氯化镁瓜尔胶复合凝固剂对豆腐凝固过程影响

分别利用氯化镁、石膏和氯化镁、瓜尔胶复配凝固剂制作豆腐,瓜尔胶降低了氯化镁制作豆腐的硬度,但复配凝固剂制作的豆腐和石膏豆腐有相似的质构特性,红外光谱对三种豆腐粉末测定的结果表明:三种凝固剂对豆腐中蛋白的二级结构并没有影响;在37℃下研究三种凝固剂对豆浆黏度变化的影响,发现瓜尔胶提高了凝固过程第一阶段的速率,但降低了第二阶段凝固过程的速率。瓜尔胶通过改变豆浆的凝固速率影响了豆腐的凝胶结构和质构特性。     

加工工艺对豆腐中异黄酮保留率的影响

讨论了不同工艺条件对豆腐中异黄酮保留率的影响。研究表明，在20℃下浸豆12h，80℃下点脑能提高豆腐中异黄酮的保留量；添加海藻酸钠和大豆分离蛋白能提高豆腐的产率和大豆异黄酮的保留率，通过使用质构仪分析和感官评价可知，这些工艺过程对豆腐的品质均没有不良影响。采用HPLC的检测可知，在传统豆腐的加工过程中，会导致约22％的异黄酮的流失，且其中糖苷型的异黄酮较苷元型的异黄酮流失量大；而新型的GDL豆腐则有利于提高制品中的异黄酮保留量。     

速冻蛋白豆腐营养成分分析及速冻工艺对其质构的影响

为探究速冻蛋白豆腐的营养成分及速冻工艺对其质构的影响,对比分析了速冻蛋白豆腐和市售4种常见大豆制品(豆腐干、素鸡、盐卤豆腐、石膏豆腐)的营养成分差异(水分、灰分、脂肪、蛋白质、氨基酸、维生素E、维生素K1、大豆异黄酮的含量)。同时,研究分析了速冻环节对于速冻蛋白豆腐质构及微观结构的影响。结果显示,在5种大豆制品中,速冻蛋白豆腐的维生素E、K1含量居于首位,分别为2. 54 mg/100 g、19. 2 mg/100 g;其他营养成分居中,其中脂肪含量为14. 0 g/100 g、蛋白质含量为11. 0 g/100 g、氨基酸含量为11. 1 g/100 g、大豆异黄酮含量为142. 6 mg/kg;经速冻工艺,豆腐持水性不变,解冻后的比未速冻的蛋白豆腐硬度与咀嚼性略高,弹性与内聚性低,在压缩比例为70%时,解冻后的速冻蛋白豆腐弹力仍能达到0. 87;通过扫描电镜观察,解冻后的速冻蛋白豆腐网格结构并未遭到破坏。结论显示,速冻蛋白豆腐的营养价值较高;速冻工艺对于速冻蛋白豆腐的质构及品质没有显著影响。     

吃豆腐能降血糖吗

正最近有人在网上和部分媒体称"吃水豆腐能降血糖",甚至说有患者的经验:自己每天早晨吃一两碗水豆腐控糖,服用10 d左右,血糖趋于平稳正常。那么,吃豆腐真能降血糖吗?糖尿病患者吃豆腐替代降糖药可取吗?传统的豆腐分两种,即石膏豆腐和卤水豆腐,水豆腐是指石膏豆腐。中医认为,豆腐有一定食疗作用,主要有益气和中、生津润燥、清热解毒、下气消痰等功效,可治疗赤眼、消渴、吐血、乳汁不通以及硫磺、烧酒中毒等。豆腐因富含蛋白质、不饱和脂肪酸、糖类、维生素及铁、钙、磷、镁等矿物质,有"植物肉"之称,也是难得的营养素食佳品。大豆是制作豆腐的主要原料。近年研究发现,大豆中含大豆异黄酮和大豆多肽有一定降糖功效。如研究发现,大豆异黄酮能降低糖尿病小鼠的血糖水平,提高其血清胰岛素浓度,缓解糖尿病症状;大豆多肽则可调节大鼠岛胰素分泌、缓冲血糖升高的作用。这两种成分虽有降糖效果,但都是采用大豆成分的浓缩物,在动物身上得出的结论。而普通豆腐中这类成分的含量极微,单靠服食大豆食品降血糖,尚未见有研究报道。此外,单纯使用大豆异黄酮、大豆多肽制剂治疗糖尿病的临床研究,也未见有相关病例的报道。     

阿拉伯胶、瓜尔豆胶复配对鸭血凝胶特性的影响

将阿拉伯胶、瓜尔豆胶及两者的复配胶分别添加到鸭血中,通过测定鸭血豆腐凝胶的质构特性、保水性 并分析鸭血豆腐的微观结构,旨在阐述食用胶体对鸭血豆腐品质的影响。结果表明：两种食用胶均能极显著提高 鸭血豆腐的硬度、弹性、回复性等质构特性和保水性能（P＜0.01）,其中阿拉伯胶对产品质构特性的影响高于瓜 尔豆胶,而瓜尔豆胶对其保水性能的提升更为突出。阿拉伯胶与瓜尔豆胶复配使用具有协同增效作用,能够改善 鸭血豆腐的凝胶特性,当复配质量比为7∶3,添加量为3.5 g/L时鸭血豆腐品质最佳,硬度、弹性与保水性分别达到 4 217.33 g、0.88和66.97%。凝胶微观结构分析显示,食用胶的添加能够使鸭血豆腐形成连续、均一、致密的凝胶 网络结构,显著提高了其凝胶性能与保水性。     

