CN110999956A - Refrigerating and fresh-keeping method for pears - Google Patents
Refrigerating and fresh-keeping method for pears Download PDFInfo
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- CN110999956A CN110999956A CN201911371911.4A CN201911371911A CN110999956A CN 110999956 A CN110999956 A CN 110999956A CN 201911371911 A CN201911371911 A CN 201911371911A CN 110999956 A CN110999956 A CN 110999956A
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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
- A23B7/16—Coating with a protective layer; Compositions or apparatus therefor
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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
- A23B7/04—Freezing; Subsequent thawing; Cooling
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Abstract
The invention discloses a cold storage and fresh-keeping method of pears, which comprises the following steps: s1, placing the picked pears in a shade overnight, and waiting for the pears to dissipate field heat; s2, coating edible nanoemulsion film coating agents on the surface of the pear, and placing the pear in a ventilated place to be dried to form a film coating layer; s3, weighing each pear respectively, wrapping the other parts except the pear bundle with white wrapping paper, and marking the weight of the pears on the paper; sleeving the pears wrapped with the white packing paper by using a foam net sleeve, and putting the pears into a carton; s4, wrapping the whole paper box filled with the pears with plastic film paper, and putting the paper box into a cold storage; and the initial temperature of the paper box in the refrigeration house is 10 ℃ on the day after the paper box is placed in the refrigeration house; and S5, performing gradient cooling on the interior of the refrigeration house. The invention can prolong the preservation period as much as possible on the premise of ensuring the quality of the pears, thereby ensuring the market competitiveness and improving the income of fruit growers.
Description
Technical Field
The invention relates to the technical field of refrigeration and preservation of agricultural products, in particular to a refrigeration and preservation method of pears.
Background
The Cuiguan pears are one of the southern early-maturing pears, the mature period is mainly in late 7 months each year, the pulp is white, the juice is more, the taste is better, and certain marketing prospect is realized in the market due to the excellent quality and the early maturing time. However, the green-crown pears are easy to rapidly rot in a high-temperature and high-humidity environment and are not easy to store in the mature period of the green-crown pears in the high-temperature weather of the south, so that the market sales and the income of fruit growers are influenced.
Disclosure of Invention
Aiming at the defects of the prior art, the invention provides a cold storage and preservation method of pears, in particular Cuiguan pears, which can prolong the preservation period as much as possible on the premise of ensuring the quality of the pears, thereby ensuring the market competitiveness of the pears and improving the income of fruit growers.
In order to solve the technical problems, the technical scheme provided by the invention is as follows:
provides a cold storage and fresh-keeping method of pears, which comprises the following steps:
s1, placing the picked pears in a shade overnight, and waiting for the pears to dissipate field heat;
s2, coating edible nanoemulsion film coating agents on the surface of the pear, and placing the pear in a ventilated place to be dried to form a film coating layer;
s3, weighing each pear respectively, wrapping the other parts except the pear bundle with white wrapping paper, and marking the weight of the pears on the paper; sleeving the pears wrapped with the white packing paper by using a foam net sleeve, and putting the pears into a carton;
s4, wrapping the whole paper box filled with the pears with plastic film paper, and putting the paper box into a cold storage; and the initial temperature of the paper box in the refrigeration house is 10 ℃ on the day after the paper box is placed in the refrigeration house;
and S5, performing gradient cooling on the interior of the refrigeration house.
Preferably, the gradient cooling method comprises the following steps: the temperature is reduced by 3 ℃ every 5 days and is finally stabilized to 1 ℃ from the day after the carton is put into the refrigerator.
Preferably, the gradient cooling method comprises the following steps: starting from the day after the carton is placed in the refrigerator, reducing the temperature by 2 ℃ every 3 days, reducing the temperature to 4 ℃, reducing the temperature by 1 ℃ every 1 day, and finally stabilizing the temperature to 1 ℃.
Preferably, before the edible nanoemulsion coating agent is coated on the surface of the pear, the pear is soaked in the bactericide, taken out, washed with water for 2-3 times and drained.
Preferably, the germicide is hydrogen peroxide solution with volume fraction of 0.2-0.3%.
Preferably, the soaking time of pear in the bactericide is 1-2 min.
Preferably, the thickness of the coating layer is 0.02-0.03 mm.
