Silken Tofu Research Articles

Formulasi Serbuk Wedang Tahu dan Pendugaan Umur Simpan Menggunakan Metode Kadar Air Kritis

Indonesia silken tofu dessert is a traditional dish made from silken tofu and ginger sauce. To enhance its shelf life, this study explored the development of silken tofu dessert into a powdered form. Traditionally, silken tofu is coagulated using calcium sulfate (CaSO₄), but there has been little research on the optimal concentration of CaSO₄ necessary for forming curd in powdered silken tofu comparable to the traditional version. This study aimed to identify the ideal concentration of CaSO₄ as a coagulant to be added to powdered silken tofu and to estimate its shelf life using the critical moisture method. Sensory testing was conducted to select the appropriate concentration of CaSO₄, comparing different levels to a control method. The results revealed significant differences between the powdered silken tofu dessert and the traditional counterpart. Among the three CaSO₄ concentrations tested (3, 5, and 7%), the dessert prepared with 3% CaSO₄ exhibited the closest resemblance to the traditional silken tofu dessert. A single serving of this powdered silken tofu dessert provides 125 kcal of total energy, accounting for 12% of the recommended daily allowance (RDA) for protein, 3% for total fat, and 6% for carbohydrates. When packaged in metallized plastic and stored at a relative humidity of 78% and a temperature of 30 °C, the shelf life of the powdered silken tofu dessert is extended up to 12 months.

MUSCULOSKELETAL DISORDERS RISK ASSESSMENT AMONG SMALL TOFU FACTORY WORKERS IN TANGERANG CITY: AN INDONESIAN CASE STUDY

Introduction: Conventional tofu production involves various manual handling tasks which increases the risk of musculoskeletal disorders (MSDs). A previous study found a very high risk of MSDs in tofu manufacturing, especially in the filtering task with a REBA score of 13. Aims: This study aims to evaluate the risk of MSDs in tofu factory workers. Methods: Workplace observations and unstructured interviews were conducted at two traditional tofu factories (X and Y) and a more modern silken tofu factory to identify the risk of MSDs. The Nordic Musculoskeletal Questionnaire and the Quick Exposure Check (QEC) method were used to determine the prevalence and risk of MSDs. A total of 52 workers voluntarily participated in this study. Results: The traditional and silken tofu manufacturing processes involved seven and fifteen tasks, respectively. This study found that workers in the traditional tofu factories had a higher prevalence of MSDs than those in the silken tofu factory. In the past 12 months, traditional tofu factory workers reported MSDs in their lower back (94.4%), right shoulder (77.8%), and neck (61.1%). On the other hand, silken tofu factory workers reported MSDs in their lower back (81.3%), right shoulder (62.5%), and upper back region (56.3%). According to the QEC method, grinding and filtering were identified as two tasks with a very high risk of MSDs in the traditional factories. In addition, transferring tofu crates from cold water to hot water tub in the silken factory was identified as a very high risk of MSDs. Conclusion: Intervention is necessary for tasks with a very high risk of MSDs in small tofu factories.

Realization of Stable Grasping of Silken Tofu by An Electric Prosthetic Hand Equipped with Soft Pressure Sensors at The Fingertips

Realization of Stable Grasping of Silken Tofu by An Electric Prosthetic Hand Equipped with Soft Pressure Sensors at The Fingertips

Divalent magnesium cation concentrations determine the formation of tofu-like precipitates with differing urea solubilities

Different coagulant concentrations can induce urea-soluble precipitates (USPs) and urea-insoluble precipitates (UIPs) during tofu-like precipitate formation. In this study, MgCl2 concentration-dependent changes in USPs were quantified using a method based on urea solubility differences in order to investigate the factors affecting USP versus UIP formation. The addition of various Mg salts revealed that anions influence the solubility of proteins in both USPs and UIPs. Moreover, addition of MgCl2/NaCl mixtures, in which the Cl− concentration was held constant, demonstrated that Mg2+ was essential for UIP formation but not for USP formation and that Cl− was inconsequential for both USP and UIP formation. NaCl addition showed that the driving force for USP formation was salting-out due to the presence of cations. Overall, our data indicated that the Mg2+ concentration determined the separation of USPs and UIPs. These results will help elucidate the molecular mechanisms mediating the separation of silken tofu and regular tofu.

