A universal method for storing and preserving fruits and vegetables in a controlled atmosphere

Abstract

The present invention belongs to the technical field of agricultural product preservation, and specifically relates to a universal controlled atmosphere storage and preservation method for fruits and vegetables. The method comprises the following steps: placing fruits and vegetables in a storage environment; gradually increasing the CO2 concentration in the storage environment; before each increase in the CO2 concentration, sampling the volatile components in the storage environment and detecting the relative content of the volatile compounds at the current CO2 volume fraction; plotting a trend graph with the CO2 volume fraction as the horizontal axis and the relative content of the measured volatile compounds as the vertical axis; when an inflection point characteristic appears in the trend graph, stopping increasing the CO2 concentration and immediately lowering the CO2 concentration to a value less than the CO2 volume fraction corresponding to the inflection point. This method can increase the appropriate CO2 concentration during storage of fruits and vegetables to the maximum limit concentration while ensuring that the fruits and vegetables do not experience sensory damage caused by CO2, thereby maximizing the controlled atmosphere preservation effect and storage quality of fruits and vegetables.

Description

Technical Field

[0001] The invention belongs to the technical field of agricultural product preservation, and specifically relates to a universal gas-controlled storage and preservation method for fruits and vegetables. Background Art

[0002] Fruits and vegetables are rich in nutrients and are an important part of the human diet. They are very popular among consumers. However, most types and varieties of fruits and vegetables are not resistant to storage after harvest. Therefore, how to store and preserve fruits and vegetables with high quality has become a major problem in the field of agricultural product preservation.

[0003] To address the post-harvest storage and preservation of fruits and vegetables, controlled atmosphere (CA) technology has emerged. This is a refrigerated storage method in a specific gaseous environment. By lowering the ambient temperature and regulating the gas composition of the fruit and vegetable storage environment, primarily by reducing O2 concentration and increasing CO2 concentration, CA suppresses the respiratory intensity (RI) of fresh fruits and vegetables. Hypoxic conditions can reduce ethylene production, inhibit respiration, and, to a certain extent, reduce transpiration and inhibit microbial growth. CO2 competes with ethylene for binding sites on receptor proteins, so increasing CO2 concentration can effectively reduce the binding of ethylene to receptor proteins. The main mechanism of CA is to maintain the physiological state of fruits and vegetables by typically lowering O2 concentration and increasing CO2 concentration to suppress the respiratory intensity of stored fruits and vegetables, reducing the consumption of substances in the fruits and vegetables, thereby delaying aging, extending storage life, and keeping them fresh and edible for a longer period of time.

[0004] The main features of controlled atmosphere storage are as follows: ① It can maintain the stability of fruits and vegetables and inhibit their ripening process; ② It can greatly reduce the low-temperature damage of fruits and vegetables, reduce physiological damage and microbial damage, and thus reduce fruit losses; ③ It can extend the storage time, well maintain the physiological structure of fruits and vegetables, maintain the original color, aroma and taste of fruits and vegetables, reduce dry loss, and improve product quality; ④ It can improve the management of fruits and vegetables and increase economic benefits.

[0005] Although the storage period of fruits and vegetables under controlled atmosphere storage can often be effectively extended, if the CO2 concentration is not properly controlled, excessively high CO2 concentrations will instead accelerate the aging of fruits and vegetables, causing CO2 damage to fruits and vegetables. Therefore, high-concentration CO2 damage to fruits and vegetables during controlled atmosphere storage after harvest is one of the common physiological diseases. In the early stages of the damage, there are no symptoms and it is difficult to detect. However, once the sensory symptoms caused by CO2 damage appear in fruits and vegetables, they cannot be recovered, resulting in significant economic losses. Therefore, in actual applications, in order to prevent the occurrence of physiological diseases such as high-concentration CO2 damage, technicians usually control the CO2 concentration to be significantly lower than the optimal concentration. For example, the volume fraction of CO2 in the controlled atmosphere storage of garlic sprouts is generally controlled at 7%, with a maximum of 8%; the volume fraction of CO2 in the controlled atmosphere storage of cabbage lettuce is generally controlled at 2%; and the volume fraction of CO2 in the controlled atmosphere storage of Yellow Fuji apples is generally controlled at 1%. Although such operation can effectively avoid the damage caused by high concentration of CO2, the CO2 concentration in the controlled atmosphere storage environment does not reach the limit level that fruits and vegetables can tolerate, so the controlled atmosphere storage cannot achieve the optimal effect. After all, in controlled atmosphere storage, the higher the CO2 concentration, the better the preservation effect.

[0006] Therefore, during the controlled atmosphere storage of fruits and vegetables after harvest, how to accurately control the CO2 concentration, make accurate predictions in advance before the sensory symptoms caused by CO2 damage appear, and control the CO2 concentration at the limit value that fruits and vegetables can tolerate, so that the controlled atmosphere storage can achieve the best effect has become an urgent problem that needs to be solved. Summary of the Invention

[0007] The present invention aims to provide a universal controlled atmosphere storage and preservation method for fruits and vegetables. This method can increase the CO2 concentration during storage to a maximum limit while ensuring that the fruits and vegetables do not experience sensory damage caused by CO2, thereby maximizing the controlled atmosphere preservation effect and storage quality of the fruits and vegetables. Compared with traditional controlled atmosphere storage of fruits and vegetables, the controlled atmosphere storage method of the present invention can extend the preservation time of fruits and vegetables by 14%-200%.

[0008] The inventors' research has found that the relative contents of six volatile compounds—styrene, o-xylene, p-xylene, mesitylene, α-farnesene, and n-hexanoic acid—in storage environments exhibit characteristic inflection points as CO2 concentrations increase. These inflection points correspond to CO2 damage points for post-harvest fruits and vegetables. Furthermore, these characteristic variations in the six volatile compounds are universal across fruits and vegetables.

[0009] The technical solutions of the present invention are as follows:

[0010] A general method for storing and preserving fruits and vegetables in a controlled atmosphere comprises the following steps:

[0011] Fruits and vegetables are placed in a controlled atmosphere storage environment, which is adjusted according to the specific fruits and vegetables being stored. For example, some fruits and vegetables require a controlled atmosphere storage environment with a temperature of 0-3.5°C and an O2 volume fraction of 3-4%.

[0012] Gradually increase the CO2 concentration in the storage environment, and its concentration is measured in volume fraction; the rest is supplementary gas, such as N2, used to fix the gas conditioning;

[0013] Before each increase in CO2 concentration, volatile components in the storage environment are sampled to detect the relative content of the volatile compounds at the current CO2 volume fraction, wherein the volatile compounds are one or more of styrene, o-xylene, p-xylene, mesitylene, α-farnesene, and n-hexanoic acid;

[0014] With the volume fraction of CO2 as the horizontal axis and the relative content of the measured volatile compounds as the vertical axis, a graph showing the change trend of the relative content of the measured volatile compounds with the increase of the volume fraction of CO2 was drawn;

[0015] When an inflection point appears in the trend graph, stop increasing the CO2 concentration and immediately reduce the CO2 concentration to a value less than the CO2 volume fraction corresponding to the inflection point.