Preferably, the humidity in the cold storage is 65-75% relatively and the air pressure is 0.8-0.9 atmospheric pressure in the whole cold storage period of the pears.
Preferably, the carton is a corrugated carton.
Preferably, the pears comprise Cuiguan pears.
Compared with the prior art, the cold storage and preservation method can ensure that the quality of pears, especially Cuiguan pears, does not change too much within two months, thereby maintaining sufficient competitiveness before other varieties of pears are on the market and improving income of fruit growers.
Drawings
FIG. 1 shows the weight loss rate of pears in example one at different time periods;
FIG. 2a is a sectional view of a pear in the first embodiment before warehousing;
FIG. 2b is a sectional view of the pears at 46 th day of warehousing in example one;
FIG. 2c is a sectional view of a pear at 70 days of warehousing in example one;
FIG. 3 shows the sugar degree of pears of example one at different time periods;
FIG. 4 is a graph of the measurable acid content of pears of example one over various time periods.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The first embodiment is as follows:
the method for refrigerating and preserving the pears (preferably the green-coronal pears) in the embodiment comprises the following steps of:
s1, placing the picked pears in a shade overnight, and waiting for the pears to dissipate field heat;
s2, soaking pears in the bactericide, taking the pears out, washing the pears for 2 to 3 times with water, and draining the pears; coating edible nanoemulsion film coating agents with the thickness of 0.02-0.03mm (preferably 0.025mm) on the surface of the pear, and placing the pear in a ventilated place for airing to form a film coating layer; the sterilizing agent is hydrogen peroxide solution with the volume fraction of 0.2-0.3%, and the soaking time of the pears in the sterilizing agent is 1-2min (preferably 1.5min), so that the pears can be sufficiently sterilized, and the problems that the sterilizing agent is remained on the surfaces of the pears due to too long soaking time and the flavor is poor are solved;
s3, weighing each pear respectively, accurately weighing the pear one decimal place later, wrapping the other parts except the bundle of the pear with white packing paper, and marking the weight of the pear on the paper; then, the pears wrapped with the white packing paper are sleeved by a foam net sleeve and put into a carton (preferably a corrugated carton);
s4, wrapping the whole paper box filled with the pears with plastic film paper, and putting the paper box into a cold storage; and the initial temperature of the paper box in the refrigeration house is 10 ℃ on the day after the paper box is placed in the refrigeration house;
s5, carrying out gradient cooling on the interior of the refrigeration house; in this embodiment, the gradient cooling method includes: the temperature is reduced by 3 ℃ every 5 days and is finally stabilized to 1 ℃ from the day after the carton is put into the refrigerator.
Further, the humidity in the cold storage is 65-75% (preferably 70%) relatively, and the air pressure is 0.8-0.9 atmospheric pressure in the whole cold storage period of the pear.
The index determination of the green-coronal pears treated in the first example is carried out as follows:
1. index determination and method
1.1 weight loss ratio
Several pears are randomly selected before the experiment, the weights of the pears are measured respectively, and are compared with the weights before warehousing, and the result is obtained through calculation.
1.2 interior color
Three pears were randomly selected, cut in half and half, and photographed with a single lens reflex.
1.3 color difference
And (4) measuring the color difference of the six cut pears by using a color difference meter and recording the data.
1.4 hardness
The hardness was measured by texture analyzer, the puncture site was the incision site, and the measurement was performed twice in each half for 12 times in total.
1.4.1 texture Analyzer parameter settings
Measuring range: the maximum force induced by the probe is less than or equal to 500N
Trigger force: 0.20N
Puncture distance: 10mm
Experiment detection speed: 60mm/min
Return speed: 600mm/min
Return distance: 60mm
1.5 soluble solids
Peeling three pears, squeezing juice in a juicer, respectively sucking a drop of pear juice, and measuring sugar degree with a sugar meter.
1.6 titratable acids
Acid-base titration is adopted, and the calculation is carried out by malic acid.
1.6.1 reagents
NaOH standard solution (0.1 mol/L): weighing 120g of NaOH in a 250mL beaker, adding 100mL of distilled water, stirring with a glass rod until the NaOH is completely dissolved, standing until the solution is cooled, after clarification, taking 5.6mL of supernatant in a 1000mL volumetric flask, and using CO-free volumetric flask2The volume of the obtained water is 1000mL, and the obtained water is transferred to 2 400mL polyethylene bottles for storage.
