Flavor-improved NFC tomato juice, preparation method thereof and composite fruit juice

Abstract

The invention relates to the technical field of tomato juice processing, in particular to flavor-improved NFC tomato juice, a preparation method thereof and compound juice. The invention provides flavor-enhanced NFC tomato juice, a preparation method thereof and composite fruit juice. The tomato NFC beverage prepared by the preparation method is bright in color, mellow and fine in taste, appropriate in sugar-acid ratio, moderate in viscosity and weakened in layering phenomenon by utilizing specific ultrasonic treatment and ultrahigh-pressure non-thermal sterilization processes, and the flavor of tomato raw materials and the flavor of tomato juice, especially the characteristic flavor of tomatoes, are enhanced under the condition of no additives. In addition, various nutrient substances in the tomatoes are reserved to the maximum extent, and the special color, flavor and nutrient components of the product are still kept in the storage period.

Description

Technical Field

[0001] The invention relates to the technical field of tomato juice processing, and in particular to flavor-enhanced NFC tomato juice and a preparation method thereof, and a composite juice. Background Art

[0002] NFC juice (Not From Concentrate, NFC) is "non-concentrated reconstituted juice". Its preparation method is to squeeze it directly from fresh fruits. Compared with traditional fruit juice beverages, it does not need to go through the process of concentration and reconstitution, and does not need to add food additives such as sweeteners, acidifiers or preservatives. It has a more natural and fresh flavor and taste, and can retain the nutrients in the raw materials to the greatest extent. It has the advantages of freshness, greenness and health. Due to the high cost of raw materials, complex transportation and storage conditions, and short shelf life, the development of NFC juice is subject to certain restrictions. However, in recent years, with the improvement of people's health awareness and the increase in demand for the quality of beverage products, its green and healthy nutritional background and fresh and delicious flavor characteristics have attracted the attention and love of consumers. At present, it has entered a stage of rapid development at home and abroad, and the market scale is constantly expanding.

[0003] Tomato (Lycopersicon esculentum), also known as tomato, is one of the most widely cultivated fruits and vegetables in the world. It is rich in nutrients, containing mineral elements, vitamins, polyphenols, organic acids, carotenoids (lycopene, β-carotene) and other nutrients, and has a very high edible value. Its unique and delicious flavor occupies an important position in the global agriculture and food industry. In the past few years, China's tomato production has ranked first in the world. Developing tomato NFC juice that is popular in the market is one of the important ways to further leverage the advantages of the domestic tomato industry.

[0004] In recent years, in order to improve the appearance, yield, disease resistance, storage and other characteristics of tomato fruits, breeders have cultivated a variety of tomato varieties, but at the same time, they have also neglected the attention to the flavor quality of tomatoes, resulting in the loss of the characteristic flavor of tomatoes and a significant decline and loss of flavor quality (Klee HJ, Tieman DM. Genetic challenges of flavor improvement in tomato [J]. Trends in Genetics, 2013, 29 (4): 257-62.). With the development of modern agriculture, greenhouses, hydroponics and other planting methods that are not restricted by seasons, soil and weather are also more widely used in tomato cultivation. The diversification of agricultural technology has also had an adverse impact on the flavor quality of tomatoes. In addition, although postharvest low-temperature storage used to extend the shelf life is beneficial to delay fruit ripening and prevent decay, this postharvest treatment method leads to the inhibition of the expression of genes related to controlling tomato flavor substances, and also has a variety of adverse effects on tomato flavor (Zhang B, Tieman DM, Jiao C, et al. Chilling-induced tomato flavor loss is associated with altered volatile synthesis and transient changes in DNA methylation[J]. Proceedings of the National Academy of Sciences of the United States of America, 2016, 113(44): 12580-5.).

[0005] At present, the food industry products using tomatoes as raw materials in the domestic and foreign markets mainly include tomato sauce, tomato preserves, tomato powder, tomato juice flavored beverages, etc. NFC tomato juice beverages are gradually emerging in the market. However, there are many problems with NFC tomato juice in the domestic and foreign markets: (1) Due to the above-mentioned loss of tomato raw material flavor, the product is seriously lacking in aroma, especially the lack of tomato characteristic aroma. The product flavor sensory perception often presents a more obvious earthy smell and grassy smell, which affects consumers' experience and preference. How to improve the flavor quality of tomatoes and tomato products is a problem that needs to be solved urgently. (2) Currently, NFC tomato juice products on the market mostly use pasteurization, high-temperature short-time sterilization, ultra-high temperature homeopathic sterilization and other processes. However, while these processes extend the shelf life of the product, they also cause a certain degree of damage to the flavor and nutritional components in the product, affecting the product quality. (3) Due to the action of pectinase after tomato crushing, the NFC tomato juice products on the market have reduced viscosity and obvious stratification. (4) In order to improve the flavor of the juice or extend the shelf life of the product, some products on the market add additives such as sweeteners and preservatives, which confuse or violate the concept of NFC products. Summary of the invention

