CN106578013A - Physical fresh keeping method of pomegranates - Google Patents

Abstract

The invention discloses a physical fresh-keeping method for pomegranates, which solves the problems of insect damage and low nutritional value of the pomegranates in the existing storage process. The technical solution is to refrigerate the fresh pomegranate after soaking, cleaning, draining, high-pressure osmosis treatment, vacuum high-voltage electric field corona discharge treatment and vacuum packaging. state, has a strong penetration ability, can penetrate into the pomegranate, and has an effective antibacterial and insecticidal effect. Through the vacuum high-voltage electric field corona discharge treatment, the molecular structure of the volatile components in the mugwort can be broken, and the odor can be further removed. The storage period of the pomegranate after the above treatment has been greatly improved, and the color, fragrance and taste are all good.

Description

A kind of physical preservation method of pomegranate

technical field

The invention belongs to the field of food preservation, and in particular relates to a physical preservation method of pomegranate.

Background technique

Pomegranate (Pomegranate) is an exotic berry with a translucent, juicy outer seed coat and a leathery inner seed coat. Pomegranate is warm in nature, sweet or sour in taste, and has the effects of promoting body fluid and quenching thirst, astringent intestines and diarrhea, killing insects and stopping dysentery. Pomegranate contains a variety of organic acids such as punicic acid, which can help digestion and absorption, and increase appetite; pomegranate has obvious astringent, antibacterial, and antiviral effects, inhibits and kills Shigella bacilli, and has a paralytic effect on internal parasites; The vitamin C and carotene contained are antioxidants, which can prevent cell cancer and atherosclerosis; pomegranate leaves can be used to make pomegranate tea, which can moisten dryness and quench thirst. If it is used for eye washing, it can also improve eyesight and eliminate eye diseases.

Nowadays, according to the nutritional characteristics of pomegranates, relevant researchers have developed a variety of pomegranate preservation methods, for example: Chinese patent application number CN201410147095. method", etc. The research content is the way of using chitosan coating film preservation or modified atmosphere preservation treatment. However, there are inevitable food safety hazards in the chemical substance coating fresh-keeping treatment, and there is a popularization problem in the modified atmosphere fresh-keeping.

Contents of the invention

The purpose of the present invention is to solve the above-mentioned technical problems and provide a physical fresh-keeping method for pomegranates with simple and reliable process, long-term freshness, color retention, good taste, no chemical reagent residue, and high nutritional value.

The physical fresh-keeping method of the pomegranate of the present invention is as follows: firstly use the mugwort essential oil gas in an approximate supercritical state to perform high-pressure permeation treatment on the fresh pomegranate, then use a high-voltage electric field corona discharge treatment on the pomegranate, and finally refrigerate the pomegranate after being vacuum-packed.

Specifically include the following steps:

(1) Soaking and cleaning: immerse the fresh pomegranate in ultrapure water to remove impurities and dust on the surface of the pomegranate, and then sonicate for 0.5 to 1 hour;

(2), draining: the pomegranate after ultrasonic treatment is drained quickly under dark and low temperature conditions, and then packed into a high-pressure air chamber;

(3) High-pressure osmosis treatment: Add mugwort essential oil into the heating chamber, promote the volatilization of mugwort essential oil at a constant temperature of 100-120°C, and use a high-pressure pump to pump the volatilized mugwort essential oil gas into the high-pressure air tank containing pomegranate. In the chamber, pressurize the high-pressure air chamber and keep it at 10-15MPa, so that the gas density of mugwort essential oil reaches an approximate supercritical state of 0.68-0.85g/ ^cm3 , and the treatment time is 30-60min;

(4), vacuum high-voltage electric field corona discharge treatment: the pomegranate after high-voltage infiltration treatment is packed in a high-voltage electric field corona discharge device, and high-voltage electric field corona discharge treatment is carried out in a vacuum state;

(5) Vacuum-pack the pomegranates treated by corona discharge in an empty high-voltage electric field, put them in a deoxidizer, and keep them refrigerated and kept fresh at 1-5°C.

