How to store apples in cold storage

Storage standard of apple cold storage

1. This standard is applicable to the cold storage of the following varieties of fresh apples.

1. 1 medium-ripe varieties, Marshal, Red Star, Red Crown, Ruby and Golden Crown.

1.2 Late-maturing varieties: Jiguan, Qinguan, Wojin, Sweet Banana, Green Banana, Daguoguang, Guoguang and Fuji.

2. This standard refers to the following standards.

2.1ISO121kloc-0/976 "Apple-Cold Storage Guide"

2.2 iso 2169-1981fruits and vegetables-physical conditions of cold storage-definition and measurement.

3. Quality requirements of stored apples

3. 1 Method for judging the maturity of apple suitable for cold storage

3. 1. 1 sensory index, the fruit of each variety should have the fruit type, size, color (including the color of pulp and seeds), texture and flavor of the variety, which can be judged by standard chromatogram or experience.

3. 1.2 hardness, measured by fruit hardness, is shown in table 1.

3. 1.3 The determination of chemical composition, suitable sugar (or soluble solids), acid content and solid-acid ratio can reflect the maturity of fruits. Generally, soluble solids are determined by sugar meter, and acid content is determined by titration.

3. 1.4 threshold of fruit growth and development. It takes a certain number of days for each variety from flowering to fruit ripening, so it is not advisable to pick it too early.

3. 1.5 The accumulated temperature of fruit growth refers to the highest and lowest temperatures recorded every day from flowering to the ninth week. The maturity and harvest time of apples can be determined by subtracting the average temperature from the basic temperature.

Daily calculation formula: maximum temperature+minimum temperature/2-7.2c.

3. 1.6 See Appendix B for iodine color reaction of starch content in fruits.

3. 1.7 Ethylene content of fruit, regularly sampling and determining ethylene content of fruit core in orchard to determine the suitable harvest time.

Any of the above methods to determine the suitable harvest time has its limitations, and the same variety has different performances in different regions. Only by using two or three methods at the same time can we get the correct results.

3.2 Basic indexes of apples before storage

The basic index wind table is 1 when the place of origin is put into storage, and the sales place should be re-sampled and determined before it is put into storage.

3.3 Quality requirements of stored fruits

The stored apples should be clean and fresh, without obvious mechanical damage, insect mouth and any visible fungal or bacterial infection spots. The mechanical damage to fruits at the place of origin should not exceed 3%; The mechanical damage of the underground warehouse during warehousing shall not exceed 10%.

3.4 Pretreatment and warehousing. After the fruit is harvested, it should be treated with necessary drugs, and the fruit should be precooled and cooled, and put into storage and refrigerated in time.

4. Refrigeration technology and quality requirements

4. 1 warehouse preparation

4. 1. 1 Before warehousing, the warehouse shall be disinfected and ventilated in time.

4. 1.2 When warehousing, the warehouse temperature shall be lowered to 0—-2C in advance.

4.2 Storage capacity

4.2. 1 Arrange the position, stacking form and height of goods reasonably according to different packaging containers. The arrangement, direction and gap of goods stacks should be consistent with the air circulation direction in the warehouse.

4.2.2 The storage density of the effective space should not exceed 250kg per cubic meter, and the storage capacity of the pallet for container loading is allowed to increase by 65,438+00%-20% to facilitate the cooling of the air circulation of the cargo stack.

4.2.3 In order to facilitate inspection, inventory and management, the stacking space should not be too large. After entering Man Ku, you should fill in the position label and the flat cargo map in time.

Cargo stacking requirements

4.2.4. 1 0.20-0.30m from the wall.

4.2.4.2 is not less than1.50m away from the air cooler.

4.2.4.3 is 0.50-0.60m from the top.

The distance between chimneys in 4.2.4.4 is 0.30-0.50 meters.

The width of the passage in 4.2.4.5 Library is 1.20- 1.80 meters.

The height of stow wood (stone) at the bottom of 4.2.4.6 Stack is 0. 10-0. 15m. .

4.3 Suitable cold storage conditions

Temperature +0

The storage of precooled apples is beneficial to quickly enter a new storage environment with suitable temperature. Try to avoid warehouse temperature fluctuation during storage, and require the warehouse temperature to enter the technical specification state within 48 hours after the warehouse is full. Suitable storage temperature of different varieties of apples.

