Foodborne microorganisms are the top threat to food safety and a global threat. The following summarizes 19 common types of microbial contamination in food for your reference.
01
Coliform group
The coliform group does not represent a single or specific genus of bacteria, but refers to a group of bacteria with certain characteristics that are associated with fecal contamination.
The coliforms are directly or indirectly derived from the feces of humans and warm blooded animals. Excessive levels of coliform bacteria in general food indicate contamination by feces from warm blooded animals, with typical coliform bacteria being recent fecal contamination and other bacterial genera possibly being old fecal contamination. Eating food with excessive coliforms may lead to intestinal infections, food poisoning, and other illnesses.
02
mould
Mold is a common name for filamentous fungi, meaning "moldy fungi". They often form densely branched mycelia, but do not produce large fruiting bodies like mushrooms. In damp and warm places, many objects grow visible fluffy, flocculent, or spider like colonies, which are called molds.
Fungi are ubiquitous in our lives and prefer warm and humid environments. Once there is a suitable environment, they will reproduce in large numbers. Measures must be taken to prevent the proliferation of fungi or cut off their transmission routes in order to get rid of fungal pollution.
Mold contamination of food not only reduces the quality of food consumption, but also produces mycotoxins. The main toxicity of mycotoxins to humans is manifested in neurological and endocrine disorders, immune suppression, carcinogenic and teratogenic effects, liver and kidney damage, and reproductive disorders.
03
yeast
Yeast is a group of single celled fungi, not a unit of systematic evolutionary classification. It is a general term for several families of single celled fungi, such as Ascomycota and Basidiomycota. It generally refers to various single celled fungi that can ferment sugars, some of which are beneficial for food processing, such as yeast and brewing yeast, while others are pathogenic bacteria.
There are a certain number of yeast in both the air and the human body, which can rapidly reproduce as long as they are in a suitable environment. Eating food contaminated with pathogenic yeast can easily cause food poisoning, and some people with low immunity may also develop yeast infections.
04
Staphylococcus aureus
Staphylococcus aureus is an important pathogenic bacterium in humans, belonging to the Staphylococcus genus and also known as "flesh loving bacteria". It is a representative of Gram positive bacteria and can cause many serious infections.
Staphylococcus aureus is ubiquitous in nature, found in air, water, dust, and human and animal excrement. Therefore, there are many opportunities for food contamination. The Centers for Disease Control and Prevention in the United States reports that infections caused by Staphylococcus aureus rank second only to Escherichia coli.
Staphylococcus aureus is the most common pathogen in human pyogenic infections, which can cause local pyogenic infections, as well as pneumonia, pseudomembranous colitis, pericarditis, and even systemic infections such as sepsis and sepsis.
05
Salmonella
Salmonella is a common foodborne pathogen. Some Salmonella species are specifically pathogenic to humans, some are only pathogenic to animals, and some are pathogenic to both humans and animals. Salmonellosis refers to the collective term for different forms of human, livestock, and wild animals caused by various types of Salmonella. Food contaminated with the feces of individuals or carriers infected with Salmonella can lead to food poisoning. According to statistics, among the types of bacterial food poisoning in various countries around the world, food poisoning caused by Salmonella often ranks first.
Salmonella mainly contaminates meat products, and fish, poultry, milk, and egg products can also be contaminated by this bacterium. Salmonella food poisoning can occur throughout the year, and consuming undercooked disease, dead livestock meat, or contaminated livestock meat at other stages after slaughter are the main causes of Salmonella food poisoning.
The main symptoms of food poisoning caused by Salmonella include nausea, vomiting, abdominal pain, headache, chills, and diarrhea, accompanied by fatigue, muscle soreness, blurred vision, moderate fever, restlessness, and drowsiness, lasting for 2-3 days, with an average mortality rate of 4.1%.
06
shigella
Shigella, commonly known as Shigella, is a type of dysentery bacterium. Shigella dysenteriae is the pathogenic bacterium that causes typical bacterial dysentery, and can be caused by a small number of individuals in sensitive populations.
Shigella food poisoning refers to bacterial food poisoning caused by Shigella. The main Shigella that causes food poisoning is Shigella sonnei. It mainly occurs in summer and autumn, and the food that causes poisoning is mainly hot meat products.
