GB/T 4789.26-2003 Microbiological examination of food hygiene - Examination of commercial sterility of canned foods

This standard specifies the basic requirements, operating procedures and result judgment of commercial sterility test of canned food. This standard is applicable to canned food that is packaged in various sealed containers, has achieved commercial sterility after appropriate heat sterilization, and can be stored for a long time at room temperature. GB/T 4789.26-2003 Food Hygiene Microbiological Test Commercial Sterility Test of Canned Food GB/T4789.26-2003 Standard Download Decompression Password: www.bzxz.net

ICS07.100.30
National Standard of the People's Republic of China
GB/T4789.26—2003
Replaces GB/T4789.26—1994
Microbiological examination of food hygiene
Examination of commercial sterilization of canned food
Microbiological examination of food hygiene-Examination of commercial sterilization of canned foodPromulgated on August 11, 2003
Ministry of Health of the People's Republic of China
Standardization Administration of the People's Republic of China
Implementation on January 1, 2004
GB/T4789.26—2003
This standard revise GB/T4789.26—1994 "Microbiological examination of food hygiene-Examination of commercial sterilization of canned food". Compared with GB/T4789.26-1994, the main changes of this standard are as follows: the format and text of the standard text are modified in accordance with GB/T1.1-2000. The "equipment and materials" in the original standard are modified and standardized. From the date of implementation of this standard, GB/T4789.26-1994 will be abolished at the same time. Appendix A of this standard is a normative appendix, and Appendix B is an informative appendix. This standard is proposed and managed by the Ministry of Health of the People's Republic of China. The drafting units of this standard are: Light Industry Food Fermentation Industry Science Research Institute, Tianjin Import and Export Commodity Inspection Bureau, Nutrition and Food Safety Institute of China Center for Disease Control and Prevention, Fujian Food Hygiene Supervision and Inspection Institute. The main drafters of this standard are: Chen Xihao, Zhang Sichuan, Hao Shihai, Bai Jingyu, Liu Renhan, Liu Naiqiao, Shang Baoying. This standard was first issued in 1989, revised for the first time in 1994, and this is the second revision. 178
1 Scope
Microbiological Examination of Food Hygiene
Testing of Commercial Sterility of Canned Food
This standard specifies the basic requirements, operating procedures and result judgment of commercial sterility test of canned food. GB/T4789.26—2003
This standard applies to canned foods that are packaged in various sealed containers, commercially sterilized after appropriate heat sterilization, and can be stored for a long time at room temperature.
2 Normative References
The clauses in the following documents become the clauses of this standard through reference in this standard. For any dated referenced document, all subsequent amendments (excluding errata) or revisions are not applicable to this standard. However, the parties to the agreement based on this standard are encouraged to study whether the latest versions of these documents can be used. For any undated referenced document, the latest version shall apply to this standard. GB/T4789.12 Microbiological examination of food hygiene Inspection of Clostridium botulinum and botulinum toxin GB/T4789.28-2003 Microbiological examination of food hygiene Staining methods, culture media and reagents 3 Terms and definitions
The following terms and definitions apply to this standard. 3.1
Commercial sterilization of canned food After appropriate heat sterilization, canned food does not contain pathogenic microorganisms, nor does it contain non-pathogenic microorganisms that can reproduce in it at normal temperature. This state is called commercial sterility. 3.2
The state in which a food container can prevent microorganisms from entering after being sealed. 3.3
Swell
The phenomenon that one or both ends of the can are bulging outwards due to the formation of positive pressure caused by the microbial activity or chemical reaction in the can to produce gas. 3.4
Jeakage
The sealing structure of the can is defective, or the seal is damaged due to impact, or the can wall is corroded and perforated, resulting in the invasion of microorganisms. 3.5
Low-acid canned food Low-acid canned food Except for alcoholic beverages, all canned foods with a balanced pH value greater than 4.6 and a water activity value greater than 0.85 after sterilization, which are originally low-acid fruits, vegetables or vegetable products, and acid is added to lower the pH value for the purpose of heating sterilization, are acidified low-acid canned foods. 3.6
Acid canned food Acid canned food
Canned food with a balanced pH value of 4.6 or less after sterilization. Tomatoes, pears and pineapples with a pH value less than 4.7 and juice made from them, as well as figs with a pH value less than 4.9 are all considered acidic foods. 179
GB/T4789.26—2003
4 Equipment and instrumentswwW.bzxz.Net
4.1 Refrigerator: 0℃～4℃,
4.2 Constant temperature incubator: 30℃±1℃, 36℃±1℃55℃±1℃; 4.3 Constant temperature water bath: 46℃±1℃.
4.4 Microscope: 10×~100×.
4.5 Rack-plate drug balance: 0g~500g, accuracy 0.5g. 4.6 Potentiometric pH meter.
Sterile pipette: 1mL (with 0.01mL scale), 10mL (with 0.1mL scale). 4.7
Sterile dish: 90mm in diameter
4.9Sterile test tube: 16mm×160mm
4.10Can opener and can puncher.
