What is the function of bread additives?

Function and influence of main components of bread improver;

1. oxidant

At present, the oxidants used in bread quality improvers mainly include potassium bromate, ascorbic acid (vc), azoformamide (ada) and calcium peroxide. The main function of oxidant is to oxidize sulfur and hydrogen in flour into disulfide bonds, thus enhancing the gas retention, elasticity and toughness of dough; Inhibit the activity of protease in flour and protect the gluten and technological characteristics of dough; Bleaching flour to improve the whiteness of bread crust. The use of oxidant in bread production, with a small amount (ranging from 10 ppm to several hundred ppm), has a significant effect on reducing production costs and improving economic benefits.

Potassium bromate was once considered as the most effective dough improver in industry. However, Japanese scholars have proved through experiments that potassium bromate is harmful to human body. 1992, who confirmed that potassium bromate is a carcinogen and should not be added to flour and bread. Most European countries have banned the use of potassium bromate; The United States is the most widely used country of potassium bromate, but the use of potassium bromate has been strictly restricted since 1990s. Most South American countries and Southeast Asian countries, including Hongkong and Taiwan Province Province, are also banned. In order to protect consumers' health, China should also consider banning the use of potassium bromate. Therefore, the research of potassium bromate substitutes has become the key direction of research and application of bread quality improvers in the future.

Azobenzamide (ada) and calcium peroxide are both fast oxidants, which play a role in the early stage of dough fermentation, but fail in the late stage of fermentation. They lack the characteristics of rapid expansion of potassium bromate in the furnace, and may cause fire and explosion when they meet organic substances such as flour, which may have hidden dangers in production safety.

With the improvement of people's awareness of food safety,

Ada will also face the possibility of being suspended. It seems that the only reassuring oxidant in the future is ascorbic acid (vc). Vc is usually regarded as a medium-speed oxidant, and its reaction principle is that vc is oxidized by oxygen in dough to dehydroascorbic acid, and then reacts with sulfhydryl groups to form disulfide bonds, and ascorbic acid is regenerated. Therefore, ascorbic acid is a redox buffer system, and excessive addition will not have adverse effects on gluten. The effect of using vc alone to increase bread volume is not as obvious as that of potassium bromate and ada, but it is still ideal to compound with emulsifier and enzyme preparation.

2. Emulsifier

The most commonly used emulsifiers for bread quality improvers are sodium stearoyl lactate (ssl), calcium stearoyl lactate (csl), diacetyl tartaric acid monoglyceride (datem), sucrose fatty acid ester (se), distilled monoglyceride (dmg) and so on. Through the interaction between starch in flour and protein, various emulsifiers form complex compounds, which can strengthen gluten, improve processing performance, improve bread texture and prolong shelf life. The addition amount is generally 0.2% ~ 0.5% (based on flour).

Sodium/calcium stearoyl lactate (ssl/csl) has the function of strengthening tendons and keeping fresh. On the one hand, it strongly interacts with protein to form gluten protein complex, which makes the gluten network more detailed and elastic, improves the gas retention of yeast fermented dough and increases the volume of baked bread; On the other hand, it interacts with amylose to form insoluble complex, thus inhibiting the aging of amylose and keeping the freshness of baked bread. Ssl/csl can improve the softness of bread while increasing its volume, but its excellent effect will be weakened when it is compounded with other emulsifiers.

Diacetyl tartaric acid monoglyceride (datem) can have a strong interaction with protein, which can improve the air-holding property of fermented dough, thus increasing the volume and elasticity of bread, especially when making soft flour. If only from the perspective of increasing bread volume, datem has the best effect among many emulsifiers, and it is also an ideal way to replace potassium bromate.

Sucrose fatty acid ester (se) is the most commonly used bread quality improver, which can improve the crispness of bread, improve the viscosity of starch paste, the volume and honeycomb structure of bread, and prevent aging. When making bread with refrigerated dough, adding sucrose ester can effectively prevent dough from denaturation during refrigeration.

Distilled monoglyceride (dmg). Its main function is as a bread tissue softener, which plays an anti-aging and fresh-keeping role in bread. It is often used in conjunction with other emulsifiers to play a synergistic role.

3. Enzyme preparation

As a biomacromolecule, enzyme preparation has high safety. Enzymes used in bread improvers generally include fungal α-amylase, xylanase and glucose oxidase. The dosage varies from a few ppm to tens of ppm.

Fungal α -amylase belongs to mesophilic amylase, which can be completely inactivated during bread baking and will not cause the bread core to become sticky due to excessive degradation. Normal flour contains enough β-amylase, but α -amylase is not enough. There is more or less broken starch in flour, which is the substrate of α -amylase By degrading broken starch and gelatinized starch particles, the membrane structure of gluten network is improved, the viscoelasticity of the membrane is increased, the volume of bread is increased, and the softness of bread is improved.

Traditionally, the xylanase used to improve dough processability and baking swelling performance is pentosanase (also called hemicellulase), and xylanase is the main enzyme. Xylanase is a more specific pentosanase, which acts on soluble and insoluble xylanases in flour, thus improving the elasticity and strength of gluten network, improving the endurance and stability of dough to excessive fermentation, and improving the volume and texture of bread.

Glucose oxidase can oxidize glucose into glucoamylase, water and oxygen, and then oxidize sulfhydryl groups in gluten into disulfide bonds, thus improving the mechanical stirring characteristics of dough, strengthening gluten network, increasing dough strength and bread volume. Its function is similar to that of oxidant, but it is safer and more efficient.

Now, the government and the public's understanding of the importance of food safety has risen to a higher level. Therefore, when the safety of potassium bromate is questioned, all kinds of laws and regulations prohibiting the use of potassium bromate in food are put on the agenda, and the research on potassium bromate substitutes has become the focus of food additive research and development workers in the future. There is no single substitute for potassium bromate, but according to different flour qualities and uses, through careful experiments and scientific analysis methods and coordination, the effect of potassium bromate can reach or exceed.