Fermented vs Unfermented Soy: An Easy + Handy Guide

Soy is a versatile legume that has been a staple in Asian cuisine for centuries. I’ve been largely consuming soy since I cut out on my meat intake and I love it. It is renowned for its high protein content, making it a valuable addition to vegetarian and vegan diets.

Soy is consumed in various forms, but there’s a crucial distinction to be made: fermented and non-fermented soy products. In this food blog post, we’ll delve deep into the world of soy, exploring the differences between these two categories and the unique culinary and nutritional attributes they offer.

I started introducing fermented and non-fermented soy products gradually into my diet, but now I can easily say they are a staple in my home. My son is growing up knowing these foods that are not usually part of our culinary tradition but that can add so much value to our wellness and lifestyle.

With the help of notable medical sources, I will share here some of the most well-known benefits of soybeans, the differences between fermented and unfermented soy, and how I use them in the kitchen.

Image: Fermented vs unfermented soy products, tempeh patties.

Understanding Soy

Before we dive into the fermented vs unfermented soy debate, let’s better understand the nutritional value of this famous yet mysterious bean.

What is soy?

Soy, scientifically known as Glycine max, is a legume native to East Asia. It has been cultivated and used for thousands of years and is prized for its nutritional value. Soybeans can be green, yellow, and black and can be used in various forms, including whole beans, tofu, tempeh, miso, and soy milk.

While it’s highly nutritious and has several health benefits, it’s extremely important that soybeans are cooked and never consumed raw. Soy, in fact, is far from being an easy legume to digest and previous soaking and cooking will not only be easier on your stomach but will also improve the assimilation of its many properties.

Soy, just like every other legume, contains the so-called antinutrients, meaning substances that reduce the body’s ability to absorb essential nutrients. This is why I always soak the soybeans for some 24 hours and cook them for 2 hours in a pressure cooker.

Nutritional benefits of soy

Soy is known for its remarkable nutritional composition. Here’s a quick overview of its precious nutrients.

  • Protein: Soy is an excellent source of plant-based protein. This is why is largely used as a meat substitute by vegetarians and vegans.
  • Fiber: It contains dietary fiber, greatly aiding in digestion and promoting heart health.
  • Healthy Fats: Soybeans are rich in polyunsaturated fats, including omega-6 and omega-3 fatty acids.
  • Vitamins and Minerals: Soy provides essential vitamins and minerals such as vitamin K1, folate, copper, manganese, phosphorus, and thiamine or vitamin B1.

But what are the differences between fermented and non-fermented soy products? Let’s dive in!

Fermented vs unfermented soy – differences and main features

The main difference that comes to mind when comparing fermented vs unfermented soy products is the process used to make them and their content of friendly bacteria.

While I consume some unfermented soy such as tofu and edamame, I largely prefer fermented soy products because they improve digestion and may contain probiotics properties useful to the intestine.

Non-fermented soy products

Non-fermented soy products are those in which soybeans are processed without undergoing the fermentation process. The most popular include tofu, soy milk, soybean oil, and obviously edamame.

Image: Scrambled tofu unfermented soy product.

Tofu: the versatile soybean curd

Tofu is perhaps the most famous non-fermented soy product. It’s made by curdling fresh soy milk and pressing the resulting curds into blocks. Tofu comes in various textures, including silken, soft, firm, and extra-firm, making it versatile for a wide range of culinary applications.

I use tofu in both savory and sweet recipes and in a very diverse range of dishes from patties to creams to stews to even vegan scrambled “non-eggs”. I love my scrambled tofu with broccoli to fill my homemade piadina flatbread.

Tofu itself is tasteless and this is mainly why it adapts to most recipes you want to make if you follow a plant-based diet or even if you simply want a lower-cholesterol meal.

Soy milk: a dairy-free alternative

Soy milk is created by blending soaked soybeans with water and straining the mixture. It’s widely used as a dairy milk substitute for those with lactose intolerance or following a vegan diet. Soy milk can be enjoyed plain, sweetened, or flavored and is commonly used in coffee, cereal, and baking.

I don’t consume dairy because I don’t tolerate it, however, I don’t find soy milk easy to digest. Soy milk is made out of RAW soybeans, which means, that before consuming it, it needs to be cooked. This is why I don’t recommend adding it to your coffee, tea, or cereals without previously boiling it. On the other hand, adding it to your cakes to bake in the oven is perfectly fine.

Edamame: the nutrient-packed snack

Edamame are young, green soybeans harvested before they are fully ripe. These soybean pods are often served as a popular appetizer in Japanese cuisine, lightly steamed or boiled and sprinkled with sea salt. I always order them as they are not only delicious but also pack a nutritional punch, offering protein, fiber, and essential vitamins and minerals.

Soybean oil: a cooking staple

Soybean oil is widely used in cooking and food processing due to its neutral flavor and high smoke point. It’s commonly found in salad dressings, frying, and as an ingredient in many packaged foods.

It’s a quite versatile cooking oil but honestly, I never use it. It’s better used unrefined and cold-pressed to preserve its properties, but this way, it turns rancid quickly. This is why, in common stores, you are mainly going to find it refined and enriched with hydrogenated fats (also called trans-fatty acids), which are not exactly the definition of healthy.

Fermented soy products

I am a big fan of fermented foods and drinks and these include also the fermented soy products. Fermented soy products undergo a transformation thanks to the action of beneficial bacteria and yeast. This results in unique flavors, textures, and nutritional benefits.

