Effect of different process parameters on the quality of soymilk and tofu from sprouted soybean

Assessment of soy genotype and processing method on trypsin inhibitors, urease and lectins content of tofu

Tofu has a high nutritional value, but it may also contain components that may have an antinutritional effect, such as trypsin inhibitors (TI), lectins and ureases. The aim of this study was to investigate the influence of the hydrothermal-cooking process of soybean in combination with commercial chymosin-pepsin rennet on the content and activity of TI, urease and lectins in tofu. High total TI content was found in tofu (5.00-16.87%). In addition, Kunitz (KTI = 3.52-4.32%) and Bowman-Birk (BBI = 5.00-12.53%) TI were registered, and BBI was detected in polymeric (1.38-2.71%) and monomeric (3.42-9.82%) forms. TI activity of tofu was very low (5.86-9.34%), corresponding to the very low activity of urease (0.51-3.07%). The percentage of lectin (2.62-4.63%) and urease (0.03-0.12%) in tofu was low. The results showed that the applied tofu production process is very effective in reducing the content and activity of TI, urease and lectin and provides the values without nutritional harmful effect.

Quality evaluation of egg-free cake from soft tofu

Soft tofu was used to produce a cake to ascertain its suitability in producing egg-free cake (EFC) for vegans and individuals allergic to eggs. A conventional cake (CVC) served as control and the quality characteristics of the EFC and CVC were evaluated. Results showed the egg-free cake had physical properties which were significantly (p < 0.05) higher in weight (1611 g), density (0.81 kg/m3) and specific volume (1.23%) than Conventional cake (1516 g, 0.61 kg/m3 and 0.25%, respectively). CVC showed significantly p < 0.05 higher height (8.50 cm) and volume (2644.78 m3) which is desirable in the baked cake. EFC showed significantly p < 0.05 higher values in ash (3.13%), moisture (24.01%), fibre (2.40%) and carbohydrate (52.34%), while CVC had significant (p < 0.05) higher values in protein (7.38%) and fat (16.34%). The taste (0.55), colour (0.55), texture (0.55) and aroma (0.55) of EFC was more preferred than CVC (0.45, 0.40, 0.45 and 0.45, respectively). Soft tofu showed suitability and an acceptable replacement for egg in making Egg-free cakes for vegetarians and individuals allergic to egg.

Effects of sprouting of soybean on the anti-nutritional, nutritional, textural and sensory quality of tofu

Soybean (Glycine max) is a superior plant food known as the miracle golden bean due to its treasure trove of inexpensive and superior protein to high-priced meat protein. Tofu is typically thought of as a salt or acid-coagulated water-based gel containing soy lipids and proteins trapped within its gel networks. Sprouted tofu is easier to digest and contains more nutrients than regular tofu. The purpose of this study was to evaluate the nutritional and sensory quality of tofu. The study was concerned with the preparation of tofu from non-germinated and germinated soybeans of 0 (T₀), 2 (T₁), 4 (T₂) and 6 (T₃) days. The length of the radicle was 0.8, 1.5, and 2 inches for T₁, T₂, and T₃, respectively. Lipoxygenase activity, phytate inhibitory activity, urease activity, trypsin inhibitory activity, protein solubility, nutritional, and sensory quality of prepared tofu were all assessed. Longer sprouting times reduced phytate, urease, trypsin, and lipoxygenase activity while increasing protein solubility. Tofu prepared from T₃ showed significantly better physicochemical properties than others. Protein, ash, and fat contents were significantly higher in T₃. The level of nutrient content for tofu samples was in the rank of T₃>T₂>T₁>T₀. The L∗, a∗ and b∗ values were followed the same ranked as nutrient content (T₃>T₂>T₁>T₀). Sensory characteristics indicated that T₃ was significantly more acceptable to the panelist. This study concludes that tofu made from 6 day sprouted soybeans with a height of 2 inches can be a good source of nutrition for consumers.

