CN106578045B - A kind of physical preservation method of chestnut - Google Patents

Abstract

The invention discloses a physical fresh-keeping method for chestnuts, which solves the problems of insect pests and low nutritional value of chestnuts in the existing storage process. The technical scheme is to refrigerate the fresh chestnuts after soaking and cleaning, draining, high-pressure infiltration treatment, vacuum high-voltage electric field corona discharge treatment and vacuum packaging. It has a strong penetrating ability and can penetrate into the chestnut to play an effective bacteriostatic and insecticidal effect. Through the vacuum high-voltage electric field corona discharge treatment, the molecular structure of the volatile components in the mugwort is broken, and the odor is further removed. The preservation period of the chestnut after the above treatment has been greatly improved, and the color, aroma and taste are all good.

Description

A kind of physical preservation method of chestnut

technical field

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

Background technique

Chestnut (scientific name: Castanea mollissima), also known as chestnut, chestnut, chestnut, wind wax, is a plant of the Fagaceae Chestnut genus, more common in mountainous areas, and has been widely cultivated by artificial. Chestnut has high nutritional value, sweet and fragrant, containing starch 51-60%, protein 5.7-10.7%, fat 2-7.4%, sugar, starch, crude fiber, carotene, vitamin A, B ₁ , B ₂ , C and calcium , phosphorus, potassium and other minerals, the nutrients that can be absorbed and utilized by the human body are as high as 98%. Calculated in ten grains, the calories are 204 calories and the fat content is less than 1 gram, which is the lowest fat content among shell fruits. Chestnut, also known as chestnut, is a health product that nourishes and cures diseases. Traditional Chinese medicine believes that chestnuts are sweet and warm in nature, and have the functions of nourishing the stomach and spleen, strengthening the kidneys and waist, strengthening the muscles and promoting blood circulation, stopping bleeding and reducing swelling. At the same time, chestnuts have a good prevention and treatment effect on hypertension, coronary heart disease, atherosclerosis, etc. The elderly often eat chestnuts, which is of great benefit to fight aging, prevent aging, and prolong life.

Nowadays, according to the nutritional characteristics of chestnut, relevant researchers have developed a variety of chestnut preservation methods, such as: Chinese patent application number CN201410796407.X "a kind of preservative for storing fresh chestnut", Chinese patent application number CN201410447773.4 "A processing method of instant chestnut" and so on. The research content is the use of chemical soaking treatment to preserve freshness. However, the chemical soaking treatment inevitably has food safety problems.

SUMMARY OF THE INVENTION

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

The physical preservation method of the chestnut of the present invention is as follows: firstly, the fresh chestnut is subjected to high-pressure infiltration treatment with mugwort essential oil gas in an approximate supercritical state, then the chestnut is treated with a high-voltage electric field corona discharge, and finally, the chestnut is vacuum-packed and then refrigerated.

Specifically include the following steps:

(1) Immersion cleaning: Immerse fresh chestnuts in ultrapure water to remove impurities and dust on the surface of chestnuts, and then ultrasonicate for 1 to 1.5 hours;

(2), drain: the chestnut after the ultrasonic treatment is drained quickly under lucifuge, low temperature conditions, and is then loaded into the high-pressure air chamber;

(3), high pressure osmosis treatment: add mugwort essential oil to the heating chamber, promote the volatilization of mugwort essential oil at a constant temperature of 100-120 ℃, and use a high-pressure pump to pump the volatilized mugwort essential oil gas into a high-pressure gas containing chestnut In the chamber, pressurize the high-pressure air chamber and keep it at 8.8-12MPa, so that the gas density of mugwort essential oil reaches the approximate supercritical state of 0.68-0.85g/ ^cm3 , and the treatment time is 50-80min;

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

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

In the step (2), after the draining, air blowing and stirring treatment is performed, and drying is performed for 30 to 50 minutes at 30 to 50° C. with a mesh belt air dryer.

In the step (2), the low temperature is controlled to be 1-10° C. when draining.

In the step (4), the high-voltage corona field intensity is controlled to be 90-150KV, and the treatment time is 12-18h.