复合凝固剂组分对豆腐品质影响的研究

在我国豆腐生产中广泛使用的是单一凝固剂。每种单一凝固剂对豆腐品质的影响不同。本文对凝固剂与豆腐品质的关系进行了研究 ,将石膏与δ 葡萄糖酸内酯按一定比例混合制成复合型凝固剂 ,并通过试验优选法获得了最佳配比。当δ 葡萄糖酸内酯与石膏质量比为 2∶1时 ,其出品率、含水率、离水率、蛋白质含量、豆腐外观、内部结构及风味等各个方面均好于单一凝固剂豆腐。     

不同类型的凝固剂对豆腐中蛋白质消化特性的影响

为了探究不同类型的凝固剂对豆腐中蛋白质消化特性的影响,分别采用酸类凝固剂葡萄糖酸内酯(glucono-δ-lactone,GDL)、盐类凝固剂石膏(CaSO4)以及二者复配的凝固剂制作豆腐.经体外模拟消化后测定其可溶性蛋白质含量、小肽含量(＜ 10 kDa)、水解度(degree hydrolysis,DH)、SDS-...     

菜汁豆腐胶凝机理的探讨

本文对豆腐的胶凝机理、影响因素进行了理论探讨，以更好地理解菜汁豆腐胶凝基本原理，并对凝固作一概括介绍。     

不同凝固剂对豆腐品质的影响

分别以石膏、MgCl_2、豆清发酵液为凝固剂,按熟浆工艺生产豆腐,并对豆腐得率、保水性、感官评分、质构特性、风味特性进行比较研究。结果表明:不同凝固剂生产的豆腐其风味特性有明显区别,可利用电子鼻检测区分;豆腐的得率和保水性差异均达极显著水平(P0.01);感官评分和质构分析结果差异均达显著水平(P0.05);就所选的3种凝固剂而言,豆清发酵液生产的豆腐感官评分最高,更适合于熟浆工艺豆腐加工。     

大豆食品对人体内异黄酮代谢水平影响的研究

探讨不同苷元含量的大豆食品的摄入对人体内异黄酮代谢水平的影响。应用现状调查方法,筛选出86名居住在哈尔滨市区健康成年男女。采用高压液相色谱法分析摄入大豆异黄酮前后尿中雌马酚等代谢物24 h排泄量,计算出产雌马酚者比例。然后从产雌马酚者中随机选取12名受试者,在3个时期分别摄入豆浆、β-葡糖苷酶处理的豆浆和豆腐。在摄入后0～48 h收集尿液。通过高压液相色谱法测定尿液中大豆苷元、染料木素和雌马酚的含量以确定糖苷或苷元的摄入是否影响异黄酮的代谢。结果是尿液中大豆苷元、染料木素和雌马酚的排泄量差异不显著。结论是人体内异黄酮的代谢可能不受大豆食品中异黄酮苷元含量的影响。     

Effect of different coagulants on yield and quality of tofu from soymilk

Soymilk tofu coagulated with four indigenous coagulants was compared in terms of chemical, textural, colour, and sensory attributes with calcium sulphate (CS) coagulated tofu. Coagulants used are Epsom salt (ES), lemon juice (LJ), alum and top water of fermented maize (TWFM). Protein and magnesium content significantly (P < 0.05) increased from 44.5 to 51.7 g/100 g and 252 to 324.6 mg/100 g, respectively, in soybean grain to soymilk. Calcium and magnesium contents increased and decreased significantly (P < 0.05) in tofu coagulated with CS and ES, respectively. Lightness (L) values were 86.3, 86.2, 77.8, 72.4 and 84.6, redness (a) values are 0.34, 0.21, 0.87, 1.05 and 0.32, and yellowness (b) values were 24.0, 23.9, 27.3, 20.3 and 23.4 for CS, ES, LJ, alum and TWFM. The hardness, chewiness and brittleness of textural properties of tofu were significantly (P < 0.05) affected by different sources of coagulation. Sensory evaluation data shows that LJ impacts a significantly acceptable sensory attribute to tofu. This study has demonstrated that tofu quality is affected by the type of coagulant used in curding the soymilk.     

高温冷冻豆腐的研究

研究高温冷冻豆腐的加工工艺,考察加热温度、加热时间和储存时间的影响,发现加热温度对于豆腐的质构和颜色是高度影响因素,而加热时间对颜色是显著影响因素,储藏温度不显著以普通硫酸钙豆腐作为对照,发现得到高温冷冻豆腐凝胶网络弱于普通硫酸钙豆腐,生产类似普通硫酸钙豆腐的最佳工艺是:加热温度112℃,加热时间为30min,储藏时间取9.3d,得到的高温冷冻豆腐的硬度为7.21±0.15N.     

