CN110296582B - Radio frequency vacuum drying method for kiwi fruit slices - Google Patents
Radio frequency vacuum drying method for kiwi fruit slices Download PDFInfo
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- CN110296582B CN110296582B CN201810232513.3A CN201810232513A CN110296582B CN 110296582 B CN110296582 B CN 110296582B CN 201810232513 A CN201810232513 A CN 201810232513A CN 110296582 B CN110296582 B CN 110296582B
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- A—HUMAN NECESSITIES
- A23—FOODS OR FOODSTUFFS; TREATMENT THEREOF, NOT COVERED BY OTHER CLASSES
- A23B—PRESERVING, e.g. BY CANNING, MEAT, FISH, EGGS, FRUIT, VEGETABLES, EDIBLE SEEDS; CHEMICAL RIPENING OF FRUIT OR VEGETABLES; THE PRESERVED, RIPENED, OR CANNED PRODUCTS
- A23B7/00—Preservation or chemical ripening of fruit or vegetables
- A23B7/005—Preserving by heating
- A23B7/0053—Preserving by heating by direct or indirect contact with heating gases or liquids
-
- A—HUMAN NECESSITIES
- A23—FOODS OR FOODSTUFFS; TREATMENT THEREOF, NOT COVERED BY OTHER CLASSES
- A23B—PRESERVING, e.g. BY CANNING, MEAT, FISH, EGGS, FRUIT, VEGETABLES, EDIBLE SEEDS; CHEMICAL RIPENING OF FRUIT OR VEGETABLES; THE PRESERVED, RIPENED, OR CANNED PRODUCTS
- A23B7/00—Preservation or chemical ripening of fruit or vegetables
- A23B7/005—Preserving by heating
- A23B7/01—Preserving by heating by irradiation or electric treatment
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F26—DRYING
- F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
- F26B21/00—Arrangements or duct systems, e.g. in combination with pallet boxes, for supplying and controlling air or gases for drying solid materials or objects
- F26B21/06—Controlling, e.g. regulating, parameters of gas supply
- F26B21/10—Temperature; Pressure
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F26—DRYING
- F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
- F26B21/00—Arrangements or duct systems, e.g. in combination with pallet boxes, for supplying and controlling air or gases for drying solid materials or objects
- F26B21/06—Controlling, e.g. regulating, parameters of gas supply
- F26B21/12—Velocity of flow; Quantity of flow, e.g. by varying fan speed, by modifying cross flow area
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F26—DRYING
- F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
- F26B3/00—Drying solid materials or objects by processes involving the application of heat
- F26B3/28—Drying solid materials or objects by processes involving the application of heat by radiation, e.g. from the sun
- F26B3/283—Drying solid materials or objects by processes involving the application of heat by radiation, e.g. from the sun in combination with convection
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F26—DRYING
- F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
- F26B5/00—Drying solid materials or objects by processes not involving the application of heat
- F26B5/04—Drying solid materials or objects by processes not involving the application of heat by evaporation or sublimation of moisture under reduced pressure, e.g. in a vacuum
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F26—DRYING
- F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
- F26B9/00—Machines or apparatus for drying solid materials or objects at rest or with only local agitation; Domestic airing cupboards
- F26B9/06—Machines or apparatus for drying solid materials or objects at rest or with only local agitation; Domestic airing cupboards in stationary drums or chambers
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- A—HUMAN NECESSITIES
- A23—FOODS OR FOODSTUFFS; TREATMENT THEREOF, NOT COVERED BY OTHER CLASSES
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- A23V2002/00—Food compositions, function of food ingredients or processes for food or foodstuffs
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P60/00—Technologies relating to agriculture, livestock or agroalimentary industries
- Y02P60/80—Food processing, e.g. use of renewable energies or variable speed drives in handling, conveying or stacking
- Y02P60/85—Food storage or conservation, e.g. cooling or drying
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Abstract
The invention discloses a radio frequency vacuum drying method of kiwi fruit slices, which comprises the following steps: slicing kiwi fruits: washing the kiwi fruits and cutting the kiwi fruits into kiwi fruit slices with consistent thickness and shape and size; weighing kiwi fruit slices and placing the kiwi fruit slices in a container: weighing the kiwi fruit slices, spreading the kiwi fruit slices in a cubic container with holes, wherein the container is made of high-temperature-resistant plastic, so that the individual kiwi fruit slices are not contacted with each other; carrying out radio frequency vacuum drying treatment on the kiwi fruit slices, wherein the radio frequency vacuum treatment time is controlled to be 2-4 hours; packaging and refrigerating: after cooling to room temperature, packaging and refrigerating in a refrigerator. The drying method of the invention makes up the blank of the existing kiwi fruit slice radio frequency vacuum drying technology, improves the drying rate and furthest reserves the original nutritional ingredients and quality of the materials.
