WO2018018362A1 - Preparation process for fresh apple juice - Google Patents

Abstract

Provided is a preparation process for fresh apple juice. An integrated coupling technique of crushing and pulping and enzyme deactivating by means of steaming is used, and ultra-fast cooling is carried out immediately after pulping and enzyme deactivating, i.e. using the coupling of vacuum cooling and brine freezing conduction cooling. The process parameters are strictly controlled and the quality of apple raw materials is protected to the utmost extent during the whole processing process. The temperature of the thermal action is decreased, the time of the thermal action is shortened, and thus the enzyme deactivating effects are excellent, and the original color, flavor and nutrients of apples are retained. The process includes: apple raw material quality control; the coupling of crushing and pulping and enzyme deactivating by means of steaming; ultra-fast cooling; filtering and separating; ultrafine grinding; formulating and homogenizing; sterilizing and fast cooling; and aseptic filling. Physical methods are used in the process to inhibit the enzymatic browning of the fresh apple juice to the utmost extent, thereby retaining the original flavor, taste and nutrients of fresh apples. No pigments, essence or preservatives, etc. are added, and a high-quality fresh apple juice can be obtained.

Description

Preparation process of fresh apple juice Technical field

The invention belongs to the technical field of food and beverage, and in particular relates to a preparation process of a freshly squeezed apple freshly squeezed juice.

Background technique

Freshly squeezed juice, referred to as NFC, is the abbreviation of English Not From Concentrate. It is called “non-concentrated reducing juice” in Chinese. It is a fresh raw fruit washed and pressed out of juice. It can be directly packed after pasteurization (without concentration and recovery). ), completely retaining the original fresh flavor of the fruit. At present, the vast majority of pure fresh juice on the market is actually a general concentrated and reduced fruit juice. It is a fruit juice that is reduced to water and sugar, preservatives, etc. into a drinkable juice. Because of its nutrition, flavor, health and low carbon, NFC juice has been rapidly developed by European and American society. From 1997 to 2010, global NFC juice sales increased by 68%, of which the UK increased by 90%. At present, NFC juices in Europe and America account for more than 10% of the juice market, and its processing technology and equipment have become the hotspots of research and development of major companies around the world.

In recent years, China's juice beverage market is developing at a high speed, and the rapid rise of the juice market is inseparable from the health awareness of consumers. Fruit juice drinks, especially NFC pure juice, are rich in essential vitamins and trace elements, and healthy and delicious food is the main cause of attracting consumers. However, at present, NFC juices at home and abroad can only be based on clear juice. A large number of fruits, such as apples, peaches, pears and bananas, are prone to browning during processing, becoming NFC juices and concentrated or non-concentrated. The biggest difficulty in fruit juice production and technical bottlenecks, these fruits are highly prone to discoloration during processing, storage and transportation, seriously affecting their sensory quality, reducing consumers' desire to purchase, thus reducing the value of commodities and even causing loss of nutrients. The nutritional value has declined. At present, there is still no fundamental solution to the problem of browning of apples and other fruits. Even the giants of fruit juice beverage companies can only cover up and adjust with natural pigments such as decolorization or carotene. This method of "treating the symptoms is not a cure" is not The long-term development of juice beverage processing technology.