Shigella invades intestinal mucosal tissue and releases endotoxins, causing symptoms. The incubation period is generally 10-14 hours. Symptoms include severe abdominal pain, diarrhea (watery stools with blood and mucus), fever, and significant urgency and urgency. Severe cases may experience spasms and shock.
07
Hemolytic streptococcus
Streptococcus pyogenes, also known as Streptococcus pyogenes, is sensitive to both heat and chemical cleaning agents and often causes infections in the tonsils, throat, middle ear, and other areas. It is also a pathogen of pyelonephritis, puerperal fever, and scarlet fever.
Generally speaking, hemolytic streptococcus often contaminates food through the following pathways:
① Food contamination caused by purulent inflammation in the mouth, nose, hands, and face of food processing or sales personnel;
② When food is contaminated with bacteria before processing, or when cows suffer from purulent mastitis or local suppuration in livestock and poultry, certain parts of their milk and meat may become contaminated;
③ Cooked food products are contaminated due to poor packaging.
Streptococcus pyogenes can often cause purulent inflammation of the skin and subcutaneous tissues, respiratory infections, explosive outbreaks of epidemic pharyngitis, as well as allergic reactions such as neonatal sepsis, bacterial endocarditis, scarlet fever and rheumatic fever, and glomerulonephritis.
08
listeria
Listeria monocytogenes, also known as Listeria monocytogenes or Listeria monocytogenes, is a facultative anaerobic bacterium and the pathogen of Listeria monocytogenes. Listeria is a Gram positive bacterium belonging to the Firmicutes phylum, named after Joseph? Liszt. It is mainly transmitted through food and is one of the deadliest foodborne pathogens.
Listeria is ubiquitous in the environment and can be found in the vast majority of foods. Meat, eggs, poultry, seafood, dairy products, vegetables, etc. have all been confirmed as sources of Listeria infection. Listeria monocytogenes is a psychrophilic bacterium that can grow and reproduce at refrigeration temperatures and in salads.
Healthy adult individuals infected with Listeria monocytogenes may experience mild flu like symptoms. Newborns, pregnant women, and immunocompromised patients may present with shortness of breath, vomiting, hemorrhagic rash, purulent conjunctivitis, fever, convulsions, coma, spontaneous abortion, meningitis, sepsis, and even death.
09
Escherichia coli
Escherichia coli is a normal resident bacterium in the intestines of humans and animals. One of the pathogenic substances of Escherichia coli is plasma coagulase. According to their pathogenicity, diarrheal Escherichia coli is divided into five types: enterotoxigenic Escherichia coli, intestinal invasive Escherichia coli, intestinal pathogenic Escherichia coli, intestinal agglomerative adhesive Escherichia coli, and enterohemorrhagic Escherichia coli.
Common poisoned foods include various cooked meat products, cold meat, beef, and raw milk, followed by eggs and egg products, cheese and vegetables, fruits, beverages, and other foods. The main cause of poisoning is that contaminated food has not been thoroughly heated before consumption. Poisoning often occurs from March to September. The symptoms of poisoning caused by different types of diarrheal Escherichia coli vary.
10
Vibrio parahaemolyticus
Vibrio parahaemolyticus is a Gram negative bacterium that takes on various shapes such as arcs, rods, and filaments, and has no dental spores.
Eating food containing this bacterium can cause food poisoning, also known as halophilic food poisoning. The main clinical symptoms include acute onset, abdominal pain, vomiting, diarrhea, and watery stools. Vibrio parahaemolyticus is a marine bacterium mainly derived from seafood such as fish, shrimp, crabs, shellfish, and seaweed. This bacterium is sensitive to acid and can be killed in 5 minutes in regular vinegar; Weak resistance to heat.
11
Botulinum toxin
Botulinum toxin is a bacterium that grows in an anaerobic environment and has strong survival ability in canned and sealed pickled foods. It is one of the most toxic bacteria. Botulinum toxin is a deadly bacterium that secretes botulinum toxin during reproduction. This toxin is currently known as the most potent toxin and can inhibit the release of acetylcholine from cholinergic nerve endings, leading to muscle relaxation paralysis.
