CN106578037A - Physical preservation method of lotus seeds - Google Patents

Abstract

The invention discloses a physical fresh-keeping method for lotus seeds, which solves the problems of pest damage and low nutritional value of lotus seeds in the existing storage process. The technical solution is to refrigerate the fresh lotus seeds after soaking, cleaning, draining, high-pressure infiltration treatment, vacuum high-voltage electric field corona discharge treatment and vacuum packaging. state, has a strong penetration ability, can penetrate into the lotus seeds, 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 preservation period of the lotus seeds 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 lotus seeds

technical field

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

Background technique

Lotus seed is the seed of lotus, an aquatic herbaceous plant of Nymphaeaceae. The content of calcium, phosphorus and potassium in lotus seeds is very rich. Each kilogram of lotus seeds contains 81.3 grams of protein, 9.8 grams of fat, 304 mg of sugar, 436 mg of calcium, 1.397 mg of phosphorus, 31.4 mg of iron, and other vitamins and trace elements Nuciferine, hypericin, lotus seeds and other substances, in addition to the components that can form bones and teeth, also have the effect of promoting blood coagulation, activating certain enzymes, maintaining nerve conduction, calming nerves, maintaining muscle elasticity and heartbeat Rhythm etc. Modern pharmacological research has also confirmed that lotus seeds have various effects such as calming, strengthening the heart, and anti-aging. Lotus seeds are very nutritious. In addition to containing a large amount of starch, they also contain β-sitosterol, alkaloids, calcium, phosphorus, iron and other minerals and vitamins. Every 100 grams of lotus seeds contains 89 mg of calcium and 285 mg of phosphorus. Although the potassium element is less than 2.1 mg, it ranks first among all animal and plant foods.

Nowadays, according to the nutritional characteristics of lotus seeds, relevant researchers have developed a variety of fresh-keeping methods for lotus seeds, such as: Chinese Patent Application No. CN201210376136.3 "A Method for Preserving the Color of Lotus Seeds", Lotus seed fresh-keeping processing and packaging technology", etc. The content of the research is to use the method of soaking with chemical substances to keep fresh. However, chemical substance immersion treatment inevitably has food safety hazards.

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 lotus seeds 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 for lotus seeds of the present invention is as follows: firstly use the mugwort essential oil gas in an approximate supercritical state to perform high-pressure osmosis treatment on the peeled fresh lotus seeds, then use high-voltage electric field corona discharge treatment on the lotus seeds, and finally refrigerate after vacuum packaging.

Specifically include the following steps:

(1) Soaking and cleaning: immerse fresh lotus seeds in ultra-pure water to remove impurities and dust on the surface of lotus seeds, and then sonicate for 1 to 1.5 hours;

(2), draining: the lotus seeds after the ultrasonic treatment are quickly drained under the condition of avoiding light and low temperature, and then packed into the 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 gas tank containing lotus seeds. In the chamber, pressurize the high-pressure air chamber and keep it at 12-16MPa, 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 20-40min;

(4), vacuum high-voltage electric field corona discharge treatment: the lotus seeds after high-voltage penetration treatment are packed into 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 lotus seeds treated by corona discharge in an empty high-voltage electric field, put in a deoxidizer, and refrigerate and keep fresh at 1-5°C.

In the step (2), after the draining, carry out air blowing and mixing treatment, and dry for 40 to 60 minutes with a mesh belt air dryer at 50 to 80°C;

In the step (2), when draining, the low temperature is controlled to be 10-20°C.

In the step (4), the intensity of the high-voltage corona field is controlled to be 80-160KV, and the treatment time is 13-18 hours.

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 lotus seeds on the metal plate is 10-25 mm, and the minimum distance between the discharge needle and the metal plate is 45 mm. ~65mm, the distance between the discharge needles is 40-45mm.

Aiming at the problems existing in the background technology, the inventor conducted in-depth research on the physical fresh-keeping method of lotus seeds, 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 is also found that it is difficult to make the mugwort essential oil penetrate into the inside of the lotus seeds 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 lotus seeds, excellent antibacterial and insecticidal effects are obtained.