China is the world's largest apple producer, with an annual average of 32 million tons, accounting for more than 50% of the world's total apple production. Apple exports about 1.5 million tons, accounting for only about 2% of the world's exports. Apple juice, canned food, dehydrated products and other fresh fruit are 8 million tons. The amount of apples consumed in the domestic market is more than 23 million tons. The pressure on Apple’s sales and prices has put tremendous pressure on farmers’ income. As the apple is processed, once the broken polyphenol oxidase contacts the substrate, it immediately triggers the enzymatic browning reaction, which brings great difficulties to the processing and product development of apple. This problem is in China and even in the world. There have been no substantive breakthroughs and progress so far. Sulfite is an effective anti-browning agent, but it can cause sulfur residue and affect people's health. The FDA restricted its use of fruits and vegetables in 1986. The currently studied alternatives to sulfites are: ascorbic acid, lysine, honey, glutathione, kojic acid, phytic acid, citric acid, etc. These anti-browning agents inhibit polyphenol oxidase (PPO). Concentration dependent. The large amount of addition not only increases the production cost, but also changes the natural flavor of the apple juice; if the amount is small, the enzymatic browning will reoccur in a short time. Vc is an anti-browning agent used earlier. When the addition amount is 0.05-0.08%, Vc degradation will cause non-enzymatic browning of the whole system; honey has a clarifying effect and is not suitable for the production of mixed juice; glutathione cost Higher. At present, no suitable anti-browning agent has been found in the industrial production of juice processing. It is found that about 83% of the browning reaction in apple processing occurs in the crushing process, so solving the enzymatic browning in the crushing process is the key to preparing high quality NFC juice.

It is not difficult to find out the reports of patents and journal articles that have been reported. Most studies or researches focusing on the research of fruit juice anti-browning agents often neglect the enzymatic browning of fruit pulp during fruit breakage; some patents use cold crushing. Then use the heat exchanger to heat the slurry to kill the enzyme, such as the patent CN201110452348.0, CN201110452142.8, CN201410366365.6, etc. In fact, once the apple is broken, the enzymatic browning starts quickly, and the whole browning is 9-10. All completed within minutes. The method of first killing the enzyme after cold crushing is actually the majority of the browning has been completed in the cold crushing process, and the subsequent inactivation of the enzyme inhibits the browning degree and the effect is extremely limited.

Summary of the invention

The present invention is directed to the problems existing in the prior art, and provides a technique for rapidly heating to an enzyme-killing process by steam during the crushing process, followed by ultra-fast cooling, thereby realizing the inactivation of the easily browned apple by physical methods. And anti-browning treatment, in line with the concept of green and safe processing of contemporary food. The pulp after the enzyme is cooled by ultra-rapid cooling to normal temperature to avoid the pulp being cooked and retaining the original taste and nutrition of the apple.

To achieve the above object, the technical solution of the present invention is as follows:

The invention provides a preparation process of apple fresh juice, comprising the following steps:

(1) Raw material selection and pretreatment: choose apples with high freshness, high maturity, no mold, rot, no insects and pesticide residues as raw materials, the sugar content is preferably greater than 10 Brix, and washed with a bubbling machine. Clean, cut each apple into 4 to 8 petals, in order to facilitate the subsequent crushing and pulping and enzyme-integrating treatment.

(2) Integration of crushing pulping and steam inactivation: the apples treated in step (1) are crushed and pulped, and the apples are crushed to a particle diameter of about 2 mm by using a fast rotating knife paddle, and the toughness of the blade is controlled by the knife blade. Degree, rotation speed and time can control the size of the crushing particle size. Here, the apple does not need to be broken too fine, in addition, the core is hard, and it is not broken as much as possible during the process of crushing and pulping. A few minutes before the start of the crushing, the steam is pre-passed to drive off the air in the crushing chamber. The steam is evenly sprayed to the broken apple. The pressure of the steam injected here is 0.12~0.22MPa, and the temperature of the pulp is rapidly increased within 1-3 minutes. After the temperature reaches 80-92 °C, the steam is stopped and maintained for 48-12 seconds. The final temperature of the temperature rise and the final temperature hold time in this step follow the linear inverse relationship: T=-t/3+96, T is the final temperature, the unit is °C, t is the holding time, the unit is s; at the same time as crushing and pulping, vitamin C or citric acid (w/w), which accounts for 0.006-0.03% of the mass of apple raw material, can be optionally added to further exert vitamin C or citric acid. The color protection function can also play a role in regulating the acidity of the pulp.

