RESUMEN

Tofu quality is determined by a controlled coagulation process using a W/O/W emulsion coagulant. The impact of adding soy protein isolate (SPI) to the inner water phase on the stability of W/O/W high-internal-phase emulsions (HIPEs) and its application as a coagulant for tofu was assessed. No creaming occurred during 7-day storage with SPI concentrations up to 0.3%, while the emulsion droplets aggregated with 0.5% and 0.7% SPI. Emulsions containing 0.3% SPI maintained a constant mean droplet size after 21 days of storage and exhibited the lowest TURBISCAN stability index value. HIPE stability against freeze-thaw cycles improved after heating. HIPEs with SPI concentrations above 0.3% demonstrated an elastic gel-like behavior. The increased viscosity and aggregation of the protein around droplets indicated that the interaction among emulsion droplets could enhance stability. W/O/W HIPE coagulants significantly increased tofu yield, reduced hardness, and produced a more homogenous tofu gel compared to a MgCl2 solution. The HIPE with 0.3% SPI was found to be optimal for use as a coagulant for tofu.

RESUMEN

Mycoprotein is an alternative protein produced through fungal fermentation. However, it typically relies on refined glucose syrup derived from starch, which can be costly and unsustainable. This study investigates the potential of soybean processing by-products (okara and soy whey) as alternative substrates for producing mycoprotein using Aspergillus oryzae. A. oryzae was cultured for 7 days at 30 °C in diluted okara (1:50) and soy whey (1:1) with or without agitation (100 rpm). Soy whey produced higher biomass yields (369.2-408.8 mg dry biomass/g dry substrate), but had a lower biomass concentration (0.783-0.867 g dry weight/L). Conversely, okara produced a higher biomass concentration (2.02 g dry weight/L) with a yield of 114.7 mg dry biomass/g dry substrate. However, biomass formation in okara was only observed in static conditions, as agitation caused biomass to entangle with soy pulp, hampering its production. Additionally, okara tended to release protein into the media, while soy whey accumulated protein within the biomass, reaching up to 53% w/w protein content. The results of this study provide a promising approach to addressing both soybean processing waste reduction and food security concerns.

RESUMEN

A new style of tofu coagulated through the fermentation of Lactobacillus plantarum SJ-L-1 was produced. L. plantarum SJ-L-1 with a high growth rate and excellent acid production ability was isolated and identified from naturally fermented soy yellow whey. The gene annotation indicated the potential outstanding isoflavone conversion capacity of L. plantarum SJ-L-1. Furthermore, fermentation tofu was prepared using L. plantarum SJ-L-1 and Lactobacillus rhamnosus 1-16 as the starter microbiota. Compared to traditional MgCl2 tofu and fermented soy whey tofu, SJ-L-1 tofu exhibited a slight increase in hardness and better structure uniformity. SJ-L-1 tofu also possessed the highest levels of total isoflavone content (76.33 µg/g) and volatile compounds (561.54 µg/kg) among the four styles of tofu. This research indicated that this new type of tofu coagulated through a combination of heat and fermentation of L. plantarum SJ-L-1 represents a promising candidate for future functional foods.

RESUMEN

In this study, three different brands of commercially available marinated tofu were analyzed and compared with homemade products to explore the effect of key flavor substances on their sensory quality, sensory properties, texture characteristics, and volatile components. The texture characteristics and flavor substances of the three brands of commercially available marinated tofu were significantly different from those of homemade products. A total of 64 volatile components were identified by headspace-gas chromatography-ion mobility spectrometry (HS-GC-IMS), mainly including 11 hydrocarbons, 11 alcohols, 10 ketones, 15 aldehydes, 4 esters, 1 acid, and 12 other volatile substances. Among these, nine key flavor compounds (ROAV > 1, VIP > 1) were identified using the relative odor activity value (ROAV) combined with a partial least squares discriminant analysis (PLS-DA) and variable importance in projection, including α-Pinene, ß-Myrcene, α-Phellandrene, 1-Penten-3-one, Butanal, 3-Methyl butanal, acetic acid ethyl ester, 1,8-Cineol, and 2-Pentyl furan. The correlation heatmap showed that sensory evaluation was positively correlated with hardness, gumminess, chewiness, and springiness while negatively correlated with 2-Pentyl furan, α-Pinene, resilience, α-Phellandrene, 1-Penten-3-one, acetic acid ethyl ester, and 1,8-Cineol. Overall, this study provides a theoretical reference for developing new instant marinated tofu snacks.

