45℃,β-折叠和α-螺旋含量降低,无规则卷曲和β-转角含量上升。随着醒面温度的升高,面团中结合水和自由水比例先上升后下降,半结合水比例先下降后上升。20~30℃,面团黏弹性模量变化不显著,30~40℃,面团黏弹性模量显著下降。在适宜的环境温度下醒发面团,面团面筋品质较好,面团具有较好的黏弹性。醒面温度过高时,面筋品质有所下降,抗拉伸能力下降。     

小麦面团及其制品的热导率

食品的热导率是预测热加工过程中导热速率的一个重要热特性参数,也是进行加工过程模拟和产品质量控制的基础.通过对1990年以来有关小麦面团及其制品热导率的测定结果进行了汇总,给出其温度、水分、孔隙度和测定方法.论述了温度、水分含量以及结构特性对热导率的影响,对热导率结构模型的最新研究进展及其在面团制品中的应用作了重点介绍并对今后的研究方向作了展望.     

醒面时间对烩面面团水分分布及麦谷蛋白大聚体的影响

采用不同的醒面时间加工烩面面团,研究其对面团水分分布状态和麦谷蛋白大聚体含量的影响。以面团的拉伸特性和湿面筋品质为指标。结果表明:醒面过程可降低面团中半结合水比例,结合水和自由水比例上升;醒面时间90 min时,面团中二硫键含量最高,巯基含量最低;随醒面时间的延长,小粒径麦谷蛋白大聚体含量逐渐降低,中、大粒径麦谷蛋白大聚体含量升高,表明麦谷蛋白大聚体发生聚合;醒面工艺提高了湿面筋品质,湿面筋含量和面筋指数显著升高;面团的最大拉伸力随醒面时间的延长,逐渐降低,拉伸距离逐渐升高,醒面时间超过90 min,面团拉伸特性改善不明显。综合比较分析,烩面面团的醒面时间应为90 min。     

红枣粉添加量对面团特性及馒头品质的影响

研究红枣粉对面团特性及馒头品质的影响,确定适宜的红枣粉小麦粉配比。探讨了添加不同比例红枣粉（0、5%、10%、15%）对混合粉理化性质、色差、面团的微观结构和粉质拉伸特性,以及对馒头比容、色差、质构和感官品质等的影响。结果表明:随着红枣粉添加量的增加,混合粉中的水分、蛋白质和脂肪含量逐渐降低,灰分和还原糖的含量逐渐升高;混合粉及馒头的颜色逐渐变红变暗;面团吸水率逐渐降低,形成时间与稳定时间呈先上升后下降,弱化度呈先下降后上升的趋势;添加不同比例红枣粉面团随着醒发时间（45、90、135 min）的延长,面团拉伸能量、最大拉伸阻力和拉伸比等指标总体呈上升趋势;面团微观结构显示随红枣粉添加量的增加,面筋蛋白结构逐渐遭到破坏;红枣粉添加量在5%~10%范围内,馒头比容与对照组馒头相比显著增大（P<0.05）;馒头的弹性、回复性随红枣粉的添加逐渐降低;感官评定显示红枣粉添加量在5%~10%范围内,总体得分均比对照组馒头要高,且易被人们接受。综合分析红枣粉对面团特性、馒头质构及感官评价等的影响结果,确定红枣粉添加量不宜超过10%。     

食盐对烩面面团品质和面筋网络结构的影响

采用低磁场核磁共振和激光共聚焦扫描显微镜,研究了食盐添加量(0~5%)对烩面面团水分分布状态和面筋网络微观结构变化的影响,并结合面团拉伸特性、动态流变学特性以及麦谷蛋白大聚体含量变化对各项试验指标进行综合分析。结果表明:添加食盐可以提高面团的弹性模量G′和黏性模量G″;食盐添加量在0%~3%范围内,结合水和半结合水比例变化不显著,自由水比例降低,食盐添加量超过3%,结合水和自由水比例降低,半结合水比例上升;随着食盐添加量的增加,面筋网络微观结构变的越来越紧密,面团的最大拉伸力逐渐升高;在0%~5%范围内,面团中麦谷蛋白大聚体含量升高,湿面筋指数上升,添加量超过3%,面团中湿面筋含量下降,面团的拉伸距离下降,麦谷蛋白大聚体含量变化不显著。综合考虑,3%以下添加量可以获得理想的烩面面团品质。     

