Working principle and process parameters design of fried potato chips

1. Fried frying is the oldest on earth and one of the most popular cooking methods in the world. It is not only a high temperature and short time food drying process, but also a processing method of cooking and drying food. Fried can kill the bacteria in food, prolong the storage period of food, improve the flavor of food, enhance the digestion of food nutrients, and because of its processing time is short, so has been widely used in the food industry, this is also Fried process for thousands of years, keep until now. With the acceleration of people's life pace and the improvement of living standards, a huge number, a wide variety of convenient food has entered thousands of households, into all aspects of our life. In the army of convenient food, there have been a TV food snack food and other recruits. And in these dazzling variety of convenient foods, fried food accounts for a large proportion. For example: fried nuts oil fried chicken leg fried chicken oil fried banana slices fried bun and traditional fried rake, the main force of convenient food- - - -instant noodles, its dehydration cooked curing process are using frying. Fried technology has played a great role in promoting the development of convenient food, and the development of convenient food for fried technology and equipment, at the same time in its own development, also greatly promoted the development of the new frying technology and equipment. In recent years, low temperature vacuum Fried high temperature pressure deep deep vacuum deep Fried water oil mixed deep Fried the emergence of new technology and new equipment, for all kinds of food requirements respectively choose suitable Fried new technology and new equipment, provides a broad heaven and earth, has a great choice, makes our daily life food more rich and colorful.

2. The principle of fried potato chips the essence of frying process is ripening;. The second is dehydration. The ripening process is irrelevant for potato chips, because the puree making potato chips itself is cooked; the process of dehydration is the main for potato chips, the role of frying is: one can effectively prevent the loss of water-soluble nutrients in potato processing, better retain the nutrients of the fresh potato; the second, frying is a paste garden, Fried potato chips is a fixed shape, hard and crisp solid garden. The moisture content of potato chips before frying is about 35%, and the oil content is about 3~5 ‰, while the moisture content of fried potato chips is only 3~5%, and the highest oil content is 40%. Therefore, for potato chips, the process of frying is the process of replacing the water in the potato chips with oil. When frying, the rate of heat transfer of the food depends on the temperature difference between the oil temperature and the inside of the food and the thermal conductivity of the food. The thermal conductivity of a food is not a fixed value for a specific food, and it is related to the temperature of the food at that time and the moisture content of the food at that time. Once these two parameters change, the thermal conductivity of the food also changes. In the process of food Fried, the temperature of the food in increasing, more important is the moisture content of the food in change, and water steam and escape from the food inside, the process caused by heat exchange and the consumption of heat energy, is the main factor of the food thermal conductivity: water steam escape, produce a lot of agitation, will greatly improve the thermal conductivity of food at this time. Water content is different, the driving force of dehydration- - - -the difference of steam pressure is also different, the heat energy it consumes and heat exchange effect is different, the stirring effect is different, so the thermal conductivity of food is different. So: the thermal conductivity of food is not a fixed value, the process of frying potato chips is the same. Fried before, the water in the potato chips is evenly distributed in starch and protein as the main component of potato puree, when the chips into the hot oil, potato chips surface temperature rose rapidly, water in high temperature water volume gradually increased, vaporization, until escape, potato chips surface form a dry layer, then, water vaporization layer gradually into the potato chips. When the drying layer forms on the surface of potato chips, the temperature gradually approaches the hot oil temperature. , While the thickness of potato chips is only 1~1.5mm, its temperature tends to hot oil temperature process is very fast. Because starch and protein heat curing and water escape, after frying, the microscopic section of potato chips is a porous structure, the porous space, formed by hot oil into, instead. That's the process of frying chips, and that's why they contain up to 40 percent of the oil.

Factors affecting the oil content of potato chips:

1. The higher the density of potato chips, that is, the lower the moisture content of potato chips before frying, the lower the oil content of potato chips after frying. The example proves that drying the potato slices can reduce the water by 25%, and the oil content of the potato chips can be reduced by 6~8% after frying.

2. The thickness of potato chips is inversely proportional to the oil content: the thinner the potato chips, the higher the oil content.