義手指先力覚の提示による電動義手での豆腐把持の実現

Our objective is to develop soft pressure sensors to control the electric arm prosthesis by measuring the movement of muscles for the control signals instead of EMG. In our previous research, we installed soft pressure sensors in the fingertips of the prosthetic hand for the soft object grasping function. As a result, it had become possible to stably grip without crushing those soft objects such as silken tofu in the prosthetic hand. In this study, we try to develope operability of electric arm. In the previous method, gripping power was controlled by computer automatically. This method, however, could not give the feeling of the gripping force to the user. Therefore, we developed a gripping force teaching mechanism to the user. Furthermore, we investigated the relationship between the force presented by the teaching mechanism and the fingertip sensor value when grasping the soft object by the electric arm in order to give the appropriate feeling for the user to control the grasping force. By using the gripping force teaching mechanism, the user was finally able to control the grasping force and the tester succeeded to pick up a piece of silken tofu by prosthetic hand.

Essential amino acids profile of differentially processed soy products and their efficiency in meeting daily requirement

Purpose – In the backdrop of declining per capita availability of pulses, soybean is the alternate source to address protein deficiency in India. The study aims to assess the efficiency of soy products available in the market for meeting the daily requirement of essential amino acids (EAAs). Design/methodology/approach – Extruded soy products, namely, soy nuggets, granules, soy flour manufactured from sprouts, spray-dried soy milk variants, ready-to-drink (RTD) soy beverage and silken tofu, were analysed for EAAs by high-performance liquid chromatography. In addition, efficiency of these products in terms of meeting the daily requirement of EAAs for an adult weighing 70 kg through a single serving (equivalent to 6 g protein) was also computed. Findings – Leucine was the most concentrated EAA in all the soy products, except in variants of soy milk. Total essential amino acids’ (TEAAs) content in soy flour was significantly higher compared to soy nuggets and granules. Spray-dried plain soymilk exhibited a significantly higher level of TEAAs content compared to flavoured variant and RTD soy beverage. Among all the products, silken tofu exhibited the highest concentration of TEAAs. RTD soy beverage was the most efficient product for meeting the daily requirement of isoleucine and valine, soy flour for aromatic amino acids and silken tofu for lysine and leucine. Originality/value – This work pertains to the determination of EAAs of commercial soy products and assesses their efficiency in terms of meeting the daily requirement of EAAs. This type of technical evaluation of soy products has not been conducted earlier.

軟体型圧力センサによる電動義手の駆動

Our objective is to develop soft pressure sensors to control the electric arm prosthesis by measuring the movement of muscles for the control signals instead of EMG. In our previous research, we made refined sensors that has black inner sidewall white inner ceiling at the topside. By using this refined sensor, we succeeded match better controllability of the finger opening speed and finger grasping force. Furthermore, we made a wrist-unit to give a rotational function of hand and drove it by the additional pressure sensors to measure the movement of the ulna and radius. In this study, we tried to install a soft grasping function by monitoring the electric current of the finger driving motor. After the experiment, we knew that the sensitivity is not so good by this current monitoring method. We succeeded to pick up a piece of firm tofu by the arm prosthesis but we could not pick up silken tofu. An over-pushing motion was also necessary to detect the softness by this function. Therefore, we decided to install soft sensors in the fingertips for the refinement of the soft object grasping function. As a result, it had become possible to stably grip without crushing those soft objects in the prosthetic hand. Furthermore, we succeeded in stable gripping the silken tofu. We also developed the pressure detection system around all lower limb surface to detect the suitable points for the control signals. We also demonstrated that we could estimate the wrist angle for the pronation-supination movements by two sensors and trained neural network. According to the estimation of palm flexion - dorsal flexion, the required sensor is only one.

