Tofu

Description

• Plant-based curd made from soy milk (from Glycine max), coagulated and pressed into blocks of varying firmness: silken, soft, firm, extra-firm, plus smoked, fermented (e.g., doufu-ru), fried, or marinated styles.

• Sensory profile: mild/neutral flavor with a light soy note; texture ranges from creamy (silken) to elastic and chewy (firm/extra-firm).

• Functional traits: high flavor absorption, strong water binding/gel formation; good cook tolerance when properly pressed.

Caloric value (per 100 g, as sold)

• Silken: ~45–65 kcal, protein 4–6 g, fat 2–3.5 g, carbohydrates 1–2 g.

• Firm/extra-firm: ~70–120 kcal, protein 8–15 g, fat 4–8 g, carbohydrates 1–3 g.

• Sodium is low in plain styles; may be higher in smoked/marinated or brined products.

• Calcium varies: higher when coagulated with calcium sulfate; magnesium is higher with nigari (magnesium chloride).

Key constituents

• Soy proteins (notably 7S β-conglycinin and 11S glycinin) with a high-quality amino-acid profile (PDCAAS/DIAAS favorable).

• Lipids dominated by linoleic (n-6) with some ALA (n-3); lecithins (emulsifying phospholipids).

• Isoflavones (e.g., genistein, daidzein); saponins in traces.

• Minerals depend on coagulant (notably calcium/magnesium), plus iron; B-vitamins vary.

• Oligosaccharides (FODMAP) lower in pressed tofu than in silken.

Production process

• Soaking & grinding soybeans → cook/extract soy milk → remove okara.

• Coagulation of hot soy milk with coagulants (e.g., calcium sulfate, nigari/MgCl₂, or glucono-δ-lactone for silken).

• Curd collection, molding in cloth/frames, pressing to target firmness.

• Cooling, cutting, packing in water or vacuum; options: pasteurization, smoking, fermentation.

• QC focus: pH, moisture, coagulant salt residuals, texture strength, microbiology (pathogens absent).

Sensory and technological properties

• Flavor uptake: excellent with marinades (soy/miso/spices); improved by pressing.

• Maillard browning: enhanced after drying/pressing or breading.

• Freeze–thaw: freezing opens pores, yielding spongier, chewier texture (helps sauce absorption).

• Water/oil binding: valuable in plant-based burgers, fillings, and sauces.

Food applications

• Asian cuisines: mapo tofu, hot pot, miso soup (silken), salt-and-pepper tofu, scrambled tofu.

• Western/plant-based: stews, grills, stir-fries, salads; desserts/cheesecakes (silken), protein smoothies.

• Key techniques: press firm styles 20–45 min; marinate 30–120 min; dust/bread for crust; cook with dry heat (oven/air-fryer) or high-heat sauté.

Nutrition and health

• High-quality protein; good satiety at moderate calories (especially firm).

• Cholesterol-free; fats are mainly unsaturated; low GI due to low carbohydrate.

• Isoflavones: may support healthy dietary patterns; individual responses vary.

• Minerals: calcium-set tofu can meaningfully add to dietary Ca; check nutrition label.

• FODMAP: generally low in pressed tofu; higher in silken.

Fat profile

• Total fat typically 4–8 g/100 g (firm). Lipids are mostly **PUFA — polyunsaturated fatty acids (linoleic n-6; potentially beneficial when balanced, more oxidation-prone) and **MUFA — monounsaturated fatty acids (oleic n-9; often neutral/beneficial), with **low SFA — saturated fatty acids (palmitic; best kept moderate overall). **TFA — trans fatty acids are negligible; **MCT — medium-chain triglycerides not significant.

Quality and specifications (typical topics)

• Texture (compression/TA), moisture, pH, consistent protein content; absence of rancid/off or abnormal acidity notes.

• Microbiology: pathogens absent/25 g; TAMC/yeasts/molds within spec; process water hygiene in brine/pack.

