Tofu

Tofu is a food first recorded in China 2000 years ago.  It spread from China to many other Asian countries and lately to most Western countries. 

Nutritional content of tofu. The various sources I have looked vary dramatically. The results I have quoted are only one possibility.  All the sites say the following: tofu contains very few calories; contains large amounts of protin; contains all the essential amino acids your body needs; most of the fat is unsaturated. The minerals it contains can vary depending on the coagulant used in manufacture but generally there is a lot of calcium (130 mg; 13%) and iron (1.1 mg; 8%).

Tofu also contains isoflavones.  The main ones function as phytoestrogen. They function in the body as estrogen.  Basically tofu contains soy isoflavones which act like estrogen.

Tofu contains anti-nutrients such as trypsin inhibitors, phytates and lectins. They interfere with the absorption and digestion of nutrients. Fermentation reduces the anti-nutrients.

100gm Tofu

291 kJ (70 kcal)

1.5 gm carbohydrates (1%)

4.8 gm fat (7%)

Dietary fiber 0.3gm (1%)

Protein 8 gm (16%)

Tofu is made from soy milk. Soya beans are soaked, ground, boiled and strained to make soy milk. The soy milk is then coagulated. Coagulation means turning the protein and oil suspension in the soy milk into a solid and a liquid. The mixture should resemble curds and whey. The thin watery liquid is strained from the solid particles.  There are many different coagulants that can be used to turn soy milk into curds and whey.

• ·         Calcium sulfate (gypsum): traditional in China. Resultant tofu is high in calcium. No taste.

• ·         Magnesium chloride and calcium chloride: Tofu is smooth and tender. No taste. Common in Western countries. Called Nigari.
• ·         Naturally occurring edible acids: Glucono delta-lactone, acetic acid, citric acid can affect the taste, create a soft smooth tofu.
• ·         Enzyme such as papain or proteases from microorganisms.
• ·         More than one coagulant can be used at once.

The amount of water extracted from the tofu curds determines the texture of the final tofu. If the curds are lightly pressed and lightly strained soft tofu is the result. Soft tofu contains the largest amount of water. Firmer tofu bounces back when pressed and more closely resembles meat. The drier forms of tofu can be processed, pickled or dried further.

Other liquids can be coagulated to produce something similar to tofu. “Tofu” has been made from almond milk, coconut milk, mango juice, eggs, sesame seeds or peanuts. Basically if a liquid contains a suspension it is possible to turn the suspension into a solid.

Tofu versus meat

In Australia tofu is generally considered a healthy alternative to meat. 

Is the protein in tofu better for you than protein in meat? No it is the same amino acids. Meat may be tougher or chewier. That is because meat contains gristle and tendons. Not because the protein is different.

How does the nutrition content of tofu compare with animal meat?  Is it healthier than meat?

100gm of meat will contain 0 carbs, 20 gm fat, 290 calories, 0 fiber and the protein equivalent to 50 gm of tofu.

Animal meat contains more protein. The fat in meat is largely unhealthy saturated fat.  Tofu largely contains healthy fat but a lot depends on how you cook the tofu. Tofu absorbs liquids and if deep fried can contain more fat than meat. If you want the cardiovascular benefits of tofu (lower total cholesterol, lower LDL) then remember tofu readily absorbs the cooking oil.

What is the ethical difference between animal meat and tofu? Growing soya beans versus killing animals. Tofu wins.

Is tofu environmentally sounder than meat? Growing soya beans versus growing pasture or a crop and then feeding it to cattle.  Tofu wins.

Cooking

In Asian cooking, tofu can be eaten raw, boiled, steamed or stir-fried. It can be cooked in a soup, cooked in a sauce, or stuffed with fillings. The idea of using tofu as a meat substitute is not common in Asia.

In Western cooking (anything except traditional Asian cooking) the firm tofu is often used as a meat substitute and grilled, fried, boiled or roasted.   The softer types are used in desserts, soups, shakes and sauces.  Tofu is bland and takes up any flavor available.  If grilled or fried then it can be marinated first. Softer tofu can be used as a cheese replacement. In any recipe you can replace the cheese with soft tofu. Tofu can be used in Indian-style curries replacing the paneer cheese.

Health and Nutrient Benefits

According to some work, replacing meat and dairy with tofu leads to an increased intake of folate, vitamin K, calcium, magnesium, iron, fiber and will lower intake of cholesterol and saturated fat.

Cardiovascular Benefits of Tofu

Fermented soy foods contain peptides that have anti-oxidant and anti-inflammatory properties and blood pressure lowering properties. 

The main effect of soy intake is the lowering of LDL cholesterol. Raising of the HDL is less likely.

Soy isoflavones can decrease blood vessel inflammation and improve their elasticity

Tofu also contains saponins which are known to improve blood cholesterol.

The theory says tofu is better than meat for cardiovascular health.

Cancer Prevention Benefits

In the lab soy isoflavones (genistein) has been shown to suppress cancer cells. The medical profession is divided. Some say genistein helps protect against breast, ovarian, endometrial and prostate cancers.  Some say large amounts of dietary soy promote hormone related cancers (breast and prostate).

What do the clinical studies show? Many show consumption of soy products and decreased incidence of breast cancer. Many clinical studies have shown no increased risk of breast cancer (even in post-menopausal women).

Cancer of the digestive system. Increased intake of tofu has been linked with less cancer.

Tofu and Prostate Cancer. Increased consumption of soy has been linked to lower risk of prostate cancer.

Obesity Benefits

Tofu contains peptides involved in obesity prevention and treatment. They lead to less fat cells in the body. Fermented tofu contains more of these favorable peptides.

One study showed intake of soy isoflavones resulted in weight loss.

Diabetic benefits

Studies have shown soy isoflavones have good effects on blood sugar levels and insulin activity. 

Animal studies also have shown soy foods lead to improved insulin activity and less risk of diabetes.

You cannot say tofu prevents diabetes but you can say tofu doesn’t cause diabetes and may be more beneficial than harmful.

Bone health      Studies suggest ingestion of soy isoflavones reduces bone loss.

Brain function     Soy isoflavones may be good for brain memory and brain function.

Skin Soy isoflavones may decrease wrinkles and improve skin elasticity.

Potential medical problems 

Certain doctors have advised certain people to avoid soy products. Doctors have been concerned about the following medical states:

Kidney or gallbladder stones. Tofu contains oxalates.

Breast tumors. Tofu has weak hormonal effects.

 

Thyroid disease. Tofu contains goitrogen.

Children.  Soy isoflavones may interfere with the development of reproductive organs.