The flour is chewy, white and delicious! Is it because of "technology and hard work"?

The staple food of many families in my country is mainly wheat, such as steamed buns, flower rolls, dumplings, steamed bread, etc. Therefore, the demand for flour is very high. China is also the world's largest wheat producer and consumer, and its wheat production accounts for 17% of the global total.

With the improvement of living standards, people's concept has changed from eating enough and eating well to paying more attention to the nutrition and safety of food. Therefore, more and more people have begun to pay attention to the food safety of flour.

Although this is a good change in concept, some people have fallen into misunderstandings. For example, there are some videos on the Internet about the "technology and hard work" of flour, which mention different types of flour and the health hazards of additives in flour, making many people afraid to even eat flour.

What are the nutritional values ​​of different flours? Should we not eat flour if it contains additives? What should we pay attention to when buying flour? This article will answer your questions and help you eat noodles with confidence!

01

Wheat becomes flour, "one wheat, multiple uses"

Most of the flour we eat is processed from wheat, which is the entire wheat including the bran, aleurone, endosperm and germ.

The bran is rich in dietary fiber, B vitamins, minerals and phytochemicals; the endosperm contains protein, fat, rich B vitamins and minerals; the endosperm contains starch and a small amount of protein; the germ is relatively nutritious, containing protein, fat, polyunsaturated fatty acids, vitamin E, B vitamins and minerals. [1]

Image source: "Dietary Guidelines for Chinese Residents 2022 Edition"

Different parts of wheat can be processed into different flours, which differ in nutrition and uses.

▶ Wheat flour: Wheat flour is the most common type of flour we see in supermarkets. It is made by removing the outer layer of the wheat grain, including the cortex, endosperm, germ, etc., and then grinding the endosperm to make flour. [2]

Therefore, the nutrients contained in wheat flour are the nutrients in the wheat endosperm, including starch and a small amount of protein. The protein content of household wheat flour is usually around 10%, and because the bran content is very small, the dietary fiber content is very low, only around 3%. [3] Moreover, the higher the processing precision, the greater the nutritional loss, but the higher the grade marked on the package.

The strong flour seen on the market is also a kind of wheat flour, also known as special first-class flour, most of which are medium-gluten flour, and the protein content is generally around 11%. If the protein content is ≥12.2%, it is high-gluten flour.

Image source: A certain brand of high-gluten flour

Ordinary wheat flour is suitable for making most common pasta such as steamed buns, flower rolls, dumplings, and cakes; while high-gluten flour can be used to make dumplings and noodles as well as bread.

▶ Wheat core flour: It is flour ground from the central part of the wheat endosperm, and is also a type of wheat flour. It is also suitable for making common pasta such as steamed buns and flower rolls, but the flour is softer in color and has a more delicate taste.

Figure: E-commerce platform

▶ Whole wheat flour: It is flour ground from the whole wheat, including all the components of wheat such as bran, endosperm and germ. The texture and taste are relatively rough, retaining the nutrients of wheat to the greatest extent. Whole wheat flour contains almost all the nutrients contained in various parts of wheat.

The protein content of whole wheat flour can reach more than 14%. [3] Since it contains wheat bran, the dietary fiber content is higher, nearly 5 times that of household wheat flour. Rich dietary fiber is helpful in improving intestinal health, preventing intestinal diseases, constipation, diabetes and cardiovascular diseases.

Whole wheat flour is also suitable for making steamed buns, flower rolls, dumplings and other foods, and can also be used to make whole wheat bread.

▶ Wheat germ powder: The germ only accounts for 2% to 3% of the wheat grain. In addition to nutrients such as protein, fat, polyunsaturated fatty acids, vitamin E, B vitamins and minerals, it also contains plant sterols, which have antioxidant and free radical scavenging effects, can reduce oxidative damage in the body, and regulate sugar metabolism. [2]

Wheat germ powder cannot be used directly to make pasta. It is usually added to food when making porridge or soy milk.

02

Are additives in flour harmful to the body?

In order to improve the texture, color and shelf life of flour, some flours on the market also contain food additives. Some videos circulating online also mentioned the "technology and hard work" of flour, and said that if you eat such flour, it will cause great harm to the body. This makes many people afraid to eat flour, but there is no need to panic.

The food additives involved in flour include azodicarbonamide and benzoyl peroxide.