4.3. 1. 1 temperature measurement, which can measure the warehouse temperature continuously or intermittently. The continuous measurement of temperature is completed by direct reading recorder, and manual observation is carried out when there is no recorder.

4.3. 1.2 The accuracy of temperature measuring instruments and thermometers shall not be greater than 0.5c.

4.3. 1.3 Selection and recording of temperature measuring points

The thermometer should be placed in a place without condensation, abnormal airflow, radiation, vibration and impact. The number of points depends on the storage capacity, that is, there are points for measuring the temperature of the fruiting body and points for measuring the air temperature (including the initial reflux point of the jet). Detailed records should be made after each measurement.

4.3. 1.4 Thermometer inspection

In order to make the measurement accurate, the thermometer should be calibrated at least once a year.

humidity

4.3.2. 1 The optimum relative humidity during storage is 85%-95%.

The accuracy of 4.3.2.2 humidity measuring instruments should be within 5%, and the selection of measuring points is the same as that of temperature measuring points.

airiness

The air cooler in the warehouse should maximize the uniform distribution of air temperature in the warehouse, narrow the spatial difference between temperature and relative temperature, and take out the gases and volatile substances produced by the metabolism of stored products from the packaging. The air speed between goods is 0.25-0.5 m/s.

ventilate

Due to the metabolic activity of apples, harmful gases such as ethylene and volatile substances (ethanol, acetaldehyde, etc.). ) will be discharged and accumulated. Therefore, in the initial stage of storage, proper ventilation can be provided at night or in the morning when the temperature is low, but the temperature and humidity in the warehouse should be prevented from fluctuating greatly.

4.4 Storage life and storage index.

4.4. 1 Under no circumstances shall the storage period be extended to affect the sales quality of apples. Therefore, it is necessary to conduct spot checks and handle problems in time. Expected storage life of different apple varieties.

4.4.2 When apples are put on the market, the hardness of apples stored for more than 4 months in the medium term shall not be less than 5.5 kg/cm; Long-term storage (more than 6 months) hardness is not less than 4.5kg/cm.

5, detection rules and detection methods

5. 1 The inspection rules for producing areas and stored fruits shall be implemented according to the national acquisition standards.

5.2 Before selling the land for storage, the quality of storage should be re-inspected.

5.2. 1 When the same variety, the same grade and the same train arrive and enter the warehouse at the same time, it can be regarded as an inspection lot.

5.2.2 The items filled in the inspection list shall be completely consistent with the goods. If the manifest is inconsistent and the variety and grade are confused, it shall be sorted before sampling.

5.2.3 Sampling personnel shall conduct packaging inspection at the same time of sampling. If the packaging container is seriously damaged, the fruit is seriously damaged mechanically and loses its storage value, it should be handled in time.

sampling method

5.2.4. 1 The samples taken must be representative, and samples should be taken in different parts of the whole batch according to the specified quantity. The inspection results of samples are applicable to the whole batch.

Sampling number of each batch of apples in 5.2.4.2: less than 50 is 2; 5 1- 100 take 3 pieces; If it exceeds 100 pieces, take 2 pieces out of 100 pieces as the base, and increase 1% for each additional 100 pieces.

5.3 Appearance quality inspection: check the samples one by one according to the specified items. Record each product on the incoming inspection record. After each batch of fruits is inspected, the inspection results are calculated to determine the purchase quantity of this batch of apples.

5.3. 1 Weight check: Calculate the received quantity based on the average of the sampled quantity of a single piece.

5.3.2 Fruiting body temperature: measured with a semiconductor point thermometer.

5.3.3 Mechanical damage and rotten fruit are determined by visual inspection, and the percentage is calculated by weighing.

5.4 Physical and chemical index inspection

5.4. 1 sample preparation: 5kg pillows with appropriate head size, color and maturity were selected from the large samples, and the fruits were washed and dried, and 20 fruits were selected for hardness measurement.

Degree and soluble solids of fruit samples. Cut the apples whose hardness has been determined into 8 petals one by one, and take one petal from each fruit. Peeling and digging out the inedible part of the core, placing it on an enamel plate or a glass plate, and cutting it into 1cm with a stainless steel knife.

Slice or knead into filaments, take the sample 150g by quartering method, add distilled water according to the ratio of 1: 1, and put it into a high-speed tissue masher, or quickly grind it into pulp with a mortar, and put it into a clean container. The prepared samples should be tested every day.

Just try it.