(3) ultra-fast cooling: the apple pulp obtained in step (2) is rapidly cooled by means of vacuum cooling and chilled brine conduction cooling, so that the slurry is rapidly cooled to below 40 ° C in 1-2 minutes, specifically The apple pulp is quickly pumped into the vacuum cooler in 1-2 minutes, and the pulp is lowered in the form of a film. The vacuum cooler uses a centrifugal scraper film vacuum evaporator, and the evaporator jacket is provided with chilled brine, vacuum The cooling vacuum is 0.085 to 0.096 MPa, and the frozen brine temperature is less than -4 °C.

(4) Post-treatment: The apple pulp prepared in the step (3) is filtered to remove the core, and then subjected to ultrafine pulverization and magnetic filtration to prepare a fresh NFC product. Among them, the 10-core mesh is used to remove the apple core; the ultra-fine pulverization uses a high-speed cutting wet superfine pulverizer to pulverize the leather and fibrous materials to 80-100 mesh, and the rotational speed of the cutting blade is generally above 2800 rpm. Comb-shaped cylindrical shape, the material is smashed between the comb cylinder and the blade under the centrifugal force of the blade, and is refined by the strong shearing force of the blade end, and the size of the comb gap can be controlled. Control the particle size of the product, have better pulverization and refinement effect on the fiber material in the apple; magnetically filter the magnetic separator to remove the fine metal impurities in the pulp; add vitamin C or citric acid to adjust the product as needed The acidity, adding sucrose or honey to adjust the sweetness of the product, so that the sweet and sour ratio is better. The product is refrigerated at a temperature of 4 to 5 ° C, and the shelf life is 1 to 5 days. If the product is pasteurized and rapidly cooled, it can be refrigerated at 4 to 5 ° C after aseptic filling, and the shelf life can be up to 30 days. Preferably, the pasteurization uses a tube-type sterilizer, the sterilization temperature is 85 to 100 ° C, and the temperature is maintained for 30 to 15 s. After sterilization, the tube or plate heat exchanger is used to rapidly cool to a normal temperature.

Preferably, the vacuum cooler used in the step (3) for ultra-fast cooling has the following structure: Referring to FIG. 1, the vacuum cooler includes a squeegee 1, an inner cylinder 2, a jacket 3, a distribution disc 4, and a block Disk 5 and motor 6. The inner cylinder 2 has a cylindrical shape, wherein the squeegee 1 is disposed inside the inner cylinder 2 and the gap with the inner cylinder 2 is 1 to 3 mm, and the jacket 3 is disposed at the outer periphery of the inner cylinder 2, the distribution disc 4 is connected above the scraper 1, the motor 6 controls the rotation of the scraper 1, the distribution disc 4 and the retaining disc 5; the vacuum cooler is provided with a vacuum port A connected to the vacuum pump, and the distribution disc 4 The feed port B is disposed at a position parallel to each other, and a coolant inlet D is provided below the jacket 3, a coolant outlet C is provided above the jacket 3, and a discharge port E is provided at the bottom of the inner cylinder 2.

In use, the motor 6 of the vacuum cooler drives the scraper 1 and the distribution disc 4 to rotate via the reducer, and the pulp enters through the feed port B through the pump, and the pulp is along the distribution disc 4 and the scraper 1 along the pulp. The inner wall of the inner cylinder 2 of the vacuum cooler is lowered in a film shape, and the vacuum pump is connected to the vacuum pump so that the inner cylinder 2 of the vacuum cooler is in a vacuum state, and the pulp is in a film-like manner under the action of gravity. Part of the water quickly evaporates and consumes latent heat of evaporation to cause the temperature of the pulp to drop rapidly. At the same time, the jacket 3 is provided with chilled brine, which enters from the coolant inlet D and flows out from the coolant outlet C, accelerating the cooling rate of the pulp. And reducing the amount of water evaporation in the pulp, is conducive to the cooling rate and product quality improvement, and finally the ultra-rapid cooling slurry is discharged from the discharge port E, collected, into the post-treatment process.