Although azodicarbonamide is an industrial product used to make rubber soles, artificial leather, and yoga mats, long-term exposure to large amounts of azodicarbonamide can affect the health of the respiratory system and easily lead to dermatitis and asthma. [4] However, the Joint Food and Agriculture Organization (FAO)/World Health Organization (WHO) Expert Committee on Food Additives (JECFA) has evaluated the safety of azodicarbonamide as a food additive and believes that the acceptable level of azodicarbonamide as a flour treatment agent is 0-45 mg/kg flour. A small amount can be added to flour to enhance elasticity and toughness.

Because when azodicarbonamide is mixed with flour to make dough, it can oxidize the sulfhydryl groups in the flour protein into disulfide bonds. The disulfide bonds can form a three-dimensional network structure between the proteins, thereby increasing the elasticity and toughness of the flour.

The usage regulations of azodicarbonamide in my country's "Food Additives Usage Standard GB 2760-2014" are consistent with international standards. Azodicarbonamide is allowed to be used as a flour treatment agent for wheat flour, with a maximum usage of 45 mg/kg. Use within the prescribed range will not cause harm to the body.

Image source: GB 2760-2014

Azodicarbonamide is very stable in dry flour, but it will be converted into biurea when it reacts with water. Biurea will not be decomposed in the digestive tract and will not be absorbed by the gastrointestinal tract. It can be excreted from the body with urine and feces. Related studies have not found that biurea is harmful to the human body. After the flour is made into pasta and heated, biurea will continue to decompose into semicarbazide under high temperature. Some studies have found that semicarbazide has a certain weak carcinogenicity to animals. The International Agency for Research on Cancer has classified it as a Class 3 carcinogen, which means that the existing evidence cannot show that semicarbazide has a carcinogenic effect on humans. [4]

In addition, azodicarbonamide can react with ethanol to produce ethyl carbamate, which is closely related to bread baking. The Food and Agriculture Organization of the United Nations, the World Health Organization and the Joint Expert Committee on Food Additives conducted a risk assessment on ethyl carbamate in 2005. The results showed that the acute toxicity of ethyl carbamate after oral administration is very low and there is no need to worry too much. [4]

Furthermore, azodicarbonamide is not often added to ordinary wheat flour, and most of it is found in bread flour or high-gluten flour. In 2016, Jinan City tested 50 types of flour from 12 well-known brands and 20 types of flour from 16 unknown brands. The results showed that the detection rate of azodicarbonamide in high-gluten flour was 42.9%, and the rate of exceeding the standard was 10.7%. The detection rate of azodicarbonamide in non-high-gluten flour was only 21.4%, and the rate of exceeding the standard was 0%. [5]

Image source: e-commerce platform

As for benzoyl peroxide, it was once a widely used whitening agent and improver in my country. Adding it to flour can whiten it, kill certain microorganisms in the flour, sterilize and preserve it, and extend the shelf life of the flour.

However, benzoyl peroxide not only destroys vitamin E, vitamin B, and carotene in flour, but is also toxic. Long-term consumption of flour containing excessive benzoyl peroxide can cause malnutrition, liver damage, and chronic benzene poisoning. [6]

Considering food safety, China has banned the addition of benzoyl peroxide to flour since May 1, 2011.

In addition, some videos also mentioned that talcum powder, bleaching powder and borax are added to make flour whiter. The former talcum powder is a food additive. my country's "Food Additives Use Standard GB 2760-2014" stipulates that talcum powder can be added to cold fruits and dried foods according to the standard, and is not allowed to be added to flour; the latter two are not food additives and are prohibited from being used in food. If they appear in food, they are illegal additives.

Image source: GB 2760-2014

In other words, as long as the flour you buy is produced by a regular company, it generally will not contain talcum powder, bleaching powder, or borax, so there is no need to worry too much about this.

03

What determines whether flour is white or not? [7, 8]

The whiter the flour, the more appetizing the steamed buns made from it look. There are many factors that affect the color of flour, and it does not always become white because of the addition of food additives.

▶ Types of wheat: At present, the whiteness of wheat flour of most wheat varieties in my country is generally around 75, and varieties with a whiteness higher than 80 are mostly weak-gluten wheat varieties. Hard wheat contains a high level of carotene and its endosperm is yellow, so the processed wheat flour will also be yellowish in color.

▶ Wheat harvesting time: Newly harvested wheat has high physiological activity, loose structure, poor quality stability, and dark color after being processed into flour.

