Bacteria <\/p>\n
Bacteria are both the largest group of food pathogens and microorganisms. They may be single-cell organisms, but it is within this group of microorganisms that some of the most deadly food pathogens exist. <\/p>\n
\u201cThey are very important to the food processor,\u201d Cutter said. Only a few cells are needed to infect a consumer with a major, hospitalizing illness. <\/p>\n
There are a variety of different types of bacteria, categorized by shape such as rods or spirals and formation of cell wall such as gram-positive or negative. <\/p>\n
Bacteria reproduce by binary fission, which is when one cell divides itself into two identical cells. Each cell has this ability, so once bacteria begin growing, they grow exponentially. Some bacteria, such as Bacillus and Clostridium, are able to produce endospores when conditions are inhospitable. These endospores are resistant to heat, drying, and chemicals \u2014 waiting until conditions are right before they start growing. <\/p>\n
\u201cThis division occurs when there\u2019s enough food, enough time, when the cells are happy,\u201d Cutter said. \u201cYou need to realize that when these conditions are right, these cells can grow in only a few minutes. Once they take off and start to grow, those two cells become four, become eight, and so forth. We want to do everything we can to control them in the lag stage \u2014 the time before they start growing.\u201d <\/p>\n
Fungi <\/p>\n
Molds are multi-cellular fungal organisms. They propagate by spores transported by air, insects, and animals. The biggest concern for molds in foods is related to spoilage, but molds also produce mycotoxins, toxins that are released by the growth of molds that can sicken consumers. <\/p>\n
Yeasts are one-cell fungi that reproduce by budding. They are mainly a problem in causing spoilage, particularly in hot dogs and ham. <\/p>\n
Viruses <\/p>\n
Viruses are submicroscopic, meaning they are very, very small \u2014 smaller than bacteria. They\u2019re also technically not a cellular organism. They\u2019re referred to as acellular in that they contain DNA or RNA inside a protein coat but that does not contain cellular processes. They are parasitic, infecting cells, including one-cell microorganisms. <\/p>\n
In slaughter facilities, viruses of most concern are enteric viruses, such as Hepatitis A or Norwalk virus or Rotovirus, which are brought in by humans. <\/p>\n
\u201cWe do know that these viruses can be transmitted by food,\u201d Cutter said, \u201cmost likely from people working in the plant.\u201d <\/p>\n
Viruses can be easily controlled by promoted good personal hygiene, such as frequent hand-washing, as well as making sure that no one is allowed to work at the plant if they are ill. <\/p>\n
Factors in Pathogen Growth <\/p>\n
Because each class of microorganism is different, it should not be surprising that each pathogen has different growth requirements and therefore controlling pathogens is not a one-size-fits-all scenario. <\/p>\n
Such factors that influence pathogen growth include: <\/p>\n
\u2022 Available Nutrients \u2014 This would be the living cells that the pathogen is infecting. <\/p>\n
\u2022 pH Range \u2014 Bacteria like a 4.0-8.8 pH, yeast like from 2.0-8.0, and molds like from 1.0-11.0. <\/p>\n
\u2022 Temperature \u2014 Microorganisms that cause spoilage like the environment to be 68-86 degrees F, human pathogens are more likely at 68-113 degrees F, but some food pathogens are able to proliferate in temperatures as low as 32 degrees F up to 113 degrees F. <\/p>\n
\u2022 Available Oxygen \u2014 Some microorganisms require free oxygen, while others like Clostridium need an oxygen-free environment to grow; still, there are some such as Lactobacillus and yeast that can grow with or without oxygen. <\/p>\n
\u2022 Available Free Moisture \u2014 Microorganism growth can be discouraged by dehydrating meats, such as with jerky, but some processing techniques that add sugar actually encourage growth. To give perspective, water in its free-flowing, liquid state represents a free moisture value of 1.0. Raw chicken or tomatoes would have a value of 0.95, cocoa powder at 0.40, and dried milk at 0.20. Bacteria like the environment to rate at 0.90-0.99, yeasts like it to be about 0.87, and molds like it to be 0.70. This is why chemical preservatives such as sodium benzoate in foods is used widespread, and why it\u2019s important to use a sanitizer on surfaces, Cutter said. <\/p>\n
Of course, pathogen control is much more complicated than going down a checklist pertaining to each of these factors. \u201cYou have to look at each of these factors together, how microbial load, temperature, and time work together or temperature, pH, and water,\u201d Cutter said. <\/p>\n