3. The higher the oil temperature, the lower the oil content of potato chips. With the rise of oil temperature, the density of oil decreases, the viscosity of oil also decreases, and the oil storage per unit space also decreases.

4. Different types of fried oil will also affect the oil content of potato chips.

5. For a certain period of time, the longer the frying time, the higher the oil content of potato chips.

3. The determination of oil temperature traditional frying process, oil temperature in more than 160℃, sometimes even reach the high temperature of 230℃, so high temperature obviously on the nutrition of food, especially some heat-sensitive substances, has a certain destructive effect. Of course, this damage depends not so much on the temperature of the oil than on the temperature of the food itself and the time the oil stays in the heat. The impact of frying on the nutrition of food and the safety of fried food companies are a common concern. The purpose of our fried potato chips is dehydration and the geometry of solidified potato chips. A lower oil temperature of less than 160℃ should be used. In this way, before the dry layer on the surface of the potato chips, the evaporation surface has gone deep into the inside of the potato chips, so that the evaporation of water and heat transfer can be carried out smoothly and stably. The water content of the potato chips is ideal, about 5%, and the color of the surface of the potato chips is also shallow. Not only in theory, but during the trial production process, the results of the trial production and a large number of trial data also prove this conclusion. Oil temperature is not only the main parameter of the frying machine, but also the most important factor that determines the nutritional composition of potato chips, finished product perception, finished product quality and quality conditions of potato chips. We determined the temperature of the frying oil at about 150℃.

Three factors determine the oil temperature:

1. Pressure and flow rate of the steam.(At present, the pressure of saturated steam produced by the boiler on the market is generally 1.0 Mpa, and the temperature of saturated steam at this pressure is 180℃).

2. Heat exchange efficiency of steam and oil. We choose the plate heat exchanger, the heat exchange efficiency of the plate heat exchanger is 0.96~0.98; the heat exchange area is 20 square meters.

3. Flow rate and temperature of the hot oil. Main factors and calculation of heat consumption of fried oil

4. The initial temperature of 40~45℃ potato chips after being fried to reach the heat energy consumed by the oil temperature QI: QI = G C (TI-T) KJ / hG- -production capacity of the fried machine, Kg / hC- -specific heat of potato chips, KJ / ℃. KgTI- -the temperature of fried chips, ℃ T- -the temperature before frying, ℃

5. The water in potato chips is sublimated into the heat energy consumed by water steam in the frying process Q: Q = G (AI-A) γ KJ / hG- -production capacity of frying machine, Kg / hAI- -water content before frying of potato chips,% A- -water content of fried potato chips,% γ - -vaporization latent heat of frying average temperature of water, KJ / Kg

6. Thermal energy consumed by steel wire mesh belt exhaust device and machine heat transfer Q: Q = GI.G (TI-T) KJ / hGI- -circulation amount of conveyor belt, Kg / hG- -specific heat of conveyor belt material, KJ / ℃. KgTI-conveyor belt temperature before frying, ℃ T-conveyor belt fried temperature, ℃

7. Heat loss of the environment, heat radiation of the equipment, heat emitted during the tide discharge, and heat loss caused by air convection Q. Q is generally calculated as the percentage of the total heat consumption Q, usually taking 5~8%. Total heat consumption Q = (QI + Q + Q) * (1 + Q) KJ / h

4. Design of the frying method:

1. In the production process of fried potato chips, the operation mode of the equipment before frying is continuous; if the frying equipment is selected as intermittent, then from continuous to intermittent, then from intermittent to continuous, the operation is very difficult; the design difficulty is also very big. Potato chips in a continuous state of production, to ensure the quality of the basic conditions are better, high yield. Intermittent is the opposite: due to the continuous / intermittent conversion, potato chips in the production process to undergo the environmental change of large secondary temperature difference, so that the internal stress of potato chips increases, and the resulting chip phenomenon increases. At the same time, the secondary continuous / intermittent conversion also increases the chance of secondary pollution. Continuous frying equipment is large, but the cost is not high; intermittent frying equipment is smaller than continuous frying equipment, and the cost is not high. However, the cost of continuous / intermittent conversion equipment is greater than that of any of the previous two, and the volume plus the volume of the intermittent frying machine greatly exceeds the volume of the continuous frying machine. For the above reasons, we decided to use the continuous frying method.

