Foodborne pathogens are microorganisms that cause diseases in humans by contaminating food. Improving the detection level of pathogenic microorganisms is an essential measure to enhance food safety. Currently, the main contents of food microbiological testing are as follows.
A colony refers to a visible cluster of bacteria formed by the growth and reproduction of bacteria on solid culture media. It is also called a single clone, which is composed of a large number of identical bacteria aggregates. According to national standard methods, the total colony count is the number of bacteria growing on a plate count agar plate at 36±1℃ and aerobic conditions for 48±2h (water product at 30±1℃ and cultured for 72±3h). The number of colonies in food indicates the rate of food spoilage and may even cause illness in consumers. Therefore, the colony count can be used as an indicator for evaluating food hygiene. The number of colonies does not represent the number of pathogenic bacteria in food, but the higher the colony count, the greater the probability of infection from pathogenic bacteria.
Coliforms are normal bacteria in the intestinal tract of the human body, including various pathogenic bacteria. According to national standards, coliforms are aerobic and facultative anaerobic gram-negative bacteria that can ferment lactose and produce acid and gas under certain conditions. When the amount of coliforms in food is high, it indicates a greater risk of direct or indirect contamination by feces, and the possibility of infection by intestinal pathogenic bacteria in consumers also increases. Therefore, coliforms are one of the indicator bacteria for microbiology test in food industry.
Molds and yeasts are widely present and can accelerate food spoilage under certain conditions, such as high humidity, low temperature, high sugar content, and low pH value. Molds and yeasts can also synthesize toxic metabolites such as mycotoxins, which can cause discomfort and illness in consumers. Therefore, molds and yeasts are also indicators for evaluating food hygiene. It is very necessary to use a microbiology lab kit to detect mold and yeast in food microbiology testing. Currently, many types of food have clear limits on the quantity of molds and yeasts in national standards.
Salmonella is the most common foodborne pathogen and is one of the most commonly detected pathogens in food microbiology exam. There are more than 2,000 serotypes and types of Salmonella, which is one of the main pathogens causing food poisoning in humans worldwide. The detection of Salmonella is an important step in the diagnosis and prevention of Salmonella poisoning, and there are standard tests for Salmonella detection both domestically and internationally.
Staphylococcus aureus is widely distributed in nature, and can survive in the air, water, and excreta of humans and animals. It can contaminate various foods, such as meat, fish, eggs, and processed foods. In recent years, there have been reports of poisonings caused by leftovers, fried eggs, and jelly noodles.
Common foodborne pathogens include E. coli O157:H7, Lactobacillus, Vibrio parahaemolyticus, Aeromonas hydrophila, Bacillus cereus, Shigella, Streptococcus pyogenes, Clostridium perfringens, Pseudomonas aeruginosa, Listeria monocytogenes, Candida albicans, and others. Different foods have different nutrient compositions and storage conditions, and thus require different types of pathogen testing. For example, Vibrio parahaemolyticus mainly contaminates aquatic products and meat products; Sakazakii is commonly detected in infant formula foods; Candida albicans is a mandatory test item for honey. Lactobacillus is a probiotic in yogurt.
In the long-term production and life, humans are constantly exploring ways to suppress harmful microorganisms and use beneficial microorganisms. Microorganisms in food are closely related to human survival and health. Understanding the contents of food microbiological testing and adopting effective control measures in life can reduce the chance of infection by pathogenic microorganisms to the greatest extent possible. Food microbiology testing technology is a powerful weapon to ensure food safety, and understanding the contents of food microbiology exam and pursuing technological progress is of great significance for food safety.
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