Treatment method for relieving oxidative browning of respiratory climacteric fruits and vegetables

Abstract

The invention discloses a treatment method for relieving respiratory climacteric fruit and vegetable oxidation browning, and belongs to the technical field of fruit and vegetable storage and fresh-keeping processing. The method comprises the following steps: soaking treatment equipment and fruits and vegetables with NaClO or 75% ethanol solution, washing with deionized water, draining, and cutting into fresh-cut fruit and vegetable slices; soaking the pretreated fresh-cut fruit and vegetable slices in a 2-50 [mu] mol / L theanine solution, taking out the fresh-cut fruit and vegetable slices after the fresh-cut fruit and vegetable slices are completely soaked, and removing moisture on the surfaces of the fresh-cut fruit and vegetable slices; and storing the fresh-cut fruit and vegetable slices, wherein the sealed storage temperature is 0.5-8 DEG C. The treatment method can effectively slow down browning of the fresh-cut fruits and vegetables, is pollution-free to the environment, safe and sanitary, can improve the edible flavor of the fresh-cut fruits, and has the advantages of being green, environment-friendly, high in quality and low in price; the method not only can be used for relieving oxidation browning of fresh-cut apples, pears and yellow peaches, but also can be applied to browning and preservation of other breath climacteric fruits and vegetables, weight loss is reduced, and the method has good economic value.

Description

Technical Field

[0001] The invention belongs to the technical field of fresh-cut fruit and vegetable preservation, and in particular relates to a treatment method for alleviating oxidative browning of respiratory climacteric fruits and vegetables. Background Art

[0002] Climax browning refers to the phenomenon that during the ripening process of climax fruits (such as apples, pears, peaches, apricots, etc.), the respiration rate suddenly increases and a large amount of ethylene is released, causing the fruit to brown rapidly. This browning is caused by the oxidation of phenolic compounds in the fruit into quinones under the catalysis of polyphenol oxidase (PPO), which then forms brown polymers, causing the appearance and quality of the fruit to deteriorate.

[0003] Fresh-cut fruits and vegetables are fresh, nutritious, convenient, and delicious foods that can meet consumers' demand for ready-to-eat healthy foods. However, fresh-cut fruits and vegetables, such as apples and yellow peaches, are very easy to deteriorate during storage, transportation, and sales. This is because the fruits and vegetables are cut and processed, and the flesh tissue is damaged, causing various physiological and biochemical reactions. Common ones include the growth of microbial pathogens, which reduces the nutritional value, mechanical damage, and oxidation and browning of the cut surface; increased respiration rate accelerates the ripening and aging of fruits and vegetables, and water loss causes fruit wilting. These problems greatly shorten the shelf life of fresh-cut fruits and vegetables. To solve these problems, fruits and vegetables are usually pre-treated in advance.

[0004] L-Theanine is a unique free amino acid in tea leaves. Theanine is γ-ethylamide of glutamic acid and has a sweet taste. Theanine accounts for 1%-2% of the weight of dry tea. The chemical structure of theanine is similar to glutamine and glutamic acid, the active substances in the brain, and is the main component of tea leaves that produces body fluids and makes it sweet. Theanine has the advantages of being natural, efficient, safe and hygienic, with low dosage and long lasting effect, and is used in medical treatment and animals. However, it is rarely reported in the storage and preservation technology of fruit and vegetable food, and there is a huge space for exploration.

[0005] Theanine is a water-soluble vitamin that is harmless to the human body and is safe and hygienic. It implements the green food concept that covers pollution-free, safe, high-quality, and nutritious requirements that the public is most concerned about, and is more likely to be accepted and welcomed by the public. At the same time, reducing oxidative browning can also reduce the loss of nutrients in apples, allowing consumers to take in more nutrition.

[0006] Apples are crisp, sweet, and have high nutritional value. They are rich in minerals and vitamins, and rich in calcium, which helps metabolize excess salt in the body. Malic acid can metabolize heat and prevent obesity in the lower body. After harvesting, its respiratory metabolism rate is faster and its enzyme activity is higher, which makes it more difficult to preserve and store. At the same time, after mechanical treatment, apples are severely damaged by mechanical damage. Due to the body's own stress resistance, the cut surface will turn brown in a short period of time, which seriously affects the appearance quality and economic value of the product. Therefore, during transportation and storage, how to effectively control the browning of fresh-cut apples and achieve the preservation effect has become a bottleneck for the rapid development of the apple market and a research hotspot for university researchers. At present, there are few reports on the research of reducing the browning of fresh-cut apples at home and abroad. Existing means of reducing browning mainly focus on the use of different preservatives, such as hydrogen sulfide, ferulic acid and aloe gel or alginate coating, lysine and arginine compound treatment, curcumin treatment, riboflavin treatment, etc. There are also a few reports on physical inhibition methods, mainly ultraviolet rays, ozone water, etc., but the effect of inhibiting browning is limited, and it has a certain degree of damage and adverse effects on the quality of fruits and vegetables, and is not safe enough. The above methods can no longer meet the processing needs of the modern fruit and vegetable processing industry for high quality, high quantity, green and environmental protection. Summary of the invention

