Several problems that should be paid attention to in coffee roasting

Conduction means that when the heat is transmitted by the heat source in the past, it causes the molecular vibration in the square and releases the heat energy, which is gradually transferred from the high temperature to the low temperature. The conduction of stainless steel has the phenomenon of uneven heating, which can easily lead to colder and hotter places in the pot.

Convection means that when the material is heated, the fluid material or gas rises due to the expansion of the heated immersion volume and the decrease of density, and its position is filled by the cooler and denser fluid communication around it, and then heated up, and the surrounding material is filled in again. The inexhaustible heating behavior of such reincarnation is convection.

Radiation does not need any preface, heat can be radiated directly to the object to heat it. The most common form of radiation used in food is the use of dielectrics, microwaves or infrared rays. On the other hand, the specific operation of baking is often based on the premise of the situation at that time, using two or three ways to bake at the same time.

To do a good job in baking, every production link should not be ignored, the selection of materials should be fastidious, the weighing of materials should be accurate, and the operation should be attentive.

The problems commonly encountered during coffee roasting are as follows:

First, when the preheating temperature of the oven is insufficient, the coffee beans are immediately put into the oven, delaying the baking time. Therefore, the loss of baking is large, and the color of coffee beans is light, which is due to the lack of heat, the lack of coking of the skin, and even the lack of gloss, and the internal tissue is coarse.

Second, the temperature of the oven is too high, the general situation of roasting coffee forms hard skin prematurely, which suppresses the expansion of the internal tissue, and because of its fast coloring, the operator mistakenly thinks that the product has been baked and finished baking ahead of time. The inside of this kind of bean is sticky and dense, it doesn't expand as it should, and it doesn't have a normal fragrance.

Third, the gap is too long after preheating. The internal furnace which has been dry and hot for too long accumulates too much heat. as soon as the coffee beans are put into the oven, all the heat sources will focus on the general situation of the beans at the initial stage of the baking process, forming too strong heat, and then the heat will disappear and drop rapidly. The constant temperature in the furnace causes the coffee beans to be difficult to ripen inside.

Fourth, the baking time is too much or less than. The baking temperature and time should be adjusted according to the number of beans. A small number of baking silos have more space, and the metal conducts more heat radiation, so the temperature is lower, while when the number is larger, the temperature can be higher. The length of baking time also needs to be adjusted quickly. Most beans are heated from the appearance and surrounding heat to the center of the beans, so the change in the appearance of the beans can be used to observe their baking.

In addition, differences in the type and function of the roaster will also lead to differences in baking time and temperature. In the past, the direct-fired gas up and down fire system is now widely used, and the convection design of energy has been continuously improved. At the same time, the addition of a fan can enhance the thermal convection, make the color of the baked beans more uniform, and save electricity and baking time.

Advanced tools and equipment make the baking process easier to operate, and operators accumulate baking experience.

In short, coffee roasting interviews will face all kinds of problems, only familiar with coffee baking, do not accumulate experience, coupled with measures to local conditions, baristas can grasp superb skills.