2. Vacuum pressure atmospheric pressure- - - -the choice of frying oil pressure I. Vacuum low temperature frying is a new process used in developed countries in the early 1970s. For Fried before moisture content of 35%, thin only for 1~1.5mm chips this specific products, vacuum Fried is the most suitable for frying process, after vacuum low temperature Fried processing potato chips have than traditional Fried process of chips have better quality: A. The main purpose of Fried is dry, and vacuum itself is one of the main means of dry, dry in vacuum state, and organic combination with 100℃ oil temperature, chips moisture evaporation condition is very good, water evaporation fast, dry time is short. After vacuum low temperature frying treatment of potato chips, both the unique quality of fried food, and some puffed food flavor. B. The temperature is low, the oil temperature of vacuum frying is only 100℃, and the temperature of the inner layer of potato chips is not exceed 100℃, so the loss of nutrients is very small. C. Low deterioration speed of oil and less oil consumption. The oil of vacuum frying is low in temperature, and in the environment of hypoxia and less oxygen, the contact between oil and oxygen is less, and the degradation rate of oil oxidation and polymerization decomposition is slow, so there is no need to add antioxidants to the oil of vacuum low temperature frying, and the fried oil can be used repeatedly. In addition, for the same food ingredients, the oil content of the product is as high as 40~50%; if the vacuum frying is used, the oil content is only 20%, which can greatly reduce the oil consumption and effectively reduce the cost; at the same time, the storage period of the product can be greatly extended.Ⅱ. High temperature pressure frying is to improve the pressure of the frying environment, improve the oil temperature, improve the boiling point of the oil, reduce the frying time of the frying process, generally used for ripening, and do not want water evaporation; or water evaporation requirements are very small food, short ultra-high temperature frying processing process. The frying temperature is generally 180~265℃. Due to the high oil temperature, the surface drying layer is formed quickly, the migration of water and heat transfer are limited by the drying layer, so that the total moisture content of the product is higher, the texture of the product can keep fresh and tender, and the preservation of flavor substances and additives is also better. But the oil deterioration speed, viscosity, black, have to often replace the fried oil, resulting in rising costs. For the main purpose of drying the potato chips fried, this process is obviously not appropriate.Ⅲ. Normal pressure and room temperature frying is the most original and the most widely used requirements of the most common frying process, but also we have discussed the most. The temperature of the oil is between 100℃ and 230℃; generally between 140℃ and 160℃; the frying time depends on the moisture content of the product. Above we discussed the vacuum low temperature high temperature pressure atmospheric temperature

Explanation of the process flow of potato chip and potato chip frying production line

1. Cleaning process of potatoes:

Cleaning is a necessary process for frying production line. The main purpose of cleaning is to clean and remove the free starch on the surface, prevent the starch from entering the frying machine and affect the service life of oil; at the same time, potato chips are not exposed to air, reduce sugar and amino acids, and brown

2. The rinse process of the potatoes

This process is necessary, after cleaning, into 65-90 degrees hot water for bleaching. Disrupt the activity of the enzyme, improve the tissue structure, make it easy to dehydration, can also exclude the potato tissue when the air frying foaming. Sodium bisulfite or sodium metabisulfite additives can be added to the ironing solution to protect the color and bleaching treatment and improve the color

3.  Fried process of potatoes

The benefits of frying assembly line measure are high degree of automation, time saving and labor saving, low labor intensity, and stable product quality, high output, low cost, green and no pollution. French fries frying line, frying time controllable, according to the product requirements to adjust the frying time, the machine microcomputer divided into multiple sections of temperature control, can control the oil temperature, so that the food frying in the temperature of *, improve product quality. Fried machine | Fried line temperature control effect is good, after feeding, the overall oil temperature fluctuation range control within 2 degrees, reduce the energy loss of heating again, save production time, yield. Fried French fries production line is a network belt type frying line, according to the size of the product demand, adjust the network belt broadband and mesh size. The whole machine is made of stainless steel, strong and durable, strong corrosion resistance, beautiful appearance, strong applicability.