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 thickness of the chestnut on the metal plate is 15-30 mm, and the minimum distance between the discharge needle and the metal plate is 60 mm. ~80mm, the spacing between the discharge needles is 60 ~ 75mm. In view of the problems existing in the background technology, the inventor carried out in-depth research on the physical preservation method of chestnut, selected mugwort among many natural insecticidal plants, and used the volatilization of mugwort essential oil to play an antibacterial and insecticidal effect. It was also found that, due to the thick skin of chestnut, it was difficult to penetrate the essential oil of mugwort into the chestnut by ordinary methods such as fumigation or soaking. In order to solve the above-mentioned problems, the inventor first uses a constant temperature environment to promote the volatilization of mugwort essential oil, and then makes the volatilized mugwort gas to be in an approximate supercritical state under high pressure conditions, so that it has a very strong penetrating ability, so that it can penetrate To the inside of the chestnut, excellent antibacterial and insecticidal effect can be obtained, so the pre-treatment stage of the chestnut can be peeled or not.

The mugwort has strong volatility, because it will also leave a pungent taste on the chestnut, which affects the taste and aroma of the chestnut. For this problem, the inventor carried out a vacuum high-voltage electric field corona discharge treatment on the chestnut, using the corona discharge process. The ion beam generated in the wormwood increases the energy of the mugwort gas molecules remaining in the chestnut, 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 eggs in the chestnut. In the vacuuming environment, on the one hand, the effect of the high-voltage corona field can be strengthened, and the odor can be further removed, and various problems caused by the use of mugwort essential oil can be completely solved.

The selected temperature to promote the volatilization of mugwort essential oil is preferably 100-120 °C, and the temperature should not be too high to avoid adverse chemical reactions of mugwort essential oil due to high temperature; The pressure capacity puts forward higher requirements, and it will increase the loss of nutrients in chestnut products during the high-pressure osmosis treatment process. If it is too low, the gas density of mugwort essential oil cannot reach a near supercritical state with a gas density of 0.68-0.85g/ ^cm3 ; the selected The high-pressure infiltration time is 50-80 minutes, and the high-pressure infiltration time should not be too long, but it should meet the requirement of full contact between the chestnut and the near-supercritical mugwort gas with extremely strong permeability, penetrate the deep layer of the chestnut, and ensure the insecticidal and bacteriostatic effect.

Further, preferably after step (2) is drained and then subjected to airflow stirring treatment to reduce the water content of the chestnut surface, further inhibit the growth of microorganisms on the chestnut surface, preferably control the airflow stirring treatment temperature is 40～60 ℃, and the time is Drying under the conditions of 40-60min, the temperature selection is too high will not only cause the destruction of heat-sensitive nutrients, but also select a higher temperature chestnut surface to meet the needs of external moisture evaporation, the internal moisture will accelerate to the surface, easily lead to the soluble carried The ingredients are precipitated on the surface, resulting in the hardening of the chestnut surface; the selected time should not be too short, which is not conducive to the drying of the chestnut surface, and it is preferable to control the chestnut moisture content to below 15%.

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.), at least including a metal plate and a vertical downward discharge needle above the metal plate, and the chestnut is on the metal plate. The maximum tiling thickness on the plate is preferably 15-30 mm, the distance between the discharge needles is 60-75 mm, and the minimum distance between the tip of the discharge needle and the metal plate is preferably 60-80 mm. The selected maximum tiling thickness and the distance between the tip of the discharge needle and the metal plate should not be too large, because the excessively large distance will not kill the eggs well, and also prolong the time of high-voltage electric field corona discharge treatment; high The intensity of the piezoelectric corona field is 90-160KV, and the high-voltage electric field corona discharge intensity is too high, which will put forward higher requirements on production conditions, and will also have an adverse effect on the quality of the chestnut, but the high-voltage corona field intensity is below 90KV, killing The effect of killing 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 chestnuts, while too short time will affect the effect of killing eggs;

Beneficial effects:

(1) The whole process does not use chemical substances for soaking treatment, which avoids the potential food safety problems caused by chemical substances. (2) In the process of high pressure infiltration, making mugwort essential oil in a near supercritical state can play a more significant antibacterial and insecticidal effect than simply using mugwort essential oil fumigation. (3) The ion beam generated in the process of corona discharge is used to break the molecular structure of volatile components in mugwort, and also has a significant killing effect on the eggs in the chestnut. In the process of corona discharge, the temperature of the material will not be raised, and at the same time, combined with the vacuuming environment, the problem of the final product odor caused by the residue of mugwort gas is also solved. (4) The chestnut prepared by the method of the present invention can be refrigerated and kept fresh for more than 70 days under the condition of 1-5° C. The color, taste, smell and nutritional value of the chestnut are effectively guaranteed, and the chestnut has a broad market application prospect.