[0007] The purpose of the present invention is to overcome the problems of the prior art in terms of taste and flavor, safety, and durability, and to provide a method for reducing the browning and oxidation of fresh-cut fruits and vegetables. The method is safe, non-toxic, convenient, and hygienic, and can effectively inhibit the oxidative browning of fresh-cut fruits and vegetables, thereby achieving the purpose of preserving freshness.

[0008] A method for reducing oxidative browning of respiratory climacteric fruits and vegetables comprises the following steps:

[0009] ① Soak the pre-cooled respiratory climacteric oxidative browning fruits and vegetables in a NaClO solution or an ethanol solution, slice them, and disinfect them after soaking to obtain pre-treated fresh-cut fruit and vegetable slices;

[0010] ② Soak the pretreated fresh-cut fruit and vegetable slices in a 2-50 μmol / L theanine solution, take them out after they are completely soaked, and remove the moisture on the surface of the fresh-cut fruit and vegetable slices;

[0011] ③ The fresh-cut fruit and vegetable slices are sealed and stored at a temperature between 0.5 and 8°C.

[0012] Wherein, the soaking time is 2 to 10 minutes.

[0013] Among them, the respiratory climacteric fruits and vegetables include apples, pears and yellow peaches.

[0014] Wherein, the thickness of the pretreated fresh-cut fruit and vegetable slices is 1-2 cm.

[0015] Beneficial Effects

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] (1) First, theanine used in the present invention has antioxidant properties and can react with oxygen first, thereby protecting polyphenols from oxidation. The antioxidant property of theanine is the basic condition for slowing down the browning of fresh-cut fruits and vegetables. It reduces the generation of oxidative browning by improving the antioxidant capacity of fresh-cut fruits and vegetables. In addition, by regulating the balance of lipid metabolism in cells, theanine may help maintain the integrity and function of cell membranes, inhibit the contact between polyphenol substrates and PPO, and inhibit the occurrence of browning reactions. Theanine may help reduce the free radicals generated during the browning process, thereby delaying the browning process.

[0018] (2) Theanine, as an antioxidant, can protect cells from oxidative stress damage. However, at too high a concentration, it may disrupt the balance of the antioxidant system, making cells more vulnerable to oxidative stress. Theanine may inhibit browning by competing with polyphenols to bind to PPO. However, at too high a concentration, this competitive relationship may change, resulting in the inability of theanine to effectively bind to PPO. Theanine may inhibit browning by regulating cell metabolism. However, at too high a concentration, it may have a negative impact on cell metabolism, leading to cell dysfunction or death. Therefore, treatment with too high a theanine concentration accelerates the occurrence of browning. The present invention takes fresh-cut fruits and vegetables that are prone to browning in adverse environments and difficult to maintain edible quality during storage as research objects, and uses theanine as an anti-browning preservative. Studies have shown that theanine solution has a very significant browning inhibition effect on fresh-cut fruits and vegetables, and significantly inhibits weight loss. Fresh-cut apples treated with the method of the present invention can still maintain their original quality and flavor after refrigeration for 9 days. The theanine used in the present invention is low in price and pollution-free to the environment, and can increase the shelf life of fruits and vegetables, thereby enabling fruits to be transported for a longer time, increasing the distribution range of fruits, and making it easier to form a system for fruit cut sales. The treated fresh-cut apples can give the product a higher added value due to their longer shelf life and good quality. For example, fresh-cut apples can be processed into fruit plates, salads, etc. of various flavors to meet the diverse needs of consumers, thereby enhancing the market competitiveness of the products. The research and application of effectively reducing the oxidative browning of fresh-cut apples has not only promoted the development of related industries, but also promoted technological innovation. For example, the introduction of new technologies such as genetic engineering technology and nano-composite packaging has provided more possibilities for the preservation of fresh-cut apples, and also promoted scientific and technological progress in related fields.