不同炒籽工艺对低芥酸浓香菜籽油风味的影响北大核心CSCD

为了研究不同炒籽工艺对低芥酸浓香菜籽油风味的影响,以低芥酸油菜籽为原料,研究入炒水分、炒籽温度、炒籽时间对低芥酸浓香菜籽油风味物质含量及感官品质的影响。结果表明:从低芥酸浓香菜籽油中共鉴定出65种挥发性风味物质;随炒籽温度上升、炒籽时间延长,低芥酸浓香菜籽油中呈现烤香味的杂环类物质总含量逐渐增加;随炒籽温度上升和入炒水分的增加,呈现刺激味的硫苷降解产物(含硫类化合物、腈类化合物)总含量逐渐增加;在感官上,低芥酸浓香菜籽油主要体现为烤香味、焦糊味,还能感知到腌菜味和刺激味;随炒籽温度升高,低芥酸浓香菜籽油中烤香味感官属性得分先上升后降低,150℃时得分最高,而焦糊味、腌菜味等感官属性得分逐渐升高;随炒籽时间延长,烤香味感官属性得分逐渐降低,焦糊味感官属性得分逐渐升高;随入炒水分增加,烤香味、焦糊味感官属性得分在一定范围内稳定波动。炒籽过程中一定的炒籽温度及增加水分能够明显提升消费者喜好度。     

水分含量及添加剂对面团玻璃化转变温度的影响

本实验应用差示扫描量热仪(DSC),测量了不同水分含量的面团的玻璃化转变温度以及NaCl、卵磷脂、抗坏血酸、明胶、海藻糖、单干酯及黄原胶等常见食品添加剂对面团玻璃化转变温度的影响。结果表明:水分含量为40%的纯精粉面团的玻璃化转变温度为-27.75℃,水分含量在38%～45%的玻璃化转变温度有逐渐降低的趋势。NaCl、抗坏血酸、海藻糖分别以5%、1%、3%加入面团以后,面团玻璃化转变温度分别为-13.68、-12.73、-15.74℃。加入明胶、单干酯、黄原胶时,面团的玻璃化转变温度提高并不明显,而卵磷脂的加入却降低了面团的玻璃化转变温度。     

面团及其制品的热导率研究进展

热导率是反映热量在食品内部传导速率的重要物理量,了解食品的热导率是进行过程模拟和质量控制的基础.简要介绍了热导率的主要测定方法,综述了20世纪90年代以来有关面团及其制品的热导率研究结果,给出了各研究者所采用的测定方法,测定温度、样品水分含量以及孔隙度等相关信息.对今后的研究方向作了展望.     

食品添加剂对面团玻璃化转变温度的影响

实现食品的玻璃化贮藏是提高食品质量的有效手段。本研究利用差示扫描量热仪探讨了适用于面团玻璃化转变温度测量的扫描程序、研究了水分含量及若干食品添加剂对面团玻璃化转变温度的影响规律。结果表明,多次扫描法是一种可行的面团玻璃化转变温度的测量方法;水分添加量对面团的玻璃化转变温度有明显影响。在本研究的范围内,面团的玻璃化转变温度随面团水分含量的增加而明显下降。食品添加剂对面团的玻璃化转变温度有显著影响。添加抗坏血酸、海藻糖及明胶时,均可不同程度的使面团的玻璃化转变温度有所升高,这对于在现有储存条件下(-18℃)实现面制品的玻璃化保存,提高速冻面制品的稳定性,改善速冻面制品的质量有重要的应用价值。     

面包加工工艺中水分的变化研究

采用红外水分测定仪测定面包在发酵、烘烤和冷却过程中各层水分的变化,研究面包在发酵、烘烤和冷却过程中各层水分的变化规律。面包面团在发酵过程中,皮部、瓤部和整个面包的水分含量上升,面包面团皮部水分上升12.7%,瓤部水分上升0.4%,整个面团上升0.8%。面包在烘焙过程中,热量随着水分汽化冷凝由面包皮层向瓤部转移而传递的,面包瓤部水分也因之升高,面包皮层水分蒸发降低。面包皮层水分从43%降到4.1%,面包瓤部水分先增加后减少,最高达到45.3%,烘烤结束后水分为44.6%,水分增加1.6%,面包整体水分下降7.5%。面包在冷却过程中,水分从面包瓤向皮部转移,面包皮层水分上升,瓤部水分下降。面包冷却结束时,水分从内到外依次下降。450 g面包在15℃下冷却30 min,水分下降到36%,达到面包包装要求的温度和水分指标。     

