Q&A on Vacuum Precooling Technology

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What is the purpose of vacuum precooling technology?

Q: What are the types of vacuum precoolers?

Question 3: What is the nature of vacuum precooling technology?

Q: What is the principle of vacuum pre cooling for preservation or quality assurance?

Q: What are the advantages of vacuum cooling compared to other cooling methods?

Question 6: Since vacuum pre cooling relies on vacuum evaporation to cool items, why do we still use a refrigeration mechanism for cooling?

Q: Since vacuum cooling can evaporate water, can it be used for drying items?

Question 8: Why cannot the theory of "vacuum pre cooling preservation technology and decompression refrigeration preservation technology both achieve preservation by reducing pressure through vacuum pumping? Therefore, they belong to the same preservation technology" be established?

Q: Vacuum pre coolers and vacuum refrigeration equipment both have vacuum pumps and refrigerators. Why are their application ranges and preservation effects different?

Question 10: Will the freshness of fresh items be better preserved after vacuum pre cooling and entering the vacuum refrigeration equipment?

Question 11: How are the vacuum pre cooling technologies and products of Shanghai Shanrushui Freshness Preservation Technology Co., Ltd. different from those of its domestic and foreign counterparts?

Question 1:What is the purpose of vacuum precooling technology?

Answer 1: Quickly cool fresh leafy vegetables, vegetables and fruits with loose tissue, edible mushrooms, and fresh cut flowers to extend their shelf life; Quickly cool cooked foods to extend their shelf life or shelf life; Rapid cooling of edible mushroom culture medium; The freshly slaughtered pork quickly cools down. The above cooling process is called pre cooling before other processing processes. Timely vacuum cooling of strawberries and bayberries in berries after harvest can extend their shelf life.

Question 2: What are the types of vacuum precoolers?

Answer 2: It can be divided into two categories: fruit and vegetable vacuum precoolers and cooked food vacuum precoolers. Fruit and vegetable vacuum pre cooling machines are divided into two types: vacuum pre cooling only and vacuum cooling drainage. The vacuum precooler for fruits and vegetables is used for rapid cooling of fresh vegetables, edible mushrooms, etc., while the vacuum precooler for cooked food is used for cooling cooked food.

Question 3: What is the nature of vacuum precooling technology?

Answer 3: It is a pollution-free green physics technology. During use, there is no need for any auxiliary techniques such as preservatives, additives, or nitrogen filling.

Question 4: What is the principle of vacuum pre cooling for preservation or quality assurance?

Answer 4: Place the item in a sealed container, i.e. a vacuum chamber, and quickly extract air and water vapor. When the pressure drops to a certain level, the item will continuously and quickly evaporate water and cool. The cooling time of fresh fruits and vegetables and cooked food can be as fast as a few minutes, depending on the nature of the item and the configuration of the machine. The item loses water due to evaporation of moisture. The water loss rate of fruits and vegetables is about 0.18% for every 1 ℃ decrease, and generally they will not wilt. The dehydration rate of cooked food decreases by about 0.15% for every 1 ℃, and the size varies depending on the type of cooked food and cooking process. Rapidly cooling vegetables, fruits, and edible mushrooms after harvesting can quickly reduce their field heat and suppress their respiratory heat, allowing them to quickly enter a dormant state. After leaving the vacuum precooler, the dormant state gradually disappears, and its "awakening" process is the preservation process or preservation period. After cooked food is released from the pot, it can quickly skip the temperature range of 30 ℃ -50 ℃ where bacteria thrive, which can extend its shelf life.

Question 5: What are the advantages of vacuum cooling compared to other cooling methods?

Answer 5: The main points are as follows:

1) Can extend the shelf life or shelf life. For example, green leafy vegetables can extend their shelf life by 1-5 days, and cooked foods do not spoil in a hot summer environment for a day;

2) The cooling time is extremely fast, ranging from a few minutes to tens of minutes, depending on the configuration of machine accessories, the type and variety of cooled materials, the quantity of primary cooling, the cooling process, and the production pace of customers;

3) Maintain the original appearance and quality of the item best. After vacuum pre cooling, the surface color of fresh lychees darkens, but it can remove the astringency of some varieties;

4) After vacuum cooling, all water droplets on the surface of bayberries, including those picked up from the water, can be removed;

5) After vacuum cooling, all small wounds on the surface of bayberry can "heal": the surface of the wound is dry and no longer drips water;

6) Cooked food can prevent secondary pollution.

Question 6: Since vacuum pre cooling relies on vacuum evaporation to cool items, why do we still use a refrigeration mechanism for cooling?

Answer 6: The vacuum precooler is equipped with a refrigerator that does not directly cool the item, but rather cools the water vapor in the cold trap (water trap). The boiling temperature of water decreases with the decrease of pressure. For example, when the pressure drops to 0.012271bar, the boiling temperature of water is 10 ℃. At this time, the volume of 1kg water transformed into steam is 106.419m3. If the vacuum pump with a pumping speed of 100m3/h is selected, it will take about 3 hours to remove such a large amount of steam. If it is cooled to 0 ℃, the volume of 1kg of water transformed into water vapor will expand by more than 200000 times. A cold trap (water trap) can condense the vast majority of water vapor into water, and the remaining mixed gas is removed by a vacuum pump, resulting in a much lower power of the vacuum pump. So, using a refrigerator is to "reduce the burden on the vacuum pump". If cooked food is cooled to room temperature, a vacuum pump is required without the need for a refrigerator. It can be seen that a vacuum precooler does not necessarily need to be equipped with a refrigerator. If there is a refrigerator, a cold trap must be used, whereas if there is a cold trap, a refrigerator must be used. Alternatively, without a cold trap, there is no need for a refrigerator.