[0019] (3) Theanine used in the present invention is a free amino acid, which is pollution-free, safe and hygienic to the environment, can improve the edible flavor of fresh-cut fruits, and has the advantages of being green, environmentally friendly, and inexpensive. The present invention can not only be used to reduce the oxidative browning of fresh-cut apples, pears and yellow peaches, but can also be applied to the browning preservation of other respiratory climacteric fruits and vegetables. The method of the present invention is simple to handle, has a good preservation effect, is highly innovative, and has broad application prospects. In modern times where the e-commerce economy is highly developed, long-term preservation of fruits is a must for online shopping. Theanine's effect of reducing the browning of fruits and vegetables has great potential for promoting the development of domestic fresh fruits. The success of this invention will promote the development of agricultural scientific and technological innovation and encourage more scientific researchers and entrepreneurs to invest in the research and development of agricultural technology. This will help to improve the overall scientific and technological level of my country's agriculture and enhance international competitiveness. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 Effects of different concentrations on browning (A), L* brightness (B), and weight loss rate (C) of fresh-cut apples.

[0021] Figure 2 Effects of different concentrations of theanine on firmness (A), soluble solids (B), titratable acidity (C), and relative conductivity (D) of fresh-cut apples.

[0022] Figure 3 Effects of 10 μM / L theanine on the browning (A), L* brightness (B) and total colony count (C) of fresh-cut apples.

[0023] Figure 4 Effects of 10 μM / L theanine on firmness (A), soluble solids (B), titratable acidity (C), and relative conductivity (D) of fresh-cut apples.

[0024] Figure 5 The effect of processing fresh-cut Dangshan pears using the two methods W+T10.

[0025] Figure 6 The effect of processing fresh-cut yellow peaches using two methods: W+T10.

[0026] Data in all graphs correspond to the mean ± standard error of independent replicates. DETAILED DESCRIPTION

[0027] The technical scheme of the present invention is further described in detail below through specific embodiments and drawings. The following embodiments are only preferred embodiments of the present invention and are not intended to limit the present invention in other forms. Any technician familiar with the profession may use the above disclosed technical content to change it into an equivalent embodiment with equivalent changes. Any simple modification or equivalent change made to the following embodiments based on the technical essence of the present invention without departing from the content of the present invention is within the protection scope of the present invention.

[0028] In the embodiment, theanine uses food grade L-theanine, and the theanine solution is a solution formed by theanine and distilled water in a certain ratio. The preparation steps of the theanine solution are as follows:

[0029] Accurately weigh L-theanine in proportion and add it into a centrifuge tube, then use a pipette to draw it up and add distilled water to finally form a transparent, non-turbid theanine solution.

[0030] Taking the preparation of theanine solution with a theanine concentration of 2 μmol / L as an example, the following steps are used to prepare it:

[0031] First, turn on the electronic balance, put the weighing paper on it, use a medicine spoon to accurately weigh 348.4mg of theanine powder from the theanine reagent, and then slowly pour it into a 10ml centrifuge tube. Use a 1ml pipette to draw 2ml of distilled water into the centrifuge tube. If there is a little theanine powder on the wall of the centrifuge tube, add it slowly along the tube wall during the process of adding 2ml of distilled water until all the powder falls to the bottom of the tube, cover the centrifuge tube cover, and shake it evenly. Prepare an iron basin, use a 1000ml measuring cylinder to measure 2L of distilled water, use a 1ul pipette to draw 4μL of theanine solution into 2L of distilled water, and stir with a glass rod to obtain a 2μmol / L theanine solution.

[0032] Similarly, theanine solutions of different concentrations can be obtained by simply changing the amount of theanine added.

[0033] The apple segments were refrigerated and various indicators were measured, as follows:

[0034] The method for measuring color difference is: the front and back sides of each sample in each group of samples are measured with a colorimeter to measure the L* value (brightness) of the sample.

[0035] The method for determining the weight loss rate is as follows: the weight loss rate of each test group during storage is expressed by the weight loss rate of fresh-cut apples marked, measured by weighing method, and calculated according to the following formula: Weight loss rate = (m 0 -m i ) / m 0 ×100%In the formula, m 0 is the initial mass of fresh-cut apples, g; mi is the mass of fresh-cut apples on the i-th day of storage, g.

[0036] The method for determining hardness is: use a knife to cut off a thin layer of the edge of the pulp of each sample, place it under a hardness tester and measure the hardness peak value of the sample in N.

[0037] The method for determining the sugar content is as follows: take 2.0 g of sample from each box, put it in gauze, squeeze out the juice from the sample, and measure the sugar content of each group of samples with a sugar meter.