Those skilled in the art know that the most important enzyme causing browning of fruit juice is polyphenol oxidase. Experimental data prove that heating at 80 ° C for 1 min or 90 ° C for 15 s can be completely inactivated. The invention has been repeatedly tested and found that the temperature is controlled at 80-92 ° C, the holding time is controlled at 48-12 s, the temperature is low for a long time, the temperature is high for a short time, and the final temperature and holding time of the temperature rise follow a linear inverse relationship: T=- t/3+96, T is the final temperature, the unit is °C; t is the holding time, the unit is s; on the other hand, the pulp after the enzyme is destroyed must be ultra-fast cooling immediately, so that the pulp is within 1 to 2 minutes. From near 90 ° C quickly to normal temperature, to avoid the ripening of the pulp. Only the close integration of "breaking pulping and steam inactivation enzymes" and "ultra-fast cooling" and strict control of process parameters can produce high quality NFC apple juice drinks. It is necessary to specially design and manufacture the equipment for rapid steam heating and enzyme elimination, such as the patent CN201510862729.4 declared by the inventor, wherein the steam pressure, flow rate and material feeding amount need to be adjustable and controllable.

The beneficial technical effects of the present invention are:

The invention realizes the physical method of killing the enzyme and creates a green safe high-quality fresh-squeezed juice production process. Steam is introduced at the same time as the steaming, the steam instantly heats the broken material to the desired temperature and maintains the required time, and can quickly inactivate the polyphenol oxidase in the fruit, and maintain the original color of the fruit well. At the same time, the technology of coupling ultra-fast cooling, because of the extremely fast cooling speed, avoids the overheating of the juice to produce a cooked taste, can maintain the original flavor and nutrition of the fruit well, and produces a high-quality apple freshly squeezed beverage. The product laid the foundation. The pulp obtained by the coupling of the crushing pulp and the steam-killing enzyme is pumped to the distribution tray and descends along the inner wall of the inner cylinder under the action of centrifugal force and gravity. At this time, the temperature of the material just entering the vacuum cooler is much greater than the vacuum degree. The saturated evaporation temperature of the water, the moisture in the pulp rapidly vaporizes and consumes the latent heat of vaporization, and is protected by the rotating scraper to ensure that the pulp is reduced in shape when the pulp is lowered, so that the moisture is vaporized and the resistance of the escape is extremely small. The drastic drop, the temperature of the frozen brine in the jacket to take the pulp away from the outer wall of the inner cylinder not only accelerates the cooling rate of the pulp, but also reduces the vacuum volatilization loss of the flavor component in the pulp, further ensuring the quality of the product.

The present invention is highly efficient and minimizes enzymatic browning. Most of the prior art adopts cold crushing, and then the heat exchanger is used to heat the slurry to destroy the enzyme; however, the method of killing the enzyme after the cold crushing is actually the majority of browning has been completed in the cold crushing process, followed by Inhibition of enzymes inhibits browning and has limited effect.

The NFC apple juice provided by the invention does not need to add additives such as flavors, pigments and preservatives. Because the enzyme is timely and efficient, the color and nutrition of the juice can be well protected, and a little natural honey and/or sugar can be added according to actual needs. Sweetness, add a small amount of vitamin C and / or citric acid to adjust the acidity, so as to get a better taste of NFC apple juice. Among them, vitamin C can be added during the beating process, or can be added during the formulation, and can inhibit the non-enzymatic browning in the later stage.

In summary, the invention adopts the integrated coupling technology of crushing pulping and steam-killing enzyme, and then immediately performs ultra-fast cooling, while strictly controlling the process parameters and minimizing the temperature and time of the heat action, thereby realizing the physical method to destroy the enzyme. And in the true sense of the completion of NFC apple juice green and high quality processing.

DRAWINGS

Figure 1 is a schematic view showing the structure of a vacuum cooler used in a preferred embodiment of the present invention.