RESUMEN

Heterocyclic amines (HCAs) have potential carcinogenic and mutagenic activity and are generated in cooked protein-rich foods. Adding proanthocyanidins (PAs) to these foods before frying is an effective way to reduce HCAs. In this study, polymeric PAs (PPA) and ultrasound-assisted acid-catalyzed/catechin nucleophilic depolymerized PAs (UAPA, a type of oligomeric PA) were prepared from Chinese quince fruits (CQF). Different levels of PPA and UAPA (0.05%, 0.1%, and 0.15%) were added to chicken meatballs and tofu; then these foods were fried, and the content of HCAs in them after frying was investigated. The results showed that PPA and, particularly, UAPA significantly inhibited the formation of HCAs in fried meatballs and tofu, and this inhibition was dose-dependent. The inhibition of HCAs by both PPA and UAPA was stronger in the chicken meatballs than in fried tofu. The level of total HCAs was significantly reduced by 57.84% (from 11.93 to 5.03 ng/g) after treatment of meatballs with 0.15% UAPA, with inhibition rates of 78.94%, 50.37%, and 17.81% for norharman, harman, and 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP), respectively. Of note, there was a negative correlation between water, lipid, protein, creatine, and glucose content and HCA content in the crust, interior, and whole (crust-plus-interior) measurements of all fried samples. Interestingly, PPA and UAPA were found more effective in inhibiting HCAs in the exterior crust than in the interior of the fried chicken meatballs. These results provide evidence that further studies on the reduction of the formation of harmful HCAs in fried foods by adding CQF PAs could be valuable to the fried food industry. PRACTICAL APPLICATION: Chinese quince proanthocyanidins treatments significantly inhibited the generation of heterocyclic amines (HCAs) in chicken meatballs and tofu when deep-fried. These results suggest that Chinese quince proanthocyanidins can be used as natural food additive for reducing HCAs in fried foods, laying the foundation for using Chinese quince fruit proanthocyanidins for HCA inhibition in the food industry.

Asunto(s)

RESUMEN

This study explored the effect of diverse coagulants (glucono-δ-lactone (GDL), gypsum (GYP), microbial transglutaminase (MTGase), and white vinegar (WVG)) on microstructure, quality, and digestion properties of tofu. The four kinds of tofu were significantly different in their structure, composition, and digestibility. Tofu coagulated with MTGase had the highest springiness and cohesiveness while GDL tofu had the highest enthalpy (6.54 J/g). However, the WVG and GYP groups outperformed others in terms of thermodynamic, and digestion properties. The WVG group exhibited the highest nitrogen release (84.3%), water content, denaturation temperature, and the highest free-SH content but the lowest S-S content. Compared to WVG, the GYP group had the highest ash content, hardness, and chewiness. Results demonstrated that the tofu prepared by WVG and GYP show high digestibility. Meanwhile, the former has better thermal properties and the latter has better texture properties.

Asunto(s)

RESUMEN

The effects of different types of acid coagulants and nano fish bone (NFB) additives on the characteristics of tofu were investigated using texture analyzers, SEM, FT-IR, and other techniques. The breaking force and penetration distance, in descending order, were found in the tofu induced by glucono-d-lactone (GDL) (180.27 g and 0.75 cm), citric acid (152.90 g and 0.74 cm), lactic acid (123.33 g and 0.73 cm), and acetic acid (69.84 g and 0.58 cm), respectively. The syneresis of these tofu samples was in the reverse order (35.00, 35.66, 39.66, and 44.50%). Lightness and whiteness were not significantly different among the different samples. Regardless of the acid type, the soluble calcium content in the soybean milk was significantly increased after adding NFB. As a result, the breaking force and penetration distance of all tofu samples increased significantly, but the syneresis decreased. Compared with tofu coagulated by other acids, GDL tofu formed a more uniform and dense gel network maintained by the highest intermolecular forces (especially hydrophobic interactions). Regarding the secondary structure, the lowest percentage of α-helix (22.72%) and, correspondingly, the highest ß-sheet (48.32%) and random coil (18.81%) were noticed in the GDL tofu. The effects of NFB on the tofu characteristics can be explained by the changes in the gel network, intermolecular forces, and secondary structure, which were in line with the acid type. The characteristics of acid-induced tofu can be most synergistically improved by coagulation with GDL and NFB.