The mugwort is highly volatile, because the irritating taste will remain on the lotus seeds, which will affect the mouthfeel and fragrance of the lotus seeds. For this problem, the inventor carried out vacuum high-voltage electric field corona discharge treatment on the lotus seeds, and used the corona discharge process to treat the lotus seeds. The ion beam generated in the air increases the energy of the mugwort gas molecules remaining in the lotus seeds, causing the hydrogen bonds between the chain molecular groups to break, 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 lotus seeds. 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 of lotus seed products in the process of 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 20-45 minutes, and the high-pressure penetration time should not be too long, but the lotus seeds must be fully in contact with the supercritical mugwort gas with strong penetrating power, and penetrate deep into the lotus seeds 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 lotus seeds and further inhibit the growth of microorganisms on the surface of lotus seeds. Drying under the condition of 40-60 minutes, 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 surface of lotus seeds 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 lotus seed surface; the selected time should not be too short, because too short time is not conducive to the drying of the lotus seed surface, and it is preferable to control the water content of the lotus seed to below 5%.

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 lotus seeds are placed on the metal plate. The maximum tile thickness on the plate is preferably 10-25 mm, the distance between the discharge needles is 45-65 mm, and the minimum distance between the tip of the discharge needle and the metal plate is preferably 40-45 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. 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 90-160KV. 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 lotus seeds. However, if the high-voltage corona field intensity is below 90KV, 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 lotus seeds, 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 break the molecular structure of the volatile components in the Artemisia argyi, and also have a significant killing effect on the insect eggs in the lotus seeds. 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 lotus seeds prepared by the method of the present invention can be refrigerated and kept fresh for more than 110 days at 1-5° C., and 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), raw material pretreatment: peel off the fresh lotus seeds from the lotus pod, remove the skin of the lotus seeds, and manually remove the lotus seeds with wormholes and mildew;

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

(3), draining, air-flow blowing and mixing treatment: the red dates after the treatment are kept away from light and drained quickly at a low temperature of 10°C, and then dried for 40min 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 100°C, and use a high-pressure pump to pump the volatilized mugwort essential oil gas into the high-pressure air chamber containing lotus seeds , and pressurize the high-pressure gas chamber to ensure that the pressure in the high-pressure gas chamber is at 12MPa. 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 20min;

(5) Vacuum high-voltage electric field corona discharge treatment: put the lotus seeds into the high-voltage electric field corona discharge device and spread them on the metal plate, ensure that the thickness of the tiles after loading the sample is 10mm, and the distance between the tip of the needle electrode and the metal plate is 45mm. The high-voltage corona field strength is 80KV, and the high-voltage electric field corona discharge treatment is carried out in a vacuum state for 13 hours. During the high-voltage electric field corona discharge treatment, vacuum treatment is carried out to ensure that the vacuum degree is 2000-2500Pa;

(6), vacuum packing: the dried lotus seeds are vacuum-packed in an aluminum foil bag, and a pouch with Fe powder deoxidizer is put in the packing by 1% (w/w);

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

Example 2

(1), raw material pretreatment: peel off the fresh lotus seeds from the lotus pod, remove the skin of the lotus seeds, and manually remove the lotus seeds with wormholes and mildew;

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

(3), draining, air-flow blowing and mixing treatment: the red dates after the treatment are kept away from light and drained quickly at a low temperature of 20°C, and then dried for 60min at 80°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 120°C, and use a high-pressure pump to pump the volatilized mugwort essential oil gas into the high-pressure air chamber containing lotus seeds , and pressurize the high-pressure gas chamber to ensure that the pressure in the high-pressure gas chamber is at 16MPa. At this time, the gas of mugwort essential oil is in an approximate supercritical state with a density of 0.68-0.85g/cm ³ , and the processing time is 40min;

(5) Vacuum high-voltage electric field corona discharge treatment: put the lotus seeds on the metal plate in the high-voltage electric field corona discharge device in the vacuum chamber, ensure that the tile thickness after sample loading is 25mm, and the distance between the tip of the needle electrode and the metal plate is 65mm. The high-voltage corona field strength is 160KV, and the high-voltage electric field corona discharge treatment is carried out in a vacuum state for 18 hours to ensure that the vacuum degree is 2000-2500Pa;

