Inhibition of Undesirable Gas Production in Tofu

Of 100 gas-producing bacterial isolates, 65% were Gram-negative. Bacterial growth and gas production in commercial tofu was accompanied by acidification, and pH decreases as low as 5.2. Coliform bacteria constituted 15% of the total bacterial flora. Sporeformers and yeast counts remained < 10³ CFU/mL. Pasteurization was effective in lowering the bacterial counts, and retarded gas production. The addition of lactic acid (reducing pH to 5.5) or lactic acid bacteria (2 × 10⁷ CFU/g) to tofu helped reduce gas production by about 50%. Addition of both lactic acid and Lactobacillus plantarum stopped gas production in contaminated tofu.     

壳聚糖-大豆分离蛋白复合涂膜对豆腐品质的影响

以壳聚糖(CH)、大豆分离蛋白(SPI)为原料制备不同浓度的涂膜液,探究单独或复合涂膜处理对豆腐菌落总数、感官、质构和色泽等品质特性的影响.研究得出:经过复合膜液(2.0％CH+0.5％SPI)处理的豆腐,菌落总数增长最慢,感官评价分值最高.另外,通过扫描电镜(SEM)观察到复合膜液(2.0％CH+0.5％SPI)处理...     

豆腐复合凝固剂的研究

实验先以凝胶强度、保水性和感官评价确定了3种单一凝固剂（葡萄糖酸-δ-内酯、乙酸钙和氯化镁）的最佳用量，然后按照优选法的原则。确定了3种凝固剂用量比例为2：1：1时，制作出的豆腐在各项品质均优于单一凝固剂。     

水豆腐保鲜技术的研究讲展

阐述了多种杀菌技术与保鲜技术在豆腐保鲜研究中所取得的成果,分析了豆腐保鲜难的部分原因,并展望了水豆腐保鲜技术的发展方向.     

3种即食鱼豆腐营养成分分析及凝胶性能评价

以3种市售即食鱼豆腐(鱼豆腐A、B、C)为研究对象,对其营养成分和凝胶性能进行分析及评价。结果表明:3种鱼豆腐的水分质量分数分别为65.94%、69.34%和67.20%;粗蛋白质量分数分别为25.63%、22.02%和23.81%;粗脂肪和灰分含量较低。氨基酸种类齐全,必需氨基酸/总氨基酸质量分数分别为39.43%、39.64%和39.57%,鲜味氨基酸/总氨基酸质量分数分别为37.11%、36.06%和36.32%;第1限制氨基酸均是亮氨酸,必需氨基酸指数评分分别为43.81、53.14和49.57。分别检出21、22、21种脂肪酸,且多不饱和脂肪酸含量丰富,分别为59.14%、63.39%和44.59%。3种鱼豆腐持水性较好,分别为84.61%、86.36%和82.98%;p H值分别为6.04、6.06、6.23;凝胶强度较高,分别为320.17、203.63、212.71?g·cm。3种鱼豆腐均属于营养种类齐全,凝胶性能良好的即食食品。研究数据为进一步评定市售鱼豆腐产品质量提供了一定参考。     

豆腐质构的感官评定与仪器评价的相关性分析

为探索最能反映豆腐感官质构的仪器指标,选取了四种市售鲜豆腐作为研究对象,采用豆腐质构仪器测定中常用的二次压缩和插入试验进行仪器指标测定,同时进行分析型感官质构评定试验,并对两者测定指标之间进行了相关性分析。结果表明:压缩试验中的5项仪器指标（硬度、弹性、咀嚼性、凝聚性及胶粘性）除凝聚性外,其余4项均与感官质构评价指标间存在较好的相关性,其中硬度与感官质构硬度相关性显著（r=0.952,P<0.05）;插入实验中的3项仪器指标（表观破断应变ε、表观破断应力σ、表观弹性率E）均与感官质构评价指标间存在较好的相关性,其中表观破断应力σ与感官硬度、细腻性之间相关性显著（r=0.989, ?0.978,P<0.05）。综合考虑,仪器评价指标中的硬度及表观破断应力可以代替感官评定指标客观准确的评价豆腐质构的好坏,在豆腐的实际生产中及豆腐质构的科研中也可考虑仅选用这两个仪器指标。     