Asunto(s)

RESUMEN

Currently, food allergies are closely related to intestinal health, and ensuring the integrity and health of intestinal mucosa could reduce the incidence of food allergies. In this study, a soybean-allergic mouse model was used to explore the mechanism of intestinal mucosa immune response induced by enzyme-cross-linked tofu. The effects of enzyme-cross-linked tofu on intestinal mucosal immunity in mice were determined by hematoxylin-eosin (HE) staining and flow cytometry. Our results reveled that the MTG-cross-linked tofu reduced the reactivity of the intestinal mucosal immune system, which mainly manifested as a decrease in the dendritic cell (DC) levels of mesenteric lymph nodes (MLNs), increasing the Th1 cells and Tregs in Peyer's patch (PP) nodes and MLNs, and inhibiting the Th2 cells. Compared with soy protein, enzyme-cross-linked tofu had less damage to the small intestinal tract of mice. Therefore, the above-mentioned results fully revealed that the enzyme-cross-linked tofu promoted the transformation of intestinal mucosal immune cells, shifted the Th1/Th2 balance toward Th1, and reduced its sensitization effect.

RESUMEN

Tofu whey, a by-product of tofu production, is rich in nutrients such as proteins, minerals, fats, sugars and polyphenols. In a previous work, protein recovery from tofu whey was studied by using a coupled environmental process of ED + EDBM to valorize this by-product. This process allowed protein recovery by reducing the ionic strength of tofu whey during the ED process and acidifying the proteins to their isoelectric point during EDBM. However, membrane fouling was not investigated. The current study focuses on the fouling of membranes at each step of this ED and EDBM process. Despite a reduction in the membrane conductivities and some changes in the mineral composition of the membranes, no scaling was evident after three runs of the process with the same membranes. However, it appeared that the main fouling was due to the presence of isoflavones, the main polyphenols in tofu whey. Indeed, a higher concentration was observed on the AEMs, giving them a yellow coloration, while small amounts were found in the CEMs, and there were no traces on the BPMs. The glycosylated forms of isoflavones were present in higher concentrations than the aglycone forms, probably due to their high amounts of hydroxyl groups, which can interact with the membrane matrices. In addition, the higher concentration of isoflavones on the AEMs seems to be due to a combination of electrostatic interactions, hydrogen bonding, and π-π stacking, whereas only π-π stacking and hydrogen bonds were possible with the CEMs. To the best of our knowledge, this is the first study to investigate the potential fouling of BPMs by polyphenols, report the fouling of IEMs by isoflavones and propose potential interactions.

RESUMEN

Alternative plant protein sources offer excellent solutions for tackling the current challenge of food insecurity and sustainability. Inspired by soy tofu, pressed gels represent a robust and versatile way to create protein-enriched plant products. Here, production of heat-induced pressed gels from canola cold-pressed cakes (CPC) and hot-pressed cakes (HPC) was investigated under varied stirring conditions. Pressed gels prepared from CPC resulted in a greater yield and protein recovery than that of HPC. While using carbohydrases as a pretreatment was ineffective in improving yield and protein recovery, applying a stirring condition during heating increased the protein recovery up to 38.3%. Also, stirring condition was proved to be able to modulate the textural properties by controlling the compactness and the size of aggregates. It is revealed that pressed gels are stabilized through a combination of hydrogen bonds, hydrophobic interactions, and disulfide bonds. In comparison to canola press cake, the pressed gels contained less glucosinolates and phenolic compounds, but more phytic acid. A mechanism of formation has been hypothesized based on the nucleation-growth mechanism, and a shift was proposed from diffusion-limited processes in non-stirred pressed gels to reaction-limited process in stirred pressed gels. In conclusion, the potential of canola heat-induced pressed gels was demonstrated both as a stand-alone product and a micro-structured protein extract.