[0016] The inflection point characteristic refers to the point at which the slope of the trend of change in the relative content of volatile compounds with increasing CO2 volume fraction changes significantly. This significant change includes the following characteristics: 1) the slope of the trend is negative before the inflection point and approaches zero after the inflection point; 2) the slope of the trend is negative before the inflection point and positive after the inflection point; 3) the slope of the trend is positive before the inflection point and negative after the inflection point.

[0017] The inflection point characteristics of the six volatile compounds mentioned above are described below:

[0018] A. Inflection point characteristics of styrene: The slope of the trend of the relative content of styrene changing with the increase of CO2 volume fraction is negative before the inflection point, and the slope of the trend tends to zero after the inflection point;

[0019] B. Inflection point characteristics of o-xylene: The slope of the trend of the relative content of o-xylene with the increase of CO2 volume fraction is negative before the inflection point, and tends to zero after the inflection point;

[0020] C. Inflection point characteristics of p-xylene: The slope of the change trend of the relative content of p-xylene with the increase of CO2 volume fraction is negative before the inflection point, and the slope of the change trend tends to zero after the inflection point;

[0021] D. Inflection point characteristics of mesitylene: The slope of the trend of the relative content of mesitylene with the increase of CO2 volume fraction is negative before the inflection point, and the slope of the trend tends to zero after the inflection point;

[0022] E. Inflection point characteristics of α-farnesene: The slope of the change trend of the relative content of α-farnesene with the increase of CO2 volume fraction is negative before the inflection point, and positive after the inflection point;

[0023] F. Inflection point characteristics of n-hexanoic acid: The slope of the change trend of the relative content of n-hexanoic acid with the increase of CO2 volume fraction is positive before the inflection point, and negative after the inflection point;

[0024] Among them, the CO2 volume fraction corresponding to the inflection point is the critical CO2 concentration for controlled atmosphere storage. If the CO2 concentration in the storage environment continues to be greater than or equal to the critical CO2 concentration, fruits and vegetables will suffer from CO2 damage.

[0025] The CO2 volume fraction corresponding to the previous rising interval of the CO2 volume fraction corresponding to the inflection point is the CO2 concentration in the controlled atmosphere storage environment of the fruits and vegetables. This CO2 concentration is the appropriate concentration for controlled atmosphere storage of the fruits and vegetables, that is, the upper limit non-toxic concentration.

[0026] The controlled atmosphere storage method for fruits and vegetables described in this invention is different from hypoxic storage, which involves reducing the O2 concentration in the storage environment without changing the CO2 concentration to preserve agricultural products. This method, on the other hand, does not change the O2 concentration but gradually increases the CO2 concentration.

[0027] The specific changing trends of one or more of the six volatile compounds before and after CO2 damage are used to comprehensively predict the critical CO2 concentration. After harvest, fruits and vegetables must be stored at the CO2 damage point for a certain period of time (for example, head lettuce requires about 25 days) before sensory changes (such as fading and the development of an odor) will occur. The time required for the six volatile compounds selected in the present invention to undergo characteristic changes in fruits and vegetables before and after the CO2 damage concentration is much faster than the phenotypic changes. Therefore, by immediately lowering the CO2 concentration after the above-mentioned inflection point characteristics appear, damage can be avoided.

[0028] The above six volatile compounds used in the controlled atmosphere storage and preservation method have the following characteristics:

[0029] (1) Consistency: The CO2 concentration corresponding to the inflection point change in the contents of the six volatile compounds described in the present invention is consistent with the CO2 damage point of post-harvest fruits and vegetables. Therefore, a comprehensive prediction of whether CO2 damage will occur can be achieved using multiple indicators, and the prediction results are more scientific and accurate.

[0030] (2) Good effect: During the controlled atmosphere storage process, by detecting the inflection point characteristic changes of one or more of the six volatile compounds, the CO2 concentration in the controlled atmosphere storage environment is adjusted in time, which can effectively avoid the occurrence of CO2 damage to fruits and vegetables and improve the controlled atmosphere preservation effect, and has high application value;

[0031] (3) Wide applicability: The characteristic variation patterns of the six volatile compounds are universal in fruits and vegetables, especially in fruits and vegetables that can tolerate CO2 concentrations of 2%-10%. They can be widely used in the prediction of CO2 damage and the determination and precise control of CO2 upper limit concentrations under controlled atmosphere storage conditions for post-harvest fruits and vegetables.

[0032] In the present invention, the general method for storing and preserving fruits and vegetables in a controlled atmosphere can be used to increase the CO2 concentration in the storage environment in any one of a, b, and c:

[0033] a. Add 1% volume fraction of CO2 every 24 hours;

[0034] b. Add 0.5% volume fraction of CO2 every 24 hours;

[0035] c. Add 2% volume fraction of CO2 every 48 hours.

[0036] Of course, the method of increasing CO2 concentration is not limited to the above situation and is adjusted according to the specific actual situation.

[0037] In the present invention, the general controlled atmosphere storage and preservation method for fruits and vegetables is performed by stopping the atmosphere before sampling. The atmosphere is stopped for a certain time (e.g., at least 8 hours) before sampling to allow the characteristic volatile compounds to accumulate to a detectable content.

[0038] In the present invention, in the general method for controlled atmosphere storage and preservation of fruits and vegetables, solid phase microextraction is used for sampling; and any one of gas chromatography-mass spectrometry, gas chromatograph, electronic nose or electronic tongue is used for detection.

[0039] The above-mentioned general controlled atmosphere storage and preservation method for fruits and vegetables is applied to the preservation of Yellow Fuji apples.

[0040] Furthermore, the general method for storing and preserving fruits and vegetables in a controlled atmosphere is applied to the preservation of Yellow Fuji apples, and the specific operation is as follows:

[0041] Fresh yellow Fuji apples were placed in a storage environment with a temperature of 0°C and an O2 volume fraction of 4%.

[0042] The CO2 concentration in the storage environment starts at 1%, and the volume fraction of CO2 is increased by 1% every 24 hours; the rest is supplementary gas N2;

[0043] Before each increase in CO2 concentration, volatile components in the storage environment are sampled to detect the relative content of the volatile compound at the current CO2 volume fraction; the volatile compound is at least one of o-xylene, p-xylene and n-hexanoic acid;

[0044] With the volume fraction of CO2 as the horizontal axis and the relative content of the measured volatile compounds as the vertical axis, a graph showing the change trend of the relative content of the measured volatile compounds with the increase of the volume fraction of CO2 was drawn;

[0045] The inflection point of the relative content of volatile compounds was obtained, and the CO2 volume fraction corresponding to the inflection point was the critical CO2 concentration. The CO2 volume fraction corresponding to the interval of increase in the CO2 volume fraction before the inflection point was the CO2 concentration in the controlled atmosphere storage environment of the fruits and vegetables.

