加工方法对冷冻豆腐品质特性影响的研究

针对冷冻豆腐耐煮性差,影响食用口感,极大限制其产业化进程。鉴于此,分别研究卤水含量、点脑温度、压制质量对冷冻豆腐的出品量、持水性、复水性、耐煮性以及复水后口感的影响。通过对冷冻豆腐复水后的感官分析,得出当卤水添加量0.7%、点脑温度80℃、压制质量700g时,其状态口感最好。通过扫描电子显微镜观察到各工艺条件下复水冷冻豆腐表面结构,可以看出卤水量越多,点脑温度越高,压制质量越大,豆腐结构越致密。     

不同添加剂对冷冻豆腐结构特性影响研究

在豆浆中添加酪蛋白酸钠、大豆分离蛋白、卡拉胶,木薯改性淀粉、明胶等添加剂,探究不同添加剂对冻豆腐感官指标、质构特性及耐煮性的影响。质构结果表明,不同添加剂对冷冻豆腐复水后的物理结构有显著影响,有较好弹性;耐煮性测定结果表明,加入添加剂的冷冻豆腐耐煮性增强,且豆腐结构不易改变;扫描电镜结果表明,冷冻豆腐复水后的空间结构变得更加致密,其孔径较传统冷冻豆腐更小。各添加剂对冻豆腐质构特性及耐煮性都有优化作用。通过SPSS分析得出豆腐质构特性正显著相关于耐煮性,并经过扫描电镜分析各添加剂最好添加量的冻豆腐,通过孔径大小观察得出最好添加剂为大豆分离蛋白,添加量为0.7%,试验采用不同添加剂结合传统工艺能制得品质优良的冻豆腐,为冻豆腐的研究提供理论依据。     

无凝固剂发酵豆腐生产工艺的初探

在不添加任何凝固剂的情况下,利用豆腐酸浆中筛选得到的优势乳酸菌直接发酵豆浆制作豆腐,通过发酵豆浆pH及二次加热温度、时间对豆腐凝胶强度及出品率的影响研究,同时采用感官评定的方法比较乳酸菌豆腐及普通卤水豆腐综合感官,探讨乳酸菌发酵豆腐的生产工艺。结果表明:发酵豆浆的pH及其二次加热温度、时间是乳酸菌发酵豆腐制作的关键因素,当发酵豆浆pH为5.8~6.0,二次加热温度、时间为95℃、5min所制得的豆腐出品率较高,质构软硬适宜。同时,通过感官评定方法比较得出,乳酸菌发酵豆腐无明显酸味,与普通卤水豆腐综合感官评分无明显差异,可以被消费者接受。     

不同收储条件对粳稻南粳5055储藏品质的影响

通过定时检测七个月储藏期的南粳5055含水率、脂肪酸值、发芽率及表面颜色等理化指标,分析收获时间和储藏温度及时间三个因素对南粳5055储藏品质的影响。结果表明,收获时间与储藏温度及时间都对储藏过程中的粳稻含水率及脂肪酸值等重要指标有极显著影响(P0.01),但收获时间对其发芽率影响不显著(P 0.05);收获时间、储藏温度及时间与粳稻表面颜色具有较高关联性。不同温度下储藏的粳稻脂肪酸值变化符合化学反应一级动力学模型,比较不同收获时间的南粳5055脂肪酸值增加的活化能(E_α)发现,抽穗后42～66 d收获的粳稻中48、54 d收获的粳稻反应活化能较高。研究表明,除储藏温度和时间外,收获时间也对南粳5055储藏品质有重要的影响。     

收获时间、储藏温度及时间对粳稻南粳5055储藏品质的影响

通过定时检测七个月储藏期的南粳5055含水率、脂肪酸值、发芽率及表面颜色等理化指标,分析收获时间和储藏温度及时间三个因素对南粳5055储藏品质的影响。结果表明,收获时间与储藏温度及时间都对储藏过程中的粳稻含水率及脂肪酸值等重要指标有极显著影响（P < 0.01）,但收获时间对其发芽率影响不显著（P > 0.05）;收获时间、储藏温度及时间与粳稻表面颜色具有较高关联性。不同温度下储藏的粳稻脂肪酸值变化符合化学反应一级动力学模型,比较不同收获时间的南粳5055脂肪酸值增加的活化能（Eα）发现,抽穗后42～66 d收获的粳稻中48、54 d收获的粳稻反应活化能较高。研究表明,除储藏温度和时间外,收获时间也对南粳5055储藏品质有重要的影响。     