4.11White sugar porcelain plate.
Sterile tweezers.
5 Culture medium and reagents
5.1Gram staining solution; see 2.2 of GB/T4789.28—2003. 5.2Meat culture medium: see 4.67 of GB/T4789.28—2003. 5.3Bromocresol purple glucose broth: see Chapter A.1. 5.4 Acid broth: see Chapter A.2;
5.5 Malt broth: see Chapter A.3;
5.6 Manganese salt nutrient agar: see Chapter A.4; 5.7 Blood agar: see 4.6 of GB/T4789.28-2003. 5.8 Yolk agar see 4.68 of GB/T4789.28-2003. 6 Inspection steps
6.1 Review of production operation records
The factory inspection department shall carefully review the following operation records of the products submitted for inspection. They shall be properly preserved for at least three years for future reference. 6.1.1 Sterilization records: Sterilization records include the recording paper of the automatic recorder and the corresponding handwritten records. The product name, specification, production date and sterilizer number shall be marked on the recording paper. Each chart record shall be recorded and signed by the sterilizer operator in person, reviewed and signed by the workshop staff, and finally signed by the factory inspection department after approval. 6.1.2 Records of determination of effective chlorine content in cooling water after sterilization. 6.1.3 Canned food sealing test records: All records of canned food sealing test shall include routine inspection records of the quality of crimping and welding of empty and full cans. The records shall be clearly marked with batch number and number of cans, etc., and signed by the inspector and supervisor. 6.2 Sampling method
One of the following methods may be adopted.
6.2.1 Sampling by sterilization pot
Two cans of low-acid food cans shall be sampled from each sterilization pot after sterilization and cooling, one can of large cans over 3kg shall be sampled from each pot, and one can of acidic food cans shall be sampled from each pot. Generally, the products of each shift shall form an inspection batch, and the sample cans of each pot shall be grouped into a sample batch for inspection. The sampling base of each batch and each variety shall not be less than three cans. If the products are divided and stacked by pot, they can also be handled by pot when problems are caused by improper sterilization operation. 6.2.2 Sampling by production shift (batch)
6.2.2.1 The sampling number is 1/6000. If the last digit exceeds 2000, one more can shall be taken. Each shift (batch) shall not be less than three cans for each variety. 6.2.2.2 If the production of some products is large, the sampling number is 1/6000 based on 30,000 cans; if the production is more than 30,000 cans, it is calculated as 180
1/20000. If the last digit exceeds 4000 cans, one more can shall be taken. GB/T4789.26-—2003
6.2.2.3 If the production of some products is too small, the same variety and specification can be combined into one batch for sampling, but the total number of combined shifts shall not exceed 5,000 cans, and the sampling number of each batch shall not be less than three cans.
6.3 Weighing Pan
Use an electronic scale or a balance to weigh cans weighing 1kg or less to 1g, and cans weighing more than 1kg to 2g. The weight of each can minus the average weight of the empty can is the net weight of the can. Record and number the samples before weighing. 6.4 Insulation
6.4.1 All sample cans shall be kept warm at the specified temperature and for the specified time according to the following classifications. See Table 1. Table 1 Sample warming time and temperature
Canned food types
Low-acid canned food
Acid canned food
Low-acid food destined for tropical areas (above 40°C)
Temperature/°C
6.4.2 During the warming process, the cans shall be checked every day. If there are any bulging or leaking phenomena, they shall be immediately removed for opening inspection. 6.5 Canning
Time/d
Take all the cans that have been kept warm, cool them to room temperature, and then open them for inspection according to aseptic operation. Wash the sample cans with warm water and detergent, rinse with tap water, and wipe dry. Put them in a sterile room and irradiate them with ultraviolet light for 30 minutes.
Move the sample can to the clean bench, wipe the uncoded end with a 75% alcohol cotton ball, and burn it for sterilization (fat cans cannot be burned). Use a sterilized sanitary can opener or can puncher to open (shake cans with soup properly before opening), and do not damage the curling structure when opening the can. 6.6 Sample retention
After opening the can, use a sterilized pipette or other appropriate tools to aseptically remove 10mL (g) to 20mL (g) of the contents, move it into a sterilized container, and store it in a refrigerator. It can be discarded after the inspection of the batch of canned food has concluded. 6.7 PH determination
Take a sample to determine the pH value, and compare it with the normal cans in the same batch to see if there is a significant difference. 6.8 Sensory inspection
In a well-lit, clean and odor-free inspection room, pour the contents of the can into a white porcelain plate. Experienced inspectors will observe and smell the appearance, color, state and smell of the product, press the food with tableware or touch it with fingers wearing thin cots to identify whether the food has signs of spoilage.