Soybean Oil Volume Fraction Effects on the Rheology Characteristics and Gelation Behavior of Glucono‐δ‐Lactone and Calcium Sulfate‐Induced Tofu Gels

AbstractThe effects soybean oil volume fraction on the rheological characteristics and gelation behavior of acid and salt‐induced soft tofu‐type gels was investigated. High oil volume fraction resulted in lower gel point temperature and shorter gelation time (tgel) while G′ at the gel point increased as the oil volume fraction in the gels increased. A power law relationship tgel, gel point temperature and oil concentration was found and also the plot of G′ versus oil concentration fitted well in the model: G′∼CA. The exponent “A” was positive in salt‐induced gels but negative in acid‐induced gels. This gelation behavior trend was demonstrated by estimating the composite gel shear modulus, which showed that, in salt‐induced gels the stiffness of the oil droplets was higher than the one of the gel matrix while it was the opposite in acid‐induced gels. Furthermore, the weak gel model was used to analyze and describe the network extension and its strength.Practical ApplicationsIn this comparative study, soybean oil volume fraction effects on the rheological characteristics and gelation behavior of acid and salt‐induced soft tofu‐type gels was established. Different coagulation temperatures and coagulants were used. The study gives new insights on the protein‐to‐oil droplets interactions during gelation at different pHs in a tofu gel like product. The better understanding of the gelation mechanism, small and large scale deformations of soy protein gels with additional oil, is industrially relevant, as it will help in better process line design, monitoring and quality control which would potentially lead to the development of novel soy‐based and dairy free cheeses products. Additionally, the parameters and conditions used were closely related to the ones used during soft silken tofu making, therefore, ensuring the process implementation much easier.

Oral challenge tests for soybean allergies in Japan: A summary of 142 cases

BackgroundSoybeans are one of causative foods for infantile onset allergies in Japan. This study aimed to analyze the results of soybean challenge tests that were conducted over approximately 7 years at our institution. Using the test data, we sought to identify the responses and clinical profiles of patients with soybean allergies, and to investigate the relationship between the responses and soybean sensitization status. MethodsBetween July 2004 and May 2010, 142 cases (125 patients) underwent food challenge tests (100 g of silken tofu) for the diagnosis of soybean allergy or confirmation of their tolerance. The patients' characteristics, soybean sensitization status, and responses to the challenge tests were retrospectively evaluated. ResultsAmong the subjects who underwent the soybean challenge test, the male/female ratio was 1.6 (87/55), and the mean age at the test was 2.8 ± 1.7 years. The positive rate for the challenge test was 38.7%. Induced symptoms were observed in the skin (81.8%), respiratory system (50.9%), and gastrointestinal system/mucosal membrane/anaphylaxis (12.7%). Intramuscular epinephrine was administered to all 7 patients who experienced an anaphylactic reaction. The sensitivity, specificity, positive predictive value, negative predictive value, and diagnostic efficiency of soybean-specific IgE titers were low for predicting the responses to the challenge test. ConclusionsSoybean allergies were diagnosed in only 18% of the subjects with positive sensitization to soybeans. Therefore, soybean-specific IgE titers are not an effective predictor of a positive response to the challenge test.

Comparison of Two Small-Scale Processing Methods for Testing Silken Tofu Quality

In developing a simple, reliable, small-scale method to assess silken tofu quality in our soybean improvement program, we examined two processing methods and two coagulants, glucono-δ-lactone (GDL) or nigari (magnesium chloride) in two experiments. Silken tofu was prepared from a commercial soybean variety (expt 1) or seven soybean varieties (V1–V7) which were grown and harvested together (expt 2). The soybeans were soaked overnight (the soak method, with 55 g soybeans) or ground dry first (the dry method, with 60 g soybeans) before processing. The quality of the silken tofu was evaluated and compared among varieties and coagulant-processing methods and their interactions. Moisture and protein content in soymilk and soybean seeds, soymilk yield and protein and solid recovery in soymilk were determined. Compared with the dry method, the soak method allowed faster soymilk extraction, produced soymilk with lower solid and higher protein content and firmer silken tofu with either GDL or nigari as coagulant. Depending on whether nigari or GDL was used as coagulant, the soak method also produced silken tofu with the highest or the lowest water loss which correlated strongly and negatively with tofu hardness (r = −0.93***). Differences were detected among varieties for the key quality attributes. Taken together, the soak method with GDL as coagulant would be the preferred combination to use to assess tofu quality.