Asunto(s)

RESUMEN

This study aimed to investigate the effects of fermented tofu processing wastewater (FTPW) on the growth performance and meat quality of Xianghuang broilers. A total of 160 six-week-old Xianghuang broilers were randomly assigned to control or FTPW groups with eight replicate pens of 10 birds each pen. Broilers received the same corn-soybean diet but different water. Broilers received ordinary water in the control group and 40% (volume: volume) FTPW (the solution has been filtered with four layers of sieve, containing Bacillus 1.52 × 10-7 CFU/mL) in FTPW group. The experiment lasted for 30 days. Results indicated that growth performance was not affected by treatment (p > 0.05). The value of pH45 min and a48 h increased and drip loss72 h and toughness decreased in breast muscle when broilers received FTPW solution compared with the control group (p < 0.05). The pH45 min, a45 min, a48 h value and crude fat concentration of thigh muscle were higher in FTPW group than that in control group (p < 0.05). Compared with control group, fibre area decreased but fibre density increased in thigh muscle when Xianghuang chickens supplemented with FTPW solution (p < 0.05). Supplementation of FTPW solution in drinking water significantly decreased malondialdehyde content in the breast muscle of Xianghuang chickens (p < 0.05). Gene expressions such as carnitine palmitoyltransferase 1A (CPT1) and glycogen synthase of breast muscle were downregulated in experimental group when compared with control group. In conclusion, FTPW supplementation in drinking water could improve meat quality of Xianghuang broilers by regulating pH value, redness and fibre morphology.

Asunto(s)

RESUMEN

BACKGROUND: Energy-saving and low-carbon baking processes, as well as the need to determine the flavor-forming mechanisms of baked dried tofu, are becoming increasingly necessary. The application of emerging catalytic infrared radiation (CIR) technology in baking of dried tofu is considered of high interest due to the low energy consumption and high baking efficiency compared to traditional baking methods. Hence, this study aimed to investigate the evolution of aroma compounds in baked dried tofu during the CIR baking process and reveal relevant relationships between physical qualities, potential flavor precursors and key volatile compounds. RESULTS: The results showed that the surface color of dried tofu gradually turned an appetizing golden yellow color during the rapid heating process, caused by the uniform infrared radiation from the radiant emitters. Meanwhile, the moisture of dried tofu experienced minimal reduction and the hardness of dried tofu gradually increased with the formation of crust on the surface. In addition, 49 volatile compounds were identified by headspace solid-phase microextraction-gas chromatography-mass spectrometry and 13 substances - 1-hexanol, 1-octen-3-ol, 1-pentanol, heptanal, nonanal, hexanal, (E,E)-2,4-decadienal, (E,Z)-2,4-decadienal, octanal, (E)-2-octenal, (E)-2-nonenal, 2-heptanone and 2-pentylfuran - were confirmed as key aroma compounds. Moreover, the amino acids aspartic acid, glutamic acid, isoleucine, lysine and arginine, and the fatty acids butyric, caprylic, capric, tridecanoic, stearic, oleic and linolenic were responsible for the unique flavor of CIR-baked dried tofu. CONCLUSION: Consequently, the findings can provide a scientific basis for manufacturers to achieve precise quality control and large-scale production of CIR-baked dried tofu products. © 2024 Society of Chemical Industry.

Asunto(s)

RESUMEN

A comparison between artificially inoculated Mao-tofu (CC) and naturally fermented Mao-tofu (MM) indicated that artificially adding Mucor plasmaticus to Mao-tofu dramatically enhanced the essential amino acid (EAA) content, as well as umami and sweet amino acids. Gas chromatography-tandem mass spectrometry (GC-MS/MS) analysis revealed that phenol (3.226 µg/g), 1-octen-3-ol (5.031 µg/g), ethyl heptanoate (1.646 µg/g), and indole (3.422 µg/g) were the key flavor components in Mao-tofu. Unlike MM, CC displayed a substantial increase in esters and a considerable decrease in foul odor substances, including sulfur-containing compounds and indole. Lactococcus raffinolactis, Enterobacter sp. 638, and Streptococcus parauberis KCTC 11537 represented the key bacterial species altering the amino acids and flavor of Mao-tofu according to PacBio single-molecule real-time (SMRT) sequencing and correlation analysis. This study presents the technical feasibility of artificially inoculating Mao-tofu to regulate the core bacterial communities and control the quality of fermented soybean products.