In the step (2), after the draining, carry out air blowing and mixing treatment, and use a mesh belt air dryer at 40-60°C to dry for 60-90 minutes;

In the step (2), when draining, the low temperature is controlled to be 1-20°C.

In the step (4), the intensity of the high-voltage corona field is controlled to be 150-220KV, and the treatment time is 15-22h.

In step (4), the degree of vacuum is controlled at 2000-2500Pa.

In the step (4), the high-voltage electric field corona discharge device at least includes a metal plate and a discharge needle, the maximum tile thickness of the pomegranate on the metal plate is 40-70 mm, and the minimum distance between the discharge needle and the metal plate is 90 mm. ~120mm, the distance between the discharge needles is 50-72mm.

Aiming at the problems existing in the background technology, the inventor conducted in-depth research on the physical fresh-keeping method of pomegranate, and selected mugwort among many natural insecticidal plants, and utilized the volatilization of mugwort essential oil to exert antibacterial and insecticidal effects, but the inventor It was also found that because the pomegranate has a thicker skin, it is difficult to make the mugwort essential oil penetrate into the pomegranate only by ordinary methods such as fumigation or soaking. In order to solve the above problems, the inventor first uses a constant temperature environment to promote the volatilization of mugwort essential oil, and then makes the volatilized mugwort gas appear in an approximate supercritical state under high pressure conditions, so that it has a strong penetrating ability, so that it can penetrate To the inside of the pomegranate, to obtain excellent antibacterial and insecticidal effects.

Described mugwort has strong volatility, because also can make pomegranate residual irritating taste, affect the mouthfeel and the fragrance of pomegranate, to this problem, inventor carries out vacuum high-voltage electric field corona discharge treatment to pomegranate, utilizes corona discharge process The ion beam generated in the pomegranate increases the energy of the mugwort gas molecules remaining in the pomegranate, causing the breakage of the hydrogen bonds between the chain molecular groups, thereby breaking the molecular structure of the volatile components in the mugwort, and quickly and effectively eliminating the mugwort. At the same time, the inventor also found that the vacuum high-voltage electric field corona discharge treatment also has a killing effect on the worm eggs in the pomegranate. In the vacuum environment, on the one hand, it can strengthen the effect of the high-voltage corona field, and it can further remove odors, and completely solve various problems caused by using mugwort essential oil.

The selected temperature to promote the volatilization of mugwort essential oil is preferably 100-120°C, and the temperature selection should not be too high to avoid adverse chemical reactions of mugwort essential oil due to high temperature; the selected pressure is 10-15 MPa. High pressure capacity puts forward higher requirements, and will increase the loss of nutrients in pomegranate products during high-pressure osmosis treatment. If it is too low, the gas density of mugwort essential oil cannot reach the approximate supercritical state of 0.68-0.85g/ ^cm3 ; the selected The high-pressure penetration time is 30-60 minutes. The high-pressure penetration time should not be too long, but the pomegranate must be fully in contact with the supercritical mugwort gas with strong penetrating power to penetrate the deep layer of the pomegranate to ensure the insecticidal and antibacterial effects.

Further, preferably after step (2) is drained, it is then processed by air blowing and mixing to reduce the moisture content on the surface of the pomegranate, further inhibiting the growth of microorganisms on the surface of the pomegranate. Dry under the condition of 60-90min. If the temperature is too high, it will not only cause the destruction of heat-sensitive nutrients, but also choose a higher temperature on the pomegranate surface to meet the needs of external water evaporation, and the internal water will migrate to the surface faster, which will easily lead to the soluble Components are precipitated on the surface, thereby causing the hardening of the pomegranate surface; the selected time should not be too short, because too short time is not conducive to the drying of the pomegranate surface, and it is preferable to control the water content of the pomegranate to below 55%.