[0046] Furthermore, before the CO2 volume fraction reaches 3%, the slope of the change trend of the relative content of o-xylene with the increase of CO2 volume fraction is negative, and after the CO2 volume fraction reaches 3%, the slope of the change trend tends to zero;

[0047] Before the CO2 volume fraction reaches 3%, the slope of the change trend of the relative content of p-xylene with the increase of CO2 volume fraction is negative, and after the CO2 volume fraction reaches 3%, the slope of the change trend tends to zero;

[0048] Before the CO2 volume fraction reaches 3%, the slope of the change trend of the relative content of n-hexanoic acid with the increase of CO2 volume fraction is positive, and after the CO2 volume fraction reaches 3%, the slope of the change trend becomes negative.

[0049] Preferably, the critical CO2 concentration for controlled atmosphere storage and preservation of Yellow Fuji apples is 3%;

[0050] The optimal storage environment for controlled atmosphere storage of Yellow Fuji apples is as follows: temperature is 0℃, O2 volume fraction is 4%, CO2 volume fraction is 2%, and the supplementary gas is N2.

[0051] The application of the above-mentioned general controlled atmosphere storage and preservation method for fruits and vegetables in the preservation of garlic sprouts.

[0052] Furthermore, the general method for storing and preserving fruits and vegetables in a controlled atmosphere is applied to the preservation of garlic sprouts, and the specific operation is as follows:

[0053] Place fresh garlic sprouts in a storage environment with a temperature of 0°C and an O2 volume fraction of 3%;

[0054] The CO2 concentration in the storage environment starts at 8%, and the volume fraction of CO2 is increased by 0.5% every 24 hours; the rest is supplementary gas N2;

[0055] Before each increase in CO2 concentration, volatile components in the storage environment are sampled to detect the relative content of the volatile compounds at the current CO2 volume fraction; the volatile compounds are one or more of styrene, o-xylene, p-xylene, mesitylene and α-farnesene;

[0056] With the volume fraction of CO2 as the horizontal axis and the relative content of the measured volatile compounds as the vertical axis, a graph showing the change trend of the relative content of the measured volatile compounds with the increase of the volume fraction of CO2 was drawn;

[0057] The inflection point of the change in the relative content of volatile compounds is obtained, and the CO2 volume fraction corresponding to the inflection point is the CO2 critical concentration; the CO2 volume fraction corresponding to the previous rising interval of the CO2 volume fraction corresponding to the inflection point is the CO2 concentration in the controlled atmosphere storage environment of the fruits and vegetables.

[0058] Furthermore, before the CO2 volume fraction reaches 10.5%, the slope of the change trend of the relative content of styrene with the increase of CO2 volume fraction is negative, and after the CO2 volume fraction reaches 10.5%, the slope of the change trend tends to zero;

[0059] Before the CO2 volume fraction reaches 10.5%, the slope of the change trend of the relative content of o-xylene with the increase of CO2 volume fraction is negative, and after the CO2 volume fraction reaches 10.5%, the slope of the change trend tends to zero;

[0060] Before the CO2 volume fraction reaches 10.5%, the slope of the change trend of the relative content of p-xylene with the increase of CO2 volume fraction is negative, and after the CO2 volume fraction reaches 10.5%, the slope of the change trend tends to zero;

[0061] Before the CO2 volume fraction reaches 10.5%, the slope of the trend of the relative content of mesitylene with the increase of CO2 volume fraction is negative, and after the CO2 volume fraction reaches 10.5%, the slope of the trend tends to zero.

[0062] Before the CO2 volume fraction reaches 10.5%, the slope of the change trend of the relative content of α-farnesene with the increase of CO2 volume fraction is negative, and after the CO2 volume fraction reaches 10.5%, the slope of the change trend becomes positive.

[0063] Preferably, the critical CO2 concentration for the controlled atmosphere storage and preservation of garlic scapes is 10.5%;

[0064] The optimal storage environment for controlled atmosphere storage of garlic sprouts is: temperature of 0℃, O2 volume fraction of 3%, CO2 volume fraction of 10%, and supplementary gas of N2.

[0065] The application of the above-mentioned general controlled atmosphere storage and preservation method for fruits and vegetables in the preservation of cabbage lettuce.

[0066] Furthermore, the application of the general controlled atmosphere storage and preservation method for fruits and vegetables in the preservation of cabbage lettuce is specifically performed as follows:

[0067] Fresh cabbage lettuce was placed in a storage environment with a temperature of 0°C and an O2 volume fraction of 3%.

[0068] The CO2 concentration in the storage environment starts at 2%, and the volume fraction of CO2 is increased by 0.5% every 24 hours; the rest is supplementary gas N2;

[0069] Before each increase in CO2 concentration, volatile components in the storage environment are sampled to detect the relative content of the volatile compounds at the current CO2 volume fraction; the volatile compounds are one or more of styrene, o-xylene, p-xylene, mesitylene and α-farnesene;

[0070] With the volume fraction of CO2 as the horizontal axis and the relative content of the measured volatile compounds as the vertical axis, a graph showing the change trend of the relative content of the measured volatile compounds with the increase of the volume fraction of CO2 was drawn;

[0071] The inflection point of the change in the relative content of volatile compounds is obtained, and the CO2 volume fraction corresponding to the inflection point is the CO2 critical concentration; the CO2 volume fraction corresponding to the previous rising interval of the CO2 volume fraction corresponding to the inflection point is the CO2 concentration in the controlled atmosphere storage environment of the fruits and vegetables.

[0072] Furthermore, before the CO2 volume fraction reaches 5.5%, the slope of the change trend of the relative content of styrene with the increase of CO2 volume fraction is negative, and after the CO2 volume fraction reaches 5.5%, the slope of the change trend tends to zero;

[0073] Before the CO2 volume fraction reaches 5.5%, the slope of the change trend of the relative content of o-xylene with the increase of CO2 volume fraction is negative, and after the CO2 volume fraction reaches 5.5%, the slope of the change trend tends to zero;

[0074] Before the CO2 volume fraction reaches 5.5%, the slope of the change trend of the relative content of p-xylene with the increase of CO2 volume fraction is negative, and after the CO2 volume fraction reaches 5.5%, the slope of the change trend tends to zero;

[0075] Before the CO2 volume fraction reaches 5.5%, the slope of the trend of the relative content of mesitylene with the increase of CO2 volume fraction is negative, and after the CO2 volume fraction reaches 5.5%, the slope of the trend tends to zero.

