Preservation method for inhibiting browning of fresh-cut lily bulb

Abstract

The present application relates to fresh-cut fruit and vegetable preservation technology field, and particularly to a preservation method for inhibiting browning of fresh-cut lily scales. The present application discloses a preservation method for inhibiting browning of fresh-cut lily scales, which comprises the following steps: selecting, peeling, washing and boxing the lily scales, and then performing X-ray irradiation treatment on the fresh-cut lily scales and storing them at low temperature. The preservation method provided by the present application is safe, environmentally friendly and easy to operate, and can effectively solve the problems of poor storage tolerance, easy browning and quality decline of fresh-cut lily. The application of the method can inhibit the browning of fresh-cut lily, prevent membrane lipid peroxidation, increase the total phenol content, maintain the appearance quality of fresh-cut lily, effectively delay the aging process, and prolong the shelf life, thereby achieving the purpose of improving the quality and efficiency of the fresh-cut lily industry.

Description

Technical Field

[0001] This invention relates to the field of fresh-cut fruit and vegetable preservation technology, specifically to a method for inhibiting browning of fresh-cut lily bulbs. Background Technology

[0002] Lily is a perennial herbaceous plant belonging to the genus *Lilium* in the family Liliaceae. It was one of the first plants in my country to be used for both medicinal and edible purposes. Its underground bulbs are pure white, fleshy, and sweet-smelling, rich in protein, vitamins, and amino acids, possessing extremely high nutritional value. It is also rich in phenols, flavonoids, polysaccharides, and other active substances, offering benefits such as moisturizing the lungs, relieving coughs, and calming the mind, thus possessing certain medicinal and health-promoting value. With the improvement of people's living standards and the acceleration of their pace of life, fresh-cut lily, as a ready-to-eat product, is favored by consumers for its freshness, nutrition, convenience, and healthy qualities, and its demand is rapidly increasing.

[0003] Browning in fresh-cut lilies is a common problem in fruit and vegetable processing. Browning accelerates spoilage and decay, affecting the quality and taste of the lily scales, reducing nutritional value, and shortening the storage period. Cutting damages the lily's tissue structure and activates phenylalanine ammonialyase (PAL) activity, leading to an increase in phenolic compounds. The cell walls and membranes lose their integrity, and phenolic compounds combine with polyphenol oxidase (PPO) and peroxidase (POD) to cause browning. Furthermore, cutting exacerbates the accumulation of reactive oxygen species (ROS), damaging the structure and function of proteins and enzymes. Unsaturated fatty acids in membrane lipids undergo peroxidation due to ROS attack, producing large amounts of malondialdehyde (MDA), increasing membrane permeability and further intensifying browning. Superoxide dismutase (SOD) and catalase (CAT) are important protective enzymes in the plant free radical scavenging system, so a decrease in their activity also exacerbates browning.

[0004] Currently, the main methods for inhibiting browning in lilies are the use of chemical preservatives, such as sulfides, chlorides, ethanol, and citric acid, which often leave chemical residues. Natural extract methods, such as tea tree oil and mulberry extract, can introduce off-flavors. Modified atmosphere packaging is costly and inefficient. The oxygen-deficient environment of vacuum packaging leads to anaerobic fermentation in fruits and vegetables, producing off-flavors. Heat processing can damage heat-sensitive substances and cause a decline in flavor and quality. Therefore, there is an urgent need to develop a green, environmentally friendly, and highly efficient method for inhibiting browning in fresh-cut lilies. Summary of the Invention

[0005] In view of this, the present invention provides a method for preserving fresh-cut lily bulbs by inhibiting browning.