The viscoelastic properties of soybean curd (tofu) as affected by soymilk concentration and type of coagulant

The viscoelastic properties of different types of tofu were investigated. Soymilk concentrations were 5, 6, 7, 8 and 9%. Coagulants used were 30 mm CaSO₄ or 30 mm glucono‐delta‐lactone (GDL). As the concentration of soymilk was increased viscosity and handling difficulties increased. A high concentration of soymilk in tofu gave a high break stress and produced hard tofu. The four‐element Burgers model fitted the creep behaviour and both viscous and elastic parameters could be acquired from model analysis, reflecting changes in elasticity and viscosity of tofu. The constant viscous parameter in the model increased with increasing soymilk concentration. The viscous parameters of viscoelastic materials like tofu gel, obtained from small deformation tests, seemed to correlate, to some extent, with the break stress obtained from large deformation tests. For hard tofu production increasing the soymilk concentration within a certain range and the partial replacement of calcium sulphate coagulant by GDL could be effective options.     

膜技术提取大豆低聚糖的研究

利用膜分离技术从加工制作豆腐产生的废水对大豆低聚糖的提取进行了研究.实验结果表明：用截留分子量为10KDa的中空纤维聚砜膜超滤豆腐废水,对蛋白和低聚糖的分离有较好的效果.经预处理和超滤后大豆低聚糖的含量为5.80g/L,回收率为81.0%.较好的预处理条件为：豆腐废水经真空抽滤后加入CaCl2,使其浓度达到3wt%,用HCl调至pH值4.3～4.6,离心20min.较适宜的超滤条件为：料液体积流量20 L/h,膜两侧平均压力差0.10MPa,室温,pH=6.4～7.较好的清洗条件可使膜通量恢复90%以上,即：浓缩液体积流量20L/h,清水超滤30min（0.03MPa,室温）,0.1wt%的NaOH超滤30min（0.10 MPa,45℃）;0.3wt%H2O2浸泡16h.     

Physiochemical Properties of Polysaccharides Extracted from Tofu Processing Wastewater

ABSTRACT: Yield, gelation, viscosity, emulsifying properties, and sugar composition of polysaccharides extracted from tofu processing wastewater under acidic conditions at different temperature levels and incubation times were determined. Optimum extraction for water-soluble polysaccharides was at pH 1.5 and 100 °C over an incubation period of 6 hours. Extraction ratio (%) and yield of high-molecular-weight polysaccharides were higher at pH ranges of 1.5 to 3.0 with extraction temperatures of 80 to 100 °C. Most water-soluble polysaccharides extracted under strong acidic conditions and above 80 °C remained fluid, while most extracted within the range of 45 to 80 °C gelled. Pure polysaccharides exhibited better emulsifying properties than water-soluble polysaccharides. Apparent viscosities of water-soluble polysaccharides were dependent on sugar concentration.     

腐乳源乳酸乳球菌17M1高密度培养条件研究

为了获得乳酸乳球菌(Lactococcus lactis)17M1的高密度培养方法,以菌体密度和活菌数为评价指标,以豆腐乳清为基础培养基,采用响应面法对该菌株的培养基组成进行优化,并研究其培养条件。结果表明,菌株17M1的最佳培养基组成为：在豆腐乳清中加入2.00%大豆蛋白胨、胰酪蛋白胨1.70%、柠檬酸铵2.30%。在此优化培养基中初始pH值6.15,于37℃培养15 h,乳酸乳球菌17M1的活菌数达到了1.17×10¹⁰CFU/mL,高于M17肉汤培养基活菌数(1.04×10⁹CFU/mL)。该研究结果为乳酸乳球菌17M1的工业化应用提供了技术支持。