The Comprehensive Utilization of Bean Dregs in High-Fiber Tofu

A large quantity of bean dregs is produced by the production of tofu and treated as animal feed or plant fertilizer, which could cause environmental pollution. The purpose of this study was to use commercially available lactone tofu to compare the effects of innovative preparation methods of high-fiber tofu, where the innovative methods used partial de-slagging followed by the addition of soybean residue cellulose to prepare high-fiber tofu. The results showed that there were no significant differences among lactone tofu samples made with 5% cellulose, 10% cellulose, or 15% cellulose and the commercially available lactone tofu during the water-holding capacity and chroma analysis. Texture indices showed that lactone tofu with 10% cellulose was similar to the commercially available lactone tofu in chewiness and hardness, and lactone tofu with 15% cellulose was similar to the commercially available lactone tofu in adhesiveness and chewiness. Magnetic resonance imaging displayed that lactone tofu with 10% cellulose had better water retention and higher moisture content. Gel electron microscopy showed that lactone tofu with 10% cellulose achieved a better gel network, and the bean dreg cellulose had less influence to a certain extent. Volatile organic compound testing by GC-IMS method indicated that the lactone tofu with 10% cellulose had more volatile organic compound content. In conclusion, these results demonstrated that lactone tofu with 10% cellulose had the best market competitiveness in ensuring the quality of high-fiber tofu.

Effect of the heating process on the physicochemical characteristics and nutritional properties of whole cotyledon soymilk and tofu

This study focused on the effect of the heating process on the whole cotyledon soymilk and tofu. Whole cotyledon soymilk was made from soybean cotyledon and processed by enzymatic hydrolysis using cellulase and high-pressure homogeneity. In this study, a one-step heating method was selected for the cooking process of whole cotyledon soybean milk, and the whole cotyledon soybean milk was heated to 90 °C and held for 4 min. Results showed that the protein, total saccharides and dietary fiber content of the whole cotyledon soymilk were higher than those of the tradition soymilk due to the existence of bean dregs (okara). Both protein aggregation and protein-polysaccharide interaction were observed during the heating process. We also found a change in soymilk physicochemical characteristics such as particle size distribution, viscosity, surface hydrophobicity and soluble protein during the heating process. The results in this study showed that compared with traditional tofu, the phytic acid and trypsin inhibitor content in whole cotyledon tofu was lower, so its protein had higher digestibility in vitro. In conclusion, whole cotyledon tofu had better health properties and application prospects.

Tailoring Physical and Sensory Properties of Tofu by the Addition of Jet-Milled, Superfine, Defatted Soybean Flour

The use of defatted soybean flour (DSF) in food as a source of dietary fiber has been limited due to its rough texture and bitter taste. Our previous work indicates that superfine DSF prepared by jet milling could overcome these problems, as it positively affected physical and sensory properties. Therefore, differently sized DSFs were incorporated in tofu, and their impacts on physical and sensory properties were investigated in this study. Coarse DSF (Dv₅₀ = 341.0 µm), fine DSF (Dv₅₀ = 105.3 µm), and superfine DSF (Dv₅₀ = 5.1 µm) were prepared by conventional sifting and jet milling. Tofu was made with a 5% addition of differently sized DSFs and without DSF (control tofu). The quality of tofu was evaluated by scanning electron microscopy, color measurement, texture profile analysis, and quantitative descriptive analysis. The tofu made with coarse and fine DSF showed negative changes in its physical and organoleptic qualities, such as reduced yields, a less pure color, a harder texture, and a rougher mouthfeel. However, the tofu made with superfine DSF showed only minimal changes in its qualities compared to the control. Therefore, superfine DSF is a promising fiber supplement that does not change the physical and sensory properties in the making of high-quality tofu.

Research progress in tofu processing: From raw materials to processing conditions

As a traditional soybean product with good quality and a healthy food with many functional components, tofu is increasingly consumed in people's daily life. Traditional tofu processing consists of numerous steps, including the soaking and grinding of soybean seeds, heating of the soybean slurry, filtering, and addition of coagulants, and others. The properties of soybean seeds, processing scale, soaking and heating conditions, type and concentration of coagulant, and other factors collectively impact the processing steps and the final tofu quality. The generation of whole soybean tofu with more nutritive value comparing with traditional tofu has been successfully reported by several studies. As one of the most important functional component, isoflavones and their presence in tofu are also influenced by the above-mentioned factors, which influence the nutritive value of tofu. Research investigating the influence of tofu processing conditions on the quality and isoflavone profiles of tofu are the subject of this review. Issues that should be further studied to investigate the influence of processing conditions on the quality and nutritive value of tofu are also introduced.