(6), vacuum packing: the dried lotus seeds are vacuum-packed in an aluminum foil bag, and a pouch with Fe powder deoxidizer is put in the packing by 1% (w/w);

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

Example 3

(1), raw material pretreatment: peel off the fresh lotus seeds from the lotus pod, remove the skin of the lotus seeds, and manually remove the lotus seeds with wormholes and mildew;

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

(3), draining, air blowing and mixing treatment: the treated lotus seeds are quickly drained at a low temperature of 15°C in the dark, and then dried for 50min at 65°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 containing lotus seeds , and pressurize the high-pressure gas chamber to ensure that the pressure in the high-pressure gas chamber is 14MPa. 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 processing time is 30 minutes;

(5), vacuum high-voltage electric field corona discharge treatment: put the lotus seeds on the metal plate in the high-voltage electric field corona discharge device, ensure that the tile thickness after loading is 18mm, and the distance between the tip of the needle electrode and the metal plate is 55mm. The halo field intensity is 130KV, and the high-voltage electric field corona discharge treatment is carried out in a vacuum state for 15 hours to ensure that the vacuum degree is 2000-2500Pa;

(6), vacuum packing: the dried lotus seeds are vacuum-packed in an aluminum foil bag, and a pouch with Fe powder deoxidizer is put in the packing by 1% (w/w);

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

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

(1), raw material pretreatment: peel off the fresh lotus seeds from the lotus pod, remove the skin of the lotus seeds, and manually remove the lotus seeds with wormholes and mildew;

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

(3), draining, air blowing and mixing treatment: the treated lotus seeds are quickly drained at a low temperature of 10°C in the dark, and then dried for 40min at 50°C with a mesh belt type airflow dryer;

(4), high-pressure infiltration treatment: 100g lotus seeds are packed in the high-pressure air chamber, and pressurize the high-pressure air chamber to ensure that the pressure in the high-pressure air chamber is at 12MPa, and the treatment time is 20min;

(5), vacuum high-voltage electric field corona discharge treatment: put the lotus seeds on the metal plate in the high-voltage electric field corona discharge device, ensure that the tile thickness after loading is 10mm, and the distance between the tip of the needle electrode and the metal plate is 45mm. The halo field intensity is 80KV, and the high-voltage electric field corona discharge treatment is carried out in a vacuum state for 13 hours to ensure that the vacuum degree is 2000-2500Pa;

(6), vacuum packing: the dried lotus seeds are vacuum-packed in an aluminum foil bag, and a pouch with Fe powder deoxidizer is put in the packing by 1% (w/w);

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

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

(1), raw material pretreatment: peel off the fresh lotus seeds from the lotus pod, remove the skin of the lotus seeds, and manually remove the lotus seeds with wormholes and mildew;

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

(3), draining, air blowing and mixing treatment: the treated lotus seeds are quickly drained at a low temperature of 10°C in the dark, and then dried for 40min 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 100°C, and use a high-pressure pump to pump the volatilized mugwort essential oil gas into the high-pressure air chamber containing lotus seeds , and pressurize the high-pressure gas chamber to ensure that the pressure in the high-pressure gas chamber is at 12MPa. 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 20min;

(5), vacuum packing: the dried lotus seeds are vacuum-packed in an aluminum foil bag, and a pouch with Fe powder deoxidizer is put in the packing 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), raw material pretreatment: peel off the fresh lotus seeds from the lotus pod, remove the skin of the lotus seeds, and manually remove the lotus seeds with wormholes and mildew;

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

(3), draining, air-flow blowing and mixing treatment: the red dates after the treatment are kept away from light and drained quickly at a low temperature of 10°C, and then dried for 40min at 50°C with a mesh belt type 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, use a high-pressure pump to pump the volatilized mugwort gas into the high-pressure air chamber containing 100g lotus seeds , the high-pressure chamber is not pressurized at this time, and the processing time is 20 minutes;