In step (4), the high-voltage electric field corona discharge device is a commercially available product (such as produced by Shanghai Zhizhao Environmental Protection Technology Co., Ltd.), which at least includes a metal plate and a vertically downward discharge needle above the metal plate, and the pomegranate is placed on the metal plate. The maximum tile thickness on the plate is preferably 40-70mm, the distance between the discharge needles is 50-72mm, and the minimum distance between the tip of the discharge needle and the metal plate is preferably 90-120mm. The selected maximum tiling thickness and the distance between the tip of the discharge needle and the metal plate should not be too large. Too large a distance will not be effective in killing insect eggs, and it will also prolong the time of high-voltage electric field corona discharge treatment; The piezoelectric corona field intensity is 150-220KV. If the high-voltage electric field corona discharge intensity is too high, it will put forward higher requirements for production conditions, and it will also have an adverse effect on the quality of pomegranates. However, if the high-voltage corona field intensity is below 150KV, it will kill The effect of killing insect eggs is not significant; too long time selection is not conducive to controlling production efficiency, and long-term high-voltage electric field corona discharge treatment is not conducive to maintaining the quality of pomegranate, and too short time will affect the effect of killing insect eggs;

Beneficial effect:

(1) No chemical substances are used for soaking treatment in the whole process, which avoids the food safety hazards caused by chemical substances. (2) In the high-pressure infiltration process, making mugwort essential oil behave in an approximate supercritical state can play a more significant antibacterial and insecticidal effect than simply using mugwort essential oil for fumigation. (3) Using the ion beam generated in the corona discharge process to destroy the molecular structure of the volatile components in Artemisia argyi, and also have a significant killing effect on the insect eggs in the pomegranate. In the process of corona discharge, the temperature of the material will not be raised, and combined with the vacuum environment, it also solves the problem of the odor of the final product caused by the residual mugwort gas. (4) The pomegranate prepared by the method of the present invention can be refrigerated and kept fresh for more than 60 days at 1-5° C., its color, taste, smell and nutritional value are effectively guaranteed, and it has broad market application prospects.

detailed description

The technical solutions in the present invention will be clearly and completely described below in conjunction with specific embodiments.

Example 1

(1) Picking: hand-picked mature pomegranates, and pay attention to avoid picking pomegranates with damaged shapes and wormholes;

(2), soaking and cleaning: immerse the pomegranate picked above in ultra-pure water, remove impurities and dust on the surface of the pomegranate, and then sonicate for 0.5h;

(3) Drain, air blowing and mixing treatment: keep the treated pomegranate away from light, drain quickly at a low temperature of 1°C, and then dry for 60 minutes at 40°C with a mesh-belt airflow dryer;

(4) High-pressure osmosis treatment: Add mugwort essential oil into the heating chamber, promote the volatilization of mugwort essential oil at a constant temperature of 100°C, and use a high-pressure pump to pump the volatilized mugwort essential oil gas into the high-pressure air chamber equipped with pomegranate , and pressurize the high-pressure air chamber to ensure that the pressure in the high-pressure air chamber is 10MPa. At this time, the mugwort essential oil gas is in an approximate supercritical state with a density of 0.68-0.85g/cm ³ , and the processing time is 30min;

(5) Vacuum high-voltage electric field corona discharge treatment: spread the dried pomegranate on the metal plate, ensure the thickness of the tile after loading the sample is 40mm, the distance between the tip of the needle electrode and the metal plate is 90mm, and the high-voltage corona field strength is 150KV , carry out high-voltage electric field corona discharge treatment for 15 hours in a vacuum state, and ensure that the vacuum degree is 2000-2500Pa;

(6), vacuum packaging: vacuum-pack the pomegranate after drying with an aluminum foil bag, and put a pouch that is packed with Fe powder deoxidizer by 1% (w/w) in the package;

(7) Refrigeration: Refrigerate and keep fresh at 1°C.

