The leavening agent, also known as baking powder, foaming powder, and baking powder, is decomposed by heat during food processing to generate gas, which makes the dough rise and form a dense porous structure, thereby making the product bulky, soft or crisp. Leavening agent is an indispensable additive in wheat flour products, and compound leavening agent is one of the most widely used leavening agents at present.
Leavening agents play an important role in food manufacturing. In order to make bread, cakes, steamed buns and other foods soft in taste, the dough must maintain a sufficient amount of gas during production. Most of the gas required for food manufacturing is provided by leavening agents. The leavening agent can not only make the food produce a soft sponge-like porous tissue, make it soft and delicious, and expand the volume, but also can make the saliva quickly penetrate into the tissue of the product when chewing, so as to exude the soluble substances in the product and stimulate the sense of taste. nerve, so that it quickly reflects the flavor of food.
Classification of leavening agents
Leavening agents can be divided into two categories: biological leavening agents and chemical leavening agents.
Biological leavening agents mainly refer to yeast and fermentation aids. Yeast widely exists in nature, has a long history of use, is non-toxic, convenient to cultivate, cheap and easy to obtain, and has good use characteristics. In the past, a large amount of fresh yeast was used in food. Since it is not suitable for storage and takes a long time to make, active dry yeast obtained by pressing and drying fresh yeast at low temperature has been widely used.
Chemical leavening agents, including alkaline leavening agents such as sodium bicarbonate (also known as "baking soda"), ammonium bicarbonate, etc., and composite leavening agents. Among them, sodium bicarbonate and ammonium bicarbonate are single leavening agents. Both are basic compounds that decompose when heated to produce gases such as carbon dioxide. Because the residues of sodium bicarbonate decomposed will have saponification reaction with oils and fats at high temperatures, resulting in poor product quality, impure taste, increased pH, darker color, and damage to the tissue structure; and ammonium bicarbonate decomposition produces Ammonia gas is easily soluble in water to form ammonia water, which makes the product smelly, increases the pH value, and seriously destroys vitamins. Therefore, sodium bicarbonate and ammonium bicarbonate are usually only used for products with low water content in products, such as biscuits . However, most of the leavening agents used in practice are composite leavening agents composed of different substances.
Compound leavening agents are usually composed of three components, namely carbonates, acidic substances and other substances such as additives. Among them, the interaction of carbonate and acidic substances can generate carbon dioxide, which makes the dough embryo start. Carbon dioxide can reduce the alkalinity of products, adjust the pH of food, remove peculiar smell, control the reaction speed, and fully improve the efficiency of the leavening agent. The compound leavening agent is mainly starch, and the dosage is about 10%-40%. Its function is to control and adjust the speed of carbon dioxide gas generation, make the bubbles uniform, prolong the preservation of the leavening agent, prevent moisture absorption, invalid.
When formulating aluminum-free compound leavening agent, various raw materials should be fully dried, crushed and sieved to make the particles fine and help to mix uniformly. Aluminum-free leavening agents have many advantages, such as safety, efficiency and convenience, and have become the first choice for food companies.
Application of compound leavening agent in food
The application of leavening agent in the food production process mainly involves three parts: kneading, proofing and heating. In this process, the effect of leavening agent must be effectively controlled in order to obtain satisfactory products.
In the noodle mixing stage, the carbon dioxide bubbles generated by the reaction of acid salts and sodium bicarbonate easily form foaming points on the water-oil interface. The number and location of these foaming points determines the final number and location of pores in the product, as no new foaming points are formed during the proofing and baking stages.
In the proofing stage, a strong bulking effect is not expected, because the proofing time varies greatly depending on the product variety, and the occurrence of the bulking effect needs to be controlled. In the baking stage, it is hoped that the bulking effect will re-occur, so that the original foaming point expands into the final large bubbles, so as to obtain the necessary softness. If the expansion is too fast at this time, the generated gas will run away when the pores of the dough are not strong enough and set, and the pores will disappear; if the reaction is too slow, a large amount of gas will be generated after the dough has been baked and solidified. It may crack the product.