5.4.2 Determination of fruit hardness

5.4.2. 1 Instrument: fruit hardness tester

5.4.2.2 determination method: peel off the predetermined part of the center of the fruit sample, which is slightly larger than the area of the manometer probe, vertically align the manometer probe with the test part of the fruit surface, apply pressure until the designated part of the manometer probe presses into the pulp, and read it directly from the manometer dial. The hardness of fruit is expressed in kg/cm.

5.4.3 Determination of soluble solids

5.4.3. 1 instrument: handheld sugar meter.

5.4.3.2 determination method: correct the focal length and position of the instrument scale, open the auxiliary prism, take 1-2 drops of apple juice, filter it out with white polyester cloth, and drop it.

In the center of the prism plane, quickly close the auxiliary prism, let it stand for 1 min, and adjust the achromatic ring to the bright place of the light source, so that a clear light-dark dividing line appears in the field of vision, and the reading corresponding to the dividing line is that the sample juice is at 20℃.

Percentage of soluble solids contained in the table below. When the ambient temperature is not 20c, it can be corrected according to the compensation temperature in the instrument schedule. When continuously measuring different samples, clean them with clean water after each use.

Dry with lens paper before continuing the test.

Determination of total acid content

5.4.4. 1 instrument

5.4.4. 1. 1 alkali burette (0.05ml graduated or semi-micro burette)

5.4.4. 1.2 volumetric flask (250ml)

5.4.4. 1.3 conical flask (250ml)

5.4.4. 1.4 pipetting bottle (50ml)

5.4.4. 1.5 funnel, absorbent cotton

5.4.4.2 reagent:

5.4.4.2.10.1n sodium hydroxide standard solution: dissolve 4g chemically pure sodium hydroxide in a 1000ml volumetric flask, add distilled water to the scale, shake well, and concentrate according to the following standards.

Put chemically pure potassium hydrogen phthalate into a 120c oven, dry it for about 1 hour to constant weight, cool it for 25 minutes, weigh 0.3-0.4g (accurate to 0.000 1g), put it in a 250ml conical flask, and add 100ml distilled water to dissolve it.

Calculation formula: N=W/V*0.2042

Where: n is the equivalent concentration of sodium hydroxide standard solution.

V refers to the number of milliliters of sodium hydroxide standard solution consumed during titration.

W-weight of potassium hydrogen phthalate, g.

0.2042- 1n sodium hydroxide standard solution 1ml is equivalent to grams of potassium phthalate.

5.4.4.2.2 Phenolphthalein indicator (1% ethanol solution): weigh phenolphthalein 1g and dissolve it in 100ml neutral ethanol.

5.4.4.3 titration: Weigh 20g (accurate to 0.0 1) sample in a small beaker, boil it with 50-80ml distilled water and cool it, and mix the samples.

Rinse it into a 250ml volumetric flask, heat it in a 75-80c water bath for 30 minutes, shake it several times to dissolve it, cool it, add distilled water to the scale, shake it evenly, and filter it with absorbent cotton. Inhale 50ml of filtrate.

Add 3-5 drops 1% phenolphthalein indicator to a 250ml conical flask, and drop it to reddish color with 0. 1N sodium hydroxide standard solution.

Calculation formula: total acid content (%)=(V*N*K*5/W)* 100.

Where: V is the number of milliliters of sodium hydroxide standard solution consumed during titration.

Equivalent concentration of standard solution of n- sodium hydroxide.

K-coefficient converted into equivalent acid. Malic acid is 0.067.

W—— sample weight (20g sample solution is equivalent to 10g actual sample).

The allowable difference of parallel test results is 0.05%, and the average value is taken.

5.4.5 Determination of color reaction of starch content:

5.4.5. Preparation of1iodine solution: weigh potassium iodide 1g and iodine 0.2g and dissolve them in 100ml distilled water.

5.4.5.2 detection: select 10 samples to observe the starch content, cut the apple in half, take half, and smear the potassium iodide-iodine solution on the cross section.

Observe the degree of discoloration after 30 seconds.

Apple refrigeration is also called apple fresh-keeping storage, apple fresh-keeping storage, fruit fresh-keeping storage, fruit and vegetable fresh-keeping storage, fresh-keeping storage and modified atmosphere storage of fruits and vegetables. , mainly used for apple preservation and food preservation at low temperature. we will

According to the characteristics of the goods you store, choose the scheme that suits you best.