[0038] The method for determining relative conductivity is: take part of the sample from a box, cut it into twelve small discs with a radius of three millimeters and a thickness of one and a half millimeters with a mold knife, wash it with pure water and wipe it dry, and put it into ultrapure water to measure the conductivity. Measure the conductivity of the sample again after three hours, then weigh it and put it into a water bath in 100-degree boiling water for fifteen minutes. After cooling, add ultrapure water to the original weight, and finally measure the conductivity again. The unit of relative conductivity is μs·cm-1.

[0039] The determination method of titratable acid is as follows: take 10 grams of sample from a box, grind it in a mortar, rinse the ground sample with pure water into a small beaker, and put it into a 250ml volumetric flask to make up the volume and let it stand for 30 minutes. After 30 minutes, shake the solution in the volumetric flask upside down, and take 40ml of the supernatant into a conical flask with a pipette, add two drops of phenolphthalein test solution, and titrate with 0.01% NaOH solution until the last half drop of NaOH solution is added, the solution changes from colorless to red, and does not fade for half a minute. Record the amount of NaOH solution consumed by each group.

[0040] The method for determining the colony count is as follows: weigh 2.0g of sample, grind it in a sterilized mortar, add 10ml of saline solution and mix it, take 1ml of the solution and add it to a sterile test tube containing 9ml of saline solution and mix it, then take 1ml of the solution from the previous test tube and add it to 9ml of saline solution twice, then take 1ml of the sample solution of three concentrations into a sterile culture dish, and pour 15mL~20mL of plate count agar medium cooled to 46℃~50℃ (can be placed in a 48℃±2℃ constant temperature device for insulation) into the culture dish in time, and rotate the culture dish to mix it evenly. Place it horizontally and wait for the agar to solidify, then turn the plate over and culture it at 36℃±1℃ for 48h±2h. Aquatic products can be cultured at 30℃±1℃ for 72h±3h. If the sample may contain colonies that spread and grow on the surface of the agar culture medium, a thin layer of plate count agar medium (about 4mL) can be covered on the surface of the solidified agar culture medium, and the plate can be turned over after solidification for culture. Finally, the colony count can be observed with the naked eye, and if necessary, a magnifying glass or colony counter can be used to record the dilution multiple and the corresponding number of colonies. The colony count is expressed in colony forming units (CFU) per gram of fresh weight of fruit, CFU / g.

[0041] Example 1

[0042] A treatment method for reducing oxidative browning of fresh-cut apples in this embodiment specifically comprises the following steps:

[0043] (1) Instrument disinfection: Spray the surface of all instruments to be used with 0.02% NaClO solution and let them stand to dry.

[0044] (2) Disinfection of packaging boxes: Rinse all plastic packaging boxes to be used with clean water, then spray the inner and outer surfaces with 0.1% NaClO for disinfection, wipe the surface with gauze, and place them upside down on the table for 20 minutes to dry.

[0045] (3) Apple sample processing: Take fresh apples that have been completely precooled in an environment of 4°C, first clean the surface with clean water, then spray the surface with 0.02% NaClO, wash with deionized water solution and dry naturally for 20 minutes. Use a slicer to cut the apples into slices of 2 cm thick to obtain apple slices of uniform size. Prepare 5 basins filled with 4L of distilled water, use a slicer to cut the apples into apple slices of similar size, and randomly distribute the apple slices into each basin, with a total of 40 slices per basin. While cutting the apples, it is necessary to clean the surface of the apples that have been soaked in distilled water. After all the apples have been cut, repeat the washing steps 3 times and then pour out the water.

[0046] (4) Theanine solution treatment: One of the fresh-cut apples was placed in 2, 10, 50, and 500 μmol / L theanine solutions. After soaking for 5 min, the apples were taken out and the surface moisture of the apples was wiped dry with gauze. The CK group was used as the control and was soaked in an equal amount of distilled water for 5 min. The other groups were treated with W, W+T2, W+T10, W+T50, and W+T500, respectively, where W: Water; T: Theanine, μmol.

[0047] (5) Material output: Put the processed apples into fresh-keeping boxes, 10 apples in one box, 4 boxes for one concentration, attach labels of corresponding concentrations, and store them in a cold storage at a constant temperature of 4°C.

[0048] The experimental results of each group stored at 4°C are shown in Figure 1 and Figure 2 shown.

[0049] Depend on Figure 1 A shows that on the 9th day of storage, the browning phenomenon of W+T2, W+T50, and W+T10 was weaker than that of the W control group. The browning phenomenon of the W control group and the W+T treatment group was very obvious, and the color of the apple segments in the W+T10 treatment group was the best. This phenomenon shows that theanine soaking treatment can reduce the degree of browning, and W+T10, i.e., 10μmol L-1 theanine solution soaking treatment of fresh-cut apples can effectively reduce it.