Pre-treatment of Soy Slurry with Viscozyme L and the Concentration of Sugars and Isoflavones and the Microstructure of Silken Tofu

Silken tofu which retains soluble solids present in the soymilk was investigated for differences in the microstructure, sugars and isoflavones content from regular silken. Soy slurry treated with Viscozyme L (2.5 mL/L) was incubated for 30 minutes at 55°C. Stachyose was the predominant oligosaccharide in treated tofu, 4.58 g/100 g and 3.30 g/100 g in control tofu, raffinose content was 1.21 and 0.75 g/100 g in treated and control tofu, respectively. Glucose was approximately duplicated in treated tofu (1.66 g/100 g) compared to control (0.74 g/100 g) while fructose content was three times higher (1.09 g/100 g). Comparing isoflavones content, malonyl conjugates were double the amount of the control tofu, with the exception of malonylgenistin, but the total amount of isoflavones was not different. The tofu of the treated slurry showed a fibrous three-dimensional network structure, but with larger protein aggregates and was more tightly connected than the control.

Influence of globulin subunit composition of soybean proteins on silken tofu quality. 1. Effect of growing location and 11SA4 and 7Sα’ deficiency

Growing location and genotypes are known to affect the subunit composition of the major storage proteins of soybeans, β-conglycinin (7S globulins) and glycinin (11S globulins), which have been associated with tofu quality. In this study, we examined 16 soybean genotypes grown at two locations in Queensland, Australia, for the influence of globulin subunit composition, growing location and genotype × growing location interaction on seed, soymilk and silken tofu properties. These genotypes comprised four groups: with all globulin subunits, without 11SA4, without 7Sα’, or without 11SA4 and 7Sα’. There were significant differences in the major protein subunits among the genotypes and the four groups and between locations. Significant genotypic and location differences were also observed in the properties of the seed, soymilk and silken tofu. There were no significant genotype × location interactions. The group without 11SA4 had less 11S and more 7S globulins, resulting in the lowest 11S/7S ratio. The silken tofu from this group had firmer texture and less water loss than the group containing all globulin subunits. The results suggested that genotypes of differing globulin subunit composition may produce tofu with different qualities and the effect of globulin subunit composition on tofu quality could be affected by growing location and the absence of certain globulin subunits.

Influence of globulin subunit composition of soybean proteins on silken tofu quality. 2. Absence of 11SA4 improves the effect of protein content on tofu hardness

Soybean variety Bunya was developed in Australia to provide a better quality bean for tofu manufacturers. It is null for globulin subunit 11SA4. We investigated the effect of both the Bunya genetic background and the11SA4 subunit on tofu properties using genotypes containing 11SA4, with and without Bunya parentage, or lacking 11SA4 with Bunya parentage. Both Bunya parentage and 11SA4 significantly influenced globulin subunit composition and tofu texture. The group lacking 11SA4 had lower seed protein content, the largest seeds and the highest 7S and the lowest 11S content and produced the hardest tofu. Examination of the impact of 11SA4 null on tofu texture at four protein contents (380–440 g kg–1) over four coagulant (2.0–3.5 g kg–1) levels revealed that the absence of 11SA4 produced firmer tofu across the protein and coagulation levels tested, and this difference was larger than that from higher protein or coagulation levels. These results demonstrated that the absence of the 11SA4 subunit could increase tofu hardness to a level that otherwise could only be achieved with much higher seed protein content.

Gelation Behavior and Rheological Properties of Salt‐ or Acid‐Induced Soy Proteins Soft Tofu‐Type Gels