烟草颗粒热解与释烟特性影响因素研究

  目的  为探索加热状态下烟草颗粒热解和烟气释放规律。  方法  采用导热系数测试仪、热分析仪（TGA）和锥形量热仪（CONE）表征分析了甘油添加量、水分含量以及粒径对烟草颗粒导热特性、热解过程和烟气释放特性的影响。  结果  （1）样品导热系数随水分和甘油含量的增加以及粒径减小整体上呈现不同程度的上升趋势,不同水分与甘油含量样品比热容变化趋势与导热系数基本一致,随粒径减小其比热容持续降低;（2）甘油大幅增加烟草颗粒在低温区（140 ℃~300 ℃）失重比例,并使其成为最主要失重阶段;水分含量对烟草颗粒失重速率影响随温度升高逐渐减弱,主要对低温区下游离态水、甘油等小分子物质释出影响较大;减小粒径,样品主要失重过程向低温区稍有平移;（3）增加甘油含量（30%以内）、降低水分含量以及减小粒径均有利于缩短烟草颗粒起始释烟时间,提高释烟速率,且释放总量整体呈上升趋势。      

含水量影响冷冻饺子皮面团力学特性的研究

随着传统文化的升温,人们对非发酵冷冻面团的需求日益增加。研究在确定不同含水量的饺子皮坯冷冻和解冻条件的基础上,重点研究了含水量为46%、48%、50%、52%的面团在冷冻前和历经冷冻、冻藏及室温下自然解冻等工序处理后的硬度、内聚性、拉伸性等力学特性的变化。结果显示:质量为20g直径约为3.5cm的饺子皮坯的在-40℃的条件下,40min后可通过最大冰晶形成带;在-18℃的冻藏条件下,2h后温度基本稳定,室温下的适宜解冻时间为1h。在力学特性方面,含水量48%的面团拉伸性能最好,含水量46%的面团硬度最大,含水量50%的面团冷冻前内聚性最好,含水量为46%的面团冷冻后内聚性最好。     

预冷冷冻过程对速冻油条加工品质的影响

以无铝油条预混粉为原料制作速冻油条,研究油条不同预冷时间、预冷温度、冷冻温度对油条物理特性(温度变化、湿基含水率变化、质构特性)及感官品质的影响,探讨速冻工艺对油条品质的影响规律及最佳速冻工艺。结果表明:随预冷时间的延长,预冷及冷冻温度的降低,油条皮和瓤的温度逐渐降低,降温速率加快;随预冷时间延长和预冷温度降低,油条皮和瓤湿基含水率降低量增加,速冻后湿基含水率降低量减小;油条的感官品质和质构品质随预冷时间的延长及预冷和冷冻温度的降低而上升。确定预冷温度0?℃,预冷时间45 min,冷冻温度-30?℃以下,冷冻时间30 min为无铝速冻油条最佳制备工艺。     

Effect of Chemical Modification, pH Change, and Freezing on the Rheological, Solubility, and Electrophoretic Pattern of Wheat Flour Proteins

ABSTRACT: In this study the effect of chemical modification and freezing of dough on the characteristics of wheat proteins and the rheological properties of dough was investigated. A slight increase in the protein solubility and disappearance of protein bands in the range of 55 to 70 KDa was observed when samples were frozen for 6 to 8 weeks. Ascorbic acid decreased and cysteine and bisulfite increased solubility of wheat proteins. Dough stability increased as pH was raised above 6.5. Two protein bands in the range of 55 to 60 KDa appeared in ascorbic acid treated doughs and the intensity of bands of less than 6.5 KDa increased in cysteine or bisulfite treated doughs. Several protein bands in the range of 30, 50, and 90 KDa appeared when the pH was raised to 7.0 and above. The results of this study suggest that high- molecular-weight proteins of wheat flour have a major influence on the properties of dough and that these proteins are affected by chemical treatment, pH change, and freezing.     