Detailed ways

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

Example 1

(1), immersion cleaning: immerse the fresh chestnut in ultrapure water to remove impurities and dust on the surface of the chestnut, and then ultrasonicate for 1h;

(2), draining, air blowing and stirring treatment: the treated chestnut was quickly drained in the dark at a low temperature of 1 °C, and then dried for 30 minutes at 30 °C with a mesh belt air dryer;

(3), high pressure osmosis treatment: add mugwort essential oil to 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 chestnut , and pressurize the high-pressure air chamber to ensure that the pressure in the high-pressure air chamber is 8.8MPa. At this time, the essential oil gas of mugwort is in an approximate supercritical state with a density of 0.68-0.85g/ ^cm3 , and the processing time is 50min;

(4), vacuum high-voltage electric field corona discharge treatment: put the chestnut into the metal plate in the high-voltage electric field corona discharge device, ensure that the thickness of the tile after loading is 15mm, the distance between the needle electrode tip and the metal plate is 60mm, and the high-voltage electric field The intensity of the corona field is 90KV, and the high-voltage electric field corona discharge treatment is carried out for 12h in a vacuum state to ensure that the vacuum degree is 2000-2500Pa;

(5), vacuum packaging: the dried chestnut is vacuum-packed with an aluminum foil bag, and a small bag packed with Fe powder deoxidizer is placed in the package by 1% (w/w);

(6) Refrigeration: refrigerate at 1°C for freshness.

Example 2

(1), raw material pretreatment: utilize the chestnut peeling machine, peel off the shell and inner skin of the chestnut, and manually remove the chestnut with worm holes and mildew;

(2), immersion cleaning: the above-mentioned chestnut is immersed in ultrapure water to remove impurities and dust on the chestnut surface, and then ultrasonic for 1h;

(3), draining, air blowing and stirring treatment: the treated chestnut was quickly drained in the dark at a low temperature of 10 ° C, and then dried for 50 min under the condition of 50 ° C with a mesh belt air dryer;

(4), high pressure osmosis treatment: add mugwort essential oil to 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 chestnut , and pressurize the high-pressure air chamber to ensure that the pressure in the high-pressure air chamber is 12MPa. At this time, the essential oil gas of mugwort is in an approximate supercritical state with a density of 0.68-0.85g/ ^cm3 , and the treatment time is 80min;

(5) Vacuum high-voltage electric field corona discharge treatment: Spread the dried chestnut on the metal plate to ensure that the thickness of the tile after loading is 30mm, the distance between the needle electrode tip and the metal plate is 80mm, and the high-voltage corona field strength is 150KV, carry out high-voltage electric field corona discharge treatment for 18h in a vacuum state to ensure that the vacuum degree is 2000-2500Pa;

(6), vacuum packaging: the dried chestnut is vacuum-packed with an aluminum foil bag, and a small bag packed with Fe powder deoxidizer is placed in the package by 1% (w/w);

(7) Refrigeration: refrigerate at 1°C for freshness.

Example 3

(1), raw material pretreatment: utilize the chestnut peeling machine, peel off the shell and inner skin of the chestnut, and manually remove the chestnut with worm holes and mildew;

(2), immersion cleaning: the above-mentioned chestnut is immersed in ultrapure water to remove impurities and dust on the chestnut surface, and then ultrasonic for 1h;

(3), draining, air blowing and stirring treatment: the treated chestnut was quickly drained in the dark at a low temperature of 5 ° C, and then dried for 40 min under the condition of 40 ° 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 110 ° C, and use a high-pressure pump to pump the volatilized mugwort essential oil gas into the high-pressure air chamber equipped with chestnut , and pressurize the high-pressure air chamber to ensure that the pressure in the high-pressure air chamber is 10MPa. At this time, the gas of mugwort essential oil is in an approximate supercritical state with a density of 0.68-0.85g/ ^cm3 , and the treatment time is 65min;

(5) Vacuum high-voltage electric field corona discharge treatment: Spread the dried chestnut on the metal plate to ensure that the thickness of the tile after loading is 20mm, the distance between the needle electrode tip and the metal plate is 70mm, and the high-voltage corona field strength is 130KV, high-voltage electric field corona discharge treatment for 15h in a vacuum state to ensure that the vacuum degree is 2000-2500Pa;

(6), vacuum packaging: the dried chestnut is vacuum-packed with an aluminum foil bag, and a small bag packed with Fe powder deoxidizer is placed in the package by 1% (w/w);

(7) Refrigeration: refrigerate at 1°C for freshness.