Among them, 1, scraper, 2, inner cylinder, 3, jacket, 4, distribution disc, 5, retaining disc, 6, motor, A, vacuum port, B, feed port, C, coolant outlet, D, coolant inlet, E, discharge port

detailed description

Example 1

(1) Choose fresh and ripe red Fuji apples, no mold and rot, no insects, pesticide residues, and the sugar content is greater than 10 Brix;

(2) Washing: the apple of step (1) is placed in a bubbling washing machine, and the apple is sufficiently washed by bubbling, stirring, or the like;

(3) Cutting the flap: use the cutting machine to make all 4 petals of the apple;

(4) Crushing and enzymatic coupling: the pressure of the selected steam is 0.12 MPa. The steam in the equipment is removed by steam for 2 minutes. The screw is dosed, and the steam is heated while being crushed. The slurry is heated to 80 ° C in 3 minutes. Discharge after 48s;

(5) ultra-fast cooling: the apple slurry described in the step (4) is quickly entered into the vacuum cooler, the degree of vacuum is 0.096 MPa, the temperature of the frozen brine in the jacket is -6 ° C, and the material is film-like, A part of the water evaporates, and the temperature of the apple slurry rapidly drops to 40 ° C in 1 minute;

(6) Filtration: the slurry is passed through a 10-mesh screen to remove the apple core;

(7) Superfine pulverization: the high-speed cutting wet superfine pulverizer is used, and the rotation speed is 2800 rpm, and the leather and fibrous materials are pulverized to 100 mesh;

(8) Magnetic filtration: a magnetic separator is used to remove fine metal impurities which may exist in the pulp;

(9) Filling to obtain the finished product, refrigerated at 4 ° C, the shelf life is 3 to 5 days.

Example 2

(1) Choose fresh and ripe red Fuji apples, no mold and rot, no insects, pesticide residues, and the sugar content is greater than 10 Brix;

(2) Washing: the apple of step (1) is placed in a bubbling washing machine, and the apple is sufficiently washed by bubbling, stirring, or the like;

(3) Cutting the flap: use the cutting machine to make all 6 petals of the apple;

(4) Crushing and enzymatic coupling: the pressure of the selected steam is 0.18 MPa, and the oxygen in the equipment is removed by steam for 3 minutes. The screw is quantitatively fed, and the steam is heated while being crushed, and the slurry is heated to 85 ° C in 2 minutes. Discharge after 33s;

(5) Ultra-fast cooling: the apple slurry described in the step (4) is quickly introduced into the vacuum cooler, the degree of vacuum is 0.085 MPa, the temperature of the frozen brine in the jacket is -5 ° C, and the material is film-like, Part of the water evaporated, the apple slurry temperature dropped to 39.8 ° C within 1.8 minutes;

(6) Filtration: the slurry is passed through a 10-mesh screen to remove the apple core;

(7) Superfine pulverization: the high-speed cutting wet superfine pulverizer is used, and the rotation speed is 2800 rpm, and the leather and fibrous materials are pulverized to 80 mesh;

(8) Magnetic filtration: a magnetic separator is used to remove fine metal impurities which may exist in the pulp;

(9) Homogeneity: the pulp is further refined by a high pressure homogenizer, and the homogenization pressure is 20 MPa;

(10) pasteurization: using a tube-type sterilizer, sterilization temperature 100 ° C, for 15 s, rapid cooling to room temperature;

(11) The finished product is filled in aseptic carton and refrigerated at 4 ° C with a shelf life of 30 days.