AbstractOscillatory tests data were analyzed using the power law and the weak gel models. Acid‐induced gels had higher storage modulus (G′) than salt‐induced gels. During gelation, both moduli increased gradually but never reached a steady state, with G′ being higher than G″. Under applied parameters, salt‐induced gels made from soybean coagulated faster than the ones made from soy protein isolate (SPI). Syneresis rate in salt‐induced gels was significantly lower than in acid‐induced gels, with SPI acid‐induced gel having the highest rate (36.72%) and soybean salt‐induced gel having the lowest (14.77%). Furthermore, salt‐induced gels resulted in a reduction in shear deformation at fracture and an increase in the shear stress at yielding, whereas the shear stress at yielding was reduced and the shear deformation at fracture was increased in both acid‐induced gels. It was observed that gels made from soybean had a more uniform and denser network with smaller network pore size than the ones made from SPI.Practical ApplicationsThe coagulation effect of calcium sulfate and glucono‐δ‐lactone was established in this comparative study, and also the use of soybean and soy protein isolate in salt‐ or acid‐induced soft tofu‐type gels have shown the effects of other soybean constituents besides proteins on the rheological properties and gelling process. Therefore, a better understanding of the gelation mechanism, small‐ and large‐scale deformations of soy protein curd, is industrially relevant, as it will allow for better process design, monitoring and quality control, thus potentially lead to the development of novel soy‐based products. In addition, the parameters and conditions used were close to the ones used during soft silken tofu making, therefore making the process application easier.

Effects of soybean protein composition and processing conditions on silken tofu properties

Texture and water holding are important for silken tofu manufacturers and are affected by many factors, including soybean variety and processing conditions. In this study we evaluated these two key quality attributes of silken tofu produced from two soybean varieties - Bunya and Cowrie - using a soak or a dry processing method with glucono-δ-lactone or nigari as coagulant at concentrations of 1.5-5.0 g kg⁻¹. The soak method produced substantially firmer silken tofu with either coagulant. The optimum coagulant concentration to achieve maximum hardness was 2.5-3.0 g kg⁻¹. At 3.0 g kg⁻¹, Bunya produced silken tofu with firmer texture for each of the coagulant-method combinations and lower water loss, an indicator for water holding capacity, for the soak method. The two varieties differed significantly in the composition of major protein subunits for the seed and soymilk. Bunya had no 11SA4, less 11S and more 7S and therefore a lower 11S/7S ratio. Both variety and processing conditions affect textural properties and water loss of silken tofu. The absence of 11SA4 and subsequent protein subunit compositions are important in determining these two key quality attributes. Variety Bunya produces silken tofu with firmer texture and lower water loss.

Effect of inulin on the rheological properties of silken tofu coagulated with glucono-δ-lactone

This study investigated the rheological properties of inulin-containing silken tofu coagulated with glucono-δ-lactone (GDL) upon heating. Inulin (Raftiline ® HP-gel) was added to a soy protein isolate-enriched cooked soymilk at 0%, 1%, 2%, 3% and 4% (w/v) levels along with 0.4% (w/v) GDL to prepare acid-induced silken tofu. Gelation was induced by heating the soymilk mixture from 20 to 90 °C at a constant rate (1 °C/min) or isothermally at 90 °C for 30 min. The gelling properties were measured with dynamic small-deformation mechanical analysis and static large-deformation compression tests. The rheological changes in soymilk during gelation were dependent upon both the pH decline (hydrolysis of GDL) and the specific temperature of heating. Control samples heated to ∼50 °C, with the pH lowered to 5.95, started to gel, showing a rapid increase in storage ( G′) and loss ( G″) moduli afterwards. The addition of 2% inulin lowered the on-set gelling temperature by 2.8 °C and improved ( P < 0.05) both rheological parameters of the tofu gel as well as hardness and rupture force (textural profile analysis) of the formed silken tofu. The results indicated that inulin enhances the viscoelastic properties of GDL-coagulated silken tofu, and the textural effect of inulin is an added benefit to its current application mainly as a prebiotical ingredient in food.

Frozen Wild Blueberry‐Tofu‐Soymilk Desserts

ABSTRACTBoth wild (lowbush) blueberries (Vaccinium angustifolium Ait.) and soybeans (Glycine max L.) possess a variety of antioxidants, and both foods appear to have multiple health benefits. Our objectives were to identify whether wild blueberry juice concentrate was more acceptable than puree in frozen desserts with a soy milk‐tofu base; to determine whether fat‐free products were as acceptable as those with 10% added fat; and to compare several levels of blueberry juice concentrate. Four frozen dessert formulations were prepared in duplicate from soy milk, silken tofu, sucrose, stabilizer, BJC or puree, soybean oil or polydextrose, sweetened dried blueberries, salt, and lemon juice. Samples were assayed for total anthocyanins, antioxidant activity using the DPPH method, color, overrun, and solids. Fifty‐five persons evaluated the samples using a 9‐point hedonic scale for color, flavor, texture, and overall acceptability. Samples containing blueberry juice concentrate were darker and less blue. Anthocyanin levels were highest in the puree sample and the fat‐free product with 7.8% blueberry juice concentrate. However, antioxidant activity was highest (28 Trolox equivalents per gram) in the samples made with soybean oil and 7.4% blueberry juice concentrate. The puree formulation received higher hedonic scores than did the low‐fat blueberry juice concentrate formulations. The puree formulation received overall acceptability scores of like very much or like extremely by 45% of the consumers. These findings may aid processors in defining potential formulations that combine 2 healthful food ingredients.