Comparative example 1: No mugwort essential oil added in high pressure osmosis

(1), raw material pretreatment: utilize the chestnut peeling machine, peel off the shell and inner skin of the chestnut, and manually remove the chestnut with worm holes and mildew;

(2), immersion cleaning: the above-mentioned chestnut is immersed in ultrapure water to remove impurities and dust on the chestnut surface, and then ultrasonic for 1h;

(3), draining, air blowing and stirring treatment: the treated chestnut was quickly drained in the dark at a low temperature of 1 °C, and then dried for 30 min at 30 °C with a mesh belt air dryer;

(4), high pressure infiltration treatment: 100g chestnuts are loaded into the high pressure air chamber, and the high pressure air chamber is pressurized to ensure that the pressure in the high pressure air chamber is 8.8MPa, and the treatment time is 50min;

(5) Vacuum high-voltage electric field corona discharge treatment: Spread the dried chestnut on the metal plate to ensure that the thickness of the tile after loading is 15mm, the distance between the needle electrode tip and the metal plate is 60mm, and the high-voltage corona field strength is 90KV, carry out high-voltage electric field corona discharge treatment for 12h in a vacuum state to ensure that the vacuum degree is 2000-2500Pa;

(6), vacuum packaging: the dried chestnut is vacuum-packed with an aluminum foil bag, and a small bag packed with Fe powder deoxidizer is placed in the package by 1% (w/w);

(7) Refrigeration: refrigerate at 1°C for freshness.

Comparative Example 2: Corona Discharge Treatment without Vacuum High Voltage Electric Field

(1), raw material pretreatment: utilize the chestnut peeling machine, peel off the shell and inner skin of the chestnut, and manually remove the chestnut with worm holes and mildew;

(2), immersion cleaning: the above-mentioned chestnut is immersed in ultrapure water to remove impurities and dust on the chestnut surface, and then ultrasonic for 1h;

(3), draining, air blowing and stirring treatment: the treated chestnut was quickly drained in the dark at a low temperature of 1 °C, and then dried for 30 min at 30 °C with a mesh belt air dryer;

(4), high pressure osmosis treatment: add mugwort essential oil to 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 chestnut , and pressurize the high-pressure air chamber to ensure that the pressure in the high-pressure air chamber is 8.8MPa. At this time, the essential oil gas of mugwort is in an approximate supercritical state with a density of 0.68-0.85g/ ^cm3 , and the processing time is 50min;

(5), vacuum packaging: the dried red dates are vacuum-packed with an aluminum foil bag, and a small bag with Fe powder deoxidizer is placed in the package at 1% (w/w);

(6) Refrigeration: refrigerate at 1°C for freshness.

Comparative Example 3: Use of mugwort essential oil without high pressure osmotic treatment

(1), raw material pretreatment: utilize the chestnut peeling machine, peel off the shell and inner skin of the chestnut, and manually remove the chestnut with worm holes and mildew;

(2), immersion cleaning: the above-mentioned chestnut is immersed in ultrapure water to remove impurities and dust on the chestnut surface, and then ultrasonic for 1h;

(3), draining, air blowing and stirring treatment: the treated chestnut was quickly drained in the dark at a low temperature of 1 °C, and then dried for 30 min at 30 °C with a mesh belt air dryer;

(4), osmotic treatment: add 10ml mugwort essential oil to 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 a high-pressure air chamber equipped with 100g of Chinese chestnut , the high-pressure air chamber is not pressurized at this time, and the processing time is 50min;

(5), vacuum high-voltage electric field corona discharge treatment: put the chestnut into the metal plate in the high-voltage electric field corona discharge device, ensure that the tile thickness after loading is 15mm, the distance between the needle electrode tip and the metal plate is 60mm, and the high-voltage electric field The intensity of the corona field is 90KV, and the high-voltage electric field corona discharge treatment is carried out for 12h in a vacuum state to ensure that the vacuum degree is 2000-2500Pa;

(6), vacuum packaging: the dried chestnut is vacuum-packed with an aluminum foil bag, and a small bag packed with Fe powder deoxidizer is placed in the package by 1% (w/w);

(7) Refrigeration: refrigerate at 1°C for freshness.