Botulinum toxin is widely distributed in nature, often detectable in soil, and occasionally present in animal feces. The gastrointestinal tract of the human body is a favorable hypoxic environment, suitable for the residence of botulinum toxin. Botulinum toxin belongs to anaerobic bacteria, strictly anaerobic. It can decompose glucose, maltose, and fructose in the gastrointestinal tract, produce acid and gas, and digest and decompose meat residue, making it black, rotten, and odorous. In anaerobic environments, this bacterium can secrete strong botulinum toxin, which can cause special symptoms of neurotoxicity, with extremely high disability and mortality rates.
Consuming food containing botulinum toxin can cause food poisoning, such as low acid canned foods (including iron cans and glass cans) with pH>4.6, or sausages and ham. After being infected with botulinum toxin, people may experience symptoms such as blurred vision, difficulty breathing, and muscle weakness. If the condition is severe, it may lead to death.
12
Vibrio cholerae
Vibrio cholerae is the pathogen of human cholera, which is one of the ancient and widely prevalent highly infectious diseases. It has caused multiple pandemics around the world, mainly manifested as severe vomiting, diarrhea, dehydration, and high mortality rates. It belongs to international quarantine infectious diseases.
Humans are the only susceptible individuals to Vibrio cholerae in natural conditions, and the main transmission routes are through contaminated water sources or undercooked food such as seafood and vegetables ingested orally. Overcrowded living, poor hygiene conditions, and especially public water sources are important factors causing outbreaks. The control in production mainly involves strict auditing of the source of raw materials and sterilization treatment in the production process.
13
proteus
Proteobacteria is a parasitic and pathogenic bacterium that affects both humans and animals. Widely distributed in nature, such as soil, water, garbage, decaying organic matter, and the intestines of humans or animals.
Can cause multiple infections. Poisoned food is mainly animal based, followed by soy products and cold dishes. The season of onset is mostly in summer and autumn, and the cause of poisoning is that contaminated food is not thoroughly heated before consumption. Proteus food poisoning is one of the common food poisoning cases in China. 2-30 hours after eating, there may be upper abdominal knife like pain and acute diarrhea, accompanied by nausea, vomiting, headache, and fever. The disease course is relatively short, usually takes 1-3 days to recover, and there are few deaths.
14
Campylobacter jejuni
The bacterial cells of Campylobacter jejuni are slightly curved and appear as punctate, resembling flies when observed under a dark field microscope. It has a capsule but does not form spores. The optimal temperature is 37-42 ℃. It cannot grow in normal atmosphere or anaerobic environment. Campylobacter jejuni is a normal host bacterium of various animals such as cattle, sheep, dogs, and poultry. There are a large number of bacteria in their reproductive tract or intestines, which can contaminate food and water through childbirth or excrement. The population is generally susceptible, and the incidence rate of children under 5 years old is the highest, which is more common in summer and autumn. Flies also play an important mediating role. It can also be infected through contact. Infected mothers can transmit the virus to their fetuses during childbirth.
Campylobacter jejuni has endotoxins that can invade the small and large intestinal mucosa, causing acute enteritis, as well as outbreaks of diarrhea or collective food poisoning. This bacterium can sometimes enter the bloodstream through the intestinal mucosa and cause sepsis and other organ infections, such as meningitis, arthritis, pyelonephritis, etc. Pregnant women infected with this bacterium can lead to miscarriage, premature birth, and can also infect newborns.
15
bacillus cereus
A species of Bacillus genus. Bacterial cells are rod-shaped, with square ends, forming short or long chains, and Gram positive. Bacillus cereus is associated with a small number of food poisoning cases (about 2-5%), including severe nausea, vomiting, and abdominal pain.
Generally speaking, bacterial food poisoning is caused by incorrect cooking methods that result in bacterial spores remaining on food. Worse still, if the food is not frozen in time, the spores may sprout. The result of bacterial reproduction is the production of enterotoxins, which can cause adverse symptoms such as vomiting and diarrhea when people consume food containing toxins.