烹饪方式对胡麻油不饱和脂肪酸的影响

通过设计不同温度下、不同加热时间、冷锅冷油及热锅冷油试验,分析其对胡麻油不饱和脂肪酸的影响。结果表明:不同加热温度、时间对胡麻油不饱和脂肪酸影响显著,随着加热温度的升高,不饱和脂肪酸含量有下降趋势,相同加热温度下时间越长,不饱和脂肪酸含量下降越快。冷锅冷油和热锅冷油的烹饪方式对胡麻油不饱和脂肪酸影响差异不显著,随着加热温度的升高,某未知物质有了显著升高,冷锅比热锅更容易生成该物质且变化明显。加热温度、加热时间与胡麻油不饱和脂肪酸呈负相关性。     

沙棘果汁点浆法生产营养豆腐的工艺研究

以沙棘果汁为凝固剂,研究果汁豆腐的点浆工艺条件。以感官评价、豆腐得率为考察指标,研究沙棘果汁添加量、蹲脑温度、压榨压力等因素对沙棘豆腐产品质量的影响,得到理想的沙棘豆腐工艺参数。确定最佳工艺参数为:沙棘果汁添加量45%、蹲脑温度70℃、压榨压力4 g/cm~2,与传统工艺制作的石膏豆腐相比,所得豆腐的营养价值显著提高,其中豆腐中维生素C含量由0增加为0.36%。     

牛油果取代黄油制作牛轧糖的工艺研究

对新鲜牛油果取代黄油制作牛轧糖的工艺参数中的电磁炉加热功率、加热时间和静置温度进行研究,通过单因素和响应面试验,以感官评分为指标得到最佳工艺条件:电磁炉加热功率270 W、加热时间11 min、静置温度19℃。运用简单描述分析法和偏好型检验法对牛油果牛轧糖与普通黄油牛轧糖的风味、质地和喜好性进行了比较。     

石膏豆腐凝胶特性的研究

豆腐凝胶特性与豆腐的品质和产率直接相关,豆腐凝胶特性与豆腐生产工艺参数相关性研究将为豆腐生产的标准化和自动化奠定理论基础。本研究从动态流变特性,质构特性和微观结构特征等方面对石膏豆腐的凝胶特性进行了表征,研究了硫酸钙含量和凝固温度对豆腐凝胶特性的影响。研究表明:在硫酸钙含量为20~50 m M时,豆腐凝胶均在85℃时获得最高的储能模量,并且凝胶过程符合一级反应动力学;在硫酸钙含量相同时,豆腐凝胶的硬度随温度的升高而升高。当硫酸钙含量为20 m M或30 m M时,豆腐凝胶网络细腻松散,且持水率都在85℃时达到最高值;随着温度升高,豆腐凝胶的弹性升高,凝胶网络变粗厚且网孔增大。当硫酸钙含量为40 m M或50 m M时,豆腐凝胶网络粗厚缜密,持水率分别在80℃和75℃时达到最高值;随着温度升高,豆腐凝胶弹性降低,孔隙增大且呈现不规则形貌。     

绿色豆腐的加工工艺优化及储藏周期影响因子研究

豆腐是我国的传统食品，豆腐的加工工艺简单，富含蛋白质且方便食用，深受国内外消费者的喜爱。随着消费者消费水平的逐渐提高，人们对食品的营养有了更高的需求，豆腐除了具有较好的风味以外，也需要更加丰富的营养物质。该研究基于此，采用单因素试验和响应面法，对绿色豆腐的加工工艺进行了研究。研究结果表明，绿色豆腐最佳的加工工艺为黄瓜汁添加量31%、GDL添加量0.2%和凝固温度82℃,此时绿色豆腐的感官评分为85分。此外，也对绿色豆腐的杀菌方式和储藏过程中理化性质的变化进行了研究，结果表明，采用巴氏杀菌法的绿色豆腐储藏期更长；采用巴氏杀菌法的同时加入保鲜剂，此时豆腐的储藏期为21 d。     

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.     

Effect of different coagulants on the isoflavone levels and physical properties of prepared firm tofu

The objective of this study was to understand the effect of different coagulants in their ability to retain isoflavones in prepared firm tofu. Harovinton beans were processed to obtain soymilk and a specific amount of this soymilk was coagulated using different types of coagulants for the preparation of tofu. A reversed phase high performance liquid chromatographic method was used for determining the concentration of isoflavones in tofu and whey. Quality parameters such as the texture, color and moisture of tofu, prepared from different coagulants were also determined in this study. Tofus coagulated with different coagulants were found to contain different amounts of isoflavones. Calcium sulfate was found to be the most suitable coagulant for tofu making in terms of its high yield, retention of maximum amount of isoflavones and in obtaining a firm, but not hard texture of tofu.     