[0006] This invention provides a method for preserving fresh-cut lily bulbs by inhibiting browning. 1. This invention maintains the sensory quality of fresh-cut lilies at a high level, ensuring commercial value and preserving their original a* and L* values. 2. During storage, this invention reduces the browning rate of fresh-cut lilies, effectively reduces PPO and POD activity, enhances SOD and CAT activity, reduces MDA accumulation, increases total phenol content, and extends shelf life. 3. This invention provides a method for inhibiting browning in fresh-cut lilies using X-ray irradiation. Results show that this method effectively inhibits browning, prevents membrane lipid peroxidation, and increases total phenol content, effectively maintaining the quality of fresh-cut lilies during storage and extending shelf life. 4. The X-rays used in this invention are high-energy photon radiation with strong penetrability, easily controlled dosage, and good uniformity. It does not require opening the lily packaging; it significantly inhibits browning of fresh-cut lilies without complex pretreatment steps, minimizing quality decline and extending shelf life to 12 days. This invention has the advantages of being safe, effective, non-toxic, pollution-free, and harmless.

[0007] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0008] This invention provides a method for preserving fresh-cut lilies by inhibiting browning, characterized by comprising the following steps:

[0009] Step 1: After grading and selecting lilies, pre-cool, peel off the petals, wash, and dry to obtain lily scales, which are then stacked in a container;

[0010] Step 2: Take the lily scales stacked in the container and subject them to X-ray irradiation treatment;

[0011] Step 3: Take the lily scales that have undergone X-ray irradiation treatment, pre-cool and refrigerate them;

[0012] The X-ray irradiation dose is 50–400 Gy, the energy is 0.5–5 MeV, the delivery speed is 0.50–3.0 m / min, and the sample is 40–80 cm away from the beam output port.

[0013] In some specific embodiments of the present invention, the lily is Lanzhou lily.

[0014] In some specific embodiments of the present invention, the dose of the X-ray irradiation is 50 Gy, 100 Gy, 200 Gy or 400 Gy.

[0015] In some specific embodiments of the present invention, the X-ray irradiation dose is 50 Gy, the energy is 3 MeV, the delivery speed is 2.0 m / min, and the sample is 60 cm away from the beam output port.

[0016] In some specific embodiments of the present invention, the diameter of the lilies after grading and selection in step 1 is 2 to 5 cm.

[0017] In some specific embodiments of the present invention, the diameter of the lilies after grading and selection is 3 to 4 cm.

[0018] In some specific embodiments of the present invention, the pre-cooling temperature in step 1 is 1-3°C and the time is 12-24 hours;

[0019] The cleaning described in step 1 is ultrasonic cleaning; the ultrasonic cleaning frequency is 40kHz and the power is 150-500w.

[0020] In some specific embodiments of the present invention, the ultrasonic cleaning is performed twice, each time for 1 minute.

[0021] In some specific embodiments of the present invention, the precooling time is 12 hours;

[0022] The ultrasonic cleaning power is 500W.

[0023] In some specific embodiments of the present invention, the drying temperature in step 1 is 20-25°C and the time is 9-11 minutes;

[0024] The thickness of the layers in step 1 is 4.5 to 5.5 cm.

[0025] In some specific embodiments of the present invention, the volume ratio of the lily scales in step 1 to the volume of the container is ≤2:3.

[0026] In some specific embodiments of the present invention, the volume ratio of the lily scales to the volume of the container is 1:2.

[0027] In some specific embodiments of the present invention, the pre-cooling temperature in step 3 is 10°C and the time is 12 hours;

[0028] The refrigeration temperature is 3-5°C and the humidity is 75-85%.

[0029] In some specific embodiments of the present invention, the preservation method for inhibiting browning of fresh-cut lilies specifically includes the following steps:

[0030] Step 1: Lily sorting and pre-cooling: Select fresh lilies with a diameter of 2-5cm and pre-cool them.

[0031] Step 2: Peeling process: Take the pre-cooled lily and clean it with ultrasonic waves twice, 1 minute each time, and then dry it at 20-25°C to obtain lily scales, which are then stored in a container.