16
flat sours
Acinetobacter is a microorganism that causes canned food to become sour and spoiled without gaining weight (i.e. producing acid but not gas), and is called Acinetobacter in the canned food industry. It is a facultative anaerobic spore forming bacterium. It is widely distributed in soil, dust, and various spoiled foods. Eating canned food that has spoiled due to ingestion of Pseudomonas aeruginosa can cause food poisoning, with symptoms such as diarrhea and vomiting.
17
yersinia
Yersinia belongs to Enterobacteriaceae, including more than ten strains of Yersinia pestis, Yersinia enterocolitica and Yersinia pseudotuberculosis, which is a kind of Gram negative bacilli.
The pathogenicity of Yersinia pestis, Yersinia enterocolitica and Yersinia pseudotuberculosis to human beings has been determined. Among them, Yersinia pestis has F1, V/W, Pgm, Pst1 and other important virulence factors. It is highly virulent, and a small number of bacteria can cause human disease. Bacteria of this genus usually first cause infections in rodents, livestock, birds, and other animals. Humans are infected through contact with infected animals, ingestion of contaminated food, or bites from arthropods.
18
Enterobacter sakazakii
Enterobacter sakazakii is a newly discovered pathogenic bacterium in dairy products in recent years. Enterobacter sakazakii can cause severe neonatal meningitis, enterocolitis, and bacteremia, with a mortality rate of over 50%. At present, microbiologists are not clear about the source of contamination by Escherichia coli, but many case reports indicate that infant formula powder is currently the main source of infection found.
19
Ascaris eggs
Ascaris eggs contaminate water and food through feces containing worm eggs. People who consume water and food contaminated with these eggs without boiling them will develop ascariasis. On the one hand, the control measures are strict control of the production process, and on the other hand, when eating fresh fruits and vegetables in daily life, they must be cleaned thoroughly.
conclusion
As can be seen from the above, consuming any food contaminated with the above-mentioned microorganisms can cause mild abdominal pain and diarrhea, and in severe cases, even death, indicating that food safety is no small matter. Therefore, as a manufacturer, whether it is strictly controlling the source of raw materials or controlling the production process, we cannot tolerate any carelessness.
Attachment: Summary of Basic Theoretical Knowledge of Food Heat Treatment and Sterilization
1. Food heat treatment
It is one of the most important processing methods used in food processing and preservation to improve food quality and extend food storage life. The main function is to kill pathogenic bacteria and other harmful microorganisms, inactivate enzymes, destroy unwanted or harmful components or factors in food, improve the quality and characteristics of food, and increase the availability and digestibility of nutrients in food. Of course, heat treatment also has certain negative effects, such as a significant impact on thermosensitive components, which can also cause adverse changes in the quality and characteristics of food, and consume a large amount of energy during the processing.
2. Industrial Cooking
As a pre-treatment process in food processing, it is usually adopted as a means of improving the sensory quality of food. Cooking usually includes several forms such as boiling, stewing, baking, frying, and roasting.
3. Baking
Baking and roasting are basically the same unit operations, both of which use high temperature to change the edible characteristics of food. The difference between the two is that baking is mainly used for noodles and fruits, while barbecue is mainly targeted at meat, nuts, and vegetables. Baking can also achieve a certain degree of sterilization and reduce the surface moisture activity of food, giving the product a certain degree of preservation. However, the storage period of baked goods is generally short, and combined with refrigeration and packaging, the storage period can be appropriately extended.
4. Deep frying
It is mainly a heat treatment method used to improve the edible quality of food. Deep frying can produce the unique color, aroma, and texture of fried foods. Fried processing also has certain bactericidal, enzyme killing, and reducing the water activity of food. The storage properties of fried foods are mainly determined by the water activity of the food after frying.
5. Hot ironing
Also known as blanching, blanching, or pre cooking. Mainly used for vegetables and certain fruits, it is usually a pre-treatment process before freezing, drying, or canning vegetables and fruits.
6. Hot extrusion
Squeezing is the process of placing food materials into an extruder, where the materials are compressed and melted by the screw, and then extruded through the mold outlet at the discharge end. Hot extrusion refers to the process of heating food materials during the squeezing process.
