超微粉碎技术在豆腐加工中的研究进展

在豆腐的制备过程中,豆浆的制取方式十分重要,直接影响豆腐的凝胶强度、弹性、内聚性和口感。超微粉碎技术作为一种新兴的制浆技术,不仅能减小豆浆的粒径、赋予产品细腻的口感、改善原料的加工性能,还能在一定程度上避免豆渣中所含营养成分的流失,在豆浆及豆腐的制备过程中使用越来约普遍。本文综述了干法超微粉碎制浆技术和超声波、胶体磨、高压均质、超高压均质等湿法超微粉碎制浆技术的研究与应用现状,比较了各种制浆技术的优、缺点,并对今后豆腐制浆技术的研究方向进行了展望,旨在为加快研究\     

Effect of Soybean Varieties and Growing Locations on the Physical and Chemical Properties of Soymilk and Tofu

ABSTRACT: Soybean varieties and growing location greatly affected the protein content and color of soymilk and the protein content and yield of tofu ( P < 0.05). Protein content of soybeans was the most important affecting factor for the qualities of soymilk and tofu. There were significant correlations between the protein contents of soybeans and soymilks ( P < 0.05). There were also significant correlation between the soybean protein and the total solid content of soymilk (P < 0.05). Tofu moisture content had significant effect on the hardness and yield of tofu (P < 0.05). The correlation between soybean protein and tofu yield was significant at P < 0.05. The protein content and yield of tofu can be predicted by analyzing soybean protein.     

折光法快速测定豆腐制品生产用氯化镁溶液的浓度

利用折射率（通过糖度计测得的糖度表示）反映已知浓度的食用氯化镁溶液的浓度,绘制质量分数一折射率（糖度）标准曲线,利用标准曲线和折射率测定未知浓度的食用氯化镁溶液的的浓度,经误差计算确定能够满足豆腐制品生产需要的溶液浓度。     

高浓度煮浆对豆腐品质提升的作用及其机制

为明确高浓度煮浆对豆腐品质的影响,本研究通过采取高浓度煮浆（固形物质量分数9.2%～12.2%）低浓度稀释（统一至8.0%）法制备豆腐,对豆腐的品质进行比较,并在此基础上对豆乳和豆乳凝固状态进行比较,明确引起豆腐品质差异的原因。结果发现,与固形物质量分数为8.0%的豆乳组相比,随着煮浆浓度的上升,豆腐的硬度和咀嚼性逐渐降低,其中9.2%时最大,而弹性、得率、水分质量分数和保水性差异较小。进一步研究发现,当固形物质量分数为9.2%时,豆乳蛋白粒子比例最小（26.2%）、蛋白表面疏水性最大,而平均粒径、Zeta电位绝对值和B亚基比例随煮浆浓度增加而呈上升趋势,α与α’比例呈下降趋势。分析凝乳速度变化趋势发现,煮浆浓度越高,凝固起始时间越早,凝固速率越快。结果表明,高浓度煮浆可促使豆乳蛋白聚集程度增加,能够优化豆乳及其凝胶的加工特性,这一结果为实际生产提供了一定的理论基础。     

利用脱皮大豆制备高膳食纤维豆浆和豆腐的研究

传统豆制品生产过程中排出的豆渣是一种利用率低且成本低廉的膳食纤维来源。选用去皮大豆,采用保留豆渣的方式生产高膳食纤维豆浆和豆腐,研究均质条件对其理化性质和品质的影响。结果表明,高压均质豆浆(High pressure homogenized soymilk,HPHS)的总膳食纤维、脂肪和黄酮含量均高于传统过滤豆浆(Filtered soymilk,FS),蛋白质含量低于FS;与FS相比,HPHS的颗粒粒径和分布范围较大,稳定性较差,但这些指标随均质强度的提升而得到明显改善,稳定性也随之增加,而加热会增大粒径和分布范围并降低稳定性;高膳食纤维豆腐(High dietary fiber content tofu,HDFT)的硬度、弹性和咀嚼性随着均质强度提高呈先升高后下降的趋势,其中均质条件为30 MPa+35 MPa与普通豆腐(Normal tofu,NT)质构性能最接近,而加热会导致豆腐的质构参数降低;NT比HDFT拥有更为紧密有序、孔洞更少的微观三维结构,但用30 MPa+35 MPa制作的HDFT比其它HDFT拥有较好的且接近NT的微观三维结构。     