[0050] Depend on Figure 1B shows that on the 9th day of storage, the fresh-cut apples treated with the W+T10, W+T50 and W control groups maintained a relatively good color, and the brightness of the W control group and the W+T50 group were 98.25% and 97.35% of the W+T10 group, respectively, while the brightness of the W+T2 and W+T500 groups was significantly lower than that of the other treatment groups, indicating that the W+T10 treatment group can reduce the browning degree of fresh-cut apples to a certain extent.

[0051] Depend on Figure 1 C shows that within 9 days of storage, the weight loss rates of the W+T2 and W+T10 treatment groups were significantly lower than that of the W control group, the weight loss of the W+T50 treatment group was close to that of the W control group, and the weight loss rate of the W+T10 treatment group was only 41.04% of that of the W control group, indicating that the W+T10 treatment group can effectively inhibit the nutrient loss of fresh-cut apples.

[0052] Depend on Figure 2 A shows that after 9 days of storage, the hardness of the W control group, W+T2, W+T50 and W+T500 treatment groups were similar, among which the W+T10 treatment group was harder than the above-mentioned different concentration treatment groups and the W control group, indicating that the W+T10 treatment group can alleviate the oxidative browning of fresh-cut apples to a certain extent.

[0053] Depend on Figure 2 B shows that after 9 days of storage, the soluble solids contents of the W control group, W+T2, W+T50 and W+T500 treatment groups were similar, among which the soluble solids content of the W+T10 treatment group was higher than those of the above-mentioned different concentration treatment groups and the W control group, indicating that the W+T10 treatment group can maintain the sweetness of fresh-cut apples to a certain extent.

[0054] Depend on Figure 2 C shows that after 9 days of storage, the titratable acid contents of the W+T10 and W+T2 treatment groups were higher than those of the W control group, and the titratable acid contents of the W+T50 and W+T500 treatment groups were lower than those of the W control group, indicating that theanine immersion treatment with an appropriate concentration can maintain the quality and taste of fresh-cut apples.

[0055] Depend on Figure 2 It can be seen from D that after 9 days of storage, the relative conductivity of fresh-cut apples treated with W+T2, W+T50, and W+T500 were all lower than that of the W control group, while that of the W+T10 group was only 1% higher than that of the W control group, indicating that theanine immersion treatment with appropriate concentrations has an inhibitory effect on the deterioration of the quality of fresh-cut apples during storage.

[0056] Example 2

[0057] A treatment method for reducing oxidative browning of fresh-cut apples in this embodiment specifically comprises the following steps:

[0058] (1) Soak the equipment to be used in 75% ethanol solution, disinfect for 30 minutes, then remove and dry.

[0059] (2) Disinfection of packaging boxes: Rinse all plastic packaging boxes to be used with clean water, then spray the inner and outer surfaces with 0.1% NaClO for disinfection, wipe the surface with gauze, and place them upside down on the table for 20 minutes to dry.

[0060] (3) Apple sample processing: Wash the surface of the pre-cooled fresh apples with clean water, then spray the surface with 0.02% NaClO, wash with deionized water solution and dry naturally for 30 minutes. Use a slicer to cut the apples into 2 cm thick slices to obtain apple slices of uniform size. Prepare 5 basins each containing 2L of distilled water. Randomly put 2 slices into each basin for each apple that has been cut into 12 slices by the slicer, and leave the remaining 2 slices unused. While cutting the apples, it is necessary to clean the surface of the apples that have been soaked in distilled water. After all the apples have been cut, repeat the washing steps 3 times and pour out the water.

[0061] (4) Theanine solution treatment: The fresh-cut apples were placed in a 10 μmol / L theanine solution for 5 min, then taken out and the surface moisture of the apples was wiped dry with gauze. The CK control group was treated with an equal amount of clean water.

[0062] (5) Material output: Put the processed apples into fresh-keeping boxes, 10 apples in one box, 4 boxes for one concentration, attach labels of corresponding concentration, and store in a cold storage at 4°C.

[0063] Depend on Figure 3 It can be seen that during the entire storage period, within 1-5 days, the W control group and the W+T10 treatment group had not undergone obvious browning relative to themselves, but on the 7th day, it can be seen that the fresh-cut apple segments treated with the W control group underwent severe browning, and during the entire 9-day storage period, the browning phenomenon of the fresh-cut apple segments treated with the W+T10 treatment group was always lighter than that of the W control group. These results indicate that W+T10 can significantly affect the browning degree of fresh-cut apples.