6.9 Smear staining microscopy
6.9.1 Smear
Canned samples that are suspicious in sensory or pH inspection results and those that are not sensitive to pH response when spoiled (such as meat, poultry, fish, etc.) should be subjected to smear staining microscopy. For canned samples with soup, the soup can be picked up with an inoculation loop and smeared on a glass slide. Solid food can be smeared directly or diluted with a small amount of sterile saline before smearing. Fix with a flame after drying. After the smear of oily food is naturally dried and flame-fixed, it should be washed with xylene flow and dried naturally.
6.9.2 Staining and microscopic examination
Use Gram staining method to stain and microscopically examine at least five fields of view, record the staining reaction, morphological characteristics and bacterial counts in each field of view. Compare with normal samples of the same batch to determine whether there is obvious microbial proliferation. 6.10 Inoculation and culture
If there is bulging or leakage during the insulation period, or abnormal pH, sensory quality, corruption and deterioration are found during the can opening inspection, and further microscopic examination finds abnormal 181
GB/T4789.26-—2003
Normal number of bacteria in the sample cans, microbial inoculation and culture should be carried out in time. For the sample cans (or retained samples) that need to be inoculated and cultured, use sterilized appropriate tools to remove about 1mL (g) of the content, and inoculate and culture them separately. The inoculation volume is about one-tenth of the culture medium. It is required to be at 55℃ culture medium tubes, which should be preheated to this temperature in a 55℃ water bath before inoculation, and immediately placed in a 55℃ incubator for culture after inoculation.
6.10.1 The inoculation medium, tube number and culture conditions for low-acid canned foods (per can) are shown in Table 2. Inspection of low-acid canned foods
Culture medium
Blister meat culture
Blister meat culture
Bromcresol purple glucose broth (with inverted tube)
Bromcresol purple glucose broth (with inverted tube)6.10.2
Culture conditions/℃
36±1 (anaerobic)
55±1 (anaerobic)
36±1 (aerobic)
55±1 (aerobic)
The inoculation medium, tube number and culture conditions for acidic canned foods (per can) are shown in Table 3. Table 3 Inspection of acidic canned food
Culture medium
Acid broth
Acid broth
Malt broth
6.11 Inspection procedure and determination of microbial culture Culture conditions/℃
55±1 (aerobic)
30±1 (aerobic)
30±1 (aerobic)
Time/h
96~120
96~120
Time/h
6.11.1 Place the culture medium tubes inoculated according to Table 2 or Table 3 in a constant temperature incubator for cultivation, and observe the culture growth every day (see Figure 1).
GB/T4789.26-2003
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GB/T4789.26—2003
For the tubes of bromocresol purple broth with bacterial growth at 36℃, observe the acid and gas production, and smear staining and microscopic examination. If it is a mixed culture containing bacilli or cocci, yeast or mold If it is a pure culture of bacteria, no further testing is required; if there is only bacillus, it is judged to be a mesophilic aerobic bacillus; if there is only bacillus without spores, it is a mesophilic aerobic bacillus. If further confirmation is needed whether it is bacillus, it can be transferred to a manganese salt nutrient agar plate and cultured at 36°C before making a judgment. For the bromcresol purple broth tube with bacterial growth cultured at 55°C, observe the acid and gas production, and smear staining and microscopic examination. If there is bacillus, it is judged to be a thermophilic aerobic bacillus; if there is only bacillus without spores, it is It is judged to be a thermophilic aerobic bacillus. If further confirmation is needed whether it is a bacillus, it can be transferred to a manganese salt nutrient agar plate and cultured at 55°C before making a judgment. For the Erlich medium tube with bacterial growth at 36°C, smear staining and microscopic examination are performed. If it is a mixed bacterial phase without bacilli, no further progress is made; if there are bacilli, with or without spores, they must be transferred to two blood agar plates (or egg yolk agar plates) and cultured aerobically and anaerobically at 36°C respectively. If spores grow on the aerobic plate, If the bacteria grows as normal spores on the anaerobic plate, it is a mesophilic anaerobic bacillus. If it is a clostridium, the original culture medium of the meat culture medium should be used for the test of clostridium botulinum and botulinum toxin (according to GB/T4789.12).
For the meat culture medium tube with bacterial growth at 55℃, smear staining and microscopic examination. If there are spores, it is a thermophilic anaerobic bacillus or sulfide spoilage bacillus: if there are no spores but only bacilli, transfer to Manganese salt nutrient agar plate, anaerobically cultured at 55℃, if there are spores, it is thermophilic anaerobic bacillus, if there are no spores, it is thermophilic anaerobic bacillus. 6.11.2 Observe the acid broth and malt extract broth tubes with microbial growth, and smear staining and microscopic examination. Determine according to the type of microorganisms found.
