EFFECT OF NATIVE AND LYOPHILIZED KEFIR GRAINS ON SENSORY AND PHYSICAL ATTRIBUTES OF WHEAT BREAD

Native and lyophilized kefir grains were added directly to bread dough or as a starter in sourdough. Because of inadequate leavening activity of kefir, yeast‐leavened breads were prepared. Kefir addition influenced the quality attributes and the shelf life of wheat bread. The pH of bread containing kefir decreased as compared to that in the control bread. The acidity of bread with kefir increased as compared to that in the control bread. An addition of kefir grains, regardless of the form, lowered the bread volume and increased the mold‐free shelf life from 4 (control) to 5–7 days. The addition of kefir grains in bread dough contributed to a milder taste, a more delicate yogurt‐like or dairy aroma. The breads made with sourdoughs containing native or lyophilized kefir grains scored higher for crumb quality number than breads made by directly adding kefir grains.     

复合酶制剂对甜酒酿面包发酵烘焙特性的影响

选用中国特色传统甜酒曲制作的甜酒酿进行面包制作,通过面团流变学分析、生物化学分析、激光共聚焦 显微观察、感官评定等多种手段对甜酒酿面团及面包的品质进行综合评估,与普通小麦面包进行对比,并使用天然 酶制剂来提高含甜酒酿面包的发酵烘焙特性。结果表明：含甜酒酿面团游离巯基含量增加,蛋白酶活力较强,甜酒 酿对面包面团面筋网络结构的形成有破坏作用,会导致面包内聚性、弹性下降,降低口感评分。但甜酒酿能给面包 带来更加诱人的色泽,其特有的酒香使面包更加可口,通过酶制剂的作用,面团面筋网络结构得到强化,含酶甜酒 酿面包品质全面提升,比普通小麦面包更受欢迎。     

传统酸面团中植物乳杆菌发酵馒头抗氧化特性及挥发性风味物质特征

以普通小麦馒头（记为WS）和植物乳杆菌标准菌株发酵馒头（记为LPS）为对照,通过测定总酚含量和1,1-二苯基-2-三硝基苯肼（1,1-diphenyl-2-picrylhydrazyl,DPPH）自由基清除能力,同时采用固相微萃取-气相色谱-质谱联用技术,研究传统酸面团中植物乳杆菌植物亚种发酵馒头（记为ZLPS）的抗氧化特性及挥发性风味物质特征。结果表明：乳酸菌发酵,尤其是植物乳杆菌植物亚种的发酵可以明显改善蒸制带来的馒头抗氧化特性降低,与WS相比,ZLPS中总酚含量增加了108.70%,DPPH自由基清除能力为WS的13.65 倍;乳酸菌发酵酸面团使得馒头的挥发性风味物质含量增高,酸面团发酵馒头的挥发性风味物质总含量分别增加了53.11%（LPS）、56.92%（ZLPS）,且ZLPS还产生了一些独特的挥发性风味物质,如乙酸异戊酯、6-甲基-5-庚烯-2-酮、3-辛醇、2-乙基己醇、乙酸-2-苯乙基酯等;ZLPS各项指标评分均较高,更具有获得消费者青睐的潜力。     

DETERMINING TOPOLOGICAL CHANGES AND CRITICAL LOAD LEVELS OF A POWER SYSTEM BY MEANS OF ARTIFICIAL NEURAL NETWORKS

ABSTRACT

In this paper, an investigation is done of the possibilities of implementing multi-layered artificial neural networks in analyzing the dynamic stability of an power system during load and topology changes. To solve this problem, a multi-layered neural network is used whose inputs are the state vector components, and whose outputs are encoded line outages and the real component of dominant eigenvalues of the system state matrix of the power system. The neural network is trained through the error back-propagation method. The proposed methodology is tested on an power system with ten nodes and four generators. The obtained results indicate the attractiveness of “on-line” application possibilities of multi-layered neural networks in order to efficiently evaluate the stability of an power system during conditions of load and topology change.     

Magnetic properties of nickel-strontium-borate oxide glasses

Abstracts are not published in this journal This revised version was published online in November 2006 with corrections to the Cover Date.     

不同发酵基质的酸面团对酵母面团体系面包烘焙及老化特性的影响

应用分离自我国传统酸面团的区域特色乳酸菌--旧金山乳杆菌分别发酵小麦粉和小麦麸皮基质制成（小麦/麦麸）酸面团,研究了两种不同发酵基质的酸面团及其添加量对酵母面团体系面包烘焙及老化特性的影响。结果表明：与小麦粉制作的空白组面包相比,小麦酸面团可以明显改善面包的比容和感官品质;添加未发酵麦麸制作的非酸面团麦麸面包品质低于空白组,但引入麦麸酸面团（10%、20%、30%）后面包比容和感官评定得分均高于相对应的非酸面团麦麸面包。小麦酸面团和麦麸酸面团以及小麦麸皮均可以改善面包的老化特性,在相同贮藏期内,酸面团面包和麦麸面包的硬度增加量、水分迁移量和老化焓值都低于空白组,并且添加麦麸酸面团的面包其硬度和老化焓值都低于相对应的非酸面团麦麸面包。