• Coagulant residues within limits; metals/pesticides compliant; barrier packaging and seal integrity verified.

Storage and shelf life

• Refrigerated (0–4 °C): unopened → to date; once opened, keep submerged in water (change daily) and use within 3–5 days.

• UHT/aseptic: ambient until expiry; refrigerate after opening and consume promptly.

• Freezable (texture becomes more porous/chewy).

Allergens and safety

• Major allergen: soy — not suitable for soy allergy.

• Naturally lactose-free and gluten-free, barring cross-contact.

• Antinutrients (e.g., trypsin inhibitors) are inactivated during soy-milk cooking; oligosaccharides are lower in pressed tofu.

INCI functions in cosmetics (when relevant)

• Related INCI from soy: Hydrolyzed Soy Protein, Glycine Soja (Soybean) Protein, Glycine Soja (Soybean) Oil (not tofu itself).

• Roles: light film-forming/conditioning; emollient (oil). Ensure claim/safety substantiation.

Troubleshooting

• Pronounced “beany” note: blanch cubes 1–2 min, then marinate; emphasize acid-salt marinades.

• Breaks in pan: choose firm/extra-firm, press and pat-dry; avoid crowding; use a well-heated pan.

• Poor marinade uptake: press first; include salt/acid; extend time; lightly prick surfaces.

• Rubbery texture: reduce press time or overall cook time; use dry heat for a crust with tender interior.

Sustainability and supply chain

• Soy can carry land-use risks: prefer traceable, non-deforested origins and credible certifications; valorize okara (feed/fiber).

• In-plant: manage effluents toward BOD/COD targets, improve water/energy efficiency, use recyclable packaging; maintain GMP/HACCP and full traceability.

Labelling

• Name: “tofu.” Ingredients: water, soybeans, coagulant (specify calcium sulfate, magnesium chloride, GDL), optional flavors/salt.

• Allergens: highlight SOY; for calcium-set products, declare calcium content; protein claims per regulation.

• Include country of origin, lot/traceability, and storage after opening.

Conclusion

Tofu is a versatile protein ingredient with low intrinsic flavor, excellent flavor uptake, and tunable textures via pressing, marination, freezing, and cooking technique. Selecting the right style, coagulant, and process delivers reliable performance from home cooking to industrial formulations.

Mini-glossary

• PDCAAS/DIAAS — protein quality scores: Indices of digestible amino-acid adequacy; soy protein scores high.

• GI — glycaemic index: Impact on blood glucose; tofu is low GI.

• FODMAP — fermentable oligo-, di-, mono-saccharides and polyols: Can cause bloating; lower in pressed tofu.

• PUFA — polyunsaturated fatty acids: Often beneficial when balanced; more oxidation-prone.

• MUFA — monounsaturated fatty acids: Typically neutral/beneficial.

• SFA — saturated fatty acids: Lower in tofu than in many animal products; best kept moderate overall.

• TFA — trans fatty acids: Negligible in tofu.

• MCT — medium-chain triglycerides: Not significant in tofu.

• GMP/HACCP — good manufacturing practice / hazard analysis and critical control points: Preventive hygiene systems with validated CCPs.

• BOD/COD — biochemical/chemical oxygen demand: Metrics for wastewater impact and treatment needs.

Studies

Soy contains several polyphenol compounds, especially isoflavones, which have positive effects on human health, but their presence in percentage varies depending on the type of soy.

Isoflavones (classified as phytoestrogens) have shown positive potential against cardiovascular disease, diabetes, cancer. osteoporosis and neurogenerative disorders. In the soybean, 12 different types were identified divided into:

• aglycones  (daizein, glicitein, genistein)
• beta-glucosides (daidzin, glicitin, genistin) (1)

In 1999, the FDA recognized soy proteins with some protection against coronary heart disease and authorized the following posology: 25 grams of soy protein per day as part of a low-fat, cholesterol-low diet.

In 2017, the FDA announced its intention to review the authorization for lack of scientific data as only 19 studies confirmed the usefulness of soy in reducing coronary risk, while 27 studies did not support this positive thesis.