[0006] The present invention provides flavor-enhanced NFC tomato juice, a preparation method thereof, and a composite juice. The present invention utilizes a unique ultrasonic treatment and ultra-high pressure non-thermal sterilization process, so that the tomato NFC beverage prepared by the preparation method has bright color, mellow and delicate taste, appropriate sugar-acid ratio, moderate viscosity, reduced stratification, and enhances the flavor of tomato raw materials and tomato juice without additives, especially the characteristic flavor of tomatoes. In addition, various nutrients in tomatoes are retained to the greatest extent, and the unique color, flavor and nutrients of the product are still maintained during the storage period.

[0007] In order to achieve the above object, the present invention provides the following technical solutions:

[0008] The present invention provides a method for preparing flavor-enhanced NFC tomato juice, which is characterized by comprising:

[0009] (1) The pre-treated tomato fruits were subjected to ultrasonic stress treatment at an acoustic density of 20 to 90 W / L for 1 to 10 min;

[0010] (2) storing the tomato fruits after the treatment in (1) at 4 to 15° C. for later use;

[0011] (3) Juice is squeezed from the tomato fruits treated in (2), and then subjected to ultrasonic stress treatment at an acoustic density of 90 to 1800 W / L for 1 to 25 min, followed by sterilization to obtain flavor-enhanced NFC tomato juice.

[0012] The present invention performs low-intensity ultrasonic stress treatment on tomato fruits, thereby enhancing the synthesis of free flavor substances in tomato fruits; and increasing the expression of glycosyltransferase, which further converts part of the newly synthesized free flavor substances into bound flavor substances for storage. In this way, the total amount of bound flavor substances in tomatoes can be increased. Then, the fruit is juiced and then subjected to high-intensity ultrasonic stress treatment to help release more flavor substances.

[0013] Among them, the sound intensity and ultrasound time of the two ultrasounds are very critical to the release of the final flavor substances. Too high sound intensity and too long time will cause a significant decrease in the viscosity of the juice and the loss of flavor substances and nutrients. Finally, low-intensity ultrasound of the fruit combined with high-intensity ultrasound of the juice, and controlling the sound intensity and ultrasound time, we obtained NFC tomato juice with better flavor.

[0014] Preferably, the tomato variety is a variety with flavor loss or flavor improvement due to improved stress resistance, storability and yield.

[0015] After the flavor-deficient varieties, such as Jinwang tomatoes, are treated according to the method provided by the present invention, the flavor of the obtained tomato juice is significantly improved. After the flavor-improved varieties, such as strawberry tomatoes, are treated according to the method provided by the present invention, the flavor of the obtained tomato juice is significantly improved.

[0016] Preferably, in step (1), the acoustic density is 40 to 70 W / L. More preferably, the acoustic density is 50 to 70 W / L. More preferably, the acoustic density is 60 W / L.

[0017] Preferably, in step (3), the acoustic density is 500 to 1500 W / L. More preferably, the acoustic density is 500 to 800 W / L. More preferably, the acoustic density is 720 W / L.

[0018] Preferably, in step (1), the pretreatment method is: the tomato fruits are washed and then stored at 15-25° C. for 10-40 hours.

[0019] Preferably, in step (1), the conditions of ultrasonic stress also include: a frequency of 20 to 80 kHz and a temperature of 4 to 25°C.

[0020] Preferably, in step (1), the ultrasonic stress treatment method is: the tomato fruits are immersed in pure water contained in a bath-type ultrasonic processor, and there is no overlap or squeezing between the fruits when they are discharged in the bath-type ultrasonic processor, and the tomato fruits are turned up and down once every 30 seconds.

[0021] Preferably, in step (2), the storage time is (0,168h].

[0022] Preferably, in step (2), the storage method is: there is no stacking between the stored fruits, the interior of the storage environment is ventilated, and the humidity is controlled between 80% and 90%.

