CN106720300A - A kind of physical fresh-keeping method of iblet - Google Patents

Abstract

The invention discloses a physical fresh-keeping method for corn kernels, which solves the problems of pest damage and low nutritional value of corn kernels in the existing storage process. The technical solution is to refrigerate the fresh corn kernels after soaking, cleaning, draining, high-pressure infiltration treatment, vacuum high-voltage electric field corona discharge treatment and vacuum packaging. Critical state, with strong penetrating ability, can penetrate into the inside of corn kernels, and play an effective antibacterial and insecticidal role. Through vacuum high-voltage electric field corona discharge treatment, the molecular structure of volatile components in mugwort can be broken and further removed. After the above treatment, the storage period of the corn kernels has been greatly improved, and the color, aroma and taste are all good.

Description

A kind of physical preservation method of corn grain

technical field

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

Background technique

Corn (scientific name: Zea mays) is an important food crop and an important source of feed, and it is also the food crop with the highest total output in the world. Although the nutritional value of corn is lower than that of other grains, isomaltooligosaccharides can be extracted from corn. Isomaltooligosaccharides are the best among prebiotics. Prebiotics are the food of probiotics and have a close relationship with the growth of probiotics in the human body. relationship, so as to achieve a balanced state of intestinal flora and make the intestinal tract healthy. In addition to eating, corn is also the main raw material for industrial alcohol and shochu. With the growth of China's corn processing industry and the expansion of the corn industry chain, the market size of the corn deep processing industry will increase significantly, and its potential will be huge.

Nowadays, according to the nutritional characteristics of corn, relevant researchers have developed a variety of corn fresh-keeping methods, for example: Chinese patent application number CN200910189780.8 "a method for keeping tender corn at room temperature", Chinese patent application number CN201310165960.9 "tender corn Preparation method of corn tender and fresh-keeping agent", etc. The content of the research is to keep fresh by soaking in chemical substances. 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 corn kernels 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 corn kernels of the present invention is as follows: firstly, the fresh corn kernels are subjected to high-pressure permeation treatment with the mugwort essential oil gas in an approximate supercritical state;

Specifically include the following steps:

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

(2), draining: quickly drain the corn kernels after ultrasonic treatment in the dark and at low temperature, and then put them 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 chamber containing corn kernels In the air 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 50-80min;

(4), vacuum high-voltage electric field corona discharge treatment: the corn kernels 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 the corn kernels treated by corona discharge in an empty high-voltage electric field, put them into 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 50-80°C to dry for 60-90 minutes;

In the step (2), when draining, the low temperature is controlled to be 5-15°C.

In the step (4), the intensity of the high-voltage corona field is controlled to be 100-180KV, and the treatment time is 14-20h.

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 corn grains on the metal plate is 10-30mm, and the minimum distance between the discharge needle and the metal plate is 40-65mm, the distance between the discharge needles is 60-80mm.

Aiming at the problems existing in the background technology, the inventor conducted in-depth research on the physical fresh-keeping method of corn kernels, and selected mugwort among many natural insecticidal plants, and used the volatilization of mugwort essential oil to exert antibacterial and insecticidal effects, but invented People have also found that because corn kernels have a thicker skin, it is difficult to make mugwort essential oil penetrate into the inside of corn kernels 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 corn kernels, excellent antibacterial and insecticidal effects are obtained.

Described mugwort has strong volatility, because also can make residual irritating taste on the corn kernel, affect the mouthfeel and fragrance of corn kernel, to this problem, inventor carries out vacuum high-voltage electric field corona discharge treatment to corn kernel, utilizes electric The ion beam generated during the corona discharge increases the energy of the mugwort gas molecules remaining in the corn kernels, causing the breakage of the hydrogen bonds between the chain molecular groups, thereby breaking the molecular structure of the volatile components in the mugwort, which is fast and effective Eliminate the irritating taste brought by mugwort, and 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 insect eggs in the corn kernels. 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 it will increase the loss of nutrients in corn grain products during the high-pressure osmotic treatment process. If it is too low, the gas density of mugwort essential oil cannot reach the approximate supercritical state of 0.68-0.85g/cm ³ ; the selected The high-pressure penetration time is 50-70 minutes, and the high-pressure penetration time should not be too long, but it must meet the full contact between the corn kernels and the supercritical mugwort gas with strong penetration power, penetrate deep into the corn kernels, and ensure the insecticidal and antibacterial effects .

Further, preferably after step (2) is drained, it is followed by air blowing and mixing treatment to reduce the moisture content on the surface of corn kernels, further inhibiting the growth of microorganisms on the surface of corn kernels, preferably controlling the temperature of air blowing and mixing treatment to be 50-80°C, The drying time is 60-90 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 corn kernels to meet the needs of external water evaporation, and the internal water will migrate to the surface faster, which will easily cause The carried soluble components are precipitated on the surface, thereby causing the hardening of the corn kernel surface; the selected time should not be too short, and the time is too short to be unfavorable for the drying of the corn kernel surface, preferably controlling the moisture content of the corn kernel to be reduced to below 12%.

