酸面团中优势乳酸菌和酵母菌对麦谷蛋白结构的影响

以分离自我国传统酸面团中的优势菌种植物乳杆菌（Lactobacillus plantarum）Sx9、旧金山乳杆菌（Lactobacillus sanfranciscensis）Gm4及酿酒酵母（Saccharomyces cerevisiae）Sq7为发酵菌种,研究其对小麦麦谷蛋白大聚体的溶解性、游离巯基含量及二级结构变化的影响。结果表明,发酵24 h后,植物乳杆菌Sx9、旧金山乳杆菌Gm4及酿酒酵母Sq7使麦谷蛋白大聚体的溶解率分别增加7.06%、2.47%、2.47%。在发酵6～12 h,植物乳杆菌Sx9对二硫键作用明显,发酵液中游离巯基含量从0.29 μmol/mg迅速增加至0.61 μmol/mg。植物乳杆菌Sx9和旧金山乳杆菌Gm4对二级结构的影响明显,发酵6 h后,无规则卷曲含量几乎为零,全部转化为β-折叠和β-转角,而酿酒酵母Sq7影响甚微,仅有极少量的转化。因此,相比于酿酒酵母Sq7,植物乳杆菌Sx9和旧金山乳杆菌Gm4对麦谷蛋白大聚体的降解效果较好,且植物乳杆菌Sx9最佳。     

冻藏时间对非发酵面团流变特性及蛋白结构的影响

冻藏时间是影响冷冻面团质量的主要因素之一。研究冻藏时间对非发酵面团质构、流变特性及蛋白结构的影响。结果表明,随着冻藏时间的延长,面团硬度不断增加,弹性、内聚性、黏附性和咀嚼度降低,冻藏至30d时其弹性、内聚性大幅度下降;弹性模量(G′)与黏性模量(G″)均不断降低;面团最大蠕变柔量(J_(max))降低,零切变黏度(η_0)增加,瞬时蠕变柔量(J_0)与迟滞蠕变柔量(J_m)不断降低,面团结构稳定性变差,受到外力后的恢复力降低;面团中游离巯基含量显著上升,谷蛋白大聚体含量显著下降,蛋白二级构象发生改变,由α-螺旋、β-转角结构向β-折叠结构转变。总之,随着冻藏时间的延长,非发酵面团品质不断下降,并且在30 d内品质下降最为显著。     

壳聚糖对小麦面团流变学特性的影响

研究壳聚糖添加量0、0.4%、0.8%、1.2%、1.6%(w/w)对小麦面团面筋含量、粉质特性、拉伸特性、动态流变特性、质构特性及巯基含量的影响。结果表明,面团流变学各项指标与壳聚糖的添加量有关。随着壳聚糖的添加量增加,湿面筋含量、干面筋含量、面筋持水率增加,而面筋指数下降。同时,面团的形成时间、稳定时间、弹性模量和粘性模量增加。质构仪(TPA)结果表明,面团硬度、咀嚼性增大。当壳聚糖添加量为0.8%时,面团拉伸特性最佳,继续添加反而使拉伸特性降低。巯基含量随壳聚糖添加量增加无显著差异,说明壳聚糖对巯基氧化所需的化学环境并没有造成影响。面团流变学特性变化的原因在于壳聚糖的高持水性和粘附性提升了面团的耐搅拌性,对面筋网络结构有破坏作用。     

木聚糖酶对面团流变性和热力学特性的影响

研究不同添加量的木聚糖酶对面粉粉质拉伸特性、面团流变学特性和热力学特性的影响,结果表明：随着木聚糖酶含量的增加,面粉的吸水率、形成时间、稳定时间降低。随着木聚糖酶的加入,面团的延展性显著提高,但抗拉伸阻力显著下降。在频率变化过程中,木聚糖酶可使面团的弹性模量和黏性模量降低,损耗正切角tanδ增大。随着温度上升,面团的弹性模量先降低再显著升高,而tanδ不断下降。热力学分析表明,木聚糖酶使面筋蛋白强度和耐操作性均下降。     