[0023] Preferably, in step (3), the conditions of ultrasonic stress also include: a frequency of 20 to 80 kHz and a temperature of 4 to 25°C.

[0024] Preferably, in step (3), the sterilization method is ultra-high pressure sterilization; the conditions of the ultra-high pressure sterilization are: pressure of 400-600 MPa, and time of 10-20 min.

[0025] Preferably, in step (3), the conditions for squeezing the juice are: a rotation speed of 20,000 to 30,000 rpm, a time of 1 to 5 min, and a temperature of 4 to 25°C.

[0026] Preferably, in the step (3), the obtained flavor-enhanced NFC tomato juice is stored at 0-4° C. after filling. More preferably, the storage temperature is 3-4° C. More preferably, the storage time is 1-30 days.

[0027] The flavor-enhanced NFC tomato juice obtained by the invention still maintains original color, flavor and nutritional components during a storage period of 1 to 30 days.

[0028] The present invention also provides a flavor-enhanced NFC tomato juice, wherein the flavor substances in the flavor-enhanced NFC tomato juice include multiple types of alcohols, aldehydes, ketones, esters, acids, phenols, hydrocarbons and ethers.

[0029] Preferably, the flavor-enhanced NFC tomato juice can be stored at 0-4°C for 1-30 days. More preferably, it can be stored at 3-4°C for 1-30 days.

[0030] Preferably, the characteristic substances in the flavor substances include 2-isobutylthiazole, β-ionone, 1-penten-3-one, hexanal, (E)-2-octenal, 6-methyl-5-heptene-2-one, β-damascenone, and phenylethyl alcohol.

[0031] The present invention also provides a compound juice, comprising the flavor-enhanced NFC tomato juice.

[0032] The flavor-enhanced NFC tomato juice provided by the present invention can be compounded with any other fruit juice, such as apple juice, carrot juice, etc., to form a compound juice with richer taste; and at the same time, the special flavor of the tomato juice can be retained.

[0033] Therefore, the present invention has the following beneficial effects:

[0034] (1) The present invention uses Chinese native tomatoes as raw materials, and combines multiple ultrasonic treatments and ultra-high pressure sterilization treatments to obtain a flavor-enhanced NFC tomato juice beverage. The product has bright color, mellow and delicate taste, appropriate sugar-acid ratio, moderate viscosity, and reduced stratification. The flavor of tomato raw materials and tomato juice, especially the characteristic flavor of tomatoes, is enhanced without additives. In addition, various nutrients in tomatoes are retained to the greatest extent, and the unique color, flavor and nutritional components of the product are still maintained during the storage period.

[0035] (2) The flavor-enhanced NFC tomato juice of the present invention uses a unique ultrasonic technology to process the raw materials and tomato homogenate, thereby enhancing the flavor of the product without adding any additives, bringing significant improvements and enhancements to the flavors of the tomato raw materials and tomato homogenate, while promoting the increase in the content of volatile flavor substances in the tomato raw materials, releasing the bound volatile flavor substances in the tomato homogenate, especially enhancing the characteristic flavor of tomatoes, solving the industry pain point of the loss of tomato flavor quality leading to the decline in the flavor of tomato products and the defect that the characteristic flavor of NFC tomato juice beverages is not obvious.

[0036] (3) The present invention uses a unique ultrasonic technology to process the raw materials, and the medium is treated with pure water, which is safe, convenient, effective and non-toxic. It can also remove impurities and pesticide residues on the surface of the fruit, effectively kill microorganisms on the surface of the tomato, and achieve the purpose of cleaning, removing pesticide residues and sterilizing.

[0037] (4) The present invention adopts low-temperature cold pressing technology to prepare fruit homogenate and uses a high-speed wall-breaking pulping machine to extract juice, so that the product texture is more uniform and the taste is more delicate.

[0038] (5) The present invention uses a unique ultrasonic technology to treat tomato homogenate, which not only produces a physical emulsification effect, but also effectively eliminates a large number of bubbles in the product to achieve a degassing effect, and improves the obvious defect of NFC tomato juice stratification, thereby reducing the stratification phenomenon of NFC tomato juice during storage.

[0039] (6) Compared with the traditional liquid food sterilization method (pasteurization, etc.), the present invention adopts non-thermal sterilization technology - ultra-high pressure non-thermal sterilization for processing. After the product is processed, almost all bacteria, molds and other microorganisms can be killed, and not only will it not cause the loss of heat-sensitive nutrients, but also the product quality indicators such as color, viscosity, flavor, etc. of the product are optimized.