Example 2

(1) Picking: hand-picked mature pomegranates, and pay attention to avoid picking pomegranates with damaged shapes and wormholes;

(2), soaking and cleaning: immerse the pomegranate picked above in ultra-pure water, remove impurities and dust on the surface of the pomegranate, and then ultrasonic for 1 hour;

(3) Drain, air blowing and mixing treatment: keep the treated pomegranate away from light, drain quickly at a low temperature of 20°C, and then dry it for 90 minutes at 60°C with a mesh belt air dryer;

(4) High-pressure osmosis treatment: Add mugwort essential oil into the heating chamber, promote the volatilization of mugwort essential oil at a constant temperature of 120°C, and use a high-pressure pump to pump the volatilized mugwort essential oil gas into the high-pressure air chamber equipped with pomegranate , and pressurize the high-pressure air chamber to ensure that the pressure in the high-pressure air chamber is 15MPa. At this time, the mugwort essential oil gas is in an approximate supercritical state with a density of 0.68-0.85g/cm ³ , and the processing time is 60min;

(5) Vacuum high-voltage electric field corona discharge treatment: spread the dried pomegranate on the metal plate, ensure that the thickness of the tile after loading is 55mm, the distance between the tip of the needle electrode and the metal plate is 100mm, and the high-voltage corona field strength is 190KV , Carry out high-voltage electric field corona discharge treatment in a vacuum state for 18 hours to ensure that the vacuum degree is 2000-2500Pa;

(6), vacuum packaging: vacuum-pack the pomegranate after drying with an aluminum foil bag, and put a pouch that is packed with Fe powder deoxidizer by 1% (w/w) in the package;

(7) Refrigeration: Refrigerate and keep fresh at 1°C.

Example 3

(1) Picking: hand-picked mature pomegranates, and pay attention to avoid picking pomegranates with damaged shapes and wormholes;

(2), soaking and cleaning: immerse the pomegranate picked above in ultrapure water, remove impurities and dust on the surface of the pomegranate, and then sonicate for 0.8h;

(3), draining, air blowing and mixing treatment: the treated pomegranate is protected from light, drained quickly at a low temperature of 10°C, and then dried for 75min at 50°C with a mesh belt type airflow dryer;

(4) High-pressure osmosis treatment: Add mugwort essential oil into the heating chamber, promote the volatilization of mugwort essential oil at a constant temperature of 110°C, and use a high-pressure pump to pump the volatilized mugwort essential oil gas into the high-pressure air chamber equipped with pomegranate , and pressurize the high-pressure air chamber to ensure that the pressure in the high-pressure air chamber is 13 MPa. At this time, the mugwort essential oil gas is in an approximate supercritical state with a density of 0.68-0.85 g/cm ³ , and the processing time is 45 minutes;

(5) Vacuum high-voltage electric field corona discharge treatment: spread the dried pomegranate on the metal plate, ensure that the thickness of the tile after loading is 55mm, the distance between the tip of the needle electrode and the metal plate is 100mm, and the high-voltage corona field strength is 190KV , Carry out high-voltage electric field corona discharge treatment in a vacuum state for 18 hours to ensure that the vacuum degree is 2000-2500Pa;

(6), vacuum packaging: vacuum-pack the pomegranate after drying with an aluminum foil bag, and put a pouch that is packed with Fe powder deoxidizer by 1% (w/w) in the package;

(7) Refrigeration: Refrigerate and keep fresh at 1°C.

Comparative Example 1: Artemisia essential oil is not added to high-pressure osmosis

(1) Picking: hand-picked mature pomegranates, and pay attention to avoid picking pomegranates with damaged shapes and wormholes;

(2), soaking and cleaning: immerse the pomegranate picked above in ultra-pure water, remove impurities and dust on the surface of the pomegranate, and then sonicate for 0.5h;

(3) Drain, air blowing and mixing treatment: keep the treated pomegranate away from light, drain quickly at a low temperature of 1°C, and then dry for 60 minutes at 40°C with a mesh-belt airflow dryer;

(4), high-pressure infiltration treatment: 100g pomegranate is packed in the high-pressure air chamber, and pressurize the high-pressure air chamber, ensure that the pressure in the high-pressure air chamber is at 10MPa, and the treatment time is 30min;

(5) Vacuum high-voltage electric field corona discharge treatment: spread the dried pomegranate on the metal plate, ensure the thickness of the tile after loading the sample is 40mm, the distance between the tip of the needle electrode and the metal plate is 90mm, and the high-voltage corona field strength is 150KV , carry out high-voltage electric field corona discharge treatment for 15 hours in a vacuum state, and ensure that the vacuum degree is 2000-2500Pa;

(6), vacuum packaging: vacuum-pack the pomegranate after drying with an aluminum foil bag, and put a pouch that is packed with Fe powder deoxidizer by 1% (w/w) in the package;

(7) Refrigeration: Refrigerate and keep fresh at 1°C.