Example 3

(1) Choose fresh and ripe red Fuji apples, no mold and rot, no insects, pesticide residues, and the sugar content is greater than 10 Brix;

(2) Washing: the apple of step (1) is placed in a bubbling washing machine, and the apple is sufficiently washed by bubbling, stirring, or the like;

(3) Cutting the flap: use the cutting machine to make all 8 petals of the apple;

(4) Crushing and enzymatic coupling: the pressure of the selected steam is 0.22 MPa. The steam in the equipment is removed by steam for 2 minutes. The screw is dosed, and the steam is heated while being crushed. The slurry is heated to 92 ° C in 1 minute. Discharge after 12s;

(5) Ultra-fast cooling: the apple slurry described in the step (4) is quickly entered into the vacuum cooler, the degree of vacuum is 0.092 MPa, the temperature of the frozen brine in the jacket is -4 ° C, and the material is film-like, part of Water evaporation, apple slurry temperature dropped rapidly to 40 ° C within 2 minutes;

(6) Filtration: the slurry is passed through a 10-mesh screen to remove the apple core;

(7) Ultra-fine pulverization: the high-speed cutting wet superfine pulverizer is used, and the rotation speed is 2800 rpm, and the leather and fibrous materials are broken to 100 mesh;

(8) Magnetic filtration: a magnetic separator is used to remove fine metal impurities which may exist in the pulp;

(9) Blending: Adding 0.02% (w/w) of vitamin C to adjust the acidity of the apple raw material and further exerting the color protection effect, adding the quality of 5% (w/w) of the artichoke honey to adjust the sweetness;

(10) Homogenization: The pulp is further refined by a high pressure homogenizer, and the homogenization pressure is 20 MPa;

(11) pasteurization: using a tube-type sterilizer, sterilization temperature 85 ° C, for 30 s, rapid cooling to room temperature;

(12) The polyester bottle is aseptically filled to obtain the finished product, which is refrigerated at 4 ° C and has a shelf life of 30 days.

Using the basic technical scheme of Example 2, some of the steps were changed to obtain Comparative Examples 1-4, as follows:

Comparative Example 1 replaced step (4) and step (5) in Example 2 with natural beating with a beater;

Comparative Example 2: Step (4) in Example 2 was replaced by natural beating with a beater, and then the pulp was quickly inactivated at 90 ° C for 15 s;

Comparative Example 3, replacing step (5) in Example 2 with the slurry being naturally cooled to room temperature;

Comparative Example 4 Step (5) in Example 2 was replaced by pumping the slurry into a vacuum cooler, and the blade was cooled to room temperature without being rotated.

The products obtained in the above Examples 1-3 and Comparative Examples 1-4 were measured, and the indicators such as sensory evaluation, browning, and polyphenol content were respectively compared, as follows.

(1) The scoring criteria of the sensory evaluation are shown in Table 1. Seven samples of Examples 1-3 and Comparative Examples 1-4 were taken, and each sample was divided into 5 portions, evaluated 3 times, and averaged. Score the color, smell, taste and overall rating of fresh apple juice, with a maximum score of 100 points.

Table 1 Apple fresh juice juice sensory evaluation score sheet

(2) Since apple browning is divided into enzymatic browning and non-enzymatic browning, enzymatic browning is a major part of browning, and is generally completed within 10 minutes after apple breaking. The L value of the color and color of the pulp was measured with time, and the color of the apple pulp with different treatment methods was measured and compared. The larger the L value, the brighter the pulp and vice versa. Due to the good browning resistance of sodium sulfite, a 2% (w/w) sodium sulfite-based apple pulp was used as a standard sample.

The L value is usually determined by HunterLab (model UltraScanPro1166, HunterLab, USA) The company) color difference meter to determine the color of the juice, the data results are expressed in L, a, b. After calibration with a standard white plate, a cylindrical sampler (diameter: 58 mm, depth: 15 mm) is used to hold the same quality of the pulp under the color difference meter (50 mm diameter). L is called the brightness index, L=0. It means black, L=100 means white; a and -a respectively represent red and green, the larger the absolute value of a, the closer the color is to pure red and pure green, the gray is a=0; b and -b respectively represent yellow and Blue, the greater the absolute value of b, the closer the color is to pure yellow and pure blue, and the gray when b=0.