[0040] (7) The flavor-enhanced NFC tomato juice beverage of the present invention contains high nutritional ingredients, a large amount of vitamins, minerals and a good amount of lycopene, has high nutritional and health functions, can meet people's needs for nutrition and health, and provides a new idea for giving full play to the advantages of the tomato industry and developing beverage products using tomatoes as raw materials.

[0041] (8) The flavor-enhanced NFC tomato juice beverage of the present invention can achieve the best taste when stored at 4°C for 14 days. This is because the viscosity decreases with increasing temperature, and through process optimization, it was found that the NFC tomato juice at 4°C has the best taste. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 This is the effect of different preparation methods on the volatile flavor compounds in "Jinwang" tomato NFC tomato juice;

[0043] Figure 2 The effect of different preparation methods on the volatile flavor compounds in "strawberry" tomato NFC tomato juice;

[0044] Figure 3 This is the effect of different sterilization methods on the volatile flavor substances in "Jinwang" tomato NFC tomato juice;

[0045] Figure 4 This is the effect of ultrasound scheme on volatile flavor compounds in "Jinwang" tomato NFC tomato juice;

[0046] Figure 5 This is the effect of ultrasound scheme on volatile flavor compounds in "Jinwang" tomato NFC tomato juice;

[0047] Figure 6 This is the effect of ultrasound scheme on volatile flavor compounds in "Jinwang" tomato NFC tomato juice;

[0048] Figure 7 This is a diagram showing the effect of ultrasound on the volatile flavor compounds in "Jinwang" tomato NFC tomato juice. DETAILED DESCRIPTION

[0049] The present invention is further described below in conjunction with specific embodiments. Those of ordinary skill in the art will be able to implement the present invention based on these descriptions. In addition, the embodiments of the present invention involved in the following description are generally only embodiments of a part of the present invention, rather than all embodiments. Therefore, based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative work should fall within the scope of protection of the present invention.

[0050] [Example]

[0051] Example 1

[0052] (1) Freshly picked tomato fruits (the flavor-deficient variety "Jinwang" tomato) were washed and stored in a greenhouse at 22°C for 24 h.

[0053] (2) After being stored for 24 hours, the tomato fruits were taken out and placed in a bath-type ultrasonic processor for ultrasonic treatment. The frequency of the ultrasonic treatment was 60 KHz, the sound density was 60 W / L, the time was 3 minutes, and the temperature was 25°C.

[0054] (3) After the ultrasonic treatment, the tomato fruits were taken out, dried, and stored at 10°C for 24 h.

[0055] (4) Taking out the tomato fruits after storage in step (3), and subjecting them to low-temperature cold pressing to obtain mixed tomato slurry. The rotation speed of the low-temperature pressing is 25000 rpm, the time is 3 minutes, and the temperature is controlled below 20°C.

[0056] (5) The mixed slurry is subjected to ultrasonic treatment to obtain a mixed slurry with enhanced flavor after ultrasonic treatment. The frequency of the ultrasonic treatment is 28 kHz, the time is 12 min, the sound density is 720 W / L, and the temperature is 20°C.

[0057] (6) The mixed slurry after ultrasonic treatment in step (5) is subjected to ultra-high pressure sterilization, and after sterilization, NFC tomato juice with enhanced flavor is obtained. The pressure of ultra-high pressure sterilization is 550 MPa, and the time is 15 minutes.

[0058] (7) The sterilized flavor-enhanced NFC tomato juice was filled into sterile PET bottles or other packaging materials and stored at 4°C for 14 days.

[0059] Example 2

[0060] (1) Freshly picked tomato fruits (market flavor improved variety "Strawberry" tomatoes) were washed and stored in a greenhouse at 22°C for 24 h.

[0061] (2) After being stored for 24 hours, the tomato fruits were taken out and placed in a bath-type ultrasonic processor for ultrasonic treatment. The ultrasonic treatment frequency was 60 KHz, the sound density was 60 W / L, the time was 3 minutes, and the temperature was 25°C.

[0062] (3) After the ultrasonic treatment, the tomato fruits were taken out, dried, and stored at 10°C for 36 h.