RESUMEN

Hairy tofu is a famous Chinese snack that is made from soybeans and rich in various nutrients. In order to further explore the antioxidant peptides of hairy tofu hydrolysates, seven proteases were used to hydrolyze hairy tofu. The results of in vitro radical scavenging activity showed that hairy tofu hydrolysates obtained by pancreatin exhibited the highest antioxidant activity. After Sephadex G-25 gel filtration and reversed-phase high-performance liquid chromatography (RP-HPLC), 97 peptides were identified in the most antioxidant fraction using liquid chromatography-mass spectrometry/mass spectrometry (LC-MS/MS). Among them, nine peptides were synthesized and their antioxidant activities were assessed using a H2O2-induced oxidative 293T cell model. Finally, four peptides (QCESHK, LAWNEGR, NLQGENEWDQK, and FTEMWR) at concentrations of < 50 µg/ml significantly decreased the malondialdehyde content compared with the model group, displaying in vivo antioxidant activity and low cytotoxicity. Overall, this research provided the choice of using hairy tofu peptides as antioxidant products in the pharmaceutical and food industries.

Asunto(s)

RESUMEN

Understanding quantitative relationships between protein and other chemical components in diverse soybean genotypes (lines) grown in different locations and the firmness of tofu can provide scientific insight for selecting soybean suitable for tofu making. Locations showed significant effects on seed components, including total protein, major storage proteins, subunits and polypeptides of the major storage proteins, and calcium, but not magnesium or phytic acid. Results showed that 11S content, but not 11S/7S ratio, was only correlated with filled tofu firmness when analyzed over all locations. A strong and positive correlation between firmness and A3 polypeptide of the 11S protein content was found for both pressed tofu (r = 0.80, p < 0.001) and filled tofu (r = 0.76, p < 0.001) over three locations (overall pooled data) and within most individual locations. The correlation of filled tofu firmness and A3 polypeptide was significant for each of the three individual locations. However, the correlation of pressed tofu firmness and A3 polypeptide content was significant at two of three locations. Mean calcium content was positively correlated with mean pressed and filled tofu firmness over all locations, but calcium was not correlated with pressed tofu firmness at any individual location, and only one location showed a significant correlation of calcium and filled tofu firmness. In addition, pressed tofu firmness was found to be negatively correlated with tofu yield. The findings that A3 polypeptide's strong relationship with tofu firmness within certain locations may be used by the food industry to select proper soybean for manufacturing tofu and to facilitate tofu soybean breeding for tofu making.

Asunto(s)

RESUMEN

This study investigated the effects of ultrasound-assisted water thawing (UWT) at different power levels (0, 100, 150, 200, and 250 W) on the thawing rate and gel properties of frozen tofu made using three different salt coagulants (CaCl2, CaSO4, and MgCl2). Tofu produced with CaCl2 and CaSO4 elicited gel structures with dense and homogeneous networks, while that with MgCl2 had rough pores and irregular networks. UWT treatment significantly decreased thawing time by 30.9-53.5% compared to the control. Water holding capacity and scanning electron microscopy analyses demonstrated that UWT-100, UWT-150, and UWT-200 should be used to increase the amount of fixed water for CaCl2, CaSO4, and MgCl2. These findings suggest that appropriate ultrasonic treatment could improve the water retention capacity of the tofu network and make the gel network structure more compact. Additionally, protein structural analysis showed a decrease in the exposure of hydrophobic groups and reduced protein denaturation when tofu prepared with all the coagulants were thawed with UWT energies of 100-200 W ultrasonication. These findings offer theoretical support for improving the frozen tofu thawing process while ensuring optimal final product quality.