L _control ---- apple plus 2% partial weight of sodium sulfite crushing pulping L value (substantially does not change with time);

L _natural ----the L value after 10 minutes of pulping by apple natural crushing and beating;

L _sample ---the L value of the apple pulp prepared in Examples 1 to 3 and Comparative Examples 1 to 4 after being left for 10 minutes.

(3) Polyphenols are important flavor substances and coloring substances of apples and processed products, and are closely related to the sensory quality of apples and processed products. Apple polyphenols mainly include catechins, proanthocyanidins, hydroxycinnamic acids, dihydrochalcones, flavonols, anthocyanins.

The total amount of polyphenols was determined by the forinol method: (1) Preparation of the standard curve, accurately taking 0.05, 0.10, 0.15, 0.20, 0.25, 0.30 mL of the gallic acid standard solution at a concentration of 100 μg/mL in a 5 mL volumetric flask. Distilled water 1.95, 1.90, 1.85, 1.80, 1.75, 1.70 mL, respectively, and then add 1.0 mL of Forint reagent, shake well for 3-4 min, add 1.0 mL of 10% Na ₂ CO ₃ solution, shake and place at constant temperature. The reaction was carried out for 2 h in a water bath; the reagent blank was simultaneously prepared, and the absorbance was measured at 765 nm, and the linear regression was performed on the absorbance of the content to obtain a regression equation. (2) Treatment of raw materials: accurately weigh 5.00g of apple pulp in a conical flask, add 80mL of 70% ethanol, and extract it by hot reflux in water bath at 80 °C for 3 times, each time for 2 hours, centrifuge at 4000r/min for 20min, collect The supernatant was combined, concentrated under a rotary evaporator at -0.09 MPa, and the ethanol was recovered. The concentrate was made up to 50 mL with distilled water, to be tested.

Principle and method of determination: Polyphenolic compounds have highly oxidizable hydroxyl groups on the molecule, which react blue with Folin-Ciocalten reagent under alkaline conditions. The reactants have maximum absorption at 765 nm, and Lambert is observed under certain conditions. -- Beer's law, the total amount of apple polyphenols can be determined using gallic acid as a reference substance. According to this measurement principle, 2 mL of the solution is taken from the above 50 mL of the test solution, and the absorbance is measured according to the standard curve preparation method. According to the regression equation, the content of polyphenol in the 2 mL sample to be tested can be obtained, and the phenols in the 1 g sample are further calculated. The content of the substance (mg/g in gallic acid, DW).

The above measurement results were subjected to data processing, and the final results were filled in Table 2 below.

Table 2: Fresh apple juice quality evaluation table prepared by different methods

Process method	Relative browning rate	Total polyphenol retention	Sensory evaluation score	Whether there is cooked flavor
Comparative example 1	100%	10%	70.2	no
Comparative example 2	91%	twenty three%	73.5	Have
Comparative example 3	2.8%	93.3%	76.6	Have
Comparative example 4	2.7%	94.1%	83.4	Have
Example 1	1.8%	95.2%	96.5	no
Example 2	1.7%	96.3%	97.0	no
Example 3	1.5%	97.2%	98.5	no

All of the raw materials in Table 2 were fresh and ripe red Fuji apples, and the same processing method was basically employed except for the change of individual steps. Analysis Table 2 shows that the traditional process in the prior art is adopted: cold-crushing, natural beating, ie, comparative example 1, cold-crushing, natural beating, heating and enzyme-inhibiting, that is, the pulp obtained by the process of Comparative Example 2 is very enzymatic browning, sensory The evaluation was also the worst, and the retention of the antioxidant active ingredient polyphenol was very low. Although the method of coupling the crushing pulp and the steam-killing enzyme is adopted, although the enzymatic browning is better suppressed, the antioxidant active components such as polyphenols are retained to some extent, but the natural cooling is the comparative example 3, and only the vacuum is used. Cooling, that is, Comparative Example 4, because the cooling rate is not fast enough, the product has a cooked taste, and the results of sensory evaluation are still not satisfactory. Only by using the ingenious combination of the crushed steam inactivating enzyme coupling and the ultra-rapid cooling provided by the present invention, as in the first, second and third embodiments, the enzymatic browning can be best suppressed, and the antioxidant active ingredients such as polyphenols are most retained. Moreover, the product has no cooked flavor and can basically maintain the original taste of the fruit and obtain high quality NFC freshly squeezed apple juice.

