Commercial sterility of canned food refers to a relatively sterile state in which there are no pathogenic microorganisms and non-pathogenic microorganisms that can reproduce in the canned food after the canned food has undergone moderate heat sterilization treatment, is an important prerequisite for canned food to achieve a longer shelf life on the basis of ensuring food safety and quality. The commercial sterility of canned food in food microbiological testing is characterized by relative sterility, no pathogenic microorganisms, and no microorganisms that can multiply in cans at room temperature.
In order to achieve acceptable commercial sterility standards, the canned food production process typically includes processes such as raw material pretreatment, canning, sealing, proper sterilization, and packaging. Manufacturers with more advanced production technology and higher quality control requirements have more complex and perfect production processes.
The commercial canned sterility inspection technology in food microbiological inspection has been relatively complete, and the analysis of its specific process is conducive to better use of this technology in practical operations to ensure the food safety of canned food. The specific process of canned commercial sterility inspection in food microbiological inspection is as follows (some more stringent third-party inspection agencies may have more inspection items):
1. Canned bacterial culture
Canned bacterial culture is one of the important processes in the commercial sterility inspection of canned food. By professionally culturing the contents of canned samples, and screening and checking the cultured bacterial colonies, the microbial components in canned food can be evaluated.
Common pathogenic microorganisms in cans include but are not limited to thermophilic bacteria, such as Bacillus stearothermophilus, Bacillus coagulans, Clostridium saccharolyticus, Clostridium niger, etc.; mesophilic anaerobic bacteria, such as botulinum toxin Clostridium, Clostridium spoilage, Clostridium butyricum, Clostridium pasteurianum, etc.; Mesophilic aerobic bacteria, such as Bacillus subtilis, Bacillus cereus, etc.; Non-spore-producing bacteria such as Escherichia coli, Streptococcus, yeast And mold, heat-resistant mold and so on. Before carrying out canned bacterial culture, be sure to measure the pH of the can in order to select the appropriate medium.
2. Sampling of test material
The sampling method is generally used for the sampling of experimental materials of canned food. When testing large batches of canned food, sampling is generally carried out according to factors such as the manufacturer, trademark, variety, source of canned food or production time. For abnormal cans such as rusted cans, deflated cans, dents, and swellings in the circulation of merchants and warehouses, specific sampling is generally carried out according to the situation. It is the basic requirement for the sampling of experimental materials to select the appropriate sampling method according to the actual situation, so as to obtain the experimental materials reflecting the quality of canned food.
3. Reserve sample
Before sample retention, operations such as weighing, keeping warm, and opening cans are required. Weigh the net weight of the can separately, depending on the type of can, it needs to be accurate to 1g or 2g. Combined with pH and temperature, the cans are kept at a constant temperature for 10 days; the cans that are fat or leaked during the process should be picked out immediately for inspection. After the heat preservation process is over, place the can at room temperature for aseptic opening. After opening the can, use appropriate tools to take 10-20 mg of the content in advance in a sterile state, transfer it into a sterilized container, and store it in the refrigerator.
4. Low acid food culture
The cultivation of low-acid foods requires special methods: cultivation of brompotassium purple broth at 36 °C, cultivation of brompotassium purple broth at 55 °C, and cultivation of cooked meat medium at 36 °C. The results are smeared and stained, and more precise screening is arranged after microscopic examination, so as to ensure the objective accuracy of the bacterial species identification experiment in low-acid foods. When culturing in the medium, focus on observing the acid production and gas production of the microbial colonies on the medium, as well as the appearance and color of the colonies, so as to confirm the specific microbial species in the food.
5. Microscopic examination
Microscopic smear examination is the most commonly used primary screening method for canned commercial sterility testing, which requires experienced quality inspectors to complete. In a sterile environment, using aseptic operation, smear the bacterial liquid of the microorganisms contained in the canned samples that have been cultured at a constant temperature in the medium, and observe the appearance of the bacteria under a high-power microscope, so as to determine the types of microorganisms in the bacterial liquid. Screening, and arrange the next step of refined culture and identification to further confirm the type of bacteria contained in the can. This step requires extremely high professional quality of the inspectors, and has also become a link that can best test the professional knowledge and skills of the inspectors.
6. Cultivation test for acidic food with pH below 4.6
For acidic foods with a pH value lower than 4.6, the food poisoning bacteria test is generally no longer required. In the specific cultivation process, in addition to using the acidic broth material as the medium, it is also necessary to use the malt extract broth as the medium for cultivation. By smearing and microscopic examination of the cultured bacterial colonies, the types of bacteria in acid cans can be determined, so as to further make a more objective and true evaluation of the food safety of acid cans.
Post time: Aug-10-2022