6.12 Canned food sealing test
All sample cans that are determined to have microbial growth should be tested for sealing to determine whether the can is leaking, see Appendix B 7 Result determination
7.1 The production and operation records of this batch of (pot) canned food have been reviewed and found to be normal: the samples taken have no bulging or leakage after the insulation test; after the cans are opened after insulation, sensory inspection, pH measurement or smear microscopy, or inoculation and culture, it is confirmed that there is no microbial proliferation, which means it is commercially sterile. 7.2 The production and operation records of this batch of (pot) canned food have been reviewed and found to be normal; the samples taken have no bulging or leakage after the insulation test; or after the cans are opened after insulation, it is confirmed that there is no microbial proliferation, which means it is commercially sterile. After the can is opened, if the presence of microbial proliferation is confirmed through sensory inspection, pH measurement or smear microscopy and inoculation culture, it is non-commercially sterile.
A.1 Bromocresol purple glucose broth
A.1.1 Ingredients
Protein tannin
Beef extract
Glucose
Sodium chloride
Bromocresol purple
Distilled water
Appendix A
(Normative Appendix)
Special culture medium
0.04g (or 2mL of 1.6% alcohol solution)
1000mL
GB/T4789.26—2003
A.1.2 Preparation method
Heat and stir the above ingredients (except bromocresol purple) to dissolve, adjust the pH to 7.0±0.2, add bromocresol purple, and dispense into medium-sized test tubes with small inverted tubes, 10mL per tube, and sterilize at 121℃ for 10min. A.2 Acidic broth
A.2.1 Ingredients
Multivalent protein
Yeast extract
Glucose
Dipotassium hydrogen phosphate
Distilled water
A.2.2 Preparation method
1000mL
Heat and stir the above ingredients to dissolve, adjust to pH 5.0±0.2, sterilize at 121℃ for 15min, do not overheat. A.3 Malt soaking soup
A.3.1 Ingredients
Malt soaking
Distilled water
A.3.2 Preparation method
1000mL
Fully dissolve the malt extract in the steamed filling water, filter with filter paper, adjust to pH4.7±0.2, divide into packages, and sterilize at 121℃ for 15min. If there is no malt soaking, it can be prepared as follows: soak full and strong barley grains in warm water, place them in a warm place to germinate, and when the young sprouts reach 2cm in length, drain the remaining water, dry them thoroughly, and grind them into malt powder. When preparing the culture medium, take 30g of malt powder, add 300mL of water, mix well, soak at 60℃～70℃ for 1h, and suck out the upper layer of water. Add water and soak once again, take the upper layer of water, combine the upper layers of water twice, and add water to 1000mL, filter with filter paper. Adjust to pH4.7±0.2, divide into packages, and sterilize at 121℃ for 15min. A.4 Manganese salt nutrient agar
Prepare nutrient agar according to GB/T4789.28-2003, add 1 mL of manganese sulfate aqueous solution (3.08 g of manganese sulfate is dissolved in 100 mL of distilled water) for every 1000 mL. Observe the spore formation for no longer than 10 days. 185
GB/T4789.26-2003
Appendix B
(Informative Appendix)
Test method for canned food sealing
Dry the cleaned empty cans at 35℃, and conduct pressure or pressure leak test according to the equipment conditions of each unit. B.1
Pressure leak test
Carefully fill the dried empty cans with clean water until 80% to 90% full, and properly place a plexiglass plate with a rubber ring on the curled edge of the open end of the can to keep it sealed. Start the vacuum pump, close the vent valve, press the cover plate with your hand, control the air pumping, and make the vacuum gauge rise from 0Pa to 6.8×10tPa (510mmHg) for more than 1 minute, and maintain this vacuum for more than 1 minute. Tilt the empty tank and carefully observe whether there are bubbles at the bottom cover curling and weld inside the tank. If bubbles are continuously generated in the same part, it should be judged as a leak. Record the time and vacuum degree of the slip, and mark the leaking part.
B.2 Pressurized leak test
Plug the opening of the empty tank with a rubber stopper, start the air compressor, slowly open the valve, and gradually increase the pressure in the tank. At the same time, immerse the empty tank in a glass tank filled with water, and carefully observe whether there are bubbles at the bottom cover curling and weld outside the tank, until the pressure rises to 0.7kg/cm2 and maintains for 2 minutes. If bubbles are continuously generated in the same part, it should be judged as a leak. Record the time and pressure of the leak, and mark the leaking part. 186
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