▶ Processing process: The higher the bran content in the flour, the poorer the whiteness will be; the higher the processing precision of the flour, the less the bran content and the higher the whiteness value; for the same batch of wheat, the lower the moisture content of the flour, the brighter the color.

▶ Storage conditions: During storage, heating and insect infestation will affect the whiteness of the flour. The color and quality of flour from aged wheat are poor. Infested wheat contains a small amount of insect eggs and their excrement, which can easily cause the flour to darken in color due to hormone reactions when it is ground into flour.

In addition, the sowing period of wheat, the minerals in the growing environment, the nitrogen content, etc. will also affect the color of wheat flour. Therefore, the white color of wheat flour does not necessarily mean the addition of whitening agents, but normal flour is not particularly white, generally milky white or slightly yellowish.

04

How to choose flour?

▶ Look at the label: First, choose flour from a regular manufacturer, and don't buy bulk flour from small vendors. Secondly, when choosing flour, look at the ingredient list on the package. If you mind food additives, choose one that only has wheat in its ingredients and has a relatively high protein content in the nutrition label.

If you choose whole wheat flour, you should also look at the dietary fiber content. The recommended standard for the grain industry issued by my country's State Grain Administration, "LS/T 3244-2015 Whole Wheat Flour", stipulates that the dietary fiber content of whole wheat flour must be ≥9%. When buying, it is best to choose one with a relatively higher content, so that you can supplement more dietary fiber.

Image source: e-commerce platform

▶ Depends on the purpose: for making steamed buns, flower rolls, dumplings, cakes, noodles and other general pasta, you can choose wheat flour, enriched flour, wheat core flour, etc.; if you want to make bread, it is recommended to choose high-gluten flour (protein content ≥12.2%); for making cakes, you can choose low-gluten flour, low-gluten flour (protein content ≤10%).

▶ Look at the color and state: The color of normal wheat flour is milky white or slightly yellowish, and there are no lumps or foreign matter; the color of whole wheat flour is yellowish brown.

▶ Smell: Normal flour has the aroma of wheat and should not have any strange smell, rancid smell or moldy smell.

Summary: Food is the most important thing for people, and food safety comes first. It is right to pay attention to food safety and choose healthy food, but don’t worry too much about it. When buying any food, as long as you buy it from a regular supermarket, you can generally eat it with confidence.

References:

[1] Chinese Nutrition Society. Dietary Guidelines for Chinese Residents[M]. People's Medical Publishing House. 2022

[2] Song Guihua, Liu Rui, Wang Xulin, Wu Guiling, Sun Junmao, Wei Yimin. Nutritional characteristics and nutritional pathways of wheat and its products[J]. Journal of the Chinese Cereals and Oils Association, 2020, 35(07): 180-187.

[3] Niu Meng, Hou Guoquan. Whole wheat flour and its products: nutritional composition, health benefits and quality improvement[J]. Journal of Cereals, Oils and Food Science and Technology, 2022, 30(02): 8-17. DOI: 10.16210/j.cnki.1007-7561.2022.02.002.

[4] Wu Han, Chen Bo. Effects of azodicarbonamide on human health[J]. Shanghai Journal of Preventive Medicine, 2017, 29(10): 813-818. DOI: 10.19428/j.cnki.sjpm.2017.10.019.

[5] Wang He, Liu Lijun, Wei Yanxin, Zhang Wenbo, Chen Fangfang, Shao Lihua. Detection and analysis of azodicarbonamide content in flour sold in Jinan[J]. Shandong Chemical Industry, 2016, 45(14): 51-52. DOI: 10.19319/j.cnki.issn.1008-021x.2016.14.020.

[6] Wu Cunbing, Tian Linshuang, Zhang Shanshan, Wu Junyan. Function and risk analysis of benzoyl peroxide in wheat flour[J]. Hubei Agricultural Sciences, 2011, 50(12): 2513-2515. DOI: 10.14088/j.cnki.issn0439-8114.2011.12.009.

[7] Zhao Xiaomin. Main factors affecting wheat flour whiteness[J]. Modern Flour Industry, 2015, 29(02):12.

[8] Li Linxuan. Discussion on factors affecting wheat flour whiteness and wheat flour quality and safety[J]. Modern Flour Industry, 2012, 26(06): 7-10.

Author: Xue Qingxin, registered nutritionist

Review | Zhang Na, Associate Researcher, Doctoral Supervisor, Peking University School of Public Health

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