[0032] Step 3: Irradiation treatment and storage: The lily scales are subjected to X-ray irradiation treatment;

[0033] Step 4: Take the lily scales that have undergone X-ray irradiation treatment, pre-cool them, and refrigerate them.

[0034] In some specific embodiments of the present invention, the pre-cooling temperature in step 1 is 1 to 3°C and the time is 12 to 24 hours.

[0035] In some specific embodiments of the present invention, the precooling time is 12 hours.

[0036] In some specific embodiments of the present invention, the ultrasonic cleaning in step 2 has a frequency of 40 kHz and a power of 150-500 W.

[0037] In some specific embodiments of the present invention, the ultrasonic cleaning power is 500W.

[0038] In some specific embodiments of the present invention, the drying temperature in step 2 is 20-25°C and the drying time is 9-11 minutes.

[0039] In some specific embodiments of the present invention, the volume ratio of the lily scales in step 2 to the volume of the container is ≤2:3.

[0040] In some specific embodiments of the present invention, the volume ratio of the lily scales to the volume of the container is 1:2.

[0041] In some specific embodiments of the present invention, the thickness of the lily scales in step 2 is 4.5 to 5.5 cm.

[0042] In some specific embodiments of the present invention, the dose of X-ray irradiation in step 3 is 50 to 400 Gy.

[0043] In some specific embodiments of the present invention, the dose of X-ray irradiation is 50 Gy.

[0044] In some specific embodiments of the present invention, the pre-cooling temperature in step 4 is 10°C and the time is 12 hours;

[0045] The refrigeration temperature is 3-5°C and the humidity is 75-85%.

[0046] This invention provides a method for preserving fresh-cut lily bulbs by inhibiting browning. The method involves selecting, peeling, washing, and packaging the lily bulbs, then subjecting the fresh-cut lilies to X-ray irradiation and low-temperature storage. This preservation method is safe, environmentally friendly, and easy to operate, effectively solving the problems of fresh-cut lilies' poor storage tolerance, easy browning, and quality degradation. Applying this method can inhibit browning, prevent membrane lipid peroxidation, and increase total phenolic content in fresh-cut lilies, while maintaining their appearance quality, effectively delaying their aging process, and extending their shelf life, thereby improving the quality and efficiency of the fresh-cut lily industry. Attached Figure Description

[0047] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below.

[0048] Figure 1 This illustrates the technical approach for implementing the present invention;

[0049] Figure 2 The effect of X-ray irradiation on the sensory quality of fresh-cut lily scales during storage is shown in the example.

[0050] Figure 3 The effect of X-ray irradiation on the browning index of fresh-cut lily scales during storage is shown in the example.

[0051] Figure 4 The effect of X-ray irradiation on the L* value of fresh-cut lily scales during storage is shown in the example.

[0052] Figure 5 The effect of X-ray irradiation on the a* value of fresh-cut lily scales during storage is shown in the example.

[0053] Figure 6 The effect of X-ray irradiation on the total phenol content of fresh-cut lily scales during storage is shown in the example.

[0054] Figure 7 The effect of X-ray irradiation (50 Gy) on the POD activity of fresh-cut lily scales during storage is shown in the example.

[0055] Figure 8 The effect of X-ray irradiation (50 Gy) on the PPO activity of fresh-cut lily scales during storage is shown in the example.

[0056] Figure 9 The effect of X-ray irradiation (50 Gy) on SOD activity of fresh-cut lily scales during storage is shown in the example.

[0057] Figure 10 The effect of X-ray irradiation (50 Gy) on CAT activity during the storage of fresh-cut lily scales is shown in the example.

[0058] Figure 11 The effect of X-ray irradiation (50 Gy) on the MDA content of fresh-cut lily scales during storage was shown in the example. Detailed Implementation

[0059] This invention discloses a method for inhibiting browning of fresh-cut lily bulbs. Those skilled in the art can refer to this document and appropriately modify the process parameters to achieve the desired result. It is particularly important to note that all similar substitutions and modifications are obvious to those skilled in the art and are considered to be included in this invention. The methods and applications of this invention have been described through preferred embodiments. Those skilled in the art can clearly modify or appropriately change and combine the methods and applications described herein without departing from the content, spirit, and scope of this invention to realize and apply the technology of this invention.