[0076] Before the CO2 volume fraction reaches 5.5%, the slope of the change trend of the relative content of α-farnesene with the increase of CO2 volume fraction is negative, and after the CO2 volume fraction reaches 5.5%, the slope of the change trend becomes positive.

[0077] Preferably, the critical concentration of CO2 for the controlled atmosphere storage and preservation of cabbage lettuce is 5.5%;

[0078] The optimal storage environment for controlled atmosphere storage of cabbage lettuce is: temperature of 0℃, O2 volume fraction of 3%, CO2 volume fraction of 5%, and supplementary gas of N2.

[0079] The beneficial effects of the present invention are as follows: the universal controlled atmosphere storage and preservation method for fruits and vegetables of the present invention can accurately and comprehensively predict the sensory symptoms caused by CO2 damage in fruits and vegetables before and after CO2 poisoning by detecting characteristic changes in the relative content of one or more of styrene, o-xylene, p-xylene, mesitylene, α-farnesene and n-hexanoic acid in post-harvest fruits and vegetables, thereby playing an early warning role. The method is simple to operate, has universality and is easy to promote.

[0080] This method can raise the CO2 concentration in a controlled atmosphere storage environment to the maximum limit without causing CO2 damage, significantly improving the post-harvest preservation and antiseptic properties of fruits and vegetables, and enhancing their post-harvest storage quality, with practical implications for the industry. For example, using the method described in this invention, head lettuce can be kept fresh for at least two months, at least 200% longer than the 30 days typically achieved with conventional controlled atmosphere storage. Furthermore, the head lettuce's color and other qualities are superior to those achieved with conventional controlled atmosphere storage methods. BRIEF DESCRIPTION OF THE DRAWINGS

[0081] Figure 1 This is a graph showing the changing trend of the relative content of o-xylene as the volume fraction of CO2 increases during the controlled atmosphere storage of Yellow Fuji apples in Example 1 of the present invention.

[0082] Figure 2 This is a graph showing the changing trend of the relative content of p-xylene as the CO2 volume fraction increases during the controlled atmosphere storage of Yellow Fuji apples in Example 1 of the present invention.

[0083] Figure 3 This is a graph showing the changing trend of the relative content of n-hexanoic acid as the volume fraction of CO2 increases during the controlled atmosphere storage of Yellow Fuji apples in Example 1 of the present invention.

[0084] Figure 4 This is a state diagram of the yellow Fuji apples in Example 1 of the present invention suffering from CO2 damage at two CO2 concentrations of 3% and 4%.

[0085] Figure 5This is a diagram showing the state of the Yellow Fuji apples in Example 1 of the present invention after 8 months of controlled atmosphere storage under the optimum CO2 concentration of 2%.

[0086] Figure 6 This is a graph showing the changing trend of the relative content of styrene in garlic sprouts during controlled atmosphere storage as the CO2 volume fraction increases in Example 2 of the present invention.

[0087] Figure 7 This is a graph showing the changing trend of the relative content of o-xylene during the controlled atmosphere storage of garlic sprouts in Example 2 of the present invention as the CO2 volume fraction increases.

[0088] Figure 8 This is a graph showing the changing trend of the relative content of p-xylene during the controlled atmosphere storage of garlic sprouts in Example 2 of the present invention as the CO2 volume fraction increases.

[0089] Figure 9 This is a graph showing the changing trend of the relative content of mesitylene during the controlled atmosphere storage of garlic sprouts in Example 2 of the present invention as the CO2 volume fraction increases.

[0090] Figure 10 This is a graph showing the changing trend of the relative content of α-farnesene during the controlled atmosphere storage of garlic sprouts in Example 2 of the present invention as the CO2 volume fraction increases.

[0091] Figure 11 This is a state diagram of the garlic sprouts in Example 2 of the present invention undergoing CO2 damage at two CO2 concentrations of 10.5% and 11%.

[0092] Figure 12 This is a diagram showing the state of garlic sprouts in Example 2 of the present invention after being stored in a controlled atmosphere at an optimum CO2 concentration of 10% CO2 for 8 months.

[0093] Figure 13 This is a graph showing the changing trend of the relative content of styrene in the head lettuce during controlled atmosphere storage as the CO2 volume fraction increases in Example 3 of the present invention.

[0094] Figure 14 This is a graph showing the changing trend of the relative content of o-xylene with increasing CO2 volume fraction during the controlled atmosphere storage of head lettuce in Example 3 of the present invention.

[0095] Figure 15 This is a graph showing the changing trend of the relative content of p-xylene with increasing CO2 volume fraction during the controlled atmosphere storage of head lettuce in Example 3 of the present invention.

[0096] Figure 16 This is a graph showing the changing trend of the relative content of mesitylene with increasing CO2 volume fraction during the controlled atmosphere storage of head lettuce in Example 3 of the present invention.

[0097] Figure 17This is a graph showing the changing trend of the relative content of α-farnesene with increasing CO2 volume fraction during controlled atmosphere storage of head lettuce in Example 3 of the present invention.

[0098] Figure 18 This is a state diagram of the head lettuce in Example 3 of the present invention undergoing CO2 damage at two CO2 concentrations of 5.5% and 6%.

[0099] Figure 19 This is a state diagram of the head lettuce in Example 3 of the present invention after 2 months of controlled atmosphere storage under the optimum CO2 concentration of 5%. DETAILED DESCRIPTION

[0100] The technical solution of the present invention is described in detail below with reference to the accompanying drawings.

[0101] 1. Solid phase microextraction extraction head: The extraction head used is a 50 / 30 μm DVB / CAR / PDMS head produced by Supelco, USA.

[0102] 2. Gas chromatography-mass spectrometry: Model GC2010 from Shimadzu Corporation, Japan.

[0103] 3. Gas chromatography-mass spectrometry conditions: A DB-WAX capillary column (30 m × 0.25 mm × 0.5 μm) was used. The temperature was programmed at 40°C for 3 min, then at 8°C / min to 80°C for 1 min, then at 9°C / min to 130°C for 1 min, and then at 6°C / min to 230°C for 12 min. The inlet temperature was 250°C, splitless, and the carrier gas was helium (99.999% purity). The column flow rate was 1.00 mL / min, the ion source temperature was 200°C, the interface temperature was 230°C, the detector relative voltage was 0.1 kV, and the scan range was 33-500 m / z. The extraction head was desorbed from the inlet for 5 min.

[0104] 4. Relative content of volatile compounds: The ratio of the peak area of ​​the specified volatile compound to the total peak area obtained by Shimadzu workstation GCMSsolution4.20 analysis.