(5) Vacuum high-voltage electric field corona discharge treatment: put the lotus seeds into the high-voltage electric field corona discharge device and spread them on the metal plate, ensure that the thickness of the tiles after loading the sample is 10mm, and the distance between the tip of the needle electrode and the metal plate is 45mm. The high-voltage corona field strength is 80KV, and the high-voltage electric field corona discharge treatment is carried out in a vacuum state for 13 hours. During the high-voltage electric field corona discharge treatment, vacuum treatment is carried out to ensure that the vacuum degree is 2000-2500Pa;

(6), vacuum packing: the dried lotus seeds are vacuum-packed in an aluminum foil bag, and a pouch with Fe powder deoxidizer is put in the packing by 1% (w/w);

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

Comparative Example 4: Processing without air blowing

(1), raw material pretreatment: peel off the fresh lotus seeds from the lotus pod, remove the skin of the lotus seeds, and manually remove the lotus seeds with wormholes and mildew;

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

(3), draining: drain the treated lotus seeds quickly at a low temperature of 10°C in the dark;

(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 containing lotus seeds , and pressurize the high-pressure gas chamber to ensure that the pressure in the high-pressure gas chamber is at 12MPa. 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 20min;

(5), vacuum high-voltage electric field corona discharge treatment: put the lotus seeds on the metal plate in the high-voltage electric field corona discharge device, ensure that the tile thickness after loading is 10mm, and the distance between the tip of the needle electrode and the metal plate is 45mm. The halo field intensity is 80KV, and the high-voltage electric field corona discharge treatment is carried out in a vacuum state for 13 hours to ensure that the vacuum degree is 2000-2500Pa;

(6), vacuum packing: the dried lotus seeds are vacuum-packed in an aluminum foil bag, and a pouch with Fe powder deoxidizer is put in the packing by 1% (w/w);

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

After the lotus seeds 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 browning degree, protein, total fat, Total sugar, insect repellent rate, and shelf life.

Table 1 Experimental results of relevant indicators in each case

Claims (7)

1. a physical fresh-keeping method of lotus seeds is characterized in that, first use the mugwort essential oil gas of approximate supercritical state to carry out high-pressure osmosis treatment to the fresh lotus seeds of peeling, then use high-voltage electric field corona discharge treatment to lotus seeds, finally pass through Refrigerate after vacuum packing. 2. the physical preservation method of lotus seeds as claimed in claim 1, is characterized in that, comprises the following steps: (1) Soaking and cleaning: immerse fresh lotus seeds in ultra-pure water to remove impurities and dust on the surface of lotus seeds, and then sonicate for 1 to 1.5 hours; (2), draining: the lotus seeds after the ultrasonic treatment are quickly drained under the condition of avoiding light and low temperature, and then packed into the 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 gas tank containing lotus seeds. In the chamber, pressurize the high-pressure air chamber and keep it at 12-16MPa, 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 20-40min; (4), vacuum high-voltage electric field corona discharge treatment: the lotus seeds after high-voltage penetration treatment are packed into 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 lotus seeds treated by corona discharge in an empty high-voltage electric field, put in a deoxidizer, and refrigerate and keep fresh at 1-5°C. 3. The physical fresh-keeping method of lotus seeds as claimed in claim 2 is characterized in that, in said step (2), after said draining, carry out air-flow blowing and mixing treatment, use mesh belt type air-flow drier at 50～80 ℃ Conditions, dry 40 ~ 60min. 4. The physical fresh-keeping method of lotus seeds according to claim 2 or 3, characterized in that, in the step (2), when draining, the low temperature is controlled to be 10-20°C. The physical fresh-keeping method for lotus seeds according to claim 2, characterized in that, in the step (4), the intensity of the high-voltage corona field is controlled to be 80-160KV, and the treatment time is 13-18h. 6. The physical preservation method for lotus seeds according to claim 2 or 5, characterized in that, in step (4), the degree of vacuum is controlled at 2000-2500Pa. 7. the physical fresh-keeping method of lotus seed as claimed in claim 2 or 5 is characterized in that, in described step (4), described high-voltage electric field corona discharge device comprises metal plate and discharge needle at least, and described lotus seed is placed on metal The maximum tile thickness on the board is 10-25mm, the minimum distance between the discharge needles and the metal plate is 45-65mm, and the distance between the discharge needles is 40-45mm.