Asunto(s)

RESUMEN

Okara, the solid byproduct of soymilk production, poses a sustainability concern, despite being rich in fiber and other healthful compounds. In this study, the physical properties of tofu made from soymilk fortified with differing levels of okara-either whole or fine (<180 µm)-and made with the traditional coagulant nigari were examined. The yield increased linearly with the okara concentration with values of 18.2-29.5% compared to 14.5% for the control. The initial moisture in the fortified samples was higher than the control (79.69-82.78% versus 76.78%), and both the expressible moisture and total moisture after compression were also greater in the fortified samples. With a few exceptions, the texture parameters did not differ between samples. Dynamic rheology showed that all samples had G' > G″. The storage moduli increased at different rates during each gelling step, with G' before and after gelling increasing with the fortification level, and was greater for the samples with fine particles than with whole particles. Consumer sensory panels using the hedonic scale showed traditional tofu had a slightly higher acceptability, but the panelists indicated they would be more willing to purchase okara-fortified tofu because of the health and sustainability benefits it might have. Thus, tofu could be produced with added okara with predictable but not profound changes in its physical properties.

RESUMEN

Food protein-induced enterocolitis syndrome (FPIES) is a non-IgE-mediated food allergy that can be caused not only by infant formula but also by infant food. Herein, we report two pediatric cases of FPIES to solid soy foods, such as tofu. The patients presented with repetitive vomiting after eating the trigger food as infant food. Although both cases promptly recovered following the cessation of the trigger food, one case required rapid intravenous hydration for compensated shock. Both cases were diagnosed with FPIES to soy based on the typical presentation and parental interviews regarding food exposure. One case had a positive response to an oral food challenge for tofu, and both cases were negative for soy-specific IgE. One of our cases did not develop FPIES from fermented soy products despite having soy-triggered FPIES. The fermentation process may reduce the allergenicity of soy, but further evidence is required to confirm this hypothesis. There are various trigger foods for solid food FPIES (SFF), and these differ among countries. Solid food FPIES to soy is more common in Japan than in other countries due to the frequent use of tofu in infant food. Increased international awareness of the possibility of tofu-triggered FPIES may be warranted due to the rising global use of tofu in infant food.

RESUMEN

Black soldier fly (BSF; Hermetia illucens) has a high capacity for amino acids and fatty acid accumulation. This study was conducted to assess the effectiveness of tofu by-products, food waste, and vegetables for BSF growth and conversion efficiency. BSFs under tofu by-product treatments showed the greatest weight at d 12 and the harvest period. Moreover, BSF larval weight was greater in the food waste treatment compared with the vegetable treatment at d 12 and harvest. The larva yield result was greater in the vegetable treatment compared with the tofu by-product. The bioconversion rate was higher in the tofu by-product treatment compared with the food waste and vegetable treatments. The protein conversion rate and lipid conversion rate were the highest in the vegetable treatment. The protein yield and lipid yield were greatest in the tofu by-product treatment. The lauric acid content was increased in BSFs fed tofu by-products compared with the food waste treatment. The concentration of C16:1 was the highest in the tofu by-product treatment. The content of oleic acid and α-linolenic acid was higher in BSFs fed tofu by-products compared with the vegetable treatment. In conclusion, the tofu by-products show benefits for larval growth and nutrient accumulation, which can improve larval quality for livestock feed ingredients.

RESUMEN

Dissimilatory sulfate reduction (DSR) is the key sulfur cycle that transforms sulfate to sulfide. This process leads to odour issues in wastewater treatment. However, few studies have focused on DSR during treating food processing wastewater with high sulfate. This study investigated DSR microbial population and functional genes in an anaerobic biofilm reactor (ABR) treating tofu processing wastewater. The tofu processing wastewater is a common food processing wastewater in Asia. The full-scale ABR was operated for over 120 days in a tofu and tofu-related products manufacturing factory. Mass balance calculations based on the reactor performance indicated that 79.6-85.1 % of the sulfate was transformed into sulfide irrelevant to dissolved oxygen supplementation. Metagenomic analysis revealed 21 metagenome-assembled genomes (MAGs) containing enzymes encoding DSR. The biofilm contained the complete functional genes of DSR pathway in the full-scale ABR, indicating that biofilm could process DSR independently. Comamonadaceae, Thiobacillus, Nitrosomonadales, Desulfatirhabdium butyrativorans, Desulfomonile tiedjei were the dominant DSR species in the ABR biofilm community. Dissolved oxygen supplementation directly inhibited DSR and mitigated HS- production. It was also found that Thiobacillus contained all the function genes encoding every necessary enzyme in DSR, and thus Thiobacillus distribution directly correlated to DSR and the ABR performance.

Asunto(s)