Sometimes, especially in the case of tempeh and natto, I think you will need to get accustomed in order to consume it a second time. But when you learn how to cook them and get used to their flavor, you will appreciate how they make you feel.

The fermentation process not only enhances the taste but also breaks down anti-nutrients found in raw soybeans, making the nutrients more bioavailable. Moreover, it makes the soybeans easier to digest and richer in properties.

Image: Miso fermented soy product.

Miso: a delicious elixir

Miso is a traditional Japanese seasoning made from fermented soybeans, salt, koji (a type of fungus), and a grain, usually rice or barley. The mixture is left to ferment for several months to several years, depending on the desired flavor and texture.

Miso comes in various colors, including white, yellow, red, and brown, each with its own distinct taste and use in recipes. It’s commonly used in soups, marinades, dressings, and even desserts.

I love miso. Like pure, unconditional love. I always have a jar of miso at home and I consume it every single day. Whether it’s for breakfast in a miso-tahin cream spread on a slice of whole-grain rye bread or in the evening in the miso soup.

I use miso also to create dressings, creams, and sometimes to season instead of salt.

Image: Tempeh fermented soy.

Tempeh: a meaty plant protein

Tempeh originates from Indonesia and is made by fermenting cooked soybeans with a specific type of mold. The result is a dense, nutty-flavored cake with a firm texture. Tempeh is an excellent source of protein and is often used in vegan and vegetarian dishes as a meat substitute.

If tofu is known as vegans’ cheese, tempeh is sometimes referred to as vegans’ meat. I think tempeh is one of the most precious products obtained from the fermentation of soybeans.

Its firm texture makes it ideal for grilling, frying, marinating, and even baking. I have used it also slightly boiled, mixed with other veggies, and then baked the patties I had made out of the batter.

Image: Natto fermented soy in the making.
My own natto in the making!

Natto: a Japanese delicacy

Natto is a fermented soybean dish that is beloved by some and met with some sort of hesitation by others (myself included) due to its strong aroma and sticky texture. It is made by fermenting soybeans with Bacillus subtilis bacteria, resulting in a gooey, pungent dish with a distinctive flavor.

Natto is commonly eaten with rice and often garnished with soy sauce and mustard. In Japan, it’s commonly eaten for breakfast because it gives a strong supply of nutrients thanks to its high content of proteins and vitamins.

The first I made natto, I didn’t like it. In fact, I was a bit hesitant about making it again but my husband immediately adored it and literally devoured it! So I made it again and little by little I started liking it too.

In fact, now I make it regularly and also my 4-year-old enjoys it. This is good news because it’s very healthy and nutrient-packed. If you want to know I make natto let me know in the comment section below and I will publish the recipe!

Soy sauce: a healthy dressing

Often, soy sauce is seen as a guilty pleasure and actually harmful. However, if you buy it organic and properly prepared, it has its own health benefits.

First of all, it’s also obtained from a process of fermentation of soybeans with the A. oryzae bacteria so it aids digestion. Second and most importantly, it’s very salty, so it should be used instead of salt and not in addition to.

You are going to find different types of soy sauce in the stores. Some will have additional ingredients that are not really part of the original recipe. Soy sauce is only made with soybeans, sea salt, water, and grain.

When they use wheat, it’s called shoyu and it contains gluten. If you are gluten intolerant, you can buy tamari, which is gluten-free soy sauce and the used grain is rice.

We use soy sauce a lot. Very often, I use it instead of salt. For example, often my dinner is very simple a grain such as rice, buckwheat, or quinoa accompanied with stir-fried veggies that I usually season simply with soy sauce at the end to avoid cooking the friendly bacteria for too long.

Image: Soybeans becoming natto fermented soy product.

Fermented vs unfermented soy: nutritional comparison

Now that we are familiar with the most famous non-fermented and fermented soy products, we can compare their nutritional profiles to understand how they differ and also how to consume them to enhance their properties.

Protein

Both non-fermented and fermented soy products are excellent sources of protein. However, the fermentation process in products like tempeh and miso can increase protein digestibility and bioavailability, making them slightly superior in this regard.

Digestibility

Fermentation breaks down anti-nutrients such as phytates and trypsin inhibitors found in raw soybeans. This process enhances the digestibility of nutrients like protein and minerals, making fermented soy products easier on the digestive system.

Probiotics

Fermented soy products like miso, tempeh, and natto are rich in beneficial probiotics. These probiotics can support gut health and improve overall digestion.

Isoflavones

Soy isoflavones are compounds that have been associated with various health benefits, including reduced risk of certain diseases (read here and here). Fermentation can alter the isoflavone composition of soy products, potentially increasing their bioavailability and health-promoting effects.

Fat content

The fat content in non-fermented soy products like tofu and soy milk is relatively low, while some fermented soy products like tempeh and natto contain slightly higher fat content. However, the type of fat in soy products is primarily unsaturated, which is heart-healthy.

Image: Smoked tofu unfermented soy.

Culinary uses

Understanding the culinary uses of both fermented and non-fermented soy products can help you incorporate them into your meals more effectively.

Experimenting with both types of soy products in your cooking can add depth and diversity to your meals while contributing to a balanced diet. Whether you’re a plant-based eater or simply curious about soy, there’s a whole world of culinary exploration waiting for you in the realm of fermented and non-fermented soy products.

Apart from the different flavors to explore, keep in mind that by cooking some of the fermented soy for too long, will waste the probiotics. For example, I don’t boil miso and soy sauce and I consume natto raw. Tempeh, on the other hand, needs to be cooked.

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