Tempeh

 

Tempeh

Composed By Muhammad Aqeel Khan
Date 15/8/2025

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Tempeh is a firm, sliceable cake made by fermenting cooked soybeans with molds of the Rhizopus genus, most commonly Rhizopus microsporus var. oligosporus. Hailing from Java, Indonesia, tempeh has been a staple protein for centuries and is now popular worldwide as a nutrient-dense, minimally processed, and remarkably versatile food. This article explains what tempeh is and how it’s made, unpacks its nutrition profile and bioactive compounds, reviews the best scientific evidence on its health effects (and limitations), and closes with practical cooking and storage tips.

What is tempeh and how is it traditionally made?

Traditional tempeh production starts by soaking and dehulling soybeans(Wikipedia), then cooking them until tender. The beans are drained thoroughly (low surface moisture is key), cooled, and inoculated with a starter culture containing Rhizopus spores. The inoculated beans are spread into a thin layer and incubated warm (usually ~30–32 °C) for about 24–48 hours. During this solid-state fermentation, the mold’s mycelium knits the beans into a cohesive “cake.” Lactic-acid–producing bacteria often accompany the mold and acidify the substrate; this acidification improves safety, flavor, and texture and can be encouraged by back-slopping or starter blends in some settings [Nout & Kiers, 2005]. The result is a pleasantly nutty, mushroomy, and slightly savory product that can be sliced, marinated, grilled, sautéed, crumbled, or steamed. Although soybeans are classic, many legumes or grains (e.g., chickpeas, lupin, or mixed pulses) can be “tempeh-ized” with appropriate adjustments to moisture and incubation conditions.

Nutrition at a glance

Per 100 g, plain tempeh typically provides roughly ~190–210 kcal, ~20 g protein, ~10–11 g fat, ~7–9 g carbohydrate, and is naturally cholesterol-free. It contains iron, magnesium, potassium, and modest calcium; exact values vary with brand and formulation [USDA FoodData Central; MyFoodData].

Why is the protein quality notable? Fermentation partially pre-digests storage proteins, reducing some antinutritional factors (e.g., trypsin inhibitors) and improving digestibility. The mold’s proteases generate small peptides that can have bioactivity (e.g., antioxidant or ACE-inhibitory actions in experimental systems) and may enhance functionality beyond the raw bean [Nout & Kiers, 2005]. Fermentation also reduces α-galactooligosaccharides—especially raffinose and stachyose—that commonly cause gas, contributing to better tolerance for many people [Gronchi et al., 2013; Nout & Kiers, 2005].

Another key change is the reduction of phytic acid, a compound that can chelate minerals and inhibit absorption. Classic food science studies show that tempeh fermentation can roughly halve phytic acid in soybeans, with further reductions during storage, which could improve mineral bioavailability in mixed diets [Egounlety & Aworh, 2003; Lopez et al., 2002; see also Yamashita et al., 1985].

A note on vitamin B₁₂

Tempeh is sometimes promoted as a plant food that “contains B₁₂.” The nuance matters. Active B₁₂ in tempeh is produced not by the Rhizopus mold but by certain bacteria (e.g., Klebsiella pneumoniae, Citrobacter freundii) that may be present during fermentation. Levels vary widely by starter, hygiene, substrate, and processing; some tempeh contains little or no active B₁₂, while experimental co-fermentations (e.g., with Propionibacterium freudenreichii) can raise levels substantially [Liem et al., 1977; Keuth & Bisping, 1994; Wolkers-Rooijackers et al., 2018]. Major nutrition reviews continue to caution that plant foods are not reliable sources of B₁₂ for vegans unless fortified or supplemented [Stabler & Allen, 2012]. Bottom line: enjoy tempeh for many reasons, but don’t rely on it as your sole B₁₂ source unless the product is specifically fortified/co-fermented and labeled accordingly.

Evidence-based health benefits

1) Heart health: lipids and blood pressure

Multiple meta-analyses show that soy protein modestly lowers LDL cholesterol (≈3–4% on average), with neutral or favorable effects on total cholesterol and triglycerides—effects relevant to cardiometabolic risk when combined with other heart-healthy diet changes [Mejia et al., 2019; Messina, 2010]. While tempeh’s exact effect hasn’t been isolated in many clinical trials, tempeh is a whole-soy protein source with fiber, unsaturated fats(Wikipedia), and minimal sodium (unless marinated), all of which support cardiometabolic profiles.