副干酪乳杆菌对小麦发酵面团流变特性与风味的影响

本研究针对小麦乳酸菌发酵型面团产品市场空缺及副干酪乳杆菌在食品工业中的应用,以高筋小麦粉、副干酪乳杆菌N1115与N3117为原料,采用Mixolab混合仪试验、旋转流变仪频率扫描试验、气相色谱-质谱联用(GC-MS)试验,测定小麦面团的黏度、流变学特性以及风味物质的组成及含量。结果表明,小麦面粉与N1115,N3117混合酵母发酵后形成的面团黏度处于正常范围,粉质曲线趋于稳定,面筋强度增加,加工特性优异;添加了N1115及N3117的小麦面团发酵后储能模量G'和损耗模量G'降低,面筋蛋白弱化度增加,面团的流变学特性略有下降;通过气-质谱联用试验在N1115与酵母菌混合添加的小麦发酵面团中检测出28种风味物质,N3117与酵母菌混合添加的小麦发酵面团中检测出63种风味物质,并且面团中酯含量大大提高,面团的香味更加浓郁。     

冷冻面团发酵技术在中式食品中的应用II．冰结构蛋白对鲜酵母及包子类冷冻面团流变发酵特性的影响

应用F3 流变发酵仪和动态流变仪研究冰结构蛋白(ISP)对冻藏0、1、2、3、4 周鲜酵母发酵特性和冷冻面团动态流变学特性的影响。结果表明：随着冻藏时间延长,所有酵母样品发酵过程中气体释放曲线最大高度H′m、产生CO2 气体总体积V总及面团最大膨胀高度Hm 均逐渐降低,冷冻面团的弹性模量(G′)和黏性模量(G 〞)逐渐下降,冷冻面团包子比容显著减小。引入冰结构蛋白(ISP)后,冻藏时间相同时,酵母发酵过程中的H′m、V 总及Hm 均有所增大,G′和G 〞下降趋势减缓,冷冻面团包子比容明显大于空白组,说明ISP 能够抑制冻藏过程中冰晶的形成和重结晶,减弱冰晶对酵母及面筋蛋白质网络结构的破坏,同时也说明ISP 能够增强面筋蛋白质网络结构的强度,提高面筋蛋白质对冰晶破坏的抵抗力。     

发酵时间对面团加工特性及馕饼品质的影响

本实验通过研究不同发酵时间条件下面团水分分布、流变特性、面筋蛋白结构及馕饼比容、质构品质和感官评分的变化规律,旨在探明发酵面团加工特性与其馕饼品质之间关系。研究表明：发酵过程可导致面团中的弱结合水转变为强结合水和自由水,面筋蛋白的无规卷曲相对含量升高、α-螺旋含量降低,但发酵面团的(G’)、黏性模量(G’’)和β-折叠含量呈先上升后下降趋势,表明适度发酵(发酵时间为1.0 h 时)有利于面筋网络结构的形成和稳定;同样地,不同发酵时间条件下馕饼的比容、高径比、硬度、弹性、内聚性和感官评分等品质特性指标表明发酵1.0 h时,馕饼的整体品质最佳;其中,组成分分析结果表明,发酵能够通过影响面团的加工特性从而改变馕饼的宏观品质。本研究可为馕饼的品质控制提供依据。     

葡萄糖氧化酶和谷氨酰胺转氨酶对发酵麦麸面团加工品质的影响

本研究旨在探讨葡萄糖氧化酶和谷氨酰胺转氨酶对发酵麦麸面团加工品质的改良效果及改良机制,为改善全麦发酵食品食用品质提供应用参考。在全麦粉中分别添加1.0、3.0和6.0 U/g的葡萄糖氧化酶或谷氨酰胺转氨酶,分析测定了全麦粉粉质特性、发酵面团质构特性以及面筋的持水率、蛋白质组成和游离巯基含量的变化情况。研究结果表明:两种酶制剂的添加对全麦粉粉质特性有显著改善作用(p<0.05),面团稳定时间延长,弱化度减小;随酶制剂添加量的增加,发酵面团的弹性和凝聚性均显著增加,面筋蛋白中谷蛋白大聚合体(GMP)含量显著升高,游离巯基的含量显著减少(p<0.05),但高添加量的谷氨酰胺转氨酶(6.0 U/g)引起面筋蛋白持水率下降。谷氨酰胺转氨酶对麦麸面团品质的改良效果显著优于葡萄糖氧化酶(p<0.05),其适宜添加量为3.0 U/g,可使麦麸面团的稳定时间由5.3 min延长至9.3 min。     