Pengaruh Penambahan Kacang Tunggak (Vigna Unguiculata) dan Konsentrasi Bahan Penggumpal (CaSO4) pada Sifat-sifat Tahu Sutera yang Dihasilkan

Soft tofu or silken tofu was usually made from soy bean. In this study, soft tofu was made of soybean substituted with cowpea bean (Vigna unguiculata). Cowpea bean have more protein, close to soy bean protein. Our objectives were to determine the effect of substitute cowpea bean and concentration coagulant (CaSO4) on the characteristic of soft tofu.. Soft tofu was made of soybean substitute with cowpea bean. The ratio was 100 : 0, 90 :10, 80 : 20 and 70 : 30 respectively. CaSO4 was used as coagulant, the ratio of the coagulant to bean were 10g/kg, 12kg/kg and 14g/kg. Moisture content, yield, protein content and texture were determined. The sensory properties were evaluated with hedonic test. The limit ratio of cowpea bean to soybean was 20 : 80. The more cowpea bean, the soft tofu had bad characteristics, they were juicy, low protein and soft texture. Moisture content was not affected by coagulant concentration but protein content and the texture were affected Yield was not affected both, substitute cowpea bean and concentration coagulant. Soft tofu made of soy bean to cowpea bean 80 : 20, with concentration coagulant 12g/kg bean was preferred and the chemical composition were moisture content 78,41%, protein content 56,19% (db), yield 229% and texture 2,86 N. keyword : soft tofu, cowpea bean, coagulant

A Small Scale Method for the Production of Soymilk and Silken Tofu

Interest in traditional Asian foods such as tofu and soymilk has developed in the USA during the past few years. Lacking, however, is a small scale, rapid test that will permit plant breeders and food technologists to evaluate the potential of various soybean [(Glycine max L.(Merr)] cultivars and breeding lines to produce these foods. A procedure is described in which 80 g of ground soybean is used to make silken tofu. Glucono‐δ‐1actone serves as the coagulant in the procedure. The method results in tofu whose characteristics are reproducible among different preparations, and whose quality compares favorably with imported Japanese silken tofu that is available commercially in the USA. To evaluate the method, soymilk and tofu were made from 182 experimental, public, and private soybean cultivars grown in Indiana in 1990. Differences were observed among cultivars for soymilk yield, tofu whiteness, and texture (tofu fracturability and hardness). Significant correlations were found between soybean protein content, soymilk protein content, and tofu fracturability. The same correlations have previously been established in the literature based on comparisons of material made by traditional large scale manufacturing methods. A correlation between soymilk solids content and fracturability was also observed when the ratio of water used to process the ground soybean was varied. The small scale method will be useful to evaluate soybean lines from breeding programs.

Effect of traditional oriental soy products on iron absorption

The effect of a variety of traditional oriental unfermented and fermented soy products on iron absorption was evaluated in 242 Indian women. When compared with a soy-flour meal containing an equal amount of protein, iron absorption was found to be significantly improved with silken tofu, natto, tempeh, rice miso, barley miso, and soybean miso. This improvement could not be adequately explained except with reference to changes in the protein composition of the products. The protein fraction profiles of the soy products were obtained by size-exclusion high-performance liquid chromatography. An inverse relationship between food iron absorption and the high-molecular-weight fraction of the soy products was demonstrated (r = 0.66, p = 0.01). However, anomalous results obtained with three products (sufu, tempeh, and fully hydrolyzed isolated soy protein) did not make it possible to reach firm conclusions concerning the effect of the protein fraction of soy on iron bioavailability.