Soy isoflavones may modestly reduce blood pressure in adults, with several meta-analyses reporting small mean decreases (more pronounced in hypertensive subgroups) [Dong et al., 2011; Liu et al., 2024; Zhang et al., 2021]. Fermentation can increase the proportion of isoflavones in their aglycone forms, which are more readily absorbed, potentially enhancing bioavailability compared to unfermented soy [Nout & Kiers, 2005; recent process reviews].

Takeaway: Replacing higher-saturated-fat animal proteins with tempeh can contribute to improved lipid profiles and, via soy bioactives, may have modest blood-pressure benefits—especially as part of an overall diet emphasizing whole plant foods.

2) Gut health and digestibility

Tempeh’s fermentation reduces gas-forming oligosaccharides and trypsin inhibitors, improves protein digestibility, and yields small peptides with antioxidant and ACE-inhibitory activity in model systems [Gronchi et al., 2013; Nout & Kiers, 2005]. The reduction in phytic acid can also support better mineral bioavailability (iron, zinc) when tempeh is eaten alongside vitamin-C–rich foods that enhance non-heme iron absorption [Yamashita et al., 1985; Lopez et al., 2002].

fruits high in vitamin c

What about probiotics? Fresh, unpasteurized tempeh contains live microbes, but tempeh is almost always cooked before eating, which inactivates them. So, think of tempeh as a fermented food with fermentation-derived benefits (digestion, bioactives), rather than a source of live probiotics at the point of consumption. That said, even heat-inactivated microbial components and fermentation-derived peptides may exert functional effects in the gut milieu—a topic of active research.

3) Weight management and satiety

High-protein foods generally enhance satiety and can support weight management in energy-reduced diets. Randomized trials and reviews show higher-protein diets (≈25–30% of energy, or ~1.2 g/kg/day) improve appetite control, preserve lean mass, and facilitate fat loss vs. lower-protein comparators [Leidy et al., 2011; Wycherley et al., 2012; Dhillon et al., 2016]. Tempeh—providing ~20 g protein per 100 g—fits easily into such patterns. Its chewy texture and ability to take on marinades also make it a satisfying meat alternative in familiar dish formats (stir-fries, tacos, kebabs), which can help adherence.

Potential drawbacks and precautions

• Soy allergy: Individuals with confirmed soy allergy should avoid tempeh. Fermentation may decrease some allergenic proteins, but it does not eliminate allergy risk [Kowalczyk et al., 2019].

• Thyroid and isoflavones: In iodine-replete adults, moderate soy intake is generally compatible with normal thyroid function. People with hypothyroidism should ensure adequate iodine and time thyroid medication away from high-fiber/soy meals, per clinical guidance.

• B₁₂ reliability: As noted, unless specifically fortified or co-fermented and labeled, tempeh shouldn’t be your sole B₁₂ source [Stabler & Allen, 2012].

Vitamin B12 Rich Foods

• Sodium and added ingredients: Plain tempeh is low in sodium, but marinades, sauces, or pre-flavored products can be saltier—check labels if managing blood pressure.

How to cook tempeh so it tastes amazing

Browning, smoke, umami, and aromatics all work in perfect harmony with the firm, nutty character of tempeh.

1. Steam first (optional but helpful): Steaming slabs for 10–15 minutes softens bitterness in some brands and primes the surface to absorb marinades.

2. Marinate smartly: Combine salty (tamari/soy sauce), sour (lime/rice vinegar), a touch of sweet (date syrup/maple), aromatics (garlic/ginger), and an umami booster (miso, tomato paste, mushroom powder). 20–60 minutes is plenty.

3. Pan-sear or roast: For crispy edges, sear slices or cubes over medium-high heat until golden on multiple sides; or roast at 200 °C (400 °F) for 18–22 minutes, flipping once.

4. Glaze and finish: Toss with a reduced glaze (gochujang-tamari-sesame oil; BBQ-smoky paprika; sambal-lime-peanut) in the last minutes of cooking for lacquered edges.

5. Crumbled tempeh ≈ minced “meat”: Pulse or hand-crumble and sauté with onions, spices, and tomato paste for taco filling, sloppy joes, or bolognese.

6. Pairings that sing: Tempeh loves ginger-scallion, garlic-black pepper, lemongrass-chili, smoked paprika-cumin, or maple-mustard.

Three quick recipe ideas

• Crispy Tempeh Tacos: Crumbled tempeh + chili powder, cumin, smoked paprika; sauté until browned; splash of lime; serve with pico, avocado, and cabbage slaw.