It's a rather controversial food.

On the one hand, some studies draw attention to isoflavones present in soy that help defend the cardiovascular system by regulating cellular and enzymatic functions in situations such as inflammation, thrombosis and atherosclerotic progression (2).

On the other hand, it is feared that it may cause damage, particularly to Alzheimer's disease, if ingested in the form of an industrial product. This study analyses the problem (3).

However, a certain amount of post-2017 scientific studies confirm the positive activity of soy bea on human health.

In a 20 km cycling race, a fermented soybean extract improved the performance of athletes both in terms of power and speed (4).

Patients with type 2 diabetes achieved improved blood conditions, increased brachial blood flow, improved endothelial function, increased total serum antioxidants and lipid profile. There was no significant effect on blood pressure and HDL cholesterol (5)

Soy and its isoflavones have a positive influence on mortality risks associated with cancer and cardiovascular disorders (6).

Soy studies

References__________________________________________

(1) Orts A, Revilla E, Rodriguez-Morgado B, Castaño A, Tejada M, Parrado J, García-Quintanilla A. Protease technology for obtaining a soy pulp extract enriched in bioactive compounds: isoflavones and peptides Heliyon. 2019 Jun 22;5(6):e01958. doi: 10.1016/j.heliyon.2019.e01958.

Abstract. This work presents a new bioprocess process for the extraction of bioactive components from soy pulp by-product (okara) using an enzymatic technology that was compared to a conventional water extraction. Okara is rich in fiber, fat, protein, and bioactive compounds such as isoflavones but its low solubility hampers the use in food and fertilizer industry. After the enzymatic attack with endoproteases half of the original insoluble proteins were converted into soluble peptides. Linked to this process occured the solubilization of isoflavones trapped in the insoluble protein matrix. We were able to extract up to 62.5% of the total isoflavones content, specially aglycones, the more bioactive isoflavone forms, whose values rose 9.12 times. This was probably due to the increased solubilization and interconversion from the original isoflavones. In conclusion, our process resulted in the formulation of a new functional product rich in aglycones and bioactive peptides with higher antioxidant potency than the original source. Therefore, we propose that the enzymatic extraction of okara bioactive compounds is an advantageous tool to replace conventional extraction.

(2)  González Cañete N, Durán Agüero S. Soya isoflavones and evidences on cardiovascular protection.  Nutr Hosp. 2014 Jun 1;29(6):1271-82. doi: 10.3305/nh.2014.29.6.7047. Spanish.

(3)  Roccisano D, Henneberg M, Saniotis A. A possible cause of Alzheimer's dementia - industrial soy foods. Med Hypotheses. 2014 Mar;82(3):250-4. doi: 10.1016/j.mehy.2013.11.033. Epub 2013 Dec 7.

(4) Seeley AD, Jacobs KA, Signorile JF. Acute Soy Supplementation Improves 20-km Time Trial Performance, Power, and Speed. Med Sci Sports Exerc. 2020 Jan;52(1):170-177. doi: 10.1249/MSS.0000000000002102. 

Abstract. Introduction: Isoflavones, a chemical class of phytoestrogens found in soybeans and soy products, may have biological functions similar to estradiol. After binding with ERβ or perhaps independently of estrogen receptors, isoflavones may augment vascular endothelial relaxation, contributing to improved limb blood flow. Purpose: To determine if acute fermented soy extract supplementation influences 20-km time trial cycling performance and cardiac hemodynamics compared with a placebo. Methods: Subjects included 25 cyclists and triathletes (31 ± 8 yr, V˙O2peak: 55.1 ± 8.4 mL·kg·min). Each subject completed a V˙O2peak assessment, familiarization, and two 20-km time trials in randomized order after ingestion of a fermented soy extract supplement or placebo. The fermented soy extract consisted of 30 g powdered supplement in 16 fl. ounces of water. The placebo contained the same quantities of organic cocoa powder and water. Each trial consisted of 60 min of rest, 30 min at 55% Wpeak, and a self-paced 20-km time trial. Results: Soy supplementation elicited a faster time to 20-km completion (-0.22 ± 0.51 min; -13 s), lower average HR (-5 ± 7 bpm), and significantly greater power (7 ± 3 W) and speed (0.42 ± 0.16 km·h) during the last 5 km of the time trial compared with placebo. Analysis of the results by relative fitness level (<57 vs ≥ 57 mL⋅kg⋅min) indicated that those with a higher level of fitness reaped the largest performance improvement alongside a reduced HR (-5 ± 7 bpm). Conclusions: Ingestion of a fermented soy extract supplement improved sprint-distance performance through improvements in both power and speed. For those with great aerobic fitness, soy supplementation may help to decrease cardiac demand alongside performance improvement.