Effect of composition and storage time on some physico-chemical and rheological properties of probiotic soy-cheese spread

Probiotic soy-cheese spread was prepared by fermenting soymilk with specific probiotic starter culture, and there after processing the coagulated mass. Soy cheese spread samples had more than 109 cfu/g of viable probiotic count at the time of preparation; and had around 17.6% protein, 25.3% fat and 19.8% total soluble sugar. Compared to commercially available dairy cheese spread, probiotic soy cheese spread had significantly higher protein and anti-oxidant activity. Soy cheese spreads, prepared from pure soymilk as well as by mixing with dairy milk, were studied with respect to the differences in their rheological behavior during storage at refrigerated conditions. A dynamic oscillatory test was used to measure the viscoelastic properties of spreads at 0, 7, 14, 21 and 28 days of storage. It was observed that the storage modulus (G') was higher than the loss modulus (G″) throughout the storage period indicating that the soy cheese spreads exhibit predominantly elastic behavior. The cheese spread sample prepared by adding okara in soymilk had the highest values of G' and complex viscosity (1120 Pa and 11.5 Pa s, respectively at an angular frequency of 100 s-1). G', G″ and viscosity of cheese spread did not change significantly up to 14 days, with values of 650, 225 Pa and 7.43 Pa s, respectively for the sample prepared from soymilk alone. However, these values increased thereafter which might be an indication of structural changes in the cheese spread samples.

Comparison of Conventional and Microwave Treatment on Soymilk for Inactivation of Trypsin Inhibitors and In Vitro Protein Digestibility

Soymilk is lower in calories compared to cow’s milk, since it is derived from a plant source (no cholesterol) and is an excellent source of protein. Despite the beneficial factors, soymilk is considered as one of the most controversial foods in the world. It contains serine protease inhibitors which lower its nutritional value and digestibility. Processing techniques for the elimination of trypsin inhibitors and lipoxygenase, which have shorter processing time and lower production costs are required for the large-scale manufacturing of soymilk. In this study, the suitable conditions of time and temperature are optimized during microwave processing to obtain soymilk with maximum digestibility with inactivation of trypsin inhibitors, in comparison to the conventional thermal treatment. The microwave processing conditions at a frequency of 2.45 GHz and temperatures of 70 °C, 85 °C and 100 °C for 2, 5 and 8 min were investigated and were compared to conventional thermal treatments at the same temperature for 10, 20 and 30 min. Response surface methodology is used to design and optimize the experimental conditions. Thermal processing was able to increase digestibility by 7% (microwave) and 11% (conventional) compared to control, while trypsin inhibitor activity reduced to 1% in microwave processing and 3% in conventional thermal treatment when compared to 10% in raw soybean.

How well do plant based alternatives fare nutritionally compared to cow's milk?

Due to the issues like lactose intolerance and milk allergy arising from the consumption of cow's milk, there has been an increased demand in the plant based alternative milks around the world. Food industry has addressed these demands by introducing various milk beverages which are promoted as alternatives coming from plant sources which include almond milk and soy milk. Though they are popularly advertised as healthy and wholesome, little research has been done in understanding the nutritional implications of consuming these milk beverages in short term and long term. Further, consumers associate these alternatives to be a direct substitute of cow's milk which might not be true in all cases. This review tries to address the issue by outlining the differences between cow's milk and commercially available alternative milks in terms of their nutrient content. Though various plant based alternate milks have been studied, only the four most consumed milk beverages are presented in this review which are consumed widely around the world. A complete nutritional outline and the corresponding health benefits of consuming these plant based milk beverages have been discussed in detail which could help the consumers make an informed decision.