The concept of "ultra-processed food" (UPF) has gained significant attention in recent years, leading many to question the healthfulness of common products. For those following a plant-based diet, this has raised concerns about traditional soy products like tofu and tempeh. While both undergo processing, labeling them as ultra-processed is a common misconception that oversimplifies their creation and nutritional value. The key to understanding this lies in differentiating between various levels of food processing, as defined by systems like the NOVA classification.
Understanding the NOVA Classification
Developed by researchers in Brazil, the NOVA classification system categorizes foods based on the nature, extent, and purpose of industrial processing they undergo, not their nutrient content alone. It is divided into four main groups:
- Group 1: Unprocessed or Minimally Processed Foods. These are foods directly from nature that have undergone minimal changes, such as washing, peeling, drying, or pasteurizing. Examples include fresh fruits, vegetables, nuts, seeds, and pasteurized milk.
- Group 2: Processed Culinary Ingredients. These are derived from Group 1 foods via processes like pressing or milling. They are used in home cooking but are not typically consumed alone. Think of vegetable oils, sugar, and salt.
- Group 3: Processed Foods. Simple processed foods are made by combining Group 1 and Group 2 ingredients. The purpose of processing at this level is to extend shelf life or enhance flavors. Examples include canned vegetables, simple cheeses, and bread made with flour, water, and salt. This is where plain tofu and tempeh typically fall.
- Group 4: Ultra-Processed Foods (UPFs). These are industrial formulations made mostly or entirely from ingredients not typically used in domestic cooking. They often include additives like flavorings, emulsifiers, and stabilizers to make them highly palatable, convenient, and profitable. Examples include sweetened cereals, soft drinks, packaged snacks, and reconstituted meat products.
How Tofu is Made: A Minimal Process
The production of plain, traditional tofu is a process that has been used for centuries and is more akin to cheesemaking than to industrial food engineering. The simple steps involved demonstrate why it is not considered ultra-processed:
- Soaking: Dried soybeans are soaked in water.
- Grinding & Cooking: The soaked beans are ground with water and then cooked to produce soy milk.
- Coagulation: A coagulant, often calcium sulfate or magnesium chloride, is added to the soy milk to separate it into curds and whey.
- Pressing: The curds are pressed into blocks of varying firmness, from silken to extra-firm, depending on the desired texture.
This simple process uses a handful of ingredients and avoids the industrial-level manipulations and additives characteristic of UPFs. Therefore, plain block tofu, with its short ingredient list, is firmly in the 'processed' category, not 'ultra-processed'.
How Tempeh is Made: The Power of Fermentation
Tempeh's production method makes it even less processed than tofu, positioning it closer to a whole food. The process involves fermentation, a traditional technique that enhances flavor and digestibility.
- Soaking & Cooking: Whole soybeans are soaked, dehulled, and cooked.
- Inoculation: A starter culture, typically Rhizopus oligosporus, is mixed with the cooled beans.
- Incubation: The mixture is pressed into a block and incubated for 24-48 hours. During this time, the mold grows and binds the soybeans together into a dense, solid cake.
Because tempeh uses whole soybeans and relies on natural fermentation, it retains more of the bean's original fiber and nutrients, making it minimally processed. This is a crucial distinction from UPFs, which are often nutrient-poor. Traditional tempeh is therefore considered a minimally processed or processed food, depending on the specific interpretation within the NOVA framework.
Tofu vs. Tempeh: A Comparison of Processing and Nutrition
While both are healthy soy products, their different production methods result in distinct nutritional profiles and textures. The table below highlights their differences:
| Feature | Tofu | Tempeh |
|---|---|---|
| Processing Level | Processed food (NOVA 3), derived from soy milk | Minimally processed (NOVA 1) or processed (NOVA 3), made from whole beans |
| Key Ingredient | Soy milk (extracted from soybeans) | Whole soybeans |
| Production Method | Coagulation of soy milk and pressing into curds | Fermentation of cooked soybeans with a mold culture |
| Texture | Smooth and soft (silken) to firm and dense (extra-firm) | Firm, dense, and chewy with a nutty texture from the whole beans |
| Flavor | Mild, neutral; easily absorbs marinades | Nutty, earthy, and savory; possesses a distinct flavor |
| Protein | Good source (approx. 8g per 100g) | Higher protein content (approx. 19g per 100g) |
| Fiber | Low in fiber | High in fiber due to use of whole beans |
| Probiotics | None in traditional, packaged tofu | Contains prebiotics and some probiotics from fermentation |
| Calcium | Often fortified with calcium (depending on coagulant) | Good source, but less than fortified tofu |
The True Ultra-Processed Soy Products
It is important to acknowledge that some soy-based products are ultra-processed. These are typically highly modified, packaged items with long ingredient lists, such as pre-fried tofu, some soy-based meat analogues, or heavily flavored ready-meals. For instance, a recent Nature study noted that while plain tofu and tempeh are processed, versions with multiple flavorings or pre-frying could be classified as ultra-processed. Similarly, products like some brands of soy-based hot dogs or chicken nuggets often use soy protein isolates and a host of industrial additives, placing them squarely in the ultra-processed category. The best advice is to always read the ingredient list: a short list of familiar ingredients is a good sign that the product is minimally processed.
