It should be pointed out that the references cited above for the effect of CO2 inhibition are based on questionable experimental methodologies (such as the use of unbuffered media, the modification of several variables in an experiment, etc.), and as a result there are certainly some potential errors.
(c) Nitrogen Nitrogen is an inert, odorless gas that controls chemical reactions. Nitrogen is the main component of air, accounting for about 78%. Neutral in contact with food, it can be used for food preservation. Compared with other commonly used gases, nitrogen does not easily penetrate the packaging film, and is mainly used as a filling gas in the modified atmosphere packaging system.
In summary, the design of the modified atmosphere packaging system should consider various factors, among which the most important factor is the relative content of CO2 and O2 in the packaging, which is mainly determined by the gas concentration in the packaging and the permeability of the packaging material.
Third, the application of fruit and vegetable modified atmosphere packaging and development of fresh fruits and vegetables in the picking, but also carried out vigorous respiration and evaporation. Absorb oxygen from the air, decompose and consume its own nutrients, produce carbon dioxide, water and heat. The main nutrient during breathing is sugar, so the respiratory reaction is mainly oxidation of sugar. When the oxygen supply is not sufficient, this kind of breathing is called hypoxic respiration, that is, intermolecular breathing. In hypoxic breathing, incomplete oxides such as alcohol will be produced.
Aerobic respiration occurs in fruits and vegetables during normal oxygen supply, and anaerobic respiration during hypoxia. Excessive aerobic respiration or anaerobic respiration causes aging or decay of fruits and vegetables. The degree of two respirations of fruits and vegetables is proportional to the concentration of oxygen in the environment. Controlling the oxygen concentration in the environment allows fruits and vegetables to produce only weak aerobic respiration without producing anaerobic respiration. The fruits and vegetables packed in plastic bags consume O2 and produce CO2 under the influence of respiration, gradually increase the CO2 in the environment and reduce the concentration of CO2. The highly transparent plastic film can be used for gas exchange with the atmosphere to supplement the consumed O2 and Exclude CO2. When the rate of permeation from the film is equal to the speed of respiration of fruits and vegetables, the gas in the package reaches a certain equilibrium concentration, so that the fruits and vegetables maintain a slight respiratory rate without generating anaerobic respiration, thereby delaying the ripening of fruits and vegetables and obtaining preservation. There are many factors that affect the equilibrium concentration of gas produced in the package, such as the breathing rate of fruits and vegetables, the air permeability of the film to O2 and CO2, and the storage temperature. There are two kinds of packaging methods for the modified atmosphere packaging of fruits and vegetables. One is called passive air conditioning. Currently, supermarkets supply plastic film exchange gas to regulate the O2 and CO2 content; the other is called active air conditioning, and it is charged according to the respiration intensity of fruits and vegetables. The gas mixture of oxygen and carbon dioxide gas exchanges with different gas permeable membranes to achieve equilibrium in gas exchange within the packaging bag as soon as possible. Obviously, active air conditioning is better than passive air conditioning. However, the technology is complex and limited by the limited number of highly breathable films. The shelf life of fresh fruits and vegetables depends on the physiological aging and moisture loss of fruits and vegetables. Modified atmosphere packaging can effectively control the above influencing factors and extend the shelf life of some important commodities. When the sugar and acid are decomposed during storage, the sensory quality of fruits and vegetables begins to change, and the rate of change is determined by their respiration. Therefore, the shelf life must be closely related to respiration. MAP reduces the anaerobic respiration rate by reducing the oxygen content.
Because the packaging system must allow the exchange of gas for respiration. Vacuum packaging does not meet this requirement. Although inflatable packaging is sometimes a method of using natural packaging, it is most commonly used to design a packaging system that achieves a suitable atmosphere of gas, allowing the breathing and package breathability to be balanced. In such a body series, the permeability of the packaging film (such as the entry of O2 and the removal of CO2) should be selected according to the respiration rate of the product (such as the consumption of O2 and the production of CO2) with the purpose of the gas composition during the storage period. Adjusted from 20.95% O2 and 0.03% CO2 to 2% to 5% and 3% to 8%. However, in fact, the MAP application is complicated because the respiration and the air permeability of the packaging film are constantly changing.
Breathing rate depends on many factors, such as the type of vegetable and the variety of fruits and vegetables (such as different lettuce varieties, breathing rate is also different), maturity (such as the respiration rate of mature bananas is 4 to 5 times that of green bananas), And the degree of damage during the preparation process (eg, the respiration intensity of a strip-shaped carrot is 6 to 7 times that of a non-cut carrot). Temperature is also one of the most important influencing factors. With a temperature increase of 10°C, the respiratory rate generally increases by 2 to 3 times. However, despite this, normal temperature storage is very common, because the cost of refrigeration is too high, and in fact CO2 is more effective than low temperature, the general respiration can be controlled to 4-5 times the low temperature.