Changes of soybean quality during storage as related to soymilk and tofu making

ABSTRACT:  Soybeans are stored and transported under various humidity and temperature conditions. Soymilk and tofu are two of the most important foods made from whole soybeans. The objective of this study was to investigate the influence of storage conditions on soybean quality as related to soymilk and tofu-making properties. Soybeans of 3 different genotypes (Proto, IA2032, and Vinton 81) were stored in varying conditions: temperature ranging from 4 to 50 °C, relative humidity from 55% to 80%, initial moisture content from 6% to14%, and storage time up to 15 mo depending upon storage conditions. The effects of different storage conditions on soybean color, solids and protein extractability, soymilk pH, tofu yield, tofu solids and protein contents, tofu color, and texture were investigated. While no significant changes occurred for the soybeans stored at 4 °C, the soybeans stored at high temperatures (30 to 50 °C) exhibited significant quality loss ( P < 0.05). The degradation of soybean lightness (Hunter L ), color difference (Δ E ), and solid extractability exhibited a linear relationship with time. Soak weight decreased at high temperature and relative humidity, but increased at mild storage conditions. Several combinations of storage conditions at temperatures exceeding 30 °C produced a drastic loss in tofu yield. Storage also affected the tofu making process by reducing optimum mixing time to produce the highest tofu yield. Varietal difference in soybean storability was observed. The results provided useful information for the soybean processing industry to store soybeans using the optimal storage conditions and to estimate soybean quality after storage.     

瓜尔豆胶与魔芋胶复配联合超声处理改善鸡血豆腐的品质

为研究鸡血豆腐加工过程中复配胶联合超声处理对其品质的影响,选择添加不同配比的瓜尔豆胶与阿拉伯胶复配或瓜尔豆胶与魔芋胶复配,通过鸡血豆腐出品率确定其加工过程中的最佳凝血时间、加热温度、加热时间、血水比及超声条件,并进一步对其保水性、色泽和质构特性进行综合分析。结果表明：添加4 g/L瓜尔豆胶与魔芋胶复配（复配比5∶5）、凝血12 min、血水体积比1∶2.5、超声功率90 W、超声时间3 min、加热温度90 ℃、加热40 min条件下制备的鸡血豆腐,4 ℃贮藏48 h时的出品率比不添加复配胶非超声组（CK1）提高了15.91%,色泽和质构均有显著提升（P＜0.05）,由此说明瓜尔豆胶与魔芋胶复配联合超声处理能明显改善鸡血豆腐的综合品质。     

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.     

豆腐中大豆异黄酮保留的实验研究

以黄豆为原料,分别以葡萄糖酸d-内酯、石膏和卤水为凝固剂点制成豆腐,比较其对豆腐中异黄酮含量的影响。同时,在石膏豆腐煮浆工序中分别加入适量的CMC、魔芋胶、果胶、明胶、b-环糊精与黄原胶、海藻酸钠等不同食用胶体,研究其对豆腐中异黄酮保留量的影响,以期制作出富含异黄酮的营养保健豆腐。     

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。     

PHYSICOCHEMICAL CHARACTERISTICS OF SOFT TOFU FORMULATED FROM SELECTED SOYBEAN VARIETIES1

Currently, hundreds of soybean varieties with a wide range of quality attributes are available. The majority of these soybean varieties have not been evaluated for their quality in soymilk and tofu. In this research, tofu was prepared using the hot ground method by coagulating soymilk from four soybean varieties (Macon, Saturn, OHIOFG1 and OHIOFG2) with calcium sulfate dihydrate. Soybean variety significantly affected yield, held water, color parameters, viscosity, storage modulus, and textural properties of tofu cakes. Soymilk with higher pH, viscosity, and protein produced tofu with higher protein, water held, and yield. Varietal differences should be considered in selecting soybeans for tofu production. Macon soybeans produced the best tofu with regards to quality attributes.     

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.     

STORAGE CONDITIONS AFFECT SOYBEAN COLOR, CHEMICAL COMPOSITION AND TOFU QUALITIES

Soybeans stored under four sets of conditions were analyzed for the changes in color, composition and their effects on yield and textural properties of tofu. Soybeans stored under the adverse conditions (84% relative humidity (RH), 30C) exhibited significant changes in tofu yield and textural quality as well as in color and total free sugar content with storage time. Significant correlations existed between soybean color and tofu yield within 6 months under the adverse storage conditions. Color changes may provide a rapid method for predicting soybean quality for making tofu after storage. Soybeans stored under mild (57% RH, 20C), cold (4C) and uncontrolled ambient conditions (garage) exhibited no significant changes in their color or composition except for moisture contents, and maintained good qualities for tofu making for up to 18 months.