[0063] (4) Taking out the tomato fruits after storage in step (3), and subjecting them to low-temperature cold pressing to obtain mixed tomato slurry. The rotation speed of the low-temperature pressing is 25000 rpm, the time is 3 minutes, and the temperature is controlled below 20°C.

[0064] (5) The mixed slurry is subjected to ultrasonic treatment to obtain a mixed slurry with enhanced flavor after ultrasonic treatment. The frequency of the ultrasonic treatment is 28 kHz, the time is 12 min, the sound density is 720 W / L, and the temperature is 20°C.

[0065] (6) The mixed slurry after ultrasonic treatment in step (5) is subjected to ultra-high pressure sterilization, and after sterilization, NFC tomato juice with enhanced flavor is obtained. The pressure of ultra-high pressure sterilization is 550 MPa, and the time is 15 minutes.

[0066] (7) The sterilized flavor-enhanced NFC tomato juice was filled into sterile PET bottles or other packaging materials and stored at 4°C for 14 days.

[0067] Comparative Example 1

[0068] (1) Freshly picked tomato fruits (the flavor-deficient variety "Jinwang" tomato) were washed and stored in a greenhouse at 22°C for 24 h.

[0069] (2) Taking out the tomato fruits stored in step (1), and subjecting them to low-temperature cold pressing to obtain mixed tomato slurry. The rotation speed of the low-temperature pressing is 25000 rpm, the time is 3 minutes, and the temperature is controlled below 20°C.

[0070] (3) The mixed slurry of step (2) is subjected to ultra-high pressure sterilization, and after sterilization, NFC tomato juice is obtained. The pressure of ultra-high pressure sterilization is 550 MPa, and the time is 15 min.

[0071] (4) The sterilized NFC tomato juice is filled into sterile PET bottles or other packaging materials and stored at 4°C for 14 days.

[0072] Comparative Example 2

[0073] (1) Freshly picked tomato fruits (market flavor improved variety "Strawberry" tomatoes) were washed and stored in a greenhouse at 22°C for 24 h.

[0074] (2) Taking out the tomato fruits stored in step (1), and subjecting them to low-temperature cold pressing to obtain mixed tomato slurry. The rotation speed of the low-temperature pressing is 25000 rpm, the time is 3 minutes, and the temperature is controlled below 20°C.

[0075] (3) The mixed slurry of step (2) is subjected to ultra-high pressure sterilization, and after sterilization, NFC tomato juice is obtained. The pressure of ultra-high pressure sterilization is 550 MPa, and the time is 15 min.

[0076] (4) The sterilized NFC tomato juice is filled into sterile PET bottles or other packaging materials and stored at 4°C for 14 days.

[0077] Comparative Example 3

[0078] (1) Freshly picked tomato fruits (the flavor-deficient variety "Jinwang" tomato) were washed and stored in a greenhouse at 22°C for 24 h.

[0079] (2) After being stored for 24 hours, the tomato fruits were taken out and placed in a bath-type ultrasonic processor for ultrasonic treatment. The ultrasonic treatment frequency was 60 KHz, the sound density was 60 W / L, the time was 3 minutes, and the temperature was 25°C.

[0080] (3) After the ultrasonic treatment, the tomato fruits were taken out, dried, and stored at 10°C for 24 h.

[0081] (4) Taking out the tomato fruits after storage in step (3), and subjecting them to low-temperature cold pressing to obtain mixed tomato slurry. The rotation speed of the low-temperature pressing is 25000 rpm, the time is 3 minutes, and the temperature is controlled below 20°C.

[0082] (5) subjecting the mixed slurry to ultrasonic treatment to obtain a mixed tomato slurry. The ultrasonic treatment frequency is 28 kHz, the time is 12 min, the sound density is 720 W / L, and the temperature is 20°C.

[0083] (6) The mixed slurry after ultrasonic treatment in step (5) is pasteurized to obtain NFC tomato juice at a temperature of 85° C. for 15 min.

[0084] (7) The sterilized NFC tomato juice is filled into sterile PET bottles or other packaging materials and stored at 4°C for 14 days.

[0085] Comparative Example 4 (Cancelling Ultrasonication of Juice)

[0086] (1) Freshly picked tomato fruits (the flavor-deficient variety "Jinwang" tomato) were washed and stored in a greenhouse at 22°C for 24 h.

[0087] (2) After being stored for 24 hours, the tomato fruits were taken out and placed in a bath-type ultrasonic processor for ultrasonic treatment. The frequency of the ultrasonic treatment was 60 KHz, the sound density was 60 W / L, the time was 3 minutes, and the temperature was 25°C.