(c) Nitrogen Nitrogen is an inert, odorless gas that controls chemical reactions. Nitrogen is the main component of air, accounting for about 78%. Neutral in contact with food, it can be used for food preservation. Compared with other commonly used gases, nitrogen does not easily penetrate the packaging film, and is mainly used as a filling gas in the modified atmosphere packaging system.
In summary, the design of the modified atmosphere packaging system should consider various factors, among which the most important factor is the relative content of CO2 and O2 in the packaging, which is mainly determined by the gas concentration in the packaging and the permeability of the packaging material.
Third, the application of fruit and vegetable modified atmosphere packaging and development of fresh fruits and vegetables in the picking, but also carried out vigorous respiration and evaporation. Absorb oxygen from the air, decompose and consume its own nutrients, produce carbon dioxide, water and heat. The main nutrient during breathing is sugar, so the respiratory reaction is mainly oxidation of sugar. When the oxygen supply is not sufficient, this kind of breathing is called hypoxic respiration, that is, intermolecular breathing. In hypoxic breathing, incomplete oxides such as alcohol will be produced.
Aerobic respiration occurs in fruits and vegetables during normal oxygen supply, and anaerobic respiration during hypoxia. Excessive aerobic respiration or anaerobic respiration causes aging or decay of fruits and vegetables. The degree of two respirations of fruits and vegetables is proportional to the concentration of oxygen in the environment. Controlling the oxygen concentration in the environment allows fruits and vegetables to produce only weak aerobic respiration without producing anaerobic respiration. The fruits and vegetables packed in plastic bags consume O2 and produce CO2 under the influence of respiration, gradually increase the CO2 in the environment and reduce the concentration of CO2. The highly transparent plastic film can be used for gas exchange with the atmosphere to supplement the consumed O2 and Exclude CO2. When the rate of permeation from the film is equal to the speed of respiration of fruits and vegetables, the gas in the package reaches a certain equilibrium concentration, so that the fruits and vegetables maintain a slight respiratory rate without generating anaerobic respiration, thereby delaying the ripening of fruits and vegetables and obtaining preservation. There are many factors that affect the equilibrium concentration of gas produced in the package, such as the breathing rate of fruits and vegetables, the air permeability of the film to O2 and CO2, and the storage temperature. There are two kinds of packaging methods for the modified atmosphere packaging of fruits and vegetables. One is called passive air conditioning. Currently, supermarkets supply plastic film exchange gas to regulate the O2 and CO2 content; the other is called active air conditioning, and it is charged according to the respiration intensity of fruits and vegetables. The gas mixture of oxygen and carbon dioxide gas exchanges with different gas permeable membranes to achieve equilibrium in gas exchange within the packaging bag as soon as possible. Obviously, active air conditioning is better than passive air conditioning. However, the technology is complex and limited by the limited number of highly breathable films. The shelf life of fresh fruits and vegetables depends on the physiological aging and moisture loss of fruits and vegetables. Modified atmosphere packaging can effectively control the above influencing factors and extend the shelf life of some important commodities. When the sugar and acid are decomposed during storage, the sensory quality of fruits and vegetables begins to change, and the rate of change is determined by their respiration. Therefore, the shelf life must be closely related to respiration. MAP reduces the anaerobic respiration rate by reducing the oxygen content.
Because the packaging system must allow the exchange of gas for respiration. Vacuum packaging does not meet this requirement. Although inflatable packaging is sometimes a method of using natural packaging, it is most commonly used to design a packaging system that achieves a suitable atmosphere of gas, allowing the breathing and package breathability to be balanced. In such a body series, the permeability of the packaging film (such as the entry of O2 and the removal of CO2) should be selected according to the respiration rate of the product (such as the consumption of O2 and the production of CO2) with the purpose of the gas composition during the storage period. Adjusted from 20.95% O2 and 0.03% CO2 to 2% to 5% and 3% to 8%. However, in fact, the MAP application is complicated because the respiration and the air permeability of the packaging film are constantly changing.
Breathing rate depends on many factors, such as the type of vegetable and the variety of fruits and vegetables (such as different lettuce varieties, breathing rate is also different), maturity (such as the respiration rate of mature bananas is 4 to 5 times that of green bananas), And the degree of damage during the preparation process (eg, the respiration intensity of a strip-shaped carrot is 6 to 7 times that of a non-cut carrot). Temperature is also one of the most important influencing factors. With a temperature increase of 10°C, the respiratory rate generally increases by 2 to 3 times. However, despite this, normal temperature storage is very common, because the cost of refrigeration is too high, and in fact CO2 is more effective than low temperature, the general respiration can be controlled to 4-5 times the low temperature.
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