[0060] The preservation method for inhibiting browning of fresh-cut lilies described above in this invention specifically includes the following steps:

[0061] (1) Lily sorting and pre-cooling: The lilies are graded and selected. Fresh lilies with no mechanical damage, pests and diseases, tightly closed bulbs and petals, and a diameter of 2-5cm are selected and pre-cooled in an environment of 2±1℃ for 12-24h.

[0062] (2) Peeling process: After peeling the petals, select lilies that are white and tender, without spots on the surface, and smooth. Clean them twice with deionized water using ultrasonic waves for 1 minute each time. Then take them out and air dry them on sterile gauze at 20-25°C. Store the dried lily scales in a food storage box.

[0063] (3) Irradiation treatment and storage: The lily scales placed in the preservation box in step (2) were subjected to X-ray irradiation treatment;

[0064] (4) After irradiation, the product was pre-cooled at 10°C for 12 hours, and then refrigerated at 4±1°C with a humidity of 80±5%.

[0065] In step (2) above, ultrasonic cleaning is performed at a frequency of 40 kHz and a power of 150–500 W.

[0066] In step (2) above, the drying time at 20-25℃ is 10±1min.

[0067] In step (3) above, the thickness of the fresh-cut lily bulbs placed in the food storage box is 5±0.5cm, and the volume ratio of the lily bulb scales to the volume of the food storage box does not exceed 2:3.

[0068] In step (3) above, the irradiation dose is 50-400 Gy, preferably 50 Gy, the energy is 0.5-5 MeV, the delivery speed is 0.50-3.0 m / min, and the sample is 40-80 cm away from the beam output port.

[0069] The sample is placed on a conveyor for irradiation, and the irradiation dose is generally controlled by adjusting the conveyor speed and energy level. The time required for the conveyor belt to complete irradiation is related to the processing time, the conveyor circumference, and the speed.

[0070] The raw materials and reagents used in the preservation method for inhibiting browning of fresh-cut lily bulbs provided by this invention are all commercially available.

[0071] The present invention will be further illustrated below with reference to the embodiments:

[0072] Example 1

[0073] (1) Lily sorting and pre-cooling: The lilies are graded and selected. Fresh lilies with no mechanical damage, pests and diseases, tightly closed bulbs and petals, and a diameter of 3.5±0.5cm are selected and placed in an environment with a temperature of 2±1℃ for 12 hours for pre-cooling.

[0074] (2) Peeling process: After peeling, select lilies that are white and tender, without spots on the surface, with neat roots without browning, no mechanical damage, and smooth surface. Clean them with deionized water using ultrasonic waves at a frequency of 40kHz and a power of 500w twice, for 1 minute each time. Then, take them out and air dry them on sterile gauze at 25℃ for 10 minutes. Store the dried lily slices in a food storage box. The thickness of the fresh-cut lilies should be 5±0.5cm, and the volume ratio of the fresh-cut lilies to the volume of the food storage box should be 1:2.

[0075] (3) Irradiation treatment and storage: The lily slices placed in the preservation box in step (2) were subjected to X-ray irradiation treatment. The irradiation dose was 50 Gy, the energy was 3 MeV, the delivery speed was 2.0 m / min, and the sample was 60 cm away from the beam output port.

[0076] (4) After irradiation, place it in an environment of 10°C for 12 hours to pre-cool, and then refrigerate it at a temperature of 4±1°C and a humidity of 80±5%.

[0077] Example 2

[0078] X-ray irradiation treatment was performed with an irradiation dose of 100 Gy, and the remaining steps were the same as in Example 1.