EFFECT OF GUM ARABIC ON THE RHEOLOGY OF CORN FLOUR DOUGHS AND FRIED PRODUCT QUALITY

Small deformation stress relaxation studies were performed on corn flour dough at 48–62%, wet basis moisture and 0–2% gum Arabic contents. Corn doughs were sensitive to moisture contents that were reflected by the values of the elastic and viscous components. The instrumental stickiness of the dough increased markedly when the moisture content was increased. The stress decay curves were modeled by using 3-element spring-dashpot models as evidenced by low values of root mean square error. Sensory assessment of the dough as well as fried products were conducted to relate the parameters obtained from stress relaxation studies.     

Specific Heat and Thermal Conductivity of the Croatian Unleavened Dough

A line heat source probe method was used to determine thermal conductivity of the Croatian unleavened dough in a temperature range of 27–125°C. For estimation of the specific heat of the Croatian unleavened dough, a mixing method was used. The maximum value of 4.0 ± 0.8 kJ/(kg °C) was determined at 57.1°C for the potato dough, and the minimum value of 1.4 ± 0.6 kJ/(kg °C) was determined at 35.3°C for the Kro?tula dough. Thermal conductivity first increased with temperature and then decreased after reaching its maximum value. Minimum value of 0.29 ± 0.04 W/(m °C) was determined at 123.8°C for the Kro?tula dough. Further on, a set of empirical equations was established using regression analysis to correlate the results and to predict the specific heat and thermal conductivity of the Croatian unleavened dough within the studied temperature range and moisture levels.     

Wheat Gluten and Glutenin Thermal Conductivity and Diffusivity at Extruder Temperatures

Thermal properties (thermal conductivity and diffusivity) of gluten and glutenin were measured in the temperature range 60-175°typically used in extrusion processing. Thermal conductivity and diffusivity of gluten decreased with increasing temperature and increased with increasing moisture content. Thermal conductivity and diffusivity of glutenin increased with temperature and moisture content. Thermal conductivity of gluten was 0.06-0.35 W/m-C and glutenin was 0.29-0.49 W/m-C for the temperature range 60-175°and moisture content range of 0-30%.     

Effect of Temperature and Moisture Content on Thermal Conductivity of Four Types of Meat

The thermal conductivity of four different types of meats (Veal, Hashi, Noeimi and Najdi) was determined for a temperature range of 5–40°C and moisture content range of 30–75% (wet basis). Thermal conductivity increased almost linearly with the increasing levels of both temperature and moisture content. Multiple regression models with high R² < 0.91) values were developed to correlate thermal conductivity as a function of temperature and moisture content. Statistical analysis revealed that both variables had significant effect on thermal conductivity of meats.     

热烫温度对小麦面团介观特性的影响机制

本实验以热烫面团为研究对象，通过凯氏定氮法、粒径分析、傅里叶变换红外光谱以及快速黏度分析等手段，研究55、65、75、85 ℃和95 ℃热烫温度下小麦面团中麦谷蛋白大聚体的质量分数、粒径分布、蛋白质二级结构以及面团中淀粉的糊化特性的变化情况。结果表明：随着热烫温度的升高，面团中麦谷蛋白大聚体质量分数呈现显著增大的趋势（P＜0.05），小粒径的麦谷蛋白大聚体向中粒径和大粒径转变；面团中蛋白质二级结构发生变化，部分α-螺旋和β-折叠结构转变为β-转角和无规卷曲。同时，面团中淀粉的糊化度随着热烫温度的升高逐渐增大；淀粉的峰值黏度、最低黏度、衰减值、最终黏度、回生值和峰值时间均呈现出减小的趋势，在热烫温度高于75 ℃时，这种变化更加显著。     

PHYSICAL and THERMAL PROPERTIES of GORGON NUT

Bulk density, true density, angle of repose, coefficient of friction on metal surfaces, specific heat, thermal diffusivity and conductivity of gorgon nut were determined using standard techniques for different sizes of nuts at moisture contents and temperatures ranging from 15 to 60% (dry basis) and 25 to 55C, respectively. the physical properties varied quadratically with moisture content. Specific heat increased with moisture and temperature but decreased with the size of the nut; whereas, the thermal diffusivity showed a reverse trend. Thermal conductivity increased with moisture content but did not follow any trend with temperature within the range of the study. the physical and thermal properties data at various moisture contents and temperatures were used to develop equations for different sizes of gorgon nuts.