[0105] Example 1

[0106] The general controlled atmosphere storage and preservation method for fruits and vegetables is applied to store and preserve Yellow Fuji apples, and the specific steps are as follows:

[0107] Fresh yellow Fuji apples were placed in a controlled atmosphere chamber at 0°C and 4% O2 volume fraction;

[0108] The CO2 concentration in the gas conditioning box starts from 1%, and the volume fraction of CO2 is increased by 1% every 24 hours; the rest is supplementary gas N2;

[0109] Before increasing the CO2 concentration each time, ventilation was stopped for 8 hours to stabilize the gas in the box. Then, the solid phase microextraction extraction head, which had been aged and impurity-removed at the gas chromatography inlet at 250°C for 1 hour, was inserted into the gas conditioning box. After extraction for 40 minutes, it was immediately inserted into the inlet of the gas chromatography-mass spectrometry instrument and desorbed at 250°C for 5 minutes. The relative contents of the three volatile compounds, o-xylene, p-xylene and n-hexanoic acid, were analyzed at the current CO2 volume fraction. The parallel test was repeated 3 times in each box.

[0110] With the volume fraction of CO2 as the horizontal axis and the relative content of the measured volatile compounds as the vertical axis, the trend diagrams of the relative content of the three volatile compounds with the increase of the volume fraction of CO2 are drawn respectively. The detailed analysis is as follows:

[0111] like Figure 1 As shown in the figure, in the variable atmosphere treatment of yellow Fuji apples, before the CO2 volume fraction reaches 3%, the relative content of o-xylene shows a continuous downward trend with the increase of CO2 concentration, that is, the slope of the trend is negative; after the CO2 volume fraction reaches 3%, the trend reaches a basically stable state, that is, the slope of the trend tends to zero.

[0112] Therefore, a turning point of change appeared when the CO2 volume fraction was 3%. At a concentration of 3%, Yellow Fuji apples would suffer from CO2 damage, while a CO2 concentration of 2% was the optimal concentration.

[0113] like Figure 2 As shown in the figure, in the variable atmosphere treatment of yellow Fuji apples, before the CO2 volume fraction reaches 3%, the relative content of p-xylene shows a continuous downward trend with the increase of CO2 concentration, that is, the slope of the trend is negative; after the CO2 volume fraction reaches 3%, the trend reaches a basically stable state, that is, the slope of the trend tends to zero.

[0114] Therefore, a turning point of change appeared when the CO2 volume fraction was 3%. At a concentration of 3%, Yellow Fuji apples would suffer from CO2 damage, while a CO2 concentration of 2% was the optimal concentration.

[0115] like Figure 3 As shown in the figure, in the variable atmosphere treatment of Yellow Fuji apples, before the CO2 volume fraction reaches 3%, the relative content of n-hexanoic acid shows a continuous upward trend with the increase of CO2 concentration, that is, the slope of the trend is positive; while after the CO2 volume fraction reaches 3%, the trend is a downward trend, that is, the slope of the trend becomes negative.

[0116] Therefore, a turning point of change appeared when the CO2 volume fraction was 3%. At a concentration of 3%, Yellow Fuji apples would suffer from CO2 damage, while a CO2 concentration of 2% was the optimal concentration.

[0117] By combining the characteristic changes of three volatile compounds, o-xylene, p-xylene and n-hexanoic acid, we can accurately predict that the critical CO2 concentration for the controlled atmosphere storage and preservation of Yellow Fuji apples is 3%.

[0118] The optimal storage environment for controlled atmosphere storage of Yellow Fuji apples is as follows: temperature is 0℃, O2 volume fraction is 4%, CO2 volume fraction is 2%, and the supplementary gas is N2.

[0119] The following comparative experiments are conducted to verify:

[0120] 1. Experimental Method: The same batch of Yellow Fuji apples was divided into 12 portions and stored at four different CO2 concentrations: 1% (the commercial CO2 concentration used for traditional controlled atmosphere storage of Yellow Fuji apples), 2%, 3%, and 4%. Three replicates were conducted at each concentration. Each portion was kept at 0°C and the O2 volume fraction was 4%.

[0121] 2. Experimental results:

[0122] 1. After 2 months of storage, the yellow Fuji apples in the 3% and 4% concentration treatment groups showed symptoms of CO2 poisoning, such as darkening of the skin patches and depression of the skin, and the sweetness of the taste decreased. Figure 4 As shown;

[0123] The yellow Fuji apples stored at 1% and 2% CO2 concentrations had smooth skin, normal color, and no damage symptoms. The yellow Fuji apples stored at 2% CO2 concentration had better quality and better preservation effect than 1%, which is the highest CO2 concentration for traditional controlled atmosphere storage of yellow Fuji apples.

[0124] 2. After 7 months of storage, the yellow Fuji apples at 1% concentration showed symptoms of fruit rot, aging and softening.

[0125] 3. After 8 months of storage, the quality of yellow Fuji apples at 2% concentration is still good, with smooth skin and no dark spots. Figure 5 As shown, 2% CO2 is the optimal concentration for controlled atmosphere storage of this batch of Yellow Fuji apples.

[0126] Example 2

[0127] The general method for storing and preserving fruits and vegetables using controlled atmosphere is applied to store and preserve garlic sprouts, and the specific steps are as follows:

[0128] Place fresh garlic scapes in a controlled atmosphere chamber at 0°C and 3% O2 ​​volume fraction;

[0129] The CO2 concentration in the gas conditioning box starts at 8%, and the volume fraction of CO2 is increased by 0.5% every 24 hours; the rest is supplementary gas N2;

[0130] Before increasing the CO2 concentration each time, ventilation was stopped for 8 hours to stabilize the gas in the box. Then, the solid phase microextraction extraction head, which had been aged and impurity-removed at the gas chromatography inlet at 250°C for 1 hour, was inserted into the gas conditioning box. After extraction for 40 minutes, it was immediately inserted into the inlet of the gas chromatography-mass spectrometry instrument and desorbed at 250°C for 5 minutes. The relative contents of five volatile compounds, namely styrene, o-xylene, p-xylene, mesitylene and α-farnesene, were analyzed at the current CO2 volume fraction. The parallel test was repeated 3 times in each box.

[0131] With the volume fraction of CO2 as the horizontal axis and the relative content of the measured volatile compounds as the vertical axis, the trend diagrams of the relative content of the five volatile compounds with the increase of the volume fraction of CO2 are drawn respectively. The detailed analysis is as follows:

[0132] like Figure 6 As shown in the figure, in the variable gas conditioning of garlic sprouts, before the CO2 volume fraction reaches 10.5%, the relative content of styrene shows a continuous downward trend with the increase of CO2 concentration, that is, the slope of the trend is negative; after the CO2 volume fraction reaches 10.5%, the trend reaches a basically stable state, that is, the slope of the trend tends to zero.