• Sweet-Spicy Tempeh Stir-Fry: Sliced tempeh seared and tossed with garlic, ginger, mixed vegetables; glaze with tamari, rice vinegar, a little maple, and chili flakes.

• Satay-Style Tempeh Skewers: Marinated cubes grilled or roasted; serve with peanut-lime sauce and cucumber salad.

Storage and food safety

• Refrigeration: Keep unopened tempeh refrigerated. Once opened, wrap tightly or store in an airtight container and consume within 3–5 days.

• Freezing: Tempeh freezes well for 2–3 months; thaw overnight in the fridge (freezing also helps sauce absorption).

• When to discard: Off-odors (sharp ammonia or putrid), sliminess, or vivid colors (pink/blue/green molds) are signs to discard. Mild gray/black spotting on edges can be normal mycelium pigmentation, but when in doubt, throw it out.

• Cooking: Heat thoroughly. Although the base fermentation is safe when properly conducted, a good cook-through ensures quality and kills incidental microbes—especially important if the package was open for a few days.

The bottom line

Tempeh is a traditional Indonesian fermented food with an impressive combination of nutrient density, high-quality plant protein, and fermentation-derived functional advantages. Solid human evidence supports soy foods (as a category) in modestly improving cholesterol and supporting cardiometabolic health, while fermentation improves digestibility and likely mineral bioavailability. As part of a varied, minimally processed diet, tempeh is a flavorful, eco-friendly protein that can help with satiety and meal satisfaction. Just don’t bank on it as your sole source of vitamin B₁₂ unless clearly fortified.

References

• Nout, M. J. R., & Kiers, J. L. (2005). Tempe fermentation, innovation and functionality: update into the third millennium. Journal of Applied Microbiology, 98(4), 789–805.

• USDA FoodData Central. Tempeh—nutrient data (accessed 2025).

• MyFoodData. Tempeh nutrition comparison tool (accessed 2025).

• Mejia, S. B., et al. (2019). A meta-analysis of 46 studies identified by the FDA demonstrates that soy protein decreases LDL cholesterol in adults. Journal of Nutrition, 149(6), 968–981.

• Dong, J.-Y., et al. (2011). Effect of soy isoflavone supplementation on blood pressure: a meta-analysis of randomized controlled trials. Nutrition, Metabolism & Cardiovascular Diseases, 21(7), 421–429.

• Liu, C., et al. (2024). Effect of soy isoflavone supplementation on blood pressure: updated meta-analysis of RCTs. Journal of Human Hypertension.

• Zhang, Z., et al. (2021). Soy intake and blood pressure in adults: systematic review and meta-analysis. Food & Function, 12(16), 7235–7247.

• Gronchi, F., et al. (2013). Effect of controlled lactic acid co-fermentation on oligosaccharides and bioactive properties of soybean tempeh. International Journal of Food Sciences and Nutrition, 64(7), 869–876.

• Yamashita, H., et al. (1985). Reduction in phytic acid levels in soybeans during tempeh fermentation and storage. Journal of Food Science, 50(5), 1257–1259.

• Lopez, H. W., et al. (2002). Phytic acid and mineral bioavailability: a review on interactions and processes that reduce phytate in foods. Journal of Food Science, 67(9), 3478–3488.

• Keuth, S., & Bisping, B. (1994). Vitamin B12 production by Citrobacter freundii or Klebsiella pneumoniae in tempeh fermentation. Applied and Environmental Microbiology, 60(5), 1495–1497.

• Wolkers-Rooijackers, J. C. M., et al. (2018). Enhanced vitamin B12 in lupin tempeh via co-fermentation with Propionibacterium freudenreichii. Food Chemistry, 245, 197–206.

• Stabler, S. P., & Allen, R. H. (2012). Vitamin B12 in health and disease. Molecular Aspects of Medicine, 33(4), 559–579.

• Leidy, H. J., et al. (2011). Higher-protein diets improve appetite and satiety during weight loss. Obesity, 19(4), 818–824.

• Wycherley, T. P., et al. (2012). Effects of high-protein diets on body weight and body composition: a meta-analysis of randomized trials. American Journal of Clinical Nutrition, 96(6), 1281–1298.

• Kowalczyk, E., et al. (2019). Degradation of soy antinutritional factors and allergenicity during tempeh fermentation. International Journal of Food Science & Technology, 54(5), 1836–1845.*

Note: Several values and effects vary by brand and process; check product labels for sodium or fortification, and consult a clinician or dietitian if you manage specific conditions (e.g., thyroid disease, food allergies).