Course:FNH200/Projects/2024/Tofu

History

Group of individuals preparing tofu

Tofu, also known as bean curd, is a popular food in many countries due to its high nutritional value. Around 2000 years ago, Tofu was discovered by a Chinese cook. Nowadays, Tofu is widely consumed by people around the world, including China, Japan, Korea, Singapore, Thailand, Americas, Australia, etc..  

Production, Processing, and packaging of tofu

Production and Processing

Coagulating Soy Milk

The ingredients for making tofu include water, soybeans, and coagulating agents.  Tofu processing begins by first carefully picking soybeans, which are cleansed thoroughly. Then the manufacturing process begins with soaking, grinding, and cooking soybeans. Once the mixture is prepared, it undergoes filtration to extract soy milk. Next, the soy milk is coagulated using different salts, acids, or enzymes depending on the desired type of tofu. The resulting curds are then pressed under controlled pressure to achieve the desired firmness and slice into one-pound blocks.

Packaging

The packaging of tofu takes place in different steps to ensure that it is fresh and safe for consumption. When the tofu has been fully produced and processed, it is then pressed down and cut into desirable shapes. Afterwards, the tofu is placed into these containers where the material is plastic and is filled with water. The reason for the water is to keep the moisture of the tofu. Then the containers are tightly sealed so that the package becomes aseptic. Then comes the labeling in which the manufactures are required to label the product with information such as branding, expiration date, nutritional facts, and other information that regulators, such as the Canadian Food Inspection Agency, would require to have.  

Pasteurizing and Storage

Tofu pasteurizer

After being packaged, tofu is pasteurized at around 82 °C to extend the shelf life to approximately 30 days. After pasteurization, tofu is put in water to chill down, then it is packed into boxes and shipped to different distribution centers. Ultra-high temperature (UHT) and aseptic package can also be used to process tofu and extend the shelf life. Following the pasteurization, tofu is then stored at low temperature in the refrigerator, below 7 °C to keep it fresh for up to 30 days.  

Regulations of tofu in Canada  

For the regulations of tofu in Canada, tofu is regulated under the Foods and Drugs Act. If you look at the nutrient content claims sections food group and reference food of the same food group, you can find tofu. This means the Canadian Food Inspection Agency (CFIA) ensures that the quality and standards of the food are met and enforced.  

Types of tofu

Silken tofu

Silken tofu is made by coagulating the soy milk without curdling the milk. It has a high-water content. It has a smooth and creamy texture. The tofu can be soft, firm, or extra firm. It is used in various types of salads, hot pots, and vegan dishes. Silken tofu works well in creamy and blended foods like smoothies, desserts, puddings, salad dressings, sauces, and dips. It can also be used as an egg substitute in baking.

Silken tofu

Firm tofu

Firm tofu can be stir-fried and pan-fried as it absorbs flavors well. It's commonly used in tofu scramble and great crumbled and as a substitute for ricotta cheese.

Extra-firm tofu

Extra-firm tofu holds its shape well and is excellent for slicing, cubing, and all kinds of frying: pan-frying, a quick stir fry, deep-frying. It can also be baked, grilled, or crumbled and used like ground meat. Andrea Nguyen, author of the Asian Tofu cookbook said that the more solid the tofu is, the more difficult it can be to infuse with flavor

Super-firm tofu

This type of tofu is high in protein and very dense. It drys out quickly when baking or grilling on high heat and won't fall apart due to the low water content.

Super firm vs extra firm tofu

Sprouted tofu

Known as the natural process of germination, soaking soybeans for a few days causes them to sprout somewhat, leading to the creation of sprouted tofu. Soybeans that have been sprouted have higher protein, amino acid, sugar, and vitamin contents, as well as improved nutrition and bioactive substances. Increased nutritional absorption results from the germination process's assistance in breaking down anti-nutrients and heavy starches, which are more difficult for humans to digest.