[0064] Depend on Figure 3 A shows that after 9 days of storage, the browning phenomenon of fresh-cut apple segments treated with W+T10 was lighter than that of the W control group, and the fresh-cut apples treated with the W control group showed obvious browning, which indicates that W+T10 can significantly affect the browning degree of fresh-cut apples.

[0065] Depend on Figure 3B shows that the browning degree of fresh-cut apples increases with the storage time, indicating that the quality of fresh-cut apples gradually decreases with the continuous extension of cold storage time, and browning continues to occur. However, the color difference of the W+T10 treatment group has always been brighter than that of the W control group during 0-9 days, and on the 9th day of storage, the brightness of the W+T10 treatment group is still 17% higher than that of the W control group, indicating that W+T10 has a significant effect in slowing down the browning of fresh-cut apples.

[0066] Depend on Figure 3 C shows that after 9 days of storage, the colony count in the W+T10 treatment group was far lower than the international standard of 15,000 CFU / g, and was only 29.7% of the W control group, indicating that the W+T10 treatment group can effectively inhibit the growth of colonies in fresh-cut apples and ensure the quality of apples.

[0067] Depend on Figure 4 A shows that during the storage period, there was almost no difference in the hardness of the W+T10 treatment group and the W control group from 1 to 7 days. On the 9th day of storage, the hardness of the W+T10 treatment group was slightly higher than that of the W control group, indicating that the W+T10 treatment group can reduce the oxidative browning of fresh-cut apples to a certain extent.

[0068] Depend on Figure 4 B shows that during the storage period, the soluble solids content of the W+T10 treatment group was almost the same as that of the W control group from 1 to 7 days. On the 9th day of storage, the soluble solids content of the W+T10 treatment group exceeded that of the W control group, indicating that the W+T10 treatment group can effectively slow down the oxidation rate of fresh-cut apples.

[0069] Depend on Figure 4 C shows that during storage 1-3 days, the titratable acid content of the W+T10 treatment group was lower than that of the W control group. During storage 5-9 days, the titratable acid content of the W+T10 treatment group and the W control group gradually decreased and finally became almost the same, both showing a trend of first increasing and then decreasing. However, the change in the titratable acid content of the W treatment group was more significantly different, indicating that the W+T10 treatment group had a more stable effect on reducing the oxidative browning of fresh-cut apples.

[0070] Depend on Figure 4 It can be seen that during the storage period, the relative conductivity of the W+T10 treatment group was almost the same as that of the W control group from 1 to 7 days. On the 9th day of storage, the relative conductivity of the W+T10 treatment group was slightly lower than that of the W control group, indicating that the W+T10 treatment group can slow down the oxidation rate of fresh-cut apples to a certain extent.

[0071] The sensory evaluation scores of fresh-cut apples treated with theanine are shown in the following table.

[0072] Assessment items Scoring Criteria Theanine treatment group (1-5 points) Control group (1-5 points) 1. Appearance color 1 = severe browning, 5 = no browning 3 1 2. Texture 1 = severe softening, 5 = brittle and crisp texture 3 3 3. Smell 1 = obvious odor, 5 = fresh apple scent 5 3 4. Taste 1 = sour / unpleasant taste, 5 = fresh taste, no unpleasant taste 3 1 5. Hydration 1 = severe water loss, 5 = sufficient water and juicy taste 5 1 6. Overall rating Taking all factors into consideration, 1 = poor quality, 5 = overall good quality 3 1

[0073] Rating explanation

[0074] 1 point: Very poor, with severe browning, soft texture or peculiar smell.

[0075] 3 points: Fair, with slight browning or taste changes.

[0076] 5 points: The best, no browning, fresh taste and smell.

[0077] As can be seen from the table, the appearance, color, smell, taste and moisture retention of fresh-cut apples treated with theanine are better than those of the control group. Therefore, theanine treatment has a unique advantage in improving the flavor of fresh-cut apples. (Note: W is pure water, T is theanine)

[0078] Example 3

[0079] A treatment method for reducing oxidative browning of fresh-cut apples in this embodiment specifically comprises the following steps:

[0080] (1) Instrument disinfection: Spray the surface of all instruments to be used with 0.02% NaClO solution and let them stand to dry.

[0081] (2) Disinfection of packaging boxes: Rinse all plastic packaging boxes to be used with clean water, then spray the inner and outer surfaces with 0.1% NaClO for disinfection, wipe the surface with gauze, and place them upside down on the table for 20 minutes to dry.