Description
Technical Field
The invention relates to a research on drying of kiwi fruit slices, in particular to a radio frequency vacuum drying method for kiwi fruit slices.
Background
China is a large Chinese goosebeery planting country, and according to the display of a combined national grain and agriculture organization statistical database (FAOSTAT), the total yield and the cultivation area of the Chinese goosebeery in 2016 are all located at the 1 st place in the world, and account for 56% of the total yield of the Chinese goosebeery in the world. The kiwi fruit has higher nutritive value, is rich in a large amount of high-quality amino acids, minerals, vitamins and other nutritive components, and particularly has the vitamin C content in the first part of fruits. However, there are strong seasonal and regional limitations to the planting and production of kiwi fruits. In addition, the kiwi fruit has high water content, and is extremely easy to rot and lose in the processes of harvesting, processing and storing, so that the kiwi fruit loss rate in China is about 30% each year. The drying technology is an important technology for post-harvest processing of agricultural products, and can control the moisture content of materials within a safe storage moisture range. At present, the drying technology adopted for the treatment of the kiwi fruits mainly comprises sun drying, hot air drying and penetration drying, but the traditional drying technology has the problems of low efficiency, high energy consumption, poor uniformity, serious quality deterioration, excessive standard of chemical additives and the like.
The radio frequency technology is a novel physical heating method, radio frequency waves (3 kHz-300 MHz) can penetrate into the material to cause oscillation migration of charged ions in the polar material, and electric energy is converted into heat energy, so that the method has the advantages of rapid heating, relatively uniform heating, good treatment quality and the like. Vacuum drying technology is currently widely used in the drying of heat sensitive substances, which can greatly reduce the moisture evaporation temperature and oxygen concentration. The radio frequency vacuum drying method is a technology combining radio frequency heating and vacuum drying, combines the advantages of the radio frequency heating and the vacuum drying, improves the heating rate, reduces the drying temperature and the oxygen concentration, can well keep the original nutrition components and the original color of the sample, and has the characteristics of energy conservation, high efficiency, uniformity, low temperature and the like. But the radio frequency heating process has the phenomenon of uneven heating, and the high-moisture kiwi fruits are extremely easy to generate the phenomena of ignition and discharge in the radio frequency-vacuum physical field heating process, so that the phenomena of uncontrollable temperature, material burning and the like are caused. At present, no mature kiwi fruit radio frequency vacuum drying process exists. In view of the above, the invention provides a high-efficiency, energy-saving, safe and better-processing-quality kiwi fruit slice radio-frequency vacuum drying method based on uniformity control, which is a problem to be solved by the industry professionals.
Disclosure of Invention
The invention aims at solving the blank of the prior art and provides a radio frequency vacuum drying method of kiwi fruit slices.
The radio frequency vacuum drying method of the kiwi fruit slices is characterized by comprising the following steps of:
slicing kiwi fruits: cleaning and peeling kiwi fruits, and then cutting the kiwi fruits into slices with consistent thickness;
weighing kiwi fruit slices and placing the kiwi fruit slices in a container: weighing the kiwi fruit slices, spreading the kiwi fruit slices in a cubic container with holes, and ensuring that the single slices are not contacted with each other;
carrying out radio frequency vacuum drying treatment on the kiwi fruit slices: carrying out radio frequency vacuum treatment on the container filled with the kiwi fruit slices by using radio frequency vacuum equipment, controlling the treatment time of the kiwi fruit slices to be 2-4 hours until the moisture content of the kiwi fruit slices is reduced to 0.18kg/kg (dry basis), closing the radio frequency, and taking out a sample;
packaging and refrigerating: and cooling the kiwi fruit slices subjected to hot air drying and radio frequency vacuum drying treatment to room temperature, carrying out conventional packaging, and then putting the kiwi fruit slices into a refrigerator for refrigeration.
Preferably, in the step of the kiwi fruit slices, the thickness of the kiwi fruit slices is 6-10 mm, and the diameter of the kiwi fruit slices is 40-50 mm.