冻融循环下柑橘纤维对冷冻预发酵面团的改良

该文探究冻融循环对冷冻预发酵面团品质的影响,并开发相关改良产品。测定冷冻预发酵面团在冻融循环过程中的物理特性、面筋结构以及成品品质变化,通过添加柑橘纤维（citrus fibre,CF）来探究其改良效果。结果表明：冻融次数增加,冷冻预发酵面团的弹性模量（G′）和黏性模量（G″）下降,水分含量则是呈现先上升后下降趋势,一定程度上破坏面筋网络结构,最终导致成品品质下降。添加柑橘纤维后的冷冻预发酵面团水分含量高于空白组（除F4）,且面筋结构更完整,成品感官品质更优。综上所述,冻融循环对普通面团、添加柑橘纤维的面团品质均有一定的影响。     

深度发酵过程面团面筋蛋白的变化

面团在深度发酵过程中面团面筋蛋白的变化对面团的持气性具有显著影响。运用排水法测定分析面团发酵情况,并且检测酵母发酵过程中面团的可洗出面筋含量、面筋指数、二硫键含量等的变化。酵母产气量和面团持气性在开始阶段均较好,随后持气性出现明显的下降趋势;面团面筋含量和面筋指数随着发酵时间的增加均明显下降;面筋蛋白中二硫键含量呈先下降后稳定的趋势;在酵母面团的发酵过程中,由于二硫键的破坏,面筋含量及面筋质量都有所下降,从而影响面团的持气性。     

植物乳杆菌ST-III发酵苦荞面团中蛋白质降解规律的研究

苦荞蛋白作为苦荞中最主要的生物活性物质以及重要的营养成分之一,具有生物价高与氨基酸比例均衡等优点。但由于苦荞蛋白的组成中面筋蛋白含量较少且本身难以被吸收等方面的问题,其加工利用一直受到较大的限制。面团发酵技术作为一种能够提升面团加工品质以及最终产品营养价值的微生物发酵技术,能够提高谷物中蛋白质的利用率。本文选用植物乳杆菌ST-III(Lactobacillus plantarum ST-III)应用于苦荞面团发酵,通过比较苦荞发酵面团(Buckwheat Sourdough,简称BS)、小麦发酵面团(Wheat Sourdough,简称WS)和混合发酵面团(Wheat-Buckwheat Sourdough,简称WBS)发酵过程中变化发现：植物乳杆菌ST-III在BS发酵过程中菌落密度始终较大且显著高于WS和WBS中植物乳杆菌ST-III的菌落密度(p＜0.05),发酵24 h后可达到13.62 logCFU/g酸面团,同时,BS的pH为6.58,接近植物乳杆菌ST-III的最适pH,总酸含量最高达到24.39 mL,其中,乳酸以及乙酸含量分别是WS 与WBS的1.61-1.75倍以及1.06-1.15倍。此外,通过对三种面团发酵过程中总蛋白、清蛋白、醇溶蛋白、谷蛋白以及游离氨基酸含量的测定,并利用SDS-PAGE凝胶电泳发现,植物乳杆菌ST-III在发酵过程中对三种酸面团中总蛋白及其各组分的降解作用有显著差异(p＜0.05),其中,植物乳杆菌ST-III发酵对BS中苦荞蛋白的降解效果最为明显,且游离氨基酸含量随着发酵的进行呈上升趋势。综上可知,利用植物乳杆菌ST-III发酵苦荞酸面团不仅能够改善苦荞中面筋蛋白含量不足导致的加工品质较差的问题,而且提升了苦荞中蛋白质的利用率。     

米酒老面发酵工艺对馒头品质的影响

为探究发酵时间、发酵温度、米酒添加量对米酒老面和米酒老面馒头品质的影响,通过3,5-二硝基水杨酸分光光度法、面筋指数测定仪、pH计、小米容积置换法、白度仪、硬度仪和感官评分等方法,以米酒老面的pH值、还原糖含量、湿面筋含量和面筋指数以及米酒老面馒头比容、白度、硬度和感官为评价指标.结果表明:随着米酒老面发酵时间的延长,...     