[0079] Example 3

[0080] X-ray irradiation was performed at a dose of 200 Gy, and the remaining steps were the same as in Example 1.

[0081] Example 4

[0082] X-ray irradiation was performed at a dose of 400 Gy, and the remaining steps were the same as in Example 1.

[0083] Comparative Example 1

[0084] No X-ray irradiation treatment was performed; the remaining steps were the same as in Example 1.

[0085] Example of effect

[0086] The technical route for implementing this invention is as follows: Figure 1 First, the appearance, color and total phenol content of lilies in the 0, 50, 100, 200 and 400 Gy treatment groups were determined. Figures 2-5 The L* value represents brightness; the larger the value, the brighter the brightness. The a* value represents the transition from red to green; the larger the value, the deeper the green.

[0087] During storage, the browning index of the X-ray treated groups was significantly lower than that of the control group. On day 12, the browning index of the 50 Gy X-ray treated group was the lowest, decreasing by 29.73% compared to the control group. Figure 3 During storage, the L* values ​​of the X-ray treated groups were significantly higher than those of the control group, and the L* values ​​of the 50 Gy treated group remained at a high level throughout. Figure 4 The 50 Gy treatment group had the lowest a* values ​​on days 9 and 12. Figure 5 On day 12, the total phenol content in the 50 Gy treatment group was 13.82% higher than that in the control group. Figure 6 The above indicates that X-ray irradiation treatment helps maintain the color of fresh-cut lily bulbs, inhibits browning, and increases the content of active ingredients, with irradiation at a dose of 50 Gy showing the best results.

[0088] like Figures 7-8 As shown, during storage, the activities of POD and PPO in the 50 Gy treatment group were lower than those in the control group. This indicates that the activities of PPO and POD enzymes in fresh-cut lily scales treated with X-ray irradiation were effectively inhibited, which will help reduce the browning degree of fresh-cut lily scales, effectively preserve the original quality of the lily, and maintain its freshness. In the early stage of storage, X-ray irradiation treatment had no significant effect on the SOD activity of Lanzhou lily. However, starting from day 6, the SOD activity of the treated group of Lanzhou lily increased rapidly. On day 9, the SOD activity of the 50 Gy treatment group was 27.19% higher than that of the control group. Figure 9 Throughout the storage period, the CAT activity of the 50 Gy irradiation group was consistently higher than that of the control group. Figure 10 At the end of the storage period, the MDA content in the 50 Gy treatment group was significantly lower than that in the control group. Figure 11 The results showed that the synergistic effect of CAT and SOD can catalyze the production of hydrogen peroxide and oxygen from superoxide anions in fresh-cut lilies, reduce the accumulation of MDA, prevent membrane lipid peroxidation, and thus delay their aging.

[0089] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preserving fresh-cut lilies by inhibiting browning, characterized in that, It consists of the following steps: Step 1: After grading and selecting lilies, pre-cool, peel off the petals, wash, and dry to obtain lily scales, which are then stacked in a container; Step 2: Take the lily scales stacked in the container and subject them to X-ray irradiation treatment; Step 3: Take the lily scales that have undergone X-ray irradiation treatment, pre-cool and refrigerate them; The X-ray irradiation dose was 50 Gy, the energy was 3 MeV, the delivery speed was 2 m / min, and the sample was 60 cm away from the beam output port. The pre-cooling temperature in step 1 is 1~3℃, and the time is 12 h; The cleaning described in step 1 is ultrasonic cleaning; the ultrasonic cleaning frequency is 40 kHz and the power is 500 W. The diameter of the lilies after grading and selection in step 1 is 3-4 cm; The drying temperature described in step 1 is 25℃, and the time is 10 min; The thickness of the layers described in step 1 is 4.5~5.5 cm; The volume ratio of the lily scales to the container in step 1 is 1:2; The pre-cooling temperature in step 3 is 10°C, and the time is 12 hours. The refrigeration temperature is 3~5℃ and the humidity is 75~85%.

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