豆腐盐类凝固剂的凝固特性与作用机理的研究

本文研究了盐类凝固剂 (氯化钙、氯化镁和硫酸钙 )对豆腐凝胶强度、保水性的影响 ,分析了盐类凝固剂的作用机理和凝固特性。增加盐类凝固剂浓度 ,可以强化豆腐凝胶强度 ,但对保水性有弱化作用。盐的阴离子对凝固特性的影响比阳离子更重要     

Rapid Measurement of Phytate in Soy Products by Mid-infrared Spectroscopy

ABSTRACT: The rapid measurement of phytate from soybean and its products, such as soy flour, defatted meal, soymilk, and tofu, was investigated using Fourier transfer infrared spectroscopy (FT-IR) with an attenuated total refraction accessory. The phytate, separated from protein by trichloroacetic acid (TCA), was precipitated completely by the addition of calcium, pH > 7.0, even in the presence of TCA. The precipitate was dissolved in citrate buffer (pH 6.0) and then used for infrared measurement. The absorbance at 1070 cm⁻¹ correlated well the phytate content of the each sample. The measurement of phytate can be done rapidly by FT-IR with an ATR accessory and gives reproducible values.     

Process Optimization for Soft Tofu

Response surface methodology (RSM) was used to determine the optimum combinations of four factors, solids content of soy milk (10–14 °Brix), concentration of coagulant (0.25–0.41%, W/V), mixing temperature (75–91°C) and stirring time (5–25 sec) for producing soft tofu on a small pilot scale. Neither brittleness nor elasticity of the top part of tofu were influenced significantly by any factors. Yield was affected (p < 0.05) by soymilk solids content and coagulant concentration. Solids and protein content of tofu were affected (p < 0.05) by 3 factors except mixing temperature. Solids content of soy milk was the most important factor affecting texture. Optimum combinations were soymilk solids 11.8 to 12.3 °Brix, coagulant 0.27 to 0.32%, mixing temperatures 85 to 91°C, and stirring times 5 to 11.3 sec.     

Statistical and Kinetic Studies of the Changes in Soybean Quality during Storage as Related to Soymilk and Tofu Making

ABSTRACT:  The objective of this study was to develop statistical equations and kinetic models to describe the changes of soybean quality during storage. Significant correlations ( P  < 0.0001) were found among most of quality attributes including color parameters (Hunter L , a , b , and Δ E ), solid extractability (as expressed by soymilk solids content), soymilk pH and protein content, tofu yield, hardness, and protein content. Regressed linear equations were developed between color indices ( L/L ₀, ΔE ) and soymilk/tofu making properties. Empirical equations were developed to relate soybean color indices ( L/L ₀, ΔE ) and storage conditions including variables of initial moisture content (MC), relative humidity (RH), temperature ( T ), and duration ( t ). Kinetics of the changes in soybean color and extractability during storage at 70% RH and 22 to 40 °C were investigated. The kinetics was well described by zero-order kinetics. The Arrhenius equation adequately described the temperature dependence of the reaction rate constants for all parameters, from which the activation energies and rate constant were obtained. The equations developed in this study provided simple methods to monitor soybean quality and predict quality changes of soybeans during storage at various conditions.     