Defined multi-species semi-liquid ready-to-use sourdough starter

This paper aimed at setting up a protocol for the manufacture of a defined multi-species semi-liquid ready-to-use sourdough starter consisting of lactic acid bacteria (LAB) selected on the basis of their capacity of rapid acidification and adaptation to several technological factors. Preliminarily, 56 strains of sourdough LAB were screened based on the acidification kinetics during sourdough fermentation. The influence of temperature (25-37 degrees C), NaCl (2%, w/w, of wheat flour), initial cell number (10(7)-10(9) cfu g(-1)), dough yield (150-180), substrate for cell cultivation (mMRS or SDB media) and phase of cell growth (exponential or stationary phases) on the kinetics of acidification was also determined. Lactobacillus casei DPPMA27, Weissella confusa DPPMA20 and Lactobacillus fructivorans DPPMA8 were selected and used to produce a defined multi-species semi-liquid sourdough starter. Fermentation was carried out in a 2l batch fermentation bioreactor (12 h at 37 degrees C), under controlled pH, by cultivating cells in a medium made of water (60%), flour and other nutrients (40%). The semi-liquid sourdough starter was stored for 30 days under different conditions and used for dough fermentation (dough yield 160). The microbial composition, acidifying activity and fermentation end-products were kept constant during 21 days of storage. The findings of this study may be useful to increase the use of sourdough in bakery industries.     

米酒老面添加量对面团及馒头品质的影响

本文研究了米酒老面添加量(40%、50%、60%、70%和80%)对面团的pH、湿面筋含量、面筋指数及馒头的比容、硬度、白度、感官评分的影响。结果表明:随着米酒老面添加量的增加,面团pH呈现下降的趋势。米酒老面添加量为60%的面团中湿面筋含量显著低于其他四种添加量(P<0.05),馒头的比容、硬度、白度和感官评分显著高于其他四种添加量(P<0.05)。相关性分析表明,面团pH与馒头的感官评分呈极显著负相关(P<0.01);面团湿面筋含量与馒头比容呈显著负相关(P<0.05),与馒头硬度呈显著正相关(P<0.05),与馒头白度呈极显著负相关(P<0.01)。面团面筋指数与馒头比容呈极显著正相关(P<0.01),与馒头硬度呈极显著负相关(P<0.01),与馒头白度呈显著正相关(P<0.05)。米酒老面的添加会改变面团和馒头的品质,其最适添加量为60%。     

Effect of sourdough starter and fungal proteases on gluten content and sensory properties of tarhana

In this study, gluten degradation during prolonged tarhana fermentation was monitored in a traditional dough as well as in dough containing sourdough starter, peptidase additives and combination of both. Gluten content, determined using the sandwich ELISA assay method, was reduced significantly in the first 5 days of fermentation for all formulations. After 30 days into fermentation, approximately 15% and 20% reduction of gluten was observed in the traditional dough and sourdough starter added dough, respectively. In enzyme supplemented formulations, the mean gluten levels were below 20 ppm by 20 days of fermentation. Results showed that proteolytic enzyme addition to the dough mix can potentially render long fermented tarhana a food which conforms to regulations set forth for gluten-free foods, even though wheat flour is one of the main production ingredients. Sensory evaluation of the 30 day fermented tarhana samples revealed differences in sourness and odour properties of the products.     

Study of the behaviour of Lactobacillus plantarum and Leuconostoc starters during a complete wheat sourdough breadmaking process

The acidification properties, metabolic activity and technological performance of four individual Lactobacillus plantarum or Leuconostoc freeze-dried starters were investigated during a complete wheat sourdough breadmaking process including 0.2 g/100 g baker's yeast. Microbiological contents (lactic acid bacteria and yeasts), acidification characteristics (pH and total titratable acidity), soluble carbohydrates (maltose, glucose and fructose) and fermentative end-products (lactic and acetic acids, ethanol) contents were evaluated during both sourdough and corresponding bread dough fermentation. Biochemical and technological analysis of the resulting bread products are also presented. Some differences among strains in acidification properties and soluble carbohydrates availability were outlined both in sourdough and bread dough. Each individual Leuconostoc or Lb. plantarum starter was able to produce a characteristic fermentation and was found to ensure the production of breads with overall satisfactory acceptance.     