Calibration: weighing 0.4-0.6 g (accurate to 0.0001g) of standard potassium hydrogen phthalate, drying in an oven at 105 ℃ until the weight of the standard potassium hydrogen phthalate is constant, adding 50mL of distilled water, shaking to dissolve the solution, adding 2 drops of phenolphthalein indicator, and titrating by using a prepared NaOH standard solution until the solution is reddish for 30s and does not fade. And simultaneously performing a blank test. The calculation formula is as follows:
in the formula: c-concentration of NaOH standard solution, mol/L;
m is the mass of the benchmark potassium hydrogen phthalate, g;
V1-the volume of NaOH standard solution consumed, mL, during calibration;
v2-volume of NaOH standard solution consumed for blank calibration, mL.
1.6.2 determination
20mL of squeezed pear juice is sucked, transferred into a conical flask, added with 2 drops of 1% phenolphthalein indicator and titrated by calibrated NaOH solution. Titration was carried out until the solution became reddish and did not fade within 30s, and the amount of NaOH titration was recorded and repeated for three groups. Titration was performed with distilled water instead of the filtrate as a blank control.
1.6.3 calculation
Calculating the content of titratable acid in the pear juice according to the consumption of NaOH titration solution, wherein the titratable acid content is expressed by mass fraction (%), and the calculation formula is as follows:
in the formula: v is the total volume of the sample extracting solution, mL;
VS-the volume of filtrate taken at the time of titration, mL;
c is the concentration of NaOH titration solution, mol/L;
v1-volume of NaOH solution consumed by titration of filtrate, mL;
v0-titration of the NaOH solution volume consumed by distilled water, mL;
m is sample mass, g;
f-conversion factor, g/mmol. Malic acid was 0.067.
2. Results and analysis
2.1 weight loss ratio
This test was weighed three times, in order before, after 46 days and after 70 days of warehousing. As can be seen from figure 1, the water loss rate is higher in the first 46 days, but gradually becomes slower with the prolonging of the storage period, so that the weight loss rate is more than 90.00% (namely 94.44%) after 70 days, and the influence is smaller, which shows that the refrigeration and preservation method can prevent the pear from being excessively dehydrated for a long time.
2.2 interior color
As shown in figure 2a, the section of the pear before warehousing is snow-white, and only the part close to the kernel slightly changes color due to oxidation; as shown in FIG. 2b, after 46 days of storage, there was almost no change in the cut surface; as shown in fig. 2c, after 70 days, the color of the section changes slightly, especially the position P where the section is partially entered into the garage and collided appears deep and lacks water, and the section becomes soft and shrinks slightly.
2.3 soluble solids
As shown in figure 3, the sugar degree of the pears is continuously increased along with the increase of the storage time, and the taste becomes better, which shows that the method can increase partial quality characteristics of the pears on the premise of prolonging the storage time, so that the pears have better quality and can better meet the market demand.
2.4 titratable acids
As shown in fig. 4, the titratable acid in the pears rapidly increases in the first half month and then slowly decreases over time, but is still higher than the content before warehousing within two months, so that the pears have the sugar-acid ratio of the cool cakes, and the taste is better.
Therefore, by the refrigeration and preservation method in the embodiment, the sweetness and the titratable acid content of the Cuiguan pears can be increased within at least two months, so that the Cuiguan pears have good sugar-acid ratio, the taste of the pears is better when the pears are picked off, the water loss degree is smaller, the color of the interior of the pears is not obviously different, and the pears are completely willing to have considerable market competitiveness before other varieties of pears are sold on the market.
Example two:
the difference between the present embodiment and the first embodiment is only that the gradient cooling method comprises: starting from the day after the carton is placed in the refrigerator, reducing the temperature by 2 ℃ every 3 days, reducing the temperature to 4 ℃, reducing the temperature by 1 ℃ every 1 day, and finally stabilizing the temperature to 1 ℃.
In conclusion, the cold storage and preservation method can ensure that the quality of the pears, especially the Cuiguan pears, does not change too much within two months, thereby maintaining enough competitiveness before other varieties of pears are sold on the market and improving the income of fruit growers.