Comparative Example 4: Treatment without air blowing

(1), raw material pretreatment: utilize the chestnut peeling machine, peel off the shell and inner skin of the chestnut, and manually remove the chestnut with worm holes and mildew;

(2), immersion cleaning: the above-mentioned chestnut is immersed in ultrapure water to remove impurities and dust on the chestnut surface, and then ultrasonic for 1h;

(3), Drain: Drain the processed chestnuts quickly 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 chestnut , and pressurize the high-pressure air chamber to ensure that the pressure in the high-pressure air chamber is 8.8MPa. At this time, the essential oil gas of mugwort is in an approximate supercritical state with a density of 0.68-0.85g/ ^cm3 , and the processing time is 50min;

(5) Vacuum high-voltage electric field corona discharge treatment: Spread the dried chestnut on the metal plate to ensure that the thickness of the tile after loading is 15mm, the distance between the needle electrode tip and the metal plate is 60mm, and the high-voltage corona field strength is 90KV, carry out high-voltage electric field corona discharge treatment for 12h in a vacuum state to ensure that the vacuum degree is 2000-2500Pa;

(6), vacuum packaging: the dried red dates are vacuum-packed with an aluminum foil bag, and a small bag with Fe powder deoxidizer is placed in the package at 1% (w/w);

(7) Refrigeration: refrigerate at 1°C for freshness.

After the chestnuts prepared in Examples 1-3 and Comparative Examples 1-4 were stored at 1°C for 30 days, 3 samples were randomly selected for each example to remove the aluminum foil packaging, and 3 samples were sampled to measure the degree of browning, protein, total fat, Total sugar, repellency, odor and shelf life.

Table 1 The experimental results of the relevant indicators of each shelled chestnut case

Claims (4)

1. a physical preservation method of Chinese chestnut, is characterized in that, Include the following steps: (1) Immersion cleaning: Immerse fresh chestnuts in ultrapure water to remove impurities and dust on the surface of chestnuts, and then ultrasonicate for 1 to 1.5 hours; (2), drain: the chestnut after the ultrasonic treatment is drained quickly under lucifuge, low temperature conditions, and is then loaded into the high-pressure air chamber; (3), high pressure osmosis treatment: add mugwort essential oil to the heating chamber, promote the volatilization of mugwort essential oil at a constant temperature of 100-120 ℃, and use a high-pressure pump to pump the volatilized mugwort essential oil gas into a high-pressure gas containing chestnut In the chamber, pressurize the high-pressure air chamber and keep it at 8.8-12MPa, so that the gas density of mugwort essential oil reaches the approximate supercritical state of 0.68-0.85g/ ^cm3 , and the treatment time is 50-80min; (4), vacuum high-voltage electric field corona discharge treatment: the chestnut after high-voltage infiltration treatment is loaded into the high-voltage electric field corona discharge device, and the high-voltage electric field corona discharge treatment is carried out in a vacuum state, and the high-voltage corona field intensity is controlled to be 90～150KV, treatment time is 12～18h, vacuum degree is 2000～2500Pa; (5) Vacuum-pack the chestnuts treated by vacuum high-voltage electric field corona discharge, put in a deoxidizer, and refrigerate and keep fresh at 1-5°C. 2. the physical preservation method of chestnut as claimed in claim 1, is characterized in that, in described step (2), after described draining, carry out air-flow stirring treatment, with mesh belt type air-flow dryer at 30～50 ℃ Under conditions, dry for 30 to 50 minutes. 3. The physical preservation method of chestnut as claimed in claim 1 or 2, characterized in that, in the step (2), the controlled low temperature temperature is 1～10 ℃ when draining. 4. the physical preservation method of chestnut as claimed in claim 1, is characterized in that, in described step (4), described high voltage electric field corona discharge device comprises metal plate and discharge needle at least, described chestnut is on metal plate The maximum tiling thickness is 15-30mm, the minimum distance between the discharge needle and the metal plate is 60-80mm, and the distance between the discharge needles is 60-75mm.