[0133] Therefore, an inflection point of change appeared when the CO2 volume fraction was 10.5%. Garlic scapes would be damaged by CO2 at a concentration of 10.5%, while the CO2 concentration of 10% was the optimal concentration.

[0134] like Figure 7 As shown in the figure, in the variable gas conditioning of garlic sprouts, before the CO2 volume fraction reaches 10.5%, the relative content of o-xylene shows a continuous downward trend with the increase of CO2 concentration, that is, the slope of the trend is negative; after the CO2 volume fraction reaches 10.5%, the trend reaches a basically stable state, that is, the slope of the trend tends to zero.

[0135] Therefore, an inflection point of change appeared when the CO2 volume fraction was 10.5%. Garlic scapes would be damaged by CO2 at a concentration of 10.5%, while the CO2 concentration of 10% was the optimal concentration.

[0136] like Figure 8 As shown in the figure, in the variable gas conditioning of garlic sprouts, before the CO2 volume fraction reaches 10.5%, the relative content of p-xylene shows a continuous downward trend with the increase of CO2 concentration, that is, the slope of the trend is negative; after the CO2 volume fraction reaches 10.5%, the trend reaches a basically stable state, that is, the slope of the trend tends to zero.

[0137] Therefore, an inflection point of change appeared when the CO2 volume fraction was 10.5%. Garlic scapes would be damaged by CO2 at a concentration of 10.5%, while the CO2 concentration of 10% was the optimal concentration.

[0138] like Figure 9 As shown in the figure, in the variable gas conditioning of garlic sprouts, before the CO2 volume fraction reaches 10.5%, the relative content of mesitylene shows a continuous downward trend with the increase of CO2 concentration, that is, the slope of the trend is negative; after the CO2 volume fraction reaches 10.5%, the trend reaches a basically stable state, that is, the slope of the trend tends to zero.

[0139] Therefore, an inflection point of change appeared when the CO2 volume fraction was 10.5%. Garlic scapes would be damaged by CO2 at a concentration of 10.5%, while the CO2 concentration of 10% was the optimal concentration.

[0140] like Figure 10 As shown in the data, in the variable gas conditioning of garlic sprouts, before the CO2 volume fraction reaches 10.5%, the relative content of α-farnesene shows a downward trend with the increase of CO2 concentration, that is, the slope of the trend is negative; after the CO2 volume fraction reaches 10.5%, the trend is an upward trend, that is, the slope of the trend becomes positive.

[0141] Therefore, an inflection point of change appeared when the CO2 volume fraction was 10.5%. Garlic scapes would be damaged by CO2 at a concentration of 10.5%, while the CO2 concentration of 10% was the optimal concentration.

[0142] Combining the characteristic changes of five volatile compounds, namely styrene, o-xylene, p-xylene, mesitylene and α-farnesene, a comprehensive prediction can accurately determine that the critical CO2 concentration for the preservation of garlic sprouts in controlled atmosphere storage is 10.5%;

[0143] The optimal storage environment for controlled atmosphere storage of garlic sprouts is: temperature of 0℃, O2 volume fraction of 3%, CO2 volume fraction of 10%, and supplementary gas of N2.

[0144] The following comparative experiments are conducted to verify:

[0145] I. Experimental Method: The same batch of garlic stalks was divided into 12 portions and stored at four different CO2 concentrations: 8% (the highest commercial CO2 concentration for controlled atmosphere storage of garlic stalks), 10%, 10.5%, and 11%. Three parallel experiments were conducted at each concentration. The temperature of each portion was 0°C, and the O2 volume fraction was 3%.

[0146] 2. Experimental results:

[0147] 1. After 2 months of storage, the garlic stalks in the treatment groups with 10.5% and 11% concentrations showed symptoms of CO2 damage, such as green fading, lignification, water-soaked appearance, and ethanol odor. Figure 11 As shown;

[0148] The garlic stalks stored at both 10% and 8% concentrations were of good quality and showed no signs of damage. The garlic stalks stored at 10% concentration were greener in color, and the controlled atmosphere preservation effect was better than that at 8%, which is the highest CO2 concentration for traditional controlled atmosphere storage of garlic stalks.

[0149] 2. After 7 months of storage, the quality of garlic stalks at 8% concentration showed signs of aging of stalks, yellowing of stalk tips, and mold growth.

[0150] 3. After 8 months of storage, the quality of garlic scapes at 10% concentration is still good and the color is still green. Figure 12 As shown, 10% CO2 is the optimal concentration for controlled atmosphere storage of this batch of garlic sprouts.

[0151] Example 3

[0152] The general controlled atmosphere storage and preservation method for fruits and vegetables is applied to store and preserve head lettuce, and the specific steps are as follows:

[0153] Fresh head lettuce was placed in a controlled atmosphere chamber at 0°C and 3% O2 ​​volume fraction;

[0154] The CO2 concentration in the gas conditioning box starts at 2%, and the volume fraction of CO2 is increased by 0.5% every 24 hours; the rest is supplementary gas N2;

[0155] Before increasing the CO2 concentration each time, ventilation was stopped for 8 hours to stabilize the gas in the box. Then, the solid phase microextraction extraction head, which had been aged and impurity-removed at the gas chromatography inlet at 250°C for 1 hour, was inserted into the gas conditioning box. After extraction for 40 minutes, it was immediately inserted into the inlet of the gas chromatography-mass spectrometry instrument and desorbed at 250°C for 5 minutes. The relative contents of five volatile compounds, namely styrene, o-xylene, p-xylene, mesitylene and α-farnesene, were analyzed at the current CO2 volume fraction. The parallel test was repeated 3 times in each box.

[0156] With the volume fraction of CO2 as the horizontal axis and the relative content of the measured volatile compounds as the vertical axis, the trend diagrams of the relative content of the five volatile compounds with the increase of the volume fraction of CO2 are drawn respectively. The detailed analysis is as follows:

[0157] like Figure 13 As shown in the figure, in the variable atmosphere of head lettuce, before the CO2 volume fraction reaches 5.5%, the relative content of styrene shows a continuous downward trend with the increase of CO2 concentration, that is, the slope of the trend is negative; after the CO2 volume fraction reaches 5.5%, the trend reaches a basically stable state, that is, the slope of the trend tends to zero.

[0158] Therefore, a turning point of change appeared when the CO2 volume fraction was 5.5%. At a concentration of 5.5%, the head lettuce would suffer from CO2 damage, and 5% CO2 concentration was the optimal concentration.