[0088] (3) After the ultrasonic treatment, the tomato fruits were taken out, dried, and stored at 10°C for 24 h.

[0089] (4) Taking out the tomato fruits after storage in step (3), and subjecting them to low-temperature cold pressing to obtain mixed tomato slurry. The rotation speed of the low-temperature pressing is 25000 rpm, the time is 3 minutes, and the temperature is controlled below 20°C.

[0090] (5) The mixed slurry is subjected to ultra-high pressure sterilization, and after the sterilization, the NFC tomato juice with enhanced flavor is obtained. The pressure of the ultra-high pressure sterilization is 550 MPa, and the time is 15 minutes.

[0091] (6) The sterilized flavor-enhanced NFC tomato juice is filled into sterile PET bottles or other packaging materials and stored at 4°C for 14 days.

[0092] Comparative Example 5 (Cancelling Ultrasonication of Fruits)

[0093] (1) Freshly picked tomato fruits (the flavor-deficient variety "Jinwang" tomato) were washed and stored in a greenhouse at 22°C for 24 h.

[0094] (2) After the ultrasonic treatment, the tomato fruits were taken out, dried, and stored at 10°C for 24 h.

[0095] (3) Taking out the tomato fruits stored in step (2), and subjecting them to low-temperature cold pressing to obtain mixed tomato slurry. The rotation speed of the low-temperature pressing is 25000 rpm, the time is 3 minutes, and the temperature is controlled below 20°C.

[0096] (4) The mixed slurry is subjected to ultrasonic treatment to obtain a mixed slurry with enhanced flavor after ultrasonic treatment. The frequency of the ultrasonic treatment is 28 kHz, the time is 12 min, the sound density is 720 W / L, and the temperature is 20°C.

[0097] (5) The mixed slurry after ultrasonic treatment in step (4) is subjected to ultra-high pressure sterilization, and after sterilization, NFC tomato juice with enhanced flavor is obtained. The pressure of ultra-high pressure sterilization is 550 MPa, and the time is 15 minutes.

[0098] (6) The sterilized flavor-enhanced NFC tomato juice is filled into sterile PET bottles or other packaging materials and stored at 4°C for 14 days.

[0099]

Performance test

[0100] The inspection of the product includes the following test indicators and methods:

[0101] 1. Sensory indicators: color, taste, flavor;

[0102] 2. Microbiological indicators: total colony count (CFU / mL);

[0103] 3. Flavor index: Volatile flavor substance content (μL / L), measured by SPME-GC-MS system, the measurement method is as follows:

[0104] (1) 5 mL of NFC tomato juice sample was added to a 20 mL headspace vial and sealed with a polytetrafluoroethylene pad. 0.6 g of NaCl was added to promote the volatilization of volatile substances, and then 1 μL of chromatography-grade cyclohexanone was added as an internal standard. The sample was equilibrated at 60 °C in a magnetic stirrer for 10 minutes. The SPME extraction fiber was then placed 1 cm from the headspace liquid surface of the vial and stirred at 60 °C and 2400 rpm for 40 minutes.

[0105] (2) Insert the extracted fiber into the gas chromatography injection port and desorb the analyte for 5 minutes. Use Agilent 7890B-5977B GC-MS system, and the measurement conditions are: capillary column Agilent DB-WAX (30m×0.25mm×0.25μm); extraction head analysis for 5 minutes, carrier gas is high-purity helium, flow rate is 1.3mL / min, no split. Temperature program: starting temperature is 35℃, keep for 0min, increase to 180℃ at a rate of 3℃ / min, then increase to 230℃ at a rate of 15℃ / min, and keep for 2min. Mass spectrometry conditions are: ion source temperature 250℃, ionization mode EI, electron energy 70eV, mass range 30~500AMU / sec. The qualitative analysis results were retrieved and analyzed using the NIST14 spectral library, and combined with references (Ortiz-Serrano P and Gil JV, Quantitation of free and glycosidically bound volatiles in and effect of glycosidase addition on three tomato varieties (Solanum lycopersicum L.) [J]. Journal of Agricultural and Food Chemistry, 2007, 55: 9170-9176; O, K, Aubert C, Dundar and Gunata Z,Characterization of the free and glycosidicallybound aroma potential of two important tomato cultivars grown in Turkey[J].Journal of Food Science and Technology,2018,55:4440-4449; Ortiz-Serrano P andGil JV,Quantitative comparison of free and bound volatiles of two commercialtomato cultivars(Solanum lycopersicum L.)during ripening[J].Journal ofAgricultural and Food Chemistry,2010,58:1106-1114;Baldwin EA,Scott JW and BaiJH,Sensory and Chemical Flavor Analyses of Tomato Genotypes Grown in Floridaduring Three Different Growing Seasons in Multiple Years[J].Journal of theAmerican Society for Horticultural Science,2015,140:490-503;Cheng G,Chang P,Shen Y,Wu L, El-Sappah AH, Zhang F and Liang Y, Comparing the Flavor Characteristics of 71Tomato (Solanum lycopersicum) Accessions in Central Shaanxi [J]. Frontiers in Plant Science, 2020, 11: 586834.) were compared to finally confirm the components in the sample. The material quantification method assumes that the response frequency of each component is the same as that of the internal standard, and calculates the content of the component to be tested by the ratio of the peak area of ​​the component to be tested to the peak area of ​​the internal standard. Calculation formula:

[0106] The content of the component to be measured (μL / L) = peak area of ​​each component × volume of the internal standard (1 μL) / (peak area of ​​the internal standard × volume of the tomato sample (5 mL)).

[0107] The results of the above indicators are shown in Table 1 and Figures 1 to 7 It can be seen from the observation that the present invention utilizes a unique ultrasonic treatment and ultra-high pressure non-thermal sterilization process, so that the tomato NFC beverage prepared by the preparation method has bright color, mellow and delicate taste, appropriate sugar-acid ratio, moderate viscosity, weakened stratification phenomenon, and enhances the flavor of tomato raw materials and tomato juice, especially the characteristic flavor of tomato, without additives.

[0108] Table 1 Effects of different preparation methods on sensory and microbiological indicators of NFC tomato juice during storage for 14 days

[0109]

[0110]

Claims

1. A method for preparing flavor-enhanced NFC tomato juice, characterized in that: include: (1) The pre-treated tomato fruits were subjected to ultrasonic stress treatment at an acoustic density of 20 to 90 W / L for 1 to 10 min; (2) storing the tomato fruits after the treatment in (1) at 4 to 15° C. for later use; (3) Juice is squeezed from the tomato fruits treated in (2), and then subjected to ultrasonic stress treatment at an acoustic density of 90 to 1800 W / L for 1 to 25 min, followed by sterilization to obtain flavor-enhanced NFC tomato juice.

2. The preparation method according to claim 1, characterized in that In the step (1), the pretreatment method is: the tomato fruits are washed and stored at 15-25° C. for 10-40 hours.

3. The preparation method according to claim 1, characterized in that: In the step (1), the conditions of ultrasonic stress also include: a frequency of 20 to 80 KHz and a temperature of 4 to 25°C.

4. The preparation method according to claim 1, characterized in that: In the step (2), the storage time is (0,168h].

5. The preparation method according to claim 1 or 3, characterized in that: In the step (3), the conditions of ultrasonic stress also include: a frequency of 20 to 80 KHz and a temperature of 4 to 25°C.

6. The preparation method according to claim 1, characterized in that: In the step (3), the sterilization method is ultra-high pressure sterilization; the conditions of the ultra-high pressure sterilization are: pressure of 400-600 MPa, time of 10-20 min.

7. The preparation method according to claim 1, characterized in that: In the step (3), the conditions for squeezing the juice are: a rotation speed of 20,000 to 30,000 rpm, a time of 1 to 5 minutes, and a temperature of 4 to 25°C.

8. The flavor-enhanced NFC tomato juice prepared by the preparation method according to any one of claims 1 to 7, characterized in that: The flavor substances in the flavor-enhanced NFC tomato juice include multiple types of alcohols, aldehydes, ketones, esters, acids, phenols, hydrocarbons and ethers; the flavor-enhanced NFC tomato juice can be stored at 0-4° C. for 1-30 days.

9. The flavor-enhanced NFC tomato juice according to claim 8, characterized in that The characteristic substances in the flavor substances include 2-isobutylthiazole, β-ionone, 1-penten-3-one, hexanal, (E)-2-octenal, 6-methyl-5-heptene-2-one, β-damasconone and phenylethyl alcohol.

10. A compound fruit juice, characterized in that: Comprising the flavor-enhanced NFC tomato juice as claimed in claim 8 or 9.

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