It should be noted that the technical features in the first to second embodiments can be combined arbitrarily, and the combined technical solutions all belong to the protection scope of the present invention. The terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.
Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.
Claims (10)
1. The cold storage and fresh keeping method of the pears is characterized by comprising the following steps:
s1, placing the picked pears in a shade overnight, and waiting for the pears to dissipate field heat;
s2, coating edible nanoemulsion film coating agents on the surface of the pear, and placing the pear in a ventilated place to be dried to form a film coating layer;
s3, weighing each pear respectively, wrapping the other parts except the pear bundle with white wrapping paper, and marking the weight of the pears on the paper; sleeving the pears wrapped with the white packing paper by using a foam net sleeve, and putting the pears into a carton;
s4, wrapping the whole paper box filled with the pears with plastic film paper, and putting the paper box into a cold storage; and the initial temperature of the paper box in the refrigeration house is 10 ℃ on the day after the paper box is placed in the refrigeration house;
and S5, performing gradient cooling on the interior of the refrigeration house.
2. The cold preservation method according to claim 1, wherein the gradient cooling method comprises the following steps: the temperature is reduced by 3 ℃ every 5 days and is finally stabilized to 1 ℃ from the day after the carton is put into the refrigerator.
3. The cold preservation method according to claim 1, wherein the gradient cooling method comprises the following steps: starting from the day after the carton is placed in the refrigerator, reducing the temperature by 2 ℃ every 3 days, reducing the temperature to 4 ℃, reducing the temperature by 1 ℃ every 1 day, and finally stabilizing the temperature to 1 ℃.
4. A cold storage preservation method as claimed in claim 1, wherein before the edible nanoemulsion coating agent is coated on the surface of the pear, the pear is soaked in the bactericide, taken out, washed with water for 2-3 times and drained.
5. A fresh-keeping method as claimed in claim 4, wherein the sterilizing agent is a hydrogen peroxide solution with a volume fraction of 0.2-0.3%.
6. A cold preservation method as claimed in claim 4, wherein the pear is soaked in the bactericide for 1-2 min.
7. A refrigerated preservation method according to claim 1 wherein the thickness of the coating layer is 0.02 to 0.03 mm.
8. A cold preservation method according to claim 1, wherein the humidity in the cold storage is 65-75% relative and the air pressure is 0.8-0.9 atm during the whole cold storage period of the pear.
9. A fresh-keeping method as claimed in claim 1, wherein the carton is a corrugated carton.
10. A refrigerated preservation method according to claim 1 wherein the pears comprise green-crown pears.
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| CN201911371911.4A CN110999956A (en) | 2019-12-26 | 2019-12-26 | Refrigerating and fresh-keeping method for pears |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115943987A (en) * | 2023-01-13 | 2023-04-11 | 贵州中康农业科技有限公司 | Fresh-keeping method and application of fresh kiwi fruits |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1220832A (en) * | 1997-12-25 | 1999-06-30 | 陈方 | Cold-storage and fresh-keeping method for sweet pear |
| US20170215444A1 (en) * | 2016-02-03 | 2017-08-03 | Universidad De Santiago De Chile | Composition and process for obtaining peeled prickly pears coated with an edible film based on cellulose derivatives |
| CN109362868A (en) * | 2018-08-30 | 2019-02-22 | 肥东县鑫丰生态农业有限公司 | A kind of preservation method of Chinese pear |
-
2019
- 2019-12-26 CN CN201911371911.4A patent/CN110999956A/en active Pending
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1220832A (en) * | 1997-12-25 | 1999-06-30 | 陈方 | Cold-storage and fresh-keeping method for sweet pear |
| US20170215444A1 (en) * | 2016-02-03 | 2017-08-03 | Universidad De Santiago De Chile | Composition and process for obtaining peeled prickly pears coated with an edible film based on cellulose derivatives |
| CN109362868A (en) * | 2018-08-30 | 2019-02-22 | 肥东县鑫丰生态农业有限公司 | A kind of preservation method of Chinese pear |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115943987A (en) * | 2023-01-13 | 2023-04-11 | 贵州中康农业科技有限公司 | Fresh-keeping method and application of fresh kiwi fruits |
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Application publication date: 20200414 |