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 corn kernels are The maximum tile thickness on the metal plate is preferably 10-30 mm, the distance between the discharge needles is 60-80 mm, and the minimum distance between the tip of the discharge needle and the metal plate is preferably 45-65 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 100-180KV. If the high-voltage electric field corona discharge intensity is too high, it will put forward higher requirements for production conditions and have adverse effects on the quality of corn kernels. However, the high-voltage corona field intensity is below 100KV. 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 corn kernels, 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 corn kernels. 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 corn kernels prepared by the method of the present invention can be kept fresh for more than 65 days under the condition of 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: hand-picking fresh corn without mildew and pests, removing bracts and filaments, and obtaining fresh corn kernels with a corn threshing machine;

(2) Soaking and cleaning: immerse the above-mentioned corn kernels in ultra-pure water to remove impurities and dust on the surface of the corn kernels, and then sonicate for 1 hour;

(3), draining, air blowing and mixing treatment: the treated corn grains are quickly drained at a low temperature of 5°C in the dark, and then dried for 60min 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 corn kernels , and pressurize the high-pressure chamber to ensure that the pressure in the high-pressure 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 50min;

(5) Vacuum high-voltage electric field corona discharge treatment: spread the dried corn kernels on the metal plate, ensure that the thickness of the tile after loading the sample is 10mm, the distance between the needle electrode tip and the metal plate is 40mm, and the high-voltage corona field strength 100KV, high-voltage electric field corona discharge treatment in vacuum state for 14 hours, to ensure that the vacuum degree is 2000-2500Pa;

(6), vacuum packaging: vacuum-pack the dried corn kernels 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), raw material pretreatment: hand-picking fresh corn without mildew and pests, removing bracts and filaments, and obtaining fresh corn kernels with a corn threshing machine;

(2) Soaking and cleaning: immerse the above-mentioned corn kernels in ultra-pure water to remove impurities and dust on the surface of the corn kernels, and then sonicate for 1 hour;

(3), draining, air blowing and mixing treatment: the treated corn kernels are quickly drained in the dark at a low temperature of 15°C, and then dried for 90min 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 corn kernels During the process, 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 70min;

(5) Vacuum high-voltage electric field corona discharge treatment: spread the dried corn kernels on the metal plate, ensure that the thickness of the tile after loading the sample is about 30mm, the distance between the tip of the needle electrode and the metal plate is 65mm, and the high-voltage corona field The strength is 180KV, and the high-voltage electric field corona discharge treatment is carried out in a vacuum state for 20 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 packaging: vacuum-pack the dried corn kernels 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), raw material pretreatment: hand-picking fresh corn without mildew and pests, removing bracts and filaments, and obtaining fresh corn kernels with a corn threshing machine;

(2) Soaking and cleaning: immerse the above-mentioned corn kernels in ultra-pure water to remove impurities and dust on the surface of the corn kernels, and then sonicate for 1 hour;

(3), draining, air blowing and mixing treatment: quickly drain the treated corn kernels in the dark at a low temperature of 10°C, and then dry them for 75min 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 corn kernels During the process, pressurize the high-pressure air chamber to ensure that the pressure in the high-pressure air chamber is 13 MPa. At this time, the gas of mugwort essential oil exhibits an approximate supercritical state with a density of 0.68-0.85 g/cm ³ , and the processing time is 70 minutes;

(5) Vacuum high-voltage electric field corona discharge treatment: spread the dried corn kernels on the metal plate, ensure that the thickness of the tile after loading the sample is about 24mm, the distance between the tip of the needle electrode and the metal plate is 55mm, and the high-voltage corona field The strength is 140KV, and the high-voltage electric field corona discharge treatment is carried out in a vacuum state for 17 hours to ensure that the vacuum degree is 2000-2500Pa;

(6), vacuum packaging: vacuum-pack the dried corn kernels 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), raw material pretreatment: hand-picking fresh corn without mildew and pests, removing bracts and filaments, and obtaining fresh corn kernels with a corn threshing machine;

(2) Soaking and cleaning: immerse the above-mentioned corn kernels in ultra-pure water to remove impurities and dust on the surface of the corn kernels, and then sonicate for 1 hour;

(3), draining, air blowing and mixing treatment: the treated corn grains are quickly drained at a low temperature of 5°C in the dark, and then dried for 60min at 50°C with a mesh belt type airflow dryer;

(4), high-pressure infiltration treatment: 100g corn kernels are packed in 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 at 10MPa, and the treatment time is 50min;

(5) Vacuum high-voltage electric field corona discharge treatment: spread the dried corn kernels on the metal plate, ensure that the thickness of the tile after loading the sample is about 10mm, the distance between the tip of the needle electrode and the metal plate is 40mm, and the high-voltage corona field The strength is 100KV, and the high-voltage electric field corona discharge treatment is carried out in a vacuum state for 14 hours to ensure that the vacuum degree is 2000-2500Pa;

(6), vacuum packaging: vacuum-pack the dried corn kernels 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), raw material pretreatment: hand-picking fresh corn without mildew and pests, removing bracts and filaments, and obtaining fresh corn kernels with a corn threshing machine;