[0082] (3) Apple sample processing: Wash the surface of the pre-cooled fresh apples with clean water, then spray the surface with 0.02% NaClO, wash with deionized water solution and dry naturally for 30 minutes. Use a slicer to cut the apples into 1 cm thick slices of uniform size. Prepare 5 basins with 4L of distilled water, use a slicer to cut the apples into apple slices of similar size, and randomly put the apple slices into each basin, with a total of 40 slices per basin. While cutting the apples, it is necessary to clean the surface of the apples that have been soaked in distilled water. After all the apples are cut, repeat the washing steps 3 times and pour out the water.

[0083] (4) Theanine solution treatment: Place one of the fresh-cut apples in a 2 μmol / L theanine solution and soak for 10 min. Then take out the apples and dry the surface moisture of the apples with cold air at 4°C.

[0084] (5) Material output: Place the processed apples in a fresh-keeping box and store them in an environment of 0.5°C.

[0085] Example 4

[0086] A treatment method for reducing oxidative browning of fresh-cut apples in this embodiment specifically comprises the following steps:

[0087] (1) Instrument disinfection: Spray the surface of all instruments to be used with 0.01% NaClO solution and let them stand to dry.

[0088] (2) Disinfection of packaging boxes: Rinse all plastic packaging boxes to be used with clean water, then spray the inner and outer surfaces with 0.05% NaClO for disinfection, wipe the surface with gauze, and place them upside down on the table for 20 minutes to dry.

[0089] (3) Apple sample processing: Wash the surface of the pre-cooled fresh apples with clean water, then spray the surface with 0.01% NaClO, wash with deionized water solution and dry naturally for 10 minutes. Use a slicer to cut the apples into 2 cm thick slices of uniform size. Prepare 5 basins with 4L of distilled water, use a slicer to cut the apples into apple slices of similar size, and randomly put the apple slices into each basin, with a total of 40 slices per basin. While cutting the apples, it is necessary to clean the surface of the apples that have been soaked in distilled water. After all the apples are cut, repeat the washing steps 3 times and pour out the water.

[0090] (4) Theanine solution treatment: Place one of the fresh-cut apples in a 50 μmol / L theanine solution and soak for 2 min. Then take out the apples and wipe off the moisture on the surface of the apples with absorbent paper.

[0091] (5) Material output: Place the processed apples in a fresh-keeping box and store them in an environment of 8°C.

[0092] Example 5

[0093] A treatment method for reducing oxidative browning of fresh-cut Dangshan pears in this embodiment specifically comprises the following steps:

[0094] (1) Instrument disinfection: Spray the surface of all instruments to be used with 0.02% NaClO solution and let them stand to dry.

[0095] (2) Disinfection of packaging boxes: Rinse all plastic packaging boxes to be used with clean water, then spray the inner and outer surfaces with 0.1% NaClO for disinfection, wipe the surface with gauze, and place them upside down on the table for 20 minutes to dry.

[0096] (3) Sample processing of Dangshan pear: Wash the surface of the pre-cooled fresh Dangshan pear with clean water, then spray the surface with 0.02% NaClO, wash with deionized water solution and dry naturally for 20 minutes. Use a petal cutting tool to cut the petals to a thickness of 1.5 cm to obtain Dangshan pear petals of uniform size. Prepare 5 basins filled with 4L distilled water, use a petal cutting tool to cut the Dangshan pear into Dangshan pear slices of similar size, and randomly distribute the Dangshan pear slices into each basin, with a total of 40 slices per basin. While cutting the Dangshan pear, it is necessary to clean the surface of the Dangshan pear that has been soaked in distilled water. After all the Dangshan pears have been cut, repeat the washing step 3 times and pour out the water.

[0097] (4) Theanine solution treatment: Place a pot of the fresh-cut Dangshan pears in a 10 μmol / L theanine solution, soak for 5 min, take out, and wipe the surface moisture of the Dangshan pears with gauze.

[0098] (5) Material output: Put the processed Dangshan pears into fresh-keeping boxes, 10 pieces in one box, 4 boxes for one concentration, attach labels of corresponding concentrations, and store in a cold storage at 4°C.

[0099] See the photo of Dangshan pear after 5 days of storage. Figure 5 As shown, the upper picture is the group treated with 10μmol / L theanine solution, and its color is close to the color of fresh pears, while the lower picture is the control group, which was not treated with theanine solution and showed obvious browning.

[0100] Example 6

[0101] A treatment method for reducing oxidative browning of fresh-cut yellow peaches in this embodiment specifically comprises the following steps:

[0102] (1) Instrument disinfection: Spray the surface of all instruments to be used with 0.02% NaClO solution and let them stand to dry.