Effects of different <Emphasis Type="Italic">Lactobacillus</Emphasis> and <Emphasis Type="Italic">Enterococcus</Emphasis> strains and chemical acidification regarding degradation of gluten proteins during sourdough fermentation

Dough quality and baking performance of wheat dough are significantly affected by the qualitative and quantitative composition of the gluten. Therefore, the degradation was studied of specific fractions of gluten proteins in sourdough as affected by starter cultures. Doughs were fermented for 0, 5, and 24 h at 30 °C after addition of Lactobacillus sakei, L. plantarum, L. sanfranciscensis or Enterococcus faecalis. Chemically acidified doughs were used as controls. All doughs were analyzed quantitatively for their content of albumins, globulins, gliadins, glutenins, and glutenin macropolymer by means of a combined extraction/HPLC procedure. Protein degradation during sourdough fermentation was primarily due to acidic proteases present in flour. While L. sakei, L. plantarum and L. sanfranciscensis were mostly non-proteolytic, E. faecalis clearly contributed to gluten proteolysis. Single gluten protein types were clearly different in their resistance to proteolytic activities of the dough system and E. faecalis, and, in contrast to total glutenins, the amounts of gluten macropolymer were significantly reduced already after 5 h of incubation. When longer fermentation times were applied, gluten was substantially degraded. The strongest decrease was found for the glutenin fraction leading to an increase of alcohol soluble oligomeric proteins in the gliadin fraction. The extent of the decrease of monomeric gliadins was strongest for the γ-type followed by the α- and the ω-types. This indicates that dough properties residing in specific types of gluten fractions can be influenced by the duration of fermentation and the application of proteolytic strains.     

受热对小麦粉品质及其面团特性的影响

小麦粉在加工过程中会受到热的影响,导致小麦粉品质发生变化。该文研究不同受热条件下小麦粉品质及其面团特性的变化,以稳定或提高小麦粉品质。采用干热处理方式,在60~90℃分别对小麦粉加热10~50 s,测定小麦粉的水分含量、干面筋含量、面筋指数、蛋白质组分含量等理化特性,以及游离巯基含量、二硫键含量、面筋蛋白二级结构等结构组成和面团质构特性。研究结果表明,受热后小麦粉水分含量显著降低,在较长时间和较高温度时,随着温度升高和时间的延长,干面筋含量总体呈先升高后降低的趋势,当温度较高时,面筋指数均低于原粉,且随时间的延长先升高后降低;随着温度升高和时间延长,清蛋白和球蛋白含量降低,醇溶蛋白和麦谷蛋白含量先升高后降低;游离巯基和二硫键含量有显著变化,蛋白质的二级结构受温度影响显著,时间仅对β-转角含量有影响;面团质构特性在起始醒发时差异不大,但在醒发45 min后差异极显著,在温度高时,面团坚实度和黏弹性的值较大。     

植物乳酸菌M616对发酵酸面团发酵特性的影响

本文研究了在酸面团发酵过程中,植物乳酸菌M616(Lactobacillus plantarum M616)对面团p H、TTA以及糖类含量变化的影响,并利用F3流变式发酵仪和吹泡仪对面团发酵力及流变特性的变化进行了研究。结果表明植物乳酸菌M616不仅对酵母菌的生长具有一定抑制作用,而且在面团p H和TTA的变化过程中起主导作用;另外,乳酸菌对淀粉的降解作用大于对还原糖的吸收,从而使面团中还原糖的含量增加,增加面团的甜味。在发酵后期,面团p H降低至3.73,这在一定程度上抑制了体系中霉菌和其它杂菌的生长。植物乳酸菌的生长代谢不仅显著提高了面团黏度、筋力,而且减缓了面团在发酵过程中韧性的降低。其中发酵酸面团对面团黏度和筋力影响最大,发酵过程中酸面团的最大黏度和筋力可以达到酵母发酵面团的2倍。