(5) Sedaghat A, Shahbazian H, Rezazadeh A, Haidari F, Jahanshahi A, Mahmoud Latifi S, Shirbeigi E. The effect of soy nut on serum total antioxidant, endothelial function and cardiovascular risk factors in patients with type 2 diabetes.  Diabetes Metab Syndr. 2019 Mar - Apr;13(2):1387-1391. doi: 10.1016/j.dsx.2019.01.057

(6) Nachvak SM, Moradi S, Anjom-Shoae J, Rahmani J, Nasiri M, Maleki V, Sadeghi O. Soy, Soy Isoflavones, and Protein Intake in Relation to Mortality from All Causes, Cancers, and Cardiovascular Diseases: A Systematic Review and Dose-Response Meta-Analysis of Prospective Cohort Studies J Acad Nutr Diet. 2019 Jul 2. pii: S2212-2672(19)30362-4. doi: 10.1016/j.jand.2019.04.011

Woo HW, Kim MK, Lee YH, Shin DH, Shin MH, Choi BY. Habitual consumption of soy protein and isoflavones and risk of metabolic syndrome in adults ≥ 40 years old: a prospective analysis of the Korean Multi-Rural Communities Cohort Study (MRCohort). Eur J Nutr. 2019 Oct;58(7):2835-2850. doi: 10.1007/s00394-018-1833-8. 

Abstract. Purpose: Although considerable attention has been paid to the potential benefits of soy protein and isoflavones for preventing metabolic syndrome (MetS) and its components, findings linking habitual consumption of these factors to MetS are limited. This study aimed to evaluate the association of MetS incidence with habitual intake of soy protein/isoflavones among Korean men and women aged ≥ 40 years old who did not have MetS at baseline (n = 5509; 2204 men and 3305 women). Methods: Dietary intake of soy protein/isoflavones at baseline and average consumption during follow-up were used. Results: A significant inverse association between dietary intake and incidence of MetS was found in women (incidence rate ratios, IRR = 0.60, 95% CI = 0.46-0.78, P for trend = 0.0094 for the highest quintile of average soy protein intake compared with the lowest quintile; IRR = 0.57, 95% CI = 0.44-0.74, P for trend = 0.0048 for the highest quintile of average isoflavones intake compared with the lowest quintile). A tendency towards an inverse association was also found in men, although it was not significant for the highest quintile (IRR = 0.80, 95% CI = 0.58-1.11, P for trend = 0.9759, comparing the lowest to the highest quintile of average soy protein intake; IRR = 0.73, 95% CI = 0.53-1.01, P for trend = 0.8956, comparing the lowest to the highest quintile of average isoflavones intake). In terms of individual abnormalities, a significant inverse association was found between soy protein and isoflavones and the incidence of low-high-density lipoprotein cholesterol in both men and women. Abdominal obesity and elevated blood pressure were inversely related to soy protein/isoflavones only in women, and an inverse association of elevated triglyceride appeared only in men. Conclusion: Our findings suggest that habitual intake of soy protein and isoflavones is inversely associated with the risk of MetS and its components. There is likely to be a reverse J-shaped association of average intake with MetS.