Sprouted tofu

Fermented tofu  

Fermented tofu is a Chinese condiment by pickling tofu in a mixture of salt, rice wine, sesame oil or vinegar and then fermenting altogether. This fermenting gives a tofu deep, savory flavor called umami. In Chinese cooking, fermented tofu is not used as an ingredient but as flavoring.

Fermented tofu

Nutrients of tofu, potential health benefits  

Tofu is an excellent source of non-animal protein, vitamins, and minerals. Tofu contains soya protein, A, C, D, E, K and B vitamins, various minerals (e.g., calcium, magnesium, iron, potassium). In addition, tofu contains omega-3 fatty acids and essential amino acids, which are important to maintain a healthy and balanced diet A block of hard tofu weighing 122 g contains 177 calories. It has 15.57 g of protein, 12.19 g of fat, 5.36 g of carbohydrates. The block also includes 421 mg of calcium, 282 mg of phosphorus, 178 mg of potassium, 65 mg of magnesium, 27 mg of folate, 3.35 mg of iron, 2 mg of zinc. Additionally, it provides small quantities of niacin, riboflavin, thiamin, vitamin B-6, choline, manganese, and selenium. The recommendation of daily consumption of protein for female and male is 46 g and 56 g, respectively; therefore, 0.80 g of decent quality protein/kg body weight/day is needed by an adult. An average adult weighing 60 kg needs 48 g protein, and a block of hard tofu contains 15.57 g of protein, which provides a substantial amount.

Tofu has various health benefits. The soy peptides found in tofu possess antioxidant and anti-inflammatory properties that help prevent oxidative and inflammatory damage in blood vessels, which is beneficial in preventing cardiovascular disease. Research shows that high tofu intake has a protective effect in breast cancer in pre- and postmenopausal women. Tofu is particularly beneficial for menopausal women as it aids in estrogen production and reduces the incidence of hot flashes. Tofu contains soy isoflavones, which increases bone mineral density significantly and decreases the bone urine deoxypyridinoline, helping in bone strengthening and prevent osteoporosis in women. Meat consumption is associated with common health issues such as high blood cholesterol and hypertension, which can be mitigated by tofu since it is rich in good cholesterol and omega-3 fatty acids.  

Tofu with mixed vegetables

Although research shows that soy-based products can help prevent breast cancer, women with a family history of breast cancer and those who are having active breast cancer diagnosis are suggested to avoid tofu. Tofu is not recommended to people with kidney and gallbladder stones. Individuals born with congenital hypothyroidism or those with hypothyroidism are suggested to avoid eating soybeans and soy products, such as tofu. Additionally, research has shown that tofu intake is likely unrelated to the risk of stroke. People may experience gas, bloating, diarrhea, nausea, or vomiting after tofu consumption; therefore, it is essential to consume tofu in moderation to gain health benefits and prevent potential health problems.

Exam Question

Question: Select all of the above that are true, regarding tofu’s nutritional benefits and potential health benefits.

Options:

A: High intake of protein has a protective effect in breast cancer in pre- and postmenopausal women.

B: Tofu will never cause any side effects like bloating, diarrhea, and nausea.

C: Women with a family history of breast cancer and those who are having active breast cancer should eat tofu.

D: Tofu is not recommended for those with kidney and gallbladder stones.

E: Tofu should be consumed regularly by individuals with congenital hypothyroidism.

Correct answers are A and D. B is wrong because Tofu sometimes can cause those side effects. C and E is wrong because individuals following that criteria should not eat tofu.  

Why this question should be on the final exam?  

This multiple answer-based question should be on the final exam because it thoroughly tests the understanding of tofu nutrition and health benefits of students. It requires those to really examine the options and do their research properly because answers like A and C both look virtually the same, but one isn’t true due to a slight difference. Furthermore, tofu is a regular dish in many cultures so it is important for everyone to know the health benefits and potential health problems it can cause.