The surface of biscuits varies in colour due to physical and chemical changes. Once the moisture is removed from the dough, the surface temperature rises quickly. When the surface reaches about 150degC, the colour changes. The dough then undergoes a process known as caramelisation, a nonenzymatic browning reaction. It is the breakdown of sugars at high temperatures that leads to colour and flavour development.
Chemically leavened bread
In a factory, chemicals are used to create doughs of a uniform consistency. These doughs are then rolled out and passed through a series of rollers to create an outline. Stamping pressure or embossed rollers then cut the desired shape into the sheet. The scrap dough is removed for reprocessing. Using docking pins, designs can be impressed into the pieces of dough. The pins help prevent excessive gas bubbles while the cutting edge penetrates the dough.
The chemicals used for chemical leavening can come in a variety of forms and can be purchased in the grocery store or online. Baking powder is an example of one type of chemical leaven. It is usually composed of baking soda and cream of tartar. These compounds are extremely fast-acting and begin to react with liquid as soon as they are mixed with the dry ingredients. This allows for a quick bread to be prepared.
Although this ingredient was first discovered in 1959, it wasn’t until the 1980s that bread makers began to find out about it. The bright yellow crystals that ACA produces break down into semicarbazide and urethane. The former is considered a human carcinogen, while the latter has not been proven to be harmful to humans. The latter, however, has been linked to asthma amongst factory workers.
The main difference between chemically leavened bread and traditional breads lies in how the two processes work. Chemical leavening agents are usually more effective than yeast as they provide a faster rise and shorter preparation time. They also provide a better release of CO2 during baking, which is essential to a successful crumb structure and air pockets. These factors ultimately affect the taste, color, and texture of the bread.
In industrial bread, the yeast is mixed with a liquid. This liquid contains both a gas and a liquid. Yeast will then convert the invert sugar to dextrose, which is the preferred form for bread. Other leavening agents are also used, including potassium bicarbonate. This model requires knowledge of the Pitzer interaction coefficients. Roy et al. (2004) published a study on this topic.
The role of agents in chemically leavened bread is controversial. It raises questions about the effectiveness of ammonium bicarbonate as a leavening agent. Moreover, the low proportion of NH3 in the gas phase makes ammonia gas escape from the biscuits and leave the baked bread with black or brown spots. A skeptic may question the efficacy of this model, but the end result is the same.
A chemically leavened bread is a product of an improved leavening agent. The improved leavening agent is coated with a lipid layer. This lipid layer protects the chemical leavening agent from water and hydration prior to baking. However, it does not prevent the bread from rising as a result of this coating. A chemically leavened bread contains a high concentration of yeast.
The prior art fluid bed coating technique provides substantially continuous coating. However, the coating contains a high percentage of leavening agent, with only a minimal percentage of coating agent. Furthermore, the prior art coating technique results in a brown spot in the baked product. This coating is too protective and makes the bread too crumbly. This coating is a compromise between safety and taste. In the end, the final product is chemically leavened and is not suitable for human consumption.