7. Thermal sterilization
It is a form of heat treatment primarily aimed at killing microorganisms. According to the different types of microorganisms to be killed, it can be divided into pasteurization and commercial sterilization. The methods of sterilization are usually divided based on pressure, temperature, time, heating medium and equipment, as well as the relationship between sterilization and canning sealing. Pressure can be used to divide sterilization into atmospheric pressure sterilization and pressurized sterilization; The heating medium for sterilization can be hot water, water vapor, a mixture of water vapor and air, and flames.
8. Damp heat sterilization
Sterilization method using steam, hot water as heat medium, or direct steam jet heating. Using a thermal energy converter (such as a boiler) to convert the heat energy of combustion into hot water or steam as a heating medium, and then transferring the heat energy of hot water or steam to food through a heat exchanger, or directly spraying steam into the food to be heated.
9. Atmospheric pressure sterilization
Mainly using water (also steam) as the heating medium, with a sterilization temperature of 100 ℃ or below, it is used for sterilizing acidic foods or low acidic foods with low sterilization requirements. During sterilization, canned goods are kept at normal pressure and are suitable for containers made of metal cans, glass bottles, and flexible packaging materials. There are intermittent and continuous sterilization equipment.
10. High pressure steam sterilization
Using saturated steam as the heating medium, the can is sterilized in saturated steam at a temperature above 100 ℃, and is used for sterilizing low acid foods. Due to the exhaust of air from the sterilization equipment during sterilization, it is beneficial for maintaining consistent temperature. At higher sterilization temperatures (with tank diameters above 102mm or below 102mm and temperatures above 121.1 ℃), air backpressure cooling is generally used for cooling. There are intermittent and continuous sterilization equipment, and cans can be stationary or rotating in the sterilization equipment. Rotary sterilization equipment can shorten sterilization time.
11. High pressure boiling for sterilization
Using water under air pressure as a heating medium, with a sterilization temperature above 100 ℃, it is mainly used for sterilizing low acid cans with glass bottles and soft materials as containers. During sterilization (including cooling), the can is submerged in water to ensure uniform heat transfer and prevent container damage caused by excessive pressure difference or temperature changes inside and outside the can. During sterilization, it is necessary to maintain good circulation of air and water to ensure uniform temperature. The sterilization equipment is mainly intermittent, but cans can maintain rotation during sterilization. When sterilizing soft cans, special trays (racks) are needed to place the soft cans to facilitate the circulation of heating media.
12. Air pressurized steam sterilization
It uses steam as the heating medium and adds compressed air to the sterilization equipment to increase the pressure outside the tank and reduce the pressure difference inside and outside the tank. Mainly used for high-temperature sterilization of glass bottles and soft cans. The sterilization temperature is above 100 ℃, and the sterilization equipment is intermittent. Its control requirements are strict, otherwise it may cause uneven temperature distribution inside the sterilization equipment during sterilization.
13. Flame sterilization
It is a high-temperature short-term sterilization method that uses flames to directly heat cans under normal pressure. During sterilization, the canned food is preheated and rolled over a high-temperature flame (temperature above 1300 ℃) to reach high temperature in a short period of time. After maintaining it for a short period of time, it is cooled by water spray. The food inside the can does not require soup as a medium for convective heat transfer, as the solid content in the contents is high. However, due to the high pressure inside the sterilization tank, it is generally only used for small metal tanks. The sterilization temperature of this method is difficult to control (usually determined by measuring the heat radiated from the can after addition).
14. Hot can sealing and sterilization
It is to heat treat the food before canning, then immediately seal the canned food while it is hot, and use the waste heat of the food to complete the sterilization or secondary sterilization of the sealed canned food. After meeting the sterilization requirements, the canned food is cooled. Mainly used for sterilizing acidic foods such as sauces and sauces. Sterilization equipment often uses tubular or sheet type, with high requirements for the cleanliness and sterility of the container. After sealing, the can is often inverted to ensure sterilization of the can lid.
15. Pre sterilized aseptic canning
It is to make the food meet the sterilization requirements during the pre sterilization process, then cool it to room temperature, and put it in a sterile container that has been sterilized and sealed (sealed) in a sterile state. Commonly used for sterilization of liquid and semi liquid foods. Pre sterilization is completed in the heat exchanger with a short time. Aseptic canning can be completed in aseptic packaging equipment or systems, and is a continuous high-temperature short-term or ultra-high temperature instantaneous sterilization method. Suitable for flexible packaging materials and metal/plastic containers.