Preferably, in the step of weighing the kiwi fruit slices, the total weight of the kiwi fruit slices is 500-1000 g, the capacity of the container is 270-400 long-400 wide-20 high mm, the container is made of high-temperature-resistant polypropylene plastic, and the distance between the individual kiwi fruit slices is 10-20 mm.
Preferably, in the process of carrying out radio frequency vacuum drying treatment on the kiwi fruit slices, the distance between the polar plates is 50-70 mm and is larger than the height of the container, and the vacuum degree of the radio frequency vacuum equipment is 0.01-0.03 MPa.
Preferably, the refrigeration temperature is 4 ℃ during the packaging and refrigeration process.
Preferably, the power of the radio frequency vacuum equipment is 3kW, and the frequency is 27.12MHz.
Compared with the prior art, the invention has the substantial characteristics and remarkable progress that:
according to the invention, the kiwi fruit slices are dried by using the radio frequency vacuum technology, so that the moisture content of the kiwi fruit slices can be reduced below the safe storage moisture content, the storage period of the kiwi fruit slices is prolonged, the drying rate of the traditional kiwi fruit slices is greatly improved by using the radio frequency vacuum technology, and the original nutritional ingredients of kiwi fruits can be well maintained. In addition, the radio frequency vacuum drying technology has the advantages of high efficiency, low energy consumption and no pollution, is beneficial to improving the degree of drying damage reduction of fruits and vegetables, and promotes the scientific competitiveness and healthy development of the dehydrated fruit and vegetable industry in China.
Drawings
FIG. 1 is a graph showing the moisture content of kiwi fruit slices as a function of drying time during hot air drying and radio frequency vacuum drying.
Detailed Description
This patent is further described below with reference to the drawings and embodiments.
Example 1: preparation of Kiwi berry slice for test
Firstly, selecting kiwi fruits with consistent maturity and same shape and size, cleaning, cutting the kiwi fruits into kiwi fruit slices with equal thickness after removing pericarps, specifically, cutting the kiwi fruit slices with the thickness of 8mm and the diameter of 45mm, and sealing for later use. Weighing kiwi fruit samples, spreading the kiwi fruit samples in a cubic container with holes to ensure that single kiwi fruit pieces are not contacted with each other, wherein the aperture of the container is 10mm, the shape of the container is cuboid, and the material is high-temperature resistant polypropylene plastic, wherein the volume of the container is 270 long x 270 wide x 20 mm-400 long x 400 wide x 20mm, the specific capacity of the container can be 400 long x 270 wide x 20mm, the total weight of the kiwi fruit pieces depends on the capacity of the adopted container, specifically 500g, and the moisture content of the fresh kiwi fruit pieces is 5.66kg/kg (dry basis);
example 2: radio frequency vacuum drying treatment of kiwi fruit slices
Experimental group: firstly, setting parameters of radio frequency vacuum equipment, including plate spacing and vacuum degree, specifically selecting the plate spacing to be 60mm and the vacuum degree to be 0.02MPa, placing a container containing a kiwi fruit slice at the center of a lower plate of the radio frequency vacuum equipment, closing a negative pressure tank door, performing radio frequency vacuum drying treatment after each parameter of the equipment reaches a preset value until the moisture content of the kiwi fruit slice is reduced to 0.18kg/kg (dry basis), closing the radio frequency, and taking out a sample;
control group: hot air drying treatment of kiwi fruit slices
Firstly, setting the temperature and the air speed of a blast drying box, specifically setting the temperature of the blast drying box to be 60 ℃ and the air speed to be 1m/s according to the common hot air drying temperature of fruits and vegetables, preheating for 30min, putting a plastic container with holes, which is filled with kiwi fruit slices, into the blast drying box until the moisture content of the kiwi fruit slices is reduced to 0.18kg/kg (dry basis), and stopping drying and taking out the samples;
example 3: packaging and refrigerating
And cooling the kiwi fruit slices subjected to hot air drying and radio frequency vacuum drying treatment to room temperature, carrying out conventional packaging, and then putting the kiwi fruit slices into a refrigerator at 4 ℃ for refrigeration.