The above is only a preferred embodiment of the present invention, and is not intended to limit the present invention in any way. Any simple modification to the above embodiments according to the technical essence of the present invention without departing from the technical scope of the present invention. Equivalent changes and modifications are still within the scope of the technical solutions of the present invention.

Claims (10)

1. A preparation process of apple fresh juice, characterized in that the method comprises the following steps:

   (1) Raw material selection and pretreatment: Select apple as raw material, wash and cut the flap;

   (2) integration of crushing pulping and steam inactivation: the apple treated in step (1) is crushed and pulped, and steam is sprayed into the apple while crushing and pulping, so that the temperature of the pulp is fast within 1 to 3 minutes. After the temperature is raised to 80-92 ° C, the steam is stopped and maintained for 48 to 12 seconds;

   (3) ultra-fast cooling: the apple pulp obtained in the step (2) is rapidly cooled by means of vacuum cooling and chilled brine conduction cooling, and rapidly cooled to below 40 ° C in 1 to 2 minutes;

   (4) Post-treatment: After the apple pulp prepared in the step (3) is filtered to remove the core, further finely pulverized, magnetically filtered and blended to obtain a finished apple fresh juice, and the finished product is refrigerated at a temperature of 4 to 5 ° C. .
2. The process according to claim 1, wherein the raw material selected in the step (1) is an apple which is fresh, mature, mold-free, rotten, free of insects and pesticide residues, and the apple sugar degree is greater than 10 Brix, and the cleaning is adopted. The bubbling cleaning machine is cut into 4 to 8 petals after cleaning.
3. The process according to claim 1, characterized in that in the step (2), a few minutes before the start of the crushing, the steam is pre-passed to drive off the air in the crushing chamber, and the steam is uniformly sprayed toward the broken apple, and the final temperature of the temperature rises. The final temperature hold time follows a linear inverse relationship: T = -t / 3 + 96, T is the final temperature, the unit is ° C, and t is the hold time, the unit is s.
4. The process of claim 1 wherein said step (2) uses a fast rotating blade to break up the apple to a particle size of about 2 mm.
5. The process according to claim 1, wherein the step (2) of injecting steam has a pressure of 0.12 to 0.22 MPa.
6. The process according to claim 1, wherein the step (3) is: pumping the apple pulp obtained in the step (2) into the vacuum cooler in 1-2 minutes, so that the pulp is reduced in a film form. The vacuum cooler adopts a centrifugal scraper type film vacuum evaporator, and a frozen brine is arranged in the evaporator jacket.
7. The process according to claim 6, wherein the vacuum degree of vacuum cooling in the step (3) is 0.085 to 0.096 MPa, and the temperature of the frozen brine in the jacket is less than -4 °C.
8. The process according to claim 1, characterized in that in the ultrafine pulverization in the step (4), the high speed cutting wet superfine pulverizer is used to control the rotational speed of the cutting blade at 2800 rpm or more.
9. The process of claim 1 wherein the formulated product is pasteurized and fast After rapid cooling and aseptic filling, it is refrigerated at a temperature of 4 to 5 ° C. The pasteurization uses a tube-type sterilizer, the sterilization temperature is 85 to 100 ° C, and the temperature is maintained for 30 to 15 s, and the tube or plate is used after sterilization. The heat exchanger is rapidly cooled to normal temperature.
10. A process according to any one of the preceding claims wherein, while crushing the pulp, 0.006 to 0.03% of vitamin C or citric acid, based on the mass of the apple raw material, is further added to further protect the color and adjust the acidity of the pulp.

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