The gas production rate of the leavening agent is adapted to the physical changes of the dough, so that the original gas production point can be expanded into air bubbles, resulting in a sponge-like honeycomb structure, so that the product texture is bulky. This kind of puffing to a certain degree during the dough mixing, the puffing is suspended or slow in the proofing stage, and the puffing starts again in the baking, steaming and frying stage to complete the whole puffing process, which is called "secondary puffing".
To sum up, only by selecting an appropriate type of acid salt, so that the reaction with carbonate is consistent with the food processing process, can the food have a good bulking effect.
The gas production rate of the compound leavening agent depends on the reaction rate of the acid salt and sodium bicarbonate. Different products require different gas production rates for the baking powder. For example, the baking powder used in cakes should be double-baking powder, because if there is too much gas in the early stage of baking, the volume will expand rapidly, the cake tissue has not yet coagulated, the finished product is easy to collapse and the tissue is thick, but it cannot continue to expand in the later stage; There is too much baking powder in the slow speed, and the initial expansion is slow. After the product is coagulated, part of the baking powder has not yet produced gas, which makes the cake small in size and loses the meaning of puffiness. The baking powder used for steamed buns and steamed buns needs to produce gas a little faster because the dough is relatively hard. If there is too much gas production after condensation, the finished product will appear "blooming". For fried foods such as fried dough sticks, you need baking powder that produces as little gas as possible at room temperature and produces gas quickly when heated. In the preparation of the compound leavening agent, the reaction between sodium bicarbonate and acid should be as thorough as possible. On the one hand, the gas production can be large; ,taste.
When yeast and compound leavening agent are used alone, each has its own shortcomings. The fermentation time of yeast alone is longer, and the sponge-like structure of the finished product is too dense; while the compound leavening agent is used alone, the production speed is fast, but the tissue structure is loose and the taste is rough. The combination of the two can produce more ideal products. Nowadays, the compound application of yeast and baking powder in the production of steamed bread and steamed buns, especially steamed buns, has become a common phenomenon, and the effect is good.
The development trend of leavening agent
Research in recent years has shown that too much aluminum in leavening agents is not good for the human body. Excessive intake of aluminum can affect human health. According to my country's "National Food Safety Standard for the Use of Food Additives" (GB2760-2014), the residual amount of aluminum in the flour-based food made by frying and baking should be ≤100 mg/kg. At present, the new compound aluminum-free leavening agent has been widely used in the market, basically replacing the leavening agent containing alum.
In the future, leavening agents should develop in the direction of specialization, serialization and customization. For different types and grades of products, adding emulsifiers, thickeners, enzymes, antioxidants, functional components, etc. to develop special leavening agents will be the development direction. According to the different raw materials, processes and formulas used by each customer, compound leavening agent products can also be customized for customers.
At present, emulsifiers have been used in leavening agents, which play an anti-aging effect and increase the volume of products to a certain extent. At the same time, the addition of the emulsifier improves the crispness of the fried products, reduces the oil absorption rate, and improves the taste. The study found that adding a thickener to fried food can improve the viscosity of fried food at high temperature, help the formation of dough network structure, and improve the product structure of fried food. At the same time, the properties of the thickener can also enhance and consolidate the puffing effect of the fried food. Therefore, in the production of fried products, thickener ingredients can be added to the aluminum-free leavening agent formula. In addition, the introduction of some enzyme preparations can improve the properties of the dough, soften the dough, and also obtain products with better leavening effect and taste. In the future, it should be aimed at Chinese-style cooking foods such as steamed buns and steamed buns, baked products such as cakes and biscuits, fried foods such as fried dough sticks, puffed foods such as sachima and twist, snack foods such as spicy and soy products, and quick-frozen buns and other quick-frozen pastries. , to develop special serialized leavening agent products to meet the needs of the constantly developing modern food industry.
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