How to Make Healthier Choices
Choosing healthier soy products involves more than just selecting tofu or tempeh. Here are a few tips:
- Read the Ingredients: Opt for plain, traditional varieties of tofu and tempeh with minimal ingredients. Avoid versions that are heavily pre-seasoned or fried, which may contain high levels of sodium, sugar, or unhealthy oils.
- Buy Whole Foods: Use whole soybeans to make your own tempeh or soy milk, giving you complete control over the processing.
- Cook at Home: When using tofu or tempeh, prepare them with fresh, whole-food ingredients rather than relying on heavily processed marinades or sauces.
- Distinguish vs. Analogues: Be mindful of the difference between traditional products like tofu and tempeh versus highly formulated meat analogues that mimic the texture and taste of meat through extensive industrial processing.
Conclusion: Processed vs. Ultra-Processed
In the grand scheme of nutrition, the label "processed" is not inherently negative. Traditional and healthy foods like plain tofu and tempeh are excellent examples of this nuance. While they do undergo processing, it is a minimal process rooted in culinary tradition, far removed from the heavy industrial techniques used to create ultra-processed products. By understanding the NOVA classification and scrutinizing ingredient lists, consumers can confidently distinguish between these nutrient-rich staples and their less healthy, ultra-processed counterparts. Choosing plain tofu and tempeh is a solid, nutritious choice for any diet, proving that processed can indeed be healthy. To learn more about the complexities of food classification and its impact on nutrition, exploring the latest research can be helpful, such as findings published in respected journals like Nature.
- Nature: Existing food processing classifications overlook the nutritional value of plant-based foods
Final Takeaway: Processed is Not Always Bad
Tofu is processed, but not ultra-processed: Traditional tofu is made using minimal ingredients and processes, similar to making cheese, and does not contain the industrial additives found in UPFs. Tempeh is even less processed than tofu: Made from whole, fermented soybeans, tempeh retains more original nutrients and fiber, placing it closer to a whole food. The key is the NOVA classification: This system differentiates processing levels based on methods and ingredients, placing plain tofu and tempeh in a healthier category than heavily industrialized products. Not all soy products are equal: Be aware that pre-flavored or heavily formulated soy-based items may be ultra-processed; always check the ingredient list. Health benefits are significant: Both tofu and tempeh offer high-quality protein, with tempeh providing additional fiber and probiotics from fermentation.
FAQs
Question: What is the NOVA food classification system? Answer: The NOVA system classifies foods into four groups based on their level of industrial processing, ranging from unprocessed (Group 1) to ultra-processed (Group 4). The classification focuses on the manufacturing process, not just the nutritional content.
Question: What makes plain tofu a processed food and not ultra-processed? Answer: Tofu is considered a processed food because it involves a few basic steps—like soaking, grinding, and coagulating soybeans—similar to traditional cheese-making. It contains minimal ingredients (soybeans, water, coagulant), unlike ultra-processed foods which have long lists of industrial additives.
Question: Why is tempeh considered less processed than tofu? Answer: Tempeh is made from whole, fermented soybeans, which means it retains more of the bean's original nutrients and fiber. Tofu is made from soy milk, an extract of the soybean, which involves more extensive processing.
Question: Are all soy products healthy? Answer: Not necessarily. While traditional soy foods like plain tofu and tempeh are very healthy, many commercial soy-based products are ultra-processed and contain high levels of sodium, sugar, or unhealthy fats. Always check the ingredient list to determine the processing level.
Question: Can tempeh and tofu be ultra-processed? Answer: Yes, but only in certain forms. If a product is heavily pre-flavored, fried, or contains multiple industrial additives, it may be classified as ultra-processed. A standard block of plain tofu or tempeh, however, is not.
Question: What is the nutritional difference between tofu and tempeh? Answer: Both are good sources of protein, but tempeh typically has more protein, fiber, and probiotics due to its fermentation process and use of whole soybeans. Tofu is a great source of calcium if made with a calcium-based coagulant.
Question: How can I tell if a soy product is ultra-processed? Answer: Look for a long list of ingredients that includes unfamiliar names, like emulsifiers, thickeners, or artificial flavors. Simple, plain products with few ingredients are generally less processed.
Question: What are the health benefits of choosing minimally processed tofu and tempeh? Answer: They offer high-quality plant protein, fiber, and essential nutrients like iron and calcium, contributing to better heart health, digestion, and weight management. Because they are less processed, they avoid the negative health impacts associated with UPFs.