(2) Soaking and cleaning: immerse the above-mentioned corn kernels in ultra-pure water to remove impurities and dust on the surface of the corn kernels, and then sonicate for 1 hour;

(3), draining, air blowing and mixing treatment: the treated corn grains are quickly drained at a low temperature of 5°C in the dark, and then dried for 60min 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 corn kernels , and pressurize the high-pressure chamber to ensure that the pressure in the high-pressure 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 50min;

(5), vacuum packaging: the dried corn kernels are vacuum-packed in 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), raw material pretreatment: hand-picking fresh corn without mildew and pests, removing bracts and filaments, and obtaining fresh corn kernels with a corn threshing machine;

(2) Soaking and cleaning: immerse the above-mentioned corn kernels in ultra-pure water to remove impurities and dust on the surface of the corn kernels, and then sonicate for 1 hour;

(3), draining, air blowing and mixing treatment: the treated corn grains are quickly drained at a low temperature of 5°C in the dark, and then dried for 60min 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, and use a high-pressure pump to pump the volatilized mugwort gas into the high-pressure air chamber containing 100g corn kernels In this case, the high-pressure chamber is not pressurized, and the processing time is 50 minutes;

(5) Vacuum high-voltage electric field corona discharge treatment: spread the dried corn kernels on the metal plate, ensure that the thickness of the tile after loading the sample is 10mm, the distance between the needle electrode tip and the metal plate is 40mm, and the high-voltage corona field strength 100KV, high-voltage electric field corona discharge treatment in vacuum state for 14 hours, to ensure that the vacuum degree is 2000-2500Pa;

(6), vacuum packaging: vacuum-pack the dried corn kernels 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), raw material pretreatment: hand-picking fresh corn without mildew and pests, removing bracts and filaments, and obtaining fresh corn kernels with a corn threshing machine;

(2) Soaking and cleaning: immerse the above-mentioned corn kernels in ultra-pure water to remove impurities and dust on the surface of the corn kernels, and then sonicate for 1 hour;

(3), draining: drain the treated corn kernels in the dark, at a low temperature of 5°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 containing corn kernels , 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 shows an approximate supercritical state with a density of 0.68-0.85g/cm ³ , and the processing time is 50min;

(5) Vacuum high-voltage electric field corona discharge treatment: spread the dried corn kernels on the metal plate, ensure that the maximum tile thickness after sample loading is about 10mm, and the minimum distance between the tip of the needle electrode and the metal plate is 40mm. The halo field intensity is 100KV, and the high-voltage electric field corona discharge treatment is carried out in a vacuum state for 14 hours to ensure that the vacuum degree is 2000-2500Pa;

(6), vacuum packaging: vacuum-pack the dried corn kernels 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 corn kernels 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, and total fat of the 3 samples. , total 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 iblet, it is characterised in that first use the argy wormwood essential oil gas of approximate supercriticality High-pressure osmosis treatment is carried out to fresh corn grain, high voltage electric field Corona discharge Treatment then is used to iblet again, most afterwards through true Refrigerated after empty package.

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

(1), soaking and washing：Fresh corn grain is immersed in ultra-pure water, the impurity and dust on iblet surface, Ran Houchao is removed 1~1.5h of sound；

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

(3), high-pressure osmosis treatment：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 , be pumped into the argy wormwood essential oil gas of volatilization in the plenum chamber equipped with iblet using high-pressure pump, and plenum chamber is added by hair 10~15MPa is pressed and be maintained at, makes argy wormwood essential oil gas density up to 0.68~0.85g/cm³Approximate supercriticality, treatment Time is 50~70min；

(4), vacuum high-pressure electric field Corona discharge Treatment：Iblet after being processed through high-pressure osmosis loads high voltage electric field corona and puts In electric installation, high voltage electric field Corona discharge Treatment is carried out under vacuum conditions；

(5) will be vacuum-packed through the iblet of outage piezoelectric field Corona discharge Treatment, be put into deoxidier, it is cold under the conditions of 1~5 DEG C Hide fresh-keeping.

3. the physical fresh-keeping method of iblet as claimed in claim 2, it is characterised in that described to drain in the step (2) Laggard promoting the circulation of qi stream blows mixes treatment, with net belt type pneumatic drier under the conditions of 50~80 DEG C, dries 60~90min.

4. the physical fresh-keeping method of iblet as claimed in claim 2 or claim 3, it is characterised in that in the step (2), drain When control cryogenic temperature be 5~15 DEG C.

5. the physical fresh-keeping method of iblet as claimed in claim 2, it is characterised in that in the step (4), controls high pressure Corona field intensity is 100~180KV, and process time is 14~20h.

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

7. the physical fresh-keeping method of the iblet as described in claim 2 or 5, it is characterised in that described in the step (4) High voltage electric field corona discharge assembly at least includes metallic plate and spray point, the iblet maximum tiling thickness on a metal plate It is 10~30mm, spray point is 40~65mm with metallic plate minimum range, and the spacing between spray point is 60~80mm.