16. DT value (exponential decay time)
It is the negative reciprocal of the slope of the thermal lethal rate curve, which can be considered as the time required to reduce 90% of viable bacteria (or spores) at a certain temperature, usually measured in minutes. Due to the fact that the thermal lethal rate curve is obtained at a certain heat treatment (lethal) temperature, in order to distinguish the D values of microorganisms at different temperatures, the temperature T of the heat treatment is generally used as a subscript and labeled on the D value, which is DT.
17. TDT value (thermal lethal time)
The time (in minutes) required to completely kill a certain concentration of live microorganisms (bacteria and spores) in food at a constant temperature (thermal lethal temperature) is generally represented by the TDT value, and the sterilization temperature is also marked in the lower right corner.
18. F-value (sterilization value)
It refers to the time (in minutes) required to completely kill a certain number of microorganisms at a certain lethal temperature.
19. Z value
The temperature value that needs to be increased or decreased when the heat induced lethal time decreases by 1/10 or increases by 10 times is generally represented by the Z-value. The Z-value is a scale used to measure the rate of microbial death and extinction during temperature changes.
20. TRT value (thermal index decay time)
The heat treatment time required to reduce the number of bacteria or spores to 10-n at a specific heat death temperature. It refers to the time (in minutes) required to reduce the viable number of microorganisms to a certain degree, such as 10-n or 1/10n (i.e. 1/10n of the original viable number), at a certain lethal temperature, denoted as TRTn, in minutes, where n is the decreasing index.
21. Acidic foods
Refers to food with a natural pH ≤ 4.6. For tomatoes, pears, pineapples, and their juices, pH＜4.7， Regarding figs, pH≤4.9， Also known as acidic food.
22. Low acidity foods
Refers to any food with a final equilibrium pH greater than 4.6 and aw greater than 0.85, including low acidity fruits and vegetable products that have been acidified to reduce pH. It does not include tomatoes, pears, pineapples and their juices with pH less than 4.7, and figs with pH ≤ 4.9.
23. Acidified foods
It refers to foods that add acid or acidic foods to achieve a final equilibrium pH of ≤ 4.6 and aw>0.85. They are also known as pickled foods. When processing food, adding acid appropriately can increase the acidity of the food to inhibit the growth of microorganisms (usually mainly Clostridium botulinum spores), reduce or shorten the sterilization temperature or time, which is called acidified food.
24. Can be refrigerated
When canned food is heated, this point has the slowest temperature change and is often used as the temperature point representing the temperature change of the food inside the canned container. The temperature at this point is the lowest during heating (also known as the lowest heating temperature point), and the temperature at this point is the highest during cooling. During heat treatment, if the food at the cold point meets the requirements for heat treatment, then the food in other parts of the can will definitely meet or exceed the required degree of heat treatment.
25. Thermal lethal time
The thermal lethal time curve is obtained using a method similar to the thermal lethal rate curve. It plots the TDT value with the corresponding temperature T on a semi logarithmic coordinate to obtain a thermal lethal time curve similar to the lethal rate curve.
26. Arrhenius equation
Reflecting the relationship between thermal destruction reaction and temperature, i.e. reaction kinetics theory.
27. Temperature coefficient Q value
Describe the effect of temperature on the reaction system. The Q value represents how much faster the reaction rate is at temperature T2 than at lower temperature T1. If the Q value represents the increase in reaction rate when the temperature increases by 10 ℃, it is generally referred to as Q10.
28. Non thermal sterilization
During the sterilization process, the temperature of the food does not rise or rises very low, which is beneficial for maintaining the physiological activity of the functional ingredients in the food, as well as for preserving the color, aroma, taste, and nutritional components. Non thermal sterilization technology mainly includes physical sterilization and chemical sterilization. Non thermal physical sterilization is achieved through physical means such as electromagnetic waves, pressure, light, etc., while chemical sterilization is achieved through the use of chemical reagents.
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