Question 7: Since vacuum cooling can evaporate water, can it be used for drying items?

Answer 7: Not necessarily feasible. Practice has shown that vacuum cooling can completely remove water droplets from the surface of bayberry, including the grooves, but it cannot completely remove water droplets from the grooves of strawberries. Most of the water content in leafy vegetables after cleaning or in clean vegetables after cutting cannot be removed, let alone dried items.

Question 8: Why cannot the theory of "vacuum pre cooling preservation technology and decompression refrigeration preservation technology both achieve preservation by reducing pressure through vacuum pumping? Therefore, they belong to the same preservation technology" be established?

Answer 8: The basic theories, preservation principles, technical sources, basic equipment composition, preservation effects, and application fields of the two are different. The principle of hypobaric storage can be found in "Q&A 6 on hypobaric storage technology". Interested parties can refer to this website's "Introduction 1. Academic Paper 19." Further Exploration of the Differences between Reduced Pressure Refrigeration, Controlled Atmosphere Refrigeration, and Vacuum Cooling Technology. "Proceedings of the 2013 China Refrigeration Society Academic Annual Meeting. Wuhan: China Refrigeration Society, 2013.

Bicycles, cars, and trains all have wheels and move forward by rolling them. Based on a deep understanding of their motion characteristics, they are not considered to belong to the same technology. Vacuum packaging also achieves preservation by reducing pressure through vacuum pumping, but no one believes that it is the same technology as vacuum pre cooling or vacuum refrigeration. It can be seen that using vacuum to reduce pressure to achieve the purpose of preservation belongs to the same technical theory, which obviously cannot be established.

Question 9: Vacuum pre coolers and vacuum refrigeration equipment both have vacuum pumps and refrigerators. Why are their application ranges and preservation effects different?

Answer 9: The performance technical parameters requirements for vacuum pumps and refrigerators are often different between the two, and the supporting equipment and components are often different or not the same. The refrigeration purpose of the vacuum precooler is shown in Answer 6. The purpose of the refrigeration machine in a vacuum refrigerated warehouse is to provide a cold source for the warehouse without the need for a cold trap.

Vacuum cooling is a pre-treatment or processing preservation technology, with a relatively short preservation time, such as a few days. Therefore, a vacuum precooler is a pre-treatment or processing equipment. Decompression refrigeration can be used as storage equipment, pre-treatment equipment, processing equipment, and transportation equipment. In recent years, our company has found through research and practice that vacuum refrigeration equipment has dual functions of storage and pretreatment. The storage function is a storage, transportation, and shelf preservation technology that has been recognized for a long time, with a preservation time of tens or hundreds of days. The pre-treatment equipment is used for preserving fresh and cut vegetables and delaying the browning of cut surfaces. It has three effects: extending the refrigerated shelf life for more than 3 days, prolonging the broken chain preservation for more than 4 hours, and delaying the browning of the cut surface. The specific method can be found in vacuum refrigeration preservation. Vacuum pre cooling does not have such a function for preservation. Usually, there is no mutual substitution between vacuum pre cooling and reduced pressure refrigeration, that is, vacuum pre cooling machines cannot have a reduced pressure refrigeration effect, and conversely, reduced pressure refrigeration equipment cannot have a vacuum pre cooling effect unless specially designed or improperly designed. Vacuum cooling and vacuum pre cooling are both vacuum preservation technologies. Due to their different basic theories, preservation principles, technical sources, and basic equipment components, although both use vacuum pumps and refrigerators, vacuum pre cooling and vacuum pre cooling have much better preservation effects and a wider range of applications. It can be seen from "Q&A 8 and 9 on hypobaric storage technology

Question 10: Will the freshness of fresh agricultural products be better preserved after vacuum pre cooling and entering the vacuum refrigeration equipment?

Answer 10: Shanru Water Company's existing practice is that fresh green leafy vegetables, beef, and pork are better preserved by vacuum pre cooling and entering vacuum refrigeration equipment, but the opposite is true for crucian carp.

Question 11: How are the vacuum pre cooling technologies and products of Shanghai Shanrushui Freshness Preservation Technology Co., Ltd. different from those of its domestic and foreign counterparts?

Answer 11: There is no substantial difference in technology between China and foreign countries.

Our company starts from the basic principle of vacuum cooling and combines the cooling characteristics of items to develop, design, and produce vacuum precoolers. Therefore, our company has unique features in terms of functionality, humanization, reliability, and other details. For example, the cross-sectional area of the door sealing groove is not square, and the cross-sectional area of the sealing strip is not cylindrical or square. The sealing strip material is a special elastic material, specially designed, and produced by a designated company. It will not age or crack after more than 10 years of use at temperatures above 150 ℃ to below 40 ℃. Therefore, our company's products have a good reputation, and the failure rate of machines after sale is extremely low. It can also provide some preservation or quality assurance techniques. In addition, we have applied data collection and control to the experimental machine of the vacuum precooler, which can store pressure, temperature and other data on a USB flash drive. The product has entered both military and civilian markets. Our company not only develops equipment but also conducts a large number of preservation experiments, focusing on both individual equipment development and the entire preservation chain research. I have gained insights in both theoretical and practical cognition. From 2007 to the end of 2014, 20 academic papers were published in domestic core journals and national academic conferences, and 12 professional articles were published in national professional journals and newspapers. Strive to write the history of vacuum preservation chains.

Note: For errors or inadequacies in the answer, please use it if instructed managers@shanrushui.com Contact and answer any questions. （2015.1.30）