The Role of Composition and Content of Protein Particles in Soymilk on Tofu Curding by Glucono-δ-lactone or Calcium Sulfate

ABSTRACT: The effects of composition and content of protein particles on tofu curding were investigated by using soymilk prepared from mixtures of glycinin-rich and β-conglycinin-rich soybeans. The breaking stress of tofu curds increased with the increase of protein particle content in soymilk. The soymilk from glycinin-rich soybeans had a high protein particle content and formed harder tofu curds. There is a significant positive correlation between the content of protein particles and the breaking stress of tofu curds. It is suggested that the increase of the quantity of protein particles reinforces the combination among protein particles during the tofu curding, thus forming a stronger network of tofu curds.     

高效液相色谱法检测豆干中的尼泊金酯

建立用高效液相色谱—二极管阵列检测器进行豆干中尼泊金酯的检测方法。豆干样品经过无水乙醇提取分离后,用0.45μm滤膜过滤进样,外标法定量。     

Content composition and antioxidant activity of isoflavones in commercial and homemade soymilk and tofu

BACKGROUND: Isoflavones, found in soymilk and tofu, are one of the phytochemicals in soy‐based products that may promote good health. Homemade tofu and various homemade soymilk samples were made using different soaking, grinding, and cooking methods. The homemade samples were compared to commercial tofu and soymilk for total isoflavone content and composition as well as their antioxidant capacity. All samples were freeze‐dried and extracted with a 58% acetonitrile solution which was subsequently used to determine the isoflavone content by reverse‐phase high‐performance liquid chromatography. The antioxidant activity of extracts was determined using a modified 2,2‐azino‐bis‐(3‐ethylbenzthiazoline‐6‐sulfonic acid) method and total antioxidant capacity was reported as ascorbic acid equivalents. RESULTS: The total isoflavone, aglycone, and antioxidant levels were significantly higher in homemade soymilk and tofu (1571 µg) than in commercial samples. Homemade soymilk made by the extended boiling method yielded the highest total isoflavone (2567 µg) and glucoside (1525 µg) content. A strong positive correlation was observed between the total isoflavone, aglycone conjugates, and genistein series concentration and antioxidant capacity of soymilk. CONCLUSION: Increased moist heating time yielded the highest concentration of total isoflavones as well as aglycone conjugates and the genistein series. Increasing the duration of boiling can increase the isoflavone content of both homemade and commercial soymilk and tofu. Copyright © 2007 Society of Chemical Industry     

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.     

冻豆腐的规模化生产工艺

冻豆腐是中国传统食品,具有丰富的营养和特殊的口感。文中主要研究了冻豆腐的生产工艺,并对部分关键工艺进行了比较和选择。实验得出的最佳生产条件为:-10℃下冷冻3 h,然后在-3℃下熟化21 d。     

Bioavailability of Calcium from Tofu as Compared with Milk in Premenopausal Women

ABSTRACT: Using a cross-over design, two studies were conducted to measure calcium absorption from calcium-set tofu compared to milk in healthy, premenopausal women. In "study 1," calcium absorption from tofu set with CaCl₂ was determined in Caucasian women by fecal recovery of the stable isotope, 44Ca. In "study 2," calcium absorption was determined in Asian women from tofu set with CaSO₄ by appearance of 45Ca in serum after 5 h. Analysis of the studies, both separately and pooled, showed that calcium absorption was similar between calcium-set tofu and milk. Calcium-set tofu is a concentrated source of bioavailable calcium.     

基于电导率快速测定豆类细胞破壁率方法的研究

为了建立一种通过电导率,能够快速准确检测豆类细胞破壁率的方法。通过测定不同处理程度的四种豆子的蛋白含量、电导率,考察了四种豆子水溶性蛋白释放量与电导率之间的关系。研究了豆浆用量、外渗时间、测定温度对破壁率的影响。利用建立的评价方法,分别测定了四种常见豆子在破壁料理机豆浆程序下的破壁率。结果表明:四种豆子破壁过程中水溶性蛋白的释放量与电导率相关性较高(R2≥0.8995),豆浆用量和外渗时间对于破壁率的测定结果影响不显著(p0.05),测定温度对于破壁率的影响非常显著(p0.01),测定温度在25℃左右时破壁率的测定结果较为稳定。四种豆子在新型破壁料理机豆浆程序下的破壁率达到90%左右。结论,利用电导率快速评价豆类细胞破壁率的方法,具有一定的可行性。     