The following steps are carried out on the kiwi fruit slices subjected to hot air drying and radio frequency vacuum drying treatment, and the color, the vitamin C content and the rehydration capability are detected:
the method for measuring the color of the kiwi fruit slices is characterized by adopting a computer vision system for detection, wherein the computer vision system consists of three parts: an illumination device, a Canon EOS 600D digital camera (18-55 mm lens, 1800 ten thousand pixels) and a Sony notebook computer preloaded with a Adobe Photoshop CS image processing system. The lighting device consisted of a studio (41L ×30W ×30H cm 3) and a photographic lamp (LS 235 5500K) mounted on top of the studio, which was turned on 15min before use. The sample is placed at the bottom of the studio, and the digital camera lens is fixed at the top of the studio. The color parameters of the kiwi fruit slices are photographed by a digital camera and stored in a computer, and the captured color values are converted into CIE LAB by using Photoshop (L, a, b) softwareL * ，a * ， b * ) Values.
Experimental group: the kiwi fruit slices processed and cooled in the embodiment 2 and the embodiment 3 are randomly taken 1 piece of kiwi fruit slices with good appearance respectively, and the kiwi fruit slices are put into a computer vision system for color detection and repeated for 3 times.
Control group: the same batch of fresh kiwi fruit slices was subjected to the same color measurement as described above to obtain the sameL * ，a * Andb * is a value of (2).
The method for measuring the vitamin C content of the kiwi fruit slices refers to the method for measuring the total ascorbic acid in vegetables and fruits and products thereof in the national food safety standard (GBT 5009.86-2003)
Experimental group: 10 g to 40g of kiwi fruit slices treated and cooled in example 2 and example 3 are respectively weighed randomly, placed in a mortar, added with 1% oxalic acid solution, ground into homogenate, poured into a 100ml volumetric flask, diluted to scale with 1% oxalic acid solution, mixed uniformly and filtered. 25ml of the filtrate is taken, 0.5g of active carbon is added, shaking is carried out for 1min, filtering is carried out, 10ml of the extracting solution is taken, 10ml of 2% thiourea solution is added, uniformly mixed and 1.0ml of 2% 2, 4-dinitrophenylhydrazine solution is added, a test tube is put into a 37 constant temperature box, the test tube is taken out and put into ice water after 3h of heat preservation, 5ml of 85% sulfuric acid is added, the absorption value is measured at the wavelength of 500nm by an ultraviolet spectrophotometer, and the process is repeated for 3 times.
Control group: the same batch of fresh kiwi fruit pieces was subjected to the same treatment as described above to determine the vitamin C content thereof.
Determination of rehydration
Experimental group: the cooled kiwi fruit slices processed in example 2 and example 3 were randomly taken 3 slices, respectively, weighed, put into a beaker filled with purified water at 50 ℃ for soaking for 15min, then taken out, the floating water was sucked by filter paper, weighed again, and the rehydration capacity= (W-W0)/W0 x 100%, W0 and W being the weights of the samples before and after rehydration, respectively, were repeated 3 times.
The experimental results are shown in fig. 1, and the moisture content of the kiwi fruit slices gradually decreases with the drying time. The time required for reducing the moisture content of the kiwi fruit slices from 5.66kg/kg to 0.18kg/kg by hot air drying is 700 minutes, and the time required for radiofrequency vacuum drying is only 250 minutes, so that the drying time of 60% is saved by hot air drying.
TABLE 1 variation of color, vitamin C and rehydration Capacity of Kiwi fruit pieces before and after RF vacuum drying and Hot air drying
As can be seen from Table 1, the kiwi fruit subjected to the RF vacuum drying treatment was compared with the fresh kiwi fruit slicesL * The value of the drop-off is reduced,a * value sumb * The values are all increased, which means that the kiwi fruit slices undergo Maillard reaction, namely browning reaction, to a certain extent in the process of radio frequency vacuum drying, but compared with the kiwi fruit slices subjected to hot air drying, the samples subjected to radio frequency vacuum drying are subjected to the process of radio frequency vacuum dryingL * ，a * ，b * The value of the kiwi fruit slices is obviously better than that of the kiwi fruit slices subjected to hot air drying treatment; in addition, the content of vitamin C in the kiwi fruit slices after the radio frequency vacuum drying treatment is obviously higher than that in the samples after the hot air drying treatment, mainly because the degradation of the vitamin C in the drying process is obviously prevented by the lower oxygen concentration and the shorter drying time in the radio frequency vacuum drying process; in the aspect of rehydration, compared with the kiwi fruit slices subjected to hot air drying treatment, the sample rehydration capability after radio frequency vacuum drying is remarkably improved, and mainly because the internal tissues of the kiwi fruit form a porous and loose tissue structure in the radio frequency vacuum drying process, and the water absorption capability of the kiwi fruit slices is improved.