[0159] like Figure 14 As shown in the figure, in the variable atmosphere of head lettuce, before the CO2 volume fraction reaches 5.5%, the relative content of o-xylene shows a continuous downward trend with the increase of CO2 concentration, that is, the slope of the trend is negative; after the CO2 volume fraction reaches 5.5%, the trend reaches a basically stable state, that is, the slope of the trend tends to zero.

[0160] Therefore, a turning point of change appeared when the CO2 volume fraction was 5.5%. At a concentration of 5.5%, the head lettuce would suffer from CO2 damage, and 5% CO2 concentration was the optimal concentration.

[0161] like Figure 15 As shown in the figure, in the variable atmosphere of head lettuce, before the CO2 volume fraction reaches 5.5%, the relative content of p-xylene shows a continuous downward trend with the increase of CO2 concentration, that is, the slope of the trend is negative; after the CO2 volume fraction reaches 5.5%, the trend reaches a basically stable state, that is, the slope of the trend tends to zero.

[0162] Therefore, a turning point of change appeared when the CO2 volume fraction was 5.5%. At a concentration of 5.5%, the head lettuce would suffer from CO2 damage, and 5% CO2 concentration was the optimal concentration.

[0163] like Figure 16 As shown in the figure, in the variable atmosphere of head lettuce, before the CO2 volume fraction reaches 5.5%, the relative content of mesitylene shows a continuous downward trend with the increase of CO2 concentration, that is, the slope of the trend is negative; after the CO2 volume fraction reaches 5.5%, the trend reaches a basically stable state, that is, the slope of the trend tends to zero.

[0164] Therefore, a turning point of change appeared when the CO2 volume fraction was 5.5%. At a concentration of 5.5%, the head lettuce would suffer from CO2 damage, and 5% CO2 concentration was the optimal concentration.

[0165] like Figure 17 As shown in the figure, in the variable atmosphere of head lettuce, before the CO2 volume fraction reaches 5.5%, the relative content of α-farnesene shows a downward trend with the increase of CO2 concentration, that is, the slope of the trend is negative; after the CO2 volume fraction reaches 5.5%, the trend is an upward trend, that is, the slope of the trend becomes positive.

[0166] Therefore, a turning point of change appeared when the CO2 volume fraction was 5.5%. At a concentration of 5.5%, the head lettuce would suffer from CO2 damage, and 5% CO2 concentration was the optimal concentration.

[0167] Combining the characteristic changes of five volatile compounds, namely styrene, o-xylene, p-xylene, mesitylene and α-farnesene, a comprehensive prediction can accurately determine that the critical CO2 concentration for the preservation of cabbage lettuce in controlled atmosphere storage is 5.5%;

[0168] The optimal storage environment for controlled atmosphere storage of cabbage lettuce is: temperature of 0℃, O2 volume fraction of 3%, CO2 volume fraction of 5%, and supplementary gas of N2.

[0169] The following comparative experiments are conducted to verify:

[0170] I. Experimental Method: The same batch of head lettuce was divided into 12 portions and stored at four different CO2 concentrations: 2% (the commercial CO2 concentration used for traditional controlled atmosphere storage of head lettuce), 5%, 5.5%, and 6%. Three replicates were conducted at each concentration. The temperature of each portion was 0°C, and the O2 volume fraction was 3%.

[0171] 2. Experimental results:

[0172] 1. After 25 days of storage, the lettuce heads in the treatment groups with 5.5% and 6% CO2 concentrations showed symptoms of CO2 damage, such as powdery core, browning of leaves, and odor. Figure 18 As shown;

[0173] The head lettuce stored at 5% and 2% concentrations were of good quality, with normal center color and no damage symptoms. The head lettuce stored at 5% concentration had better quality and better controlled atmosphere preservation effect than 2%.

[0174] 2. After 30 days of storage, the outer leaves of the head lettuce at a concentration of 5% showed signs of aging, water loss, mildew and rot.

[0175] 3. After 2 months of storage, the quality of the head lettuce at 5% concentration is still good. Figure 19 Therefore, 5% CO2 is the most suitable concentration for controlled atmosphere storage of this batch of cabbage lettuce.

Claims

1. A method for storing and preserving yellow Fuji apples in a controlled atmosphere, characterized in that: The following steps are involved: Yellow Fuji apples were placed in a controlled atmosphere storage environment, and the CO2 concentration in the storage environment was gradually increased, and the concentration was measured in volume fraction. Before each increase in CO2 concentration, sampling volatile components in the storage environment to detect the relative content of the volatile compound at the current CO2 volume fraction, wherein the volatile compound is at least one of o-xylene, p-xylene and n-hexanoic acid; With the volume fraction of CO2 as the horizontal axis and the relative content of the measured volatile compounds as the vertical axis, a graph showing the change trend of the relative content of the measured volatile compounds with the increase of the volume fraction of CO2 was drawn; When an inflection point appears in the trend graph, stop increasing the CO2 concentration and immediately reduce the CO2 concentration to a value less than the CO2 volume fraction corresponding to the inflection point. The inflection point characteristic refers to the point where the slope of the trend of change of the relative content of volatile compounds with the increase of CO2 volume fraction changes significantly; The obvious changes include the following features: 1) The slope of the trend before the inflection point is negative, and the slope of the trend after the inflection point tends to zero; 2) The slope of the trend before the inflection point is negative, and the slope of the trend after the inflection point is positive; 3) The slope of the trend before the inflection point is positive, and the slope of the trend after the inflection point is negative.

2. A method for storing and preserving garlic sprouts in a controlled atmosphere, characterized in that: The following steps are involved: Place the garlic scapes in a controlled atmosphere storage environment and gradually increase the CO2 concentration in the storage environment, the concentration of which is measured in volume fraction; Before each increase in CO2 concentration, sampling the volatile components in the storage environment to detect the relative content of the volatile compounds at the current CO2 volume fraction, wherein the volatile compounds are one or more of styrene, o-xylene, p-xylene, mesitylene and α-farnesene; With the volume fraction of CO2 as the horizontal axis and the relative content of the measured volatile compounds as the vertical axis, a graph showing the change trend of the relative content of the measured volatile compounds with the increase of the volume fraction of CO2 was drawn; When an inflection point appears in the trend graph, stop increasing the CO2 concentration and immediately reduce the CO2 concentration to a value less than the CO2 volume fraction corresponding to the inflection point. The inflection point characteristic refers to the point where the slope of the trend of change of the relative content of volatile compounds with the increase of CO2 volume fraction changes significantly; The obvious changes include the following features: 1) The slope of the trend before the inflection point is negative, and the slope of the trend after the inflection point tends to zero; 2) The slope of the trend before the inflection point is negative, and the slope of the trend after the inflection point is positive; 3) The slope of the trend before the inflection point is positive, and the slope of the trend after the inflection point is negative.