Comparative Example 2: Corona discharge treatment without vacuum high voltage electric field

(1) Picking: hand-picked mature pomegranates, and pay attention to avoid picking pomegranates with damaged shapes and wormholes;

(2), soaking and cleaning: immerse the pomegranate picked above in ultra-pure water, remove impurities and dust on the surface of the pomegranate, and then sonicate for 0.5h;

(3) Drain, air blowing and mixing treatment: keep the treated pomegranate away from light, drain quickly at a low temperature of 1°C, and then dry for 60 minutes at 40°C with a mesh-belt airflow dryer;

(4) High-pressure osmosis treatment: Add mugwort essential oil into the heating chamber, promote the volatilization of mugwort essential oil at a constant temperature of 100°C, and use a high-pressure pump to pump the volatilized mugwort essential oil gas into the high-pressure air chamber equipped with pomegranate , and pressurize the high-pressure air chamber to ensure that the pressure in the high-pressure air chamber is 10MPa. At this time, the mugwort essential oil gas is in an approximate supercritical state with a density of 0.68-0.85g/cm ³ , and the processing time is 30min;

(5), vacuum packaging: the pomegranate after drying is vacuum-packed with an aluminum foil bag, and a pouch with Fe powder deoxidizer is put in the package by 1% (w/w);

(6) Refrigeration: Refrigerate and keep fresh at 1°C.

Comparative example 3: Using mugwort essential oil without high pressure osmotic treatment

(1) Picking: hand-picked mature pomegranates, and pay attention to avoid picking pomegranates with damaged shapes and wormholes;

(2), soaking and cleaning: immerse the pomegranate picked above in ultra-pure water, remove impurities and dust on the surface of the pomegranate, and then sonicate for 0.5h;

(3) Drain, air blowing and mixing treatment: keep the treated pomegranate away from light, drain quickly at a low temperature of 1°C, and then dry for 60 minutes at 40°C with a mesh-belt airflow dryer;

(4) Osmosis treatment: Add 10ml mugwort essential oil into the heating chamber, promote the volatilization of mugwort essential oil at a constant temperature of 100°C, and use a high-pressure pump to pump the volatilized mugwort gas into the high-pressure air chamber containing 100g pomegranate , the high-pressure chamber is not pressurized at this time, and the processing time is 30 minutes;

(5) Vacuum high-voltage electric field corona discharge treatment: spread the dried pomegranate on the metal plate, ensure the thickness of the tile after loading the sample is 40mm, the distance between the tip of the needle electrode and the metal plate is 90mm, and the high-voltage corona field strength is 150KV , carry out high-voltage electric field corona discharge treatment for 15 hours in a vacuum state, and ensure that the vacuum degree is 2000-2500Pa;

(6), vacuum packaging: vacuum-pack the pomegranate after drying with an aluminum foil bag, and put a pouch that is packed with Fe powder deoxidizer by 1% (w/w) in the package;

(7) Refrigeration: Refrigerate and keep fresh at 1°C.

Comparative Example 4: Processing without air blowing

(1) Picking: hand-picked mature pomegranates, and pay attention to avoid picking pomegranates with damaged shapes and wormholes;

(2), soaking and cleaning: immerse the pomegranate picked above in ultra-pure water, remove impurities and dust on the surface of the pomegranate, and then sonicate for 0.5h;

(3) Drain: quickly drain the treated pomegranate in the dark at a low temperature of 1°C;

(4) High-pressure osmosis treatment: Add mugwort essential oil into the heating chamber, promote the volatilization of mugwort essential oil at a constant temperature of 100°C, and use a high-pressure pump to pump the volatilized mugwort essential oil gas into the high-pressure air chamber equipped with pomegranate , and pressurize the high-pressure air chamber to ensure that the pressure in the high-pressure air chamber is 10MPa. At this time, the mugwort essential oil gas is in an approximate supercritical state with a density of 0.68-0.85g/cm ³ , and the processing time is 30min;