Specific Pathogens <\/p>\n
All food pathogens are important to be aware of, but there are a few \u2014 mainly bacteria \u2014 that food processors have to pay particular attention to. These are the pathogens that cause the most concern leading to food recalls or national food safety warnings: <\/p>\n
\u2022 Salmonella \u2014 This bacterium causes fever, vomiting, diarrhea, and sometimes arthritis. The infective dose can be as little as 20 cells. Onset of illness is typically 12 to 14 hours after ingestion of the infected meat. Symptoms usually last two or three days, but some people can get a case of reactive arthritis two to three months later. Salmonella is associated with undercooked meat, poultry, eggs, cereal, peanut butter, and produce; it can survive in dry and\/or refrigerated foods for prolonged periods of time. This pathogen can grow with or without oxygen and in a wide range of pH, 4.5-9.5, and temperature, from 35-129 degrees F. Salmonella\u2019s primary source of contamination is the intestinal tract of animals, but another source is birds, insects, and contaminated eggs and produce. <\/p>\n
\u2022 E. coli O157:H7 \u2014 This bacterium causes bloody diarrhea and sometimes kidney failure due to hemolytic uremic syndrome. This is an extremely deadly strain of E. coli; in fact, half of all people infected by this pathogen require dialysis. It is associated with undercooked beef, particularly ground meat, contaminated with manure. This pathogen can grow with or without oxygen, and meat needs to be cooked to a high temperature in order to kill the bacteria. It\u2019s important to prevent cross-contamination between manure and the carcass or meat cuts. <\/p>\n
\u2022 Camphobacter \u2014 This bacterium causes bloody diarrhea, fever, and sometimes partial paralysis. It is associated with meat and poultry. This pathogen is very difficult to grow in a laboratory setting, because it requires very low amounts of oxygen and is very sensitive to drying. Contamination sources include rodents and birds, livestock, and water. <\/p>\n
\u2022 Listeria \u2014 This bacterium causes meningitis, septicemia, and abortion. In particular, risk groups are pregnant women and immune-suppressed individuals. It is associated with deli meats, ice cream, and cabbage. It likes environments that are cold and moist, with a low pH, and contamination sources can be any animals, plants, or water. Listeria won\u2019t grow in high-salt situations, such as in brine solutions, but it will still survive, waiting for a more ideal environment. To control this hardy pathogen, it\u2019s important to evaluate transfer points in the facility, as it often enters the plant on the underside of workers\u2019 shoes. It\u2019s also important to control moisture, getting rid of any standing water. And, Cutter said, keep in mind that freezing will not kill this pathogen. <\/p>\n
\u2022 Spoilage Organisms \u2014 While some of these pathogens have the potential to sicken consumers, the bigger concern is that they shorten shelf life. In this category are bacteria such as Streptococcus, Lactobacillus, Lactococcus, Pediococcus, and Clostridium; yeasts; and molds. <\/p>\n
Meat Processors <\/p>\n
The best strategy for controlling pathogen growth is prevention, and the number-one tool in prevention is testing the meat, equipment, and other surfaces around the facility for pathogens, said Bucknavage. There are two types of tests considered standard \u2014 one that tests for the presence or the absence of pathogens, and the other that goes for an actual count of pathogens. <\/p>\n
Counts, such as the Aerobic Plate or the Fecal Coliform, are better for detecting aerobic pathogens, those requiring oxygen to grow, but are not great at assessing spoilage. Presence\/absence analyses, such as ELISA or PCR or PFGE, are better for testing of various locations around the plant; the majority of testing will be done on phones, forklifts, or the slaughter equipment, although random sampling should also be done of food products, surfaces, people, and even air. <\/p>\n
\u201cThe larger number of samples you take, the greater chance you have to find a pathogen,\u201d Bucknavage said. For example, taking 15 samples versus 60 increases the risk of missing a pathogen by 50 percent. <\/p>\n
The purpose of testing is to determine how to move forward with a sanitation plan, Bucknavage said. \u201cWe can start to see trends, if counts start to pop up.\u201d <\/p>\n<\/p>\n
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\nMicrobiology 101<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"