酸浆豆腐冷藏期间的品质变化分析

为探究酸浆豆腐在低温贮藏条件下品质及风味成分变化规律,测定分析了4℃冷藏期间酸浆豆腐的p H值、感官特性、质构特性和主要风味成分含量变化情况。结果表明,冷藏期间,酸浆豆腐p H值保持相对稳定,从第1 d的6.03±0.09变为第7 d的5.73±0.02,但感官评分呈逐渐下降趋势;硬度和咀嚼性在前3 d呈显著增加趋势(p0.05),在第3 d达到峰值,分别为8.15 N和6.28 N,随后开始下降。通过顶空气相离子迁移谱技术(HS-GC-IMS)共定性出30种挥发性组分,其中冷藏初期以酯、醇类化合物为主,冷藏中期以醛、酮、醇与酸类化合物为主,冷藏后期以醛类、醇、含硫类化合物为主。随着冷藏期间的延长,酸浆豆腐中乙酸乙酯与乙酸丙酯等香气组分含量降低,己醛、1-辛烯-3-醇与二甲基三硫等不良香气组分含量增加。因此,酸浆豆腐质构和风味成分的变化是导致感官分值下降的主要原因,结合酸浆豆腐的品质与风味分析,在4℃条件下,未添加防腐剂的酸浆豆腐货架期为5 d,货架期内酸浆豆腐食用安全且保持良好的口感风味。     

利用3种凝固剂制作新鲜软质大豆干酪的工艺研究

以豆乳为原料,分别以葡萄糖酸内酯、氯化镁和木瓜蛋白酶为凝固剂制作新鲜软质大豆干酪。用正交试验法对发酵剂、凝固剂及食盐的添加量等参数进行优化,并将3种大豆干酪的主要理化指标及感官与牛奶新鲜软质干酪进行比较。结果表明,以葡萄糖酸内酯为凝固剂制备新鲜软质大豆干酪的最适工艺参数为发酵剂添加量0.020%、葡萄糖酸内酯添加量0.20%、食盐添加量1.0%;氯化镁为凝固剂的最适工艺参数为发酵剂添加量0.020%、氯化镁添加量0.20%、食盐添加量1.0%;木瓜蛋白酶为凝固剂的最适工艺参数为发酵剂添加量0.010%、CaCl2添加量0.02%、木瓜蛋白酶添加量0.05%、食盐添加量1.0%。3种大豆干酪的水分含量相近,木瓜蛋白酶大豆干酪感官得分最高,氯化镁大豆干酪的蛋白含量最高,而葡萄糖酸内酯大豆干酪的产率最高。与相同工艺下制作出的牛乳新鲜软质干酪相比,新鲜软质大豆干酪蛋白质含量与之相近,脂肪含量只有牛乳干酪的1/3,水分含量和出品率高于牛乳干酪,而感官评分上大豆干酪略低。新鲜软质大豆干酪可作为一种牛乳新鲜软质干酪的低脂保健型替代品。     

细菌纤维素在传统豆腐中的应用

目的：改善传统豆腐中纤维素含量及豆腐品质。方法：将细菌纤维素作为一种膳食纤维应用到传统豆腐加工中,研究其对传统豆腐凝胶强度、保水性、感官等品质特性的影响。结果：当细菌纤维素添加量为3.0g/100mL时,豆腐品质特性较好。豆腐凝胶强度为181g,失水率为17.2%,与未添加细菌纤维素豆腐样品相比,凝胶强度无显著变化,但失水率降低了9.5%。结论：添加细菌纤维素的豆腐质地细腻光滑,有弹性,无明显粗糙感,其膳食纤维含量得到进一步强化。