(5) Vacuum high-voltage electric field corona discharge treatment: spread the dried pomegranate on the metal plate, ensure the thickness of the tile after loading the sample is 40mm, the distance between the tip of the needle electrode and the metal plate is 90mm, and the high-voltage corona field strength is 150KV , carry out high-voltage electric field corona discharge treatment for 15 hours in a vacuum state, and ensure that the vacuum degree is 2000-2500Pa;

(6), vacuum packaging: vacuum-pack the pomegranate after drying with an aluminum foil bag, and put a pouch that is packed with Fe powder deoxidizer by 1% (w/w) in the package;

(7) Refrigeration: Refrigerate and keep fresh at 1°C.

After the pomegranates prepared in Examples 1-3 and Comparative Examples 1-4 were stored at 1°C for 30 days, each example randomly selected 3 samples to remove the aluminum foil packaging, and took samples to measure the rate of turning red, decay rate, and V _C of the 3 samples. , soluble sugar, insect repellent rate, odor and shelf life.

Table 1 Experimental results of relevant indicators in each case

Claims (7)

1. a kind of physical fresh-keeping method of pomegranate, it is characterised in that first using the argy wormwood essential oil gas pair of approximate supercriticality Fresh pomegranate carries out high-pressure osmosis process, then again to pomegranate use high voltage electric field Corona discharge Treatment, most after Jing vacuum packaging After refrigerate.

2. the physical fresh-keeping method of pomegranate as claimed in claim 1, it is characterised in that comprise the following steps：

(1), soaking and washing：Fresh pomegranate is immersed in ultra-pure water, the impurity and dust on pomegranate surface is removed, then ultrasound 0.5～1h；

(2), drain：Pomegranate after will be sonicated quickly drains under lucifuge, cryogenic conditions, is then charged into plenum chamber In；

(3), high-pressure osmosis are processed：Argy wormwood essential oil is added in heating chamber, in waving for 100-120 DEG C of promotion argy wormwood essential oil of constant temperature Send out, the argy wormwood essential oil gas of volatilization is pumped in the plenum chamber equipped with pomegranate using high-pressure pump, and plenum chamber is pressurizeed And 10～15MPa is maintained at, argy wormwood essential oil gas density is made up to 0.68～0.85g/cm³Approximate supercriticality, during process Between be 30～60min；

(4), vacuum high-pressure electric field Corona discharge Treatment：Pomegranate Jing after high-pressure osmosis process is loaded into high voltage electric field corona discharge In device, high voltage electric field Corona discharge Treatment is carried out under vacuum conditions；

(5) pomegranate of Jing outage piezoelectric field Corona discharge Treatments is vacuum-packed, is put into deoxidier, refrigerated under the conditions of 1～5 DEG C It is fresh-keeping.

3. the physical fresh-keeping method of pomegranate as claimed in claim 2, it is characterised in that in the step (2), it is described drain after Carry out air-flow and blow to mix process, with net belt type pneumatic drier under the conditions of 40～60 DEG C, be dried 60～90min.

4. the physical fresh-keeping method of pomegranate as claimed in claim 2 or claim 3, it is characterised in that in the step (2), when draining Cryogenic temperature is controlled for 1～20 DEG C.

5. the physical fresh-keeping method of pomegranate as claimed in claim 2, it is characterised in that in the step (4), controls high-tension electricity Intensity of having stage fright is 150～220KV, and process time is 15～22h.

6. the physical fresh-keeping method of the pomegranate as described in claim 2 or 5, it is characterised in that in step (4), controls vacuum In 2000～2500Pa.

7. the physical fresh-keeping method of the pomegranate as described in claim 2 or 5, it is characterised in that in the step (4), the height Piezoelectric field corona discharge assembly at least includes metallic plate and spray point, and the pomegranate maximum tiling thickness on a metal plate is 40 ～70mm, spray point is 90～120mm with metallic plate minimum range, and the spacing between spray point is 50-72mm.