Compared with the existing hot air drying technology of kiwi fruit slices, the invention has the substantial characteristics and remarkable progress that:
according to the invention, the kiwi fruit slices are dried by using the radio frequency vacuum technology, the moisture content of the kiwi fruit slices is reduced below the safe storage moisture content, so that the storage period of the kiwi fruit slices is prolonged, the drying rate of the kiwi fruit slices is greatly improved by using the radio frequency vacuum technology, and the original color, luster, nutritional ingredients and the like of the kiwi fruits can be well maintained. In addition, the radio frequency vacuum drying technology has the advantages of high efficiency, low energy consumption and no pollution, is beneficial to improving the degree of drying damage reduction of fruits and vegetables, and promotes the scientific competitiveness and healthy development of the dehydrated fruit and vegetable industry in China.
Claims (6)
1. The radio frequency vacuum drying method of the kiwi fruit slices is characterized by comprising the following steps of:
slicing kiwi fruits: cleaning and peeling kiwi fruits, and then cutting the kiwi fruits into slices with consistent thickness;
weighing kiwi fruit slices and placing the kiwi fruit slices in a container: weighing the kiwi fruit slices, spreading the kiwi fruit slices in a cubic container with holes, and ensuring that the single slices are not contacted with each other;
carrying out radio frequency vacuum drying treatment on the kiwi fruit slices: carrying out radio frequency vacuum drying treatment on the container filled with the kiwi fruit slices by using radio frequency vacuum equipment, controlling the treatment time of the kiwi fruit slices to be 2-4 hours until the moisture content of the kiwi fruit slices is reduced to 0.18kg/kg (dry basis), then closing the radio frequency, and taking out a sample;
packaging and refrigerating: and cooling the kiwi fruit slices subjected to the radio frequency vacuum drying treatment to room temperature, carrying out conventional packaging, and then putting the kiwi fruit slices into a refrigerator for refrigeration.
2. The method for radio frequency vacuum drying of kiwi fruit slices as claimed in claim 1, wherein in said step of slicing kiwi fruit, said kiwi fruit slices have a thickness of 6-10 mm and a diameter of 40-50 mm.
3. The method of radio frequency vacuum drying of kiwi fruit slices as claimed in claim 1, wherein the step of weighing the kiwi fruit slices is carried out in a container, the total weight of the kiwi fruit slices is 500-1000 g, the capacity of the container is 270-400 long-400 wide-20 mm, the material of the container is high temperature resistant polypropylene plastic, and the distance between the individual kiwi fruit slices is 10-20 mm.
4. The method for radio frequency vacuum drying of kiwi fruit slices as claimed in claim 1, wherein in the process of carrying out radio frequency vacuum drying treatment on the kiwi fruit slices, the distance between polar plates is 50-70 mm and is larger than the height of the container, and the vacuum degree of radio frequency vacuum equipment is 0.01-0.03 MPa.
5. A method of radio frequency vacuum drying kiwi fruit slices as claimed in claim 1, wherein the temperature of refrigeration is 4 ℃ during the packaging and refrigeration process.
6. A method for radio frequency vacuum drying of kiwi fruit slices as claimed in claim 1, wherein the power of the radio frequency vacuum equipment is 3kW and the frequency is 27.12MHz.
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| Application Number | Priority Date | Filing Date | Title |
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| CN201810232513.3A CN110296582B (en) | 2018-03-21 | 2018-03-21 | Radio frequency vacuum drying method for kiwi fruit slices |
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| CN201810232513.3A CN110296582B (en) | 2018-03-21 | 2018-03-21 | Radio frequency vacuum drying method for kiwi fruit slices |
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| RU2735914C1 (en) * | 2019-11-28 | 2020-11-10 | Общество с ограниченной ответственностью "АгроИнТех" | Method of producing products in vacuum microwave drier |
| CN111972486A (en) * | 2020-07-19 | 2020-11-24 | 北京工商大学 | Combined drying method for blueberries |
| CN111972488A (en) * | 2020-07-19 | 2020-11-24 | 北京工商大学 | Combined drying method of blackcurrants |
| CN111937953A (en) * | 2020-07-19 | 2020-11-17 | 北京工商大学 | Combined drying method of mulberries |
| CN114304489B (en) * | 2021-12-14 | 2023-08-01 | 西北农林科技大学 | Method for drying fine dried noodles by low-frequency electromagnetic field |
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