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Fried Food Processing Technology (Part 2)

Sep. 22, 2020

3. How to deep-fry food?

The key to frying machine is the control of oil temperature and frying time.

The oil temperature and the length of frying time should be properly controlled according to factors such as product variety, raw material conditions, block size and thickness, and heated surface agent size.

The oil temperature is high, which may make the product unripe or incompletely fried;

If the oil temperature is too low, the product will have a light color, fragile, and bad taste, which will not meet the quality requirements, but will also consume oil and time.

1) Control of oil temperature

It is better to use a thermometer to control the oil temperature, and it can also be mastered with long-term skilled operation experience. When the temperature is too high or too low, positive measures should be taken to reduce or increase the oil temperature to reach the required temperature of the fried products.

Generally, when the temperature is too high, control the fire source, add cold oil and increase the number of green bodies to reduce the oil temperature;

When the temperature is too low, the firepower can be increased, the number of green bodies can be reduced, and the temperature can rise.

2) The proper temperature for frying

The so-called appropriate temperature for frying refers to the oil temperature at which the inside of the food reaches an edible state and the surface just reaches a certain color requirement.

From the perspective of pastry frying, the temperature of frying oil is divided into two categories:

①Warm oil: generally refers to the oil temperature of 80~150℃, that is, 30 to 50% of the oil temperature in the industry. Warm oil is suitable for deep-fried layered pastry products, and pig frying is often used, which can better ensure the original color and shape of the product. For example, the lily cake and magnolia cake made by pig fried are as white as jade, and the shape and color are lifelike.

②Hot oil: generally refers to the oil temperature above 180℃, that is, 70% oil temperature. Hot oil products mostly use vegetable oil as frying oil. The product has a golden color, crispy taste or slag, or crisp outside and tenders inside, and the filling is sweet and delicious.

Regardless of warm oil or hot frying, the specific oil temperature should be determined according to the variety. High or low oil temperature will affect the quality of the finished products.

3) Frying must be kept clean

During the frying process, some slags will be scattered on the product, and some sugar and protein will be precipitated. These substances will be carbonized at high temperatures, which will darken the oil color and affect the color of the product, and it will be easy to wear on the surface of the product and affect the appearance.

Especially for varieties with delicate patterns, such as phoenix-tail crisp glass oil cake, chrysanthemum crisp, etc., if the surface adsorbs impurities, it will affect the pattern formation and cause the pattern to break.

Under the action of high temperature, air, and falling impurities, the oil that has been used many times will deteriorate in taste, decrease in smoke point, and change from golden yellow to opaque black-brown, easy to foam, low nutritional value, and toxic Substances are produced, and then using such fried foods will not only have poor color and taste but also affect health.

Therefore, the frying oil should always be clear of impurities and replaced with new oil after repeated use.

4) The frying technology can be divided into normal pressure frying, low-pressure frying, and high-pressure frying

The pressure in the oil kettle for atmospheric frying is the same as the ambient atmospheric pressure. It is usually open, which is the most common method of frying. It has a wide range of applications. However, the loss of nutrients and natural pigments during the atmospheric frying process is greater. Therefore, normal pressure frying is more suitable for frying foods. Such as the dehydration of fried cakes, fried bread, fried instant noodles, etc.

Low-pressure frying is also called vacuum frying. Food is fried and dehydrated in edible oil to fully evaporate the water in the raw materials. The frying temperature in the frying kettle is generally below 100℃, and the vacuum degree is 92~98.7 a. The method can maintain good color, shape and crispness of the product. Due to the low oxygen environment, the degree of deterioration of the product and oil will be reduced correspondingly, and the loss of nutrients will be less.

High-pressure frying is a frying method in which the pressure in the frying kettle is higher than normal pressure. High-pressure frying can solve the problem of food quality that needs to be fried for a long time. This method has a high temperature, low moisture, and oil loss, and the product is crispy on the outside and tender on the inside. It is most suitable for frying meat products, such as fried chicken legs and deep-fried. Steak etc.

Industrial Electric Fryer

Industrial Electric Fryer

5. Industrial electric fryer has a traditional continuous fryer, water filter fryer, and oil-drenching fryer

The traditional continuous fryer is the main model used in the frying process in the convenience food production line, and it is also a piece of indispensable frying equipment for mechanized large and medium-sized food processing plants.

The water filter fryer is designed using the different specific gravity of oil and water, immiscibility with each other, and automatic layering. The oil tank is provided with a high-temperature oil layer (heating oil layer), a buffer oil layer (filter oil layer), and a water layer (precipitation layer). Before the high-temperature oil layer is not carbonized, the slag falling from the bombed material will fall into the water layer through the buffer oil layer and be discharged from the slag discharge port regularly. The residues floating on the surface of the hot oil are driven by the hot oil circulation pump into the filter oil tank and then filtered out.

Because the water molecules in the water below continuously enter the high-temperature oil layer during the frying process to supplement the water in the frying layer, it not only guarantees the frying quality of the material but also greatly extends the life of the oil, which is an ordinary frying method 2 to 3 times.

The oil-drenching fryer is suitable for low-temperature fried food, such as deep-fried chili oil. The oil temperature required for this kind of material is low, and the oil temperature is too high, it will fry, so the mesh belt type continuous fryer or the water filter type fryer cannot be used. At present, most of the frying of materials such as chili is artificial frying, which has problems such as low productivity, easy frying, and workers often choked by spicy oil fume. Based on the characteristics of materials such as peppers, a specially designed oil fryer can be used.

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