青梅汁酸凝豆腐质构优化及显微结构研究

为了改善青梅汁作为单一酸性凝固剂制作的豆腐硬度低、质构差的缺点,添加天然食用胶与钙盐进行质构的优化研究。以豆腐的硬度与持水力作为响应值,采用响应曲面法优化食用胶与钙盐的最佳添加量。结果表明：食用胶与钙盐的最佳添加量为乳酸钙0.291 mmol/100 mL、卡拉胶0.032 8 g/100 mL,此条件下青梅汁酸凝豆腐硬度为49.3 g,持水力为73.43%。扫描电镜显微观察表明,添加卡拉胶与乳酸钙的豆腐凝胶网络结构更加均匀、致密。     

Yield and Quality of Tofu as Affected by Soybean and Soymilk Characteristics. Calcium Sulfate Coagulant

Nine light hilum soybean (Glycine max (L.) Merr.) varieties were used to study the characteristics of soybeans and soymilk that affect the yield and quality of tofu coagulated with calcium sulfate. The yield of tofu was not affected by the size of soybeans. Soybean varieties high in protein, fat and phosphorus contents produce tofu with higher protein, fat and phosphorus contents. Two models for predicting the yield of tofu were proposed. According to model one, soymilk with higher pH and total solids gives a higher yield of tofu. According to model two, soybeans high in protein and ash and low in phosphorus give a higher yield of tofu.     

The effect of different varieties of soybean and calcium ion concentration on the quality of tofu

The Japanese food tofu (bean curd) was prepared by the traditional method using 15 varieties of soybeans. The tofu quality was evaluated on the basis of colour, taste and texture. The texture measurements were subjective and instrumental (hardness and cohesiveness).A slight variation in the texture of tofu was due to the 7S and 11S proteins in the soybean but an important factor affecting the texture of tofu was found to be the amount of calcium ions added during processing. The firmness and coarseness of the product increased with increases in the amount of calcium ions added and a linear relationship was found between the protein content of the beans and the calcium sulphate concentration required for good quality tofu.     

Yield and Quality of Tofu as Affected by Soybean and Soymilk Characteristics: Glucono-delta-lactone Coagulant

Nine light hilum soybean [Glycine max (L.) Merr] cultivars were used to study characteristics that affect yield and quality of tofu (soybean curd) coagulated with glucono-delta-lactone (GDL). Pressed and packed (nonpressed) curds were examined. Yield of tofu was not affected by size of beans. Protein and total solids in soymilk increased when protein and moisture increased in soybeans. Yield of pressed GDL tofu increased with protein content of soybeans (or soymilk) plus decreased calcium content. Fracturability of pressed GDL tofu increased with levels of phosphorus. Hardness of packed tofu increased with protein content in soymilk. Yield of pressed GDL tofu was 20% higher than CaSO₄ tofu.     

豆渣添加量对豆腐凝胶特性和保水性的影响

采用超微处理的豆渣添加到豆浆中制作豆腐。凝固剂为葡萄糖酸内酯（内酯）和硫酸钙。研究结果表明,适量的豆渣可以提高硫酸钙豆腐的凝胶强度和粘附性,但对内酯豆腐来讲,降低了凝胶强度和粘附性。内酯豆腐和硫酸钙豆腐凝胶的硬度都表现出下降的趋势,而弹性和保水性在一定程度上得到增加。结果有益于提高豆腐营养价值,改善豆腐的品质。     

Micronization Effects on Composition and Properties of Tofu

The effect of infra-red heating (micronization) was investigated on the composition and textural, biochemical and nutritional properties of soymilk and tofu. The yield, protein content and textural properties of tofu made from micronized beans using the common procedures (70°C as coagulating temperature and CaSO₄2H ₂O as coagulating agent) were lower than those of tofu from unprocessed beans; tofu prepared from micronized beans and coagulated at 90°C using a mixture of citric acid (0.01M) and calcium sulfate (0.03M) showed improved characteristics. The microstructure of tofu prepared from micronized beans lacked the regularity of the honeycomb-like structure shown by tofu from unprocessed beans. The heat treatment by micronization had little effect on the protein components of soymilk and tofu as determined by polyacrylamide disc gel electrophoresis.     

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.     

Rapid Method for Determining Optimum Coagulant Concentration in Tofu Manufacture

Four methods of determining optimum coagulation levels in tofu manufacture were compared. Full-fat soyflakes were used to produce 5% solids soymilk. Each soymilk batch was coagulated with calcium sulfate dihydrate (0.000–0.0450 N). Electrical conductance of the coagulating batches was recorded at 72°C and 21°C. Coagulated batches were pressed to make tofu and whey volume, pH, transmittance (400 nm) and tofu composition were measured. Whey transmittance and conductance correlated with coagulant concentration (r=0.87). Tofu yield, conductivity, and absorbance data were also related. Measuring the conductance of the coagulating soymilk was faster than obtaining pH and spectrophotometric values. Conductivity and transmittance could be used to optimize tofu coagulation.