3. A method for storing and preserving cabbage lettuce in a controlled atmosphere, characterized in that: The following steps are involved: The head lettuce was placed in a controlled atmosphere storage environment, and the CO2 concentration in the storage environment was gradually increased, and the concentration was measured by volume fraction. Before each increase in CO2 concentration, volatile components in the storage environment are sampled to detect the relative content of the volatile compounds at the current CO2 volume fraction, wherein the volatile compounds are one or more of styrene, o-xylene, p-xylene, mesitylene and α-farnesene; With the volume fraction of CO2 as the horizontal axis and the relative content of the measured volatile compounds as the vertical axis, a graph showing the change trend of the relative content of the measured volatile compounds with the increase of the volume fraction of CO2 was drawn; When an inflection point appears in the trend graph, stop increasing the CO2 concentration and immediately reduce the CO2 concentration to a value less than the CO2 volume fraction corresponding to the inflection point. The inflection point characteristic refers to the point where the slope of the trend of change of the relative content of volatile compounds with the increase of CO2 volume fraction changes significantly; The obvious changes include the following features: 1) The slope of the trend before the inflection point is negative, and the slope of the trend after the inflection point tends to zero; 2) The slope of the trend before the inflection point is negative, and the slope of the trend after the inflection point is positive; 3) The slope of the trend before the inflection point is positive, and the slope of the trend after the inflection point is negative.

4. The controlled atmosphere storage and preservation method according to any one of claims 1 to 3, characterized in that: The method of increasing the CO2 concentration in the storage environment is selected from any one of a, b, and c: a. Add 1% volume fraction of CO2 every 24 hours; b. Add 0.5% volume fraction of CO2 every 24 hours; c. Add 2% volume fraction of CO2 every 48 hours.

5. The controlled atmosphere storage and preservation method according to any one of claims 1 to 3, characterized in that: Stop gas conditioning before sampling.

6. The controlled atmosphere storage and preservation method according to any one of claims 1 to 3, characterized in that: Sampling is done by solid phase microextraction; detection is done by gas chromatography-mass spectrometry, gas chromatograph, electronic nose or electronic tongue.

7. The method for storing and preserving yellow Fuji apples in a controlled atmosphere according to claim 1, wherein: The specific operations are as follows: Fresh yellow Fuji apples were placed in a storage environment with a temperature of 0°C and an O2 volume fraction of 4%. The CO2 concentration in the storage environment starts at 1%, and the volume fraction of CO2 is increased by 1% every 24 hours; the rest is supplementary gas N2; Before each increase in CO2 concentration, volatile components in the storage environment are sampled to detect the relative content of the volatile compound at the current CO2 volume fraction; the volatile compound is at least one of o-xylene, p-xylene and n-hexanoic acid; With the volume fraction of CO2 as the horizontal axis and the relative content of the measured volatile compounds as the vertical axis, a graph showing the change trend of the relative content of the measured volatile compounds with the increase of the volume fraction of CO2 was drawn; The inflection point of the change in the relative content of volatile compounds is obtained, and the CO2 volume fraction corresponding to the inflection point is the CO2 critical concentration; the CO2 volume fraction corresponding to the previous rising interval of the CO2 volume fraction corresponding to the inflection point is the CO2 concentration in the controlled atmosphere storage environment of the fruits and vegetables.

8. The method for storing and preserving yellow Fuji apples in a controlled atmosphere according to claim 7, wherein: The critical concentration of CO2 for the preservation of Yellow Fuji apples in controlled atmosphere storage is 3%; The optimal storage environment for controlled atmosphere storage of Yellow Fuji apples is as follows: temperature is 0℃, O2 volume fraction is 4%, CO2 volume fraction is 2%, and the supplementary gas is N2.

9. The method for storing and preserving garlic sprouts in a controlled atmosphere according to claim 2, wherein: The specific operations are as follows: Fresh garlic sprouts were placed in a storage environment with a temperature of 0°C and an O2 volume fraction of 3%. The CO2 concentration in the storage environment starts at 8%, and the volume fraction of CO2 is increased by 0.5% every 24 hours; the rest is supplementary gas N2; Before each increase in CO2 concentration, volatile components in the storage environment are sampled to detect the relative content of the volatile compounds at the current CO2 volume fraction; the volatile compounds are one or more of styrene, o-xylene, p-xylene, mesitylene and α-farnesene; With the volume fraction of CO2 as the horizontal axis and the relative content of the measured volatile compounds as the vertical axis, a graph showing the change trend of the relative content of the measured volatile compounds with the increase of the volume fraction of CO2 was drawn; The inflection point of the change in the relative content of volatile compounds is obtained, and the CO2 volume fraction corresponding to the inflection point is the CO2 critical concentration; the CO2 volume fraction corresponding to the previous rising interval of the CO2 volume fraction corresponding to the inflection point is the CO2 concentration in the controlled atmosphere storage environment of the fruits and vegetables.

10. The method for storing and preserving garlic sprouts in a controlled atmosphere according to claim 9, wherein: The critical concentration of CO2 for the preservation of garlic sprouts in controlled atmosphere storage is 10.5%; The optimal storage environment for garlic sprouts in controlled atmosphere storage is: temperature 0℃, O2 volume fraction 3%, CO2 volume fraction 10%, and supplementary gas N2.

11. The method for storing and preserving head lettuce in a controlled atmosphere according to claim 3, wherein: The specific operations are as follows: Fresh cabbage lettuce was placed in a storage environment with a temperature of 0°C and an O2 volume fraction of 3%. The CO2 concentration in the storage environment starts at 2%, and the volume fraction of CO2 is increased by 0.5% every 24 hours; the rest is supplementary gas N2; Before each increase in CO2 concentration, volatile components in the storage environment are sampled to detect the relative content of the volatile compounds at the current CO2 volume fraction; the volatile compounds are one or more of styrene, o-xylene, p-xylene, mesitylene and α-farnesene; With the volume fraction of CO2 as the horizontal axis and the relative content of the measured volatile compounds as the vertical axis, a graph showing the change trend of the relative content of the measured volatile compounds with the increase of the volume fraction of CO2 was drawn; The inflection point of the change in the relative content of volatile compounds is obtained, and the CO2 volume fraction corresponding to the inflection point is the CO2 critical concentration; the CO2 volume fraction corresponding to the previous rising interval of the CO2 volume fraction corresponding to the inflection point is the CO2 concentration in the controlled atmosphere storage environment of the fruits and vegetables.

12. The method for storing and preserving head lettuce in a controlled atmosphere according to claim 11, wherein: The critical concentration of CO2 for the preservation of cabbage lettuce in controlled atmosphere storage is 5.5%; The optimal storage environment for controlled atmosphere storage of cabbage lettuce is: temperature 0℃, O2 volume fraction 3%, CO2 volume fraction 5%, and supplementary gas N2.

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