[0103] (2) Disinfection of packaging boxes: Rinse all plastic packaging boxes to be used with clean water, then spray the inner and outer surfaces with 0.1% NaClO for disinfection, wipe the surface with gauze, and place them upside down on the table for 20 minutes to dry.

[0104] (3) Peach sample processing: Wash the surface of the pre-cooled fresh peach with clean water, then spray the surface with 0.02% NaClO, wash with deionized water and dry naturally for 20 minutes. Use a slicer to cut the peach into slices of similar size and randomly place the slices in each pot, with a total of 40 slices per pot. While cutting the peach, wash the surface of the peach slices that have been soaked in distilled water. After all the peaches have been cut, repeat the washing steps 3 times and pour out the water.

[0105] (4) Treatment with theanine solution: Place the above-mentioned fresh-cut yellow peaches in a 10 μmol / L theanine solution, soak for 5 min, take them out, and wipe the surface moisture of the yellow peaches with gauze.

[0106] (5) Material output: Put the processed yellow peaches into fresh-keeping boxes, 10 pieces in one box, a total of 21 boxes, four boxes in a group, a total of five groups, the observation period is set at 9 days, and the remaining box is used for the observation of the weight loss rate of fresh-cut yellow peaches. A label with the corresponding observation time is affixed and stored in a cold storage at 4°C.

[0107] See the photo of yellow peach after 5 days of storage. Figure 6 As shown, the upper picture is the group treated with 10μmol / L theanine solution, and its color is close to the color of freshly cut yellow peaches, while the lower picture is the control group, which was not treated with theanine solution and showed obvious browning.

[0108] Example 7

[0109] A treatment method for reducing oxidative browning of fresh-cut potatoes in this embodiment specifically comprises the following steps:

[0110] (1) Instrument disinfection: Spray the surface of all instruments to be used with 0.02% NaClO solution and let them stand to dry.

[0111] (2) Disinfection of packaging boxes: Rinse all plastic packaging boxes to be used with clean water, then spray the inner and outer surfaces with 0.1% NaClO for disinfection, wipe the surface with gauze, and place them upside down on the table for 20 minutes to dry.

[0112] (3) Potato sample processing: Wash the surface of the pre-cooled fresh potatoes with clean water, then spray the surface with 0.02% NaClO, wash with deionized water and dry naturally for 20 minutes. Use a slicer to cut the potatoes into potato slices of similar size, and randomly put the potato slices into each pot, with a total of 40 slices per pot. While cutting the potatoes, the surface of the potato slices that have been soaked in distilled water needs to be washed. After all the potatoes have been cut, repeat the washing steps 3 times and then pour out the water.

[0113] (4) Theanine solution treatment: Place the above-mentioned fresh-cut potatoes in a 10 μmol / L theanine solution, soak for 5 min, take them out, and wipe the surface moisture of the potatoes with gauze.

[0114] (5) Material output: Put the processed potatoes into fresh-keeping boxes, 10 potatoes in one box, a total of 21 boxes, four boxes in a group, a total of five groups, the observation period is set at 9 days, and the remaining box is used to observe the weight loss rate of fresh-cut potatoes. A label with the corresponding observation time is affixed and stored in a cold storage at 4°C.

[0115] The experimental results showed that after 3 days of storage, the color of fresh-cut potatoes treated with theanine was close to that of fresh fresh-cut potatoes, while the control group without theanine showed obvious browning.

[0116] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, the embodiments should be considered exemplary and non-restrictive in all respects, and the scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims be included in the present invention.

[0117] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A method for reducing oxidative browning of climacteric fruits and vegetables, characterized in that: The processing method comprises: ① Soak the pre-cooled respiratory climacteric oxidative browning fruits and vegetables in a NaClO solution or an ethanol solution, slice them, and disinfect them after soaking to obtain pre-treated fresh-cut fruit and vegetable slices; ② Soak the pretreated fresh-cut fruit and vegetable slices in a 2-50 μmol / L theanine solution, take them out after they are completely soaked, and remove the moisture on the surface of the fresh-cut fruit and vegetable slices; ③ The fresh-cut fruit and vegetable slices are sealed and stored at a temperature between 0.5 and 8°C.

2. The method for reducing climacteric oxidative browning of fruits and vegetables according to claim 1, characterized in that: The soaking time is 2 to 10 minutes.

3. The method for reducing climacteric oxidative browning of fruits and vegetables according to claim 1, characterized in that: The respiratory climacteric fruits and vegetables include apples, pears and yellow peaches.

4. The method for reducing climacteric oxidative browning of fruits and vegetables according to claim 1, characterized in that: The thickness of the pretreated fresh-cut fruit and vegetable slices is 1-2 cm.

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