Salmonella, E. coli and botulism are a few of the bacteria we're warned that can come from eating contaminated, undercooked or improperly stored food. Nausea, diarrhoea and neurological complications are a few of the issues food-borne bacteria can cause. However, some bacteria are necessary to make foods or to give them tastes and textures. In some cases, such as with yoghurt, eating foods with live bacteria cultures can have health benefits. Scientists believe good bacteria in food, also known as probiotics, can help bodies process mineral and nutrients, as well as fend off certain pathogens. Whether the bacteria in a food affects someone's health for better or worse depends on the type ingested.
The most common type of food that intentionally contains bacteria is dairy. Food producers need curdled milk in order to make cheese, and in order to make curds, they need bacteria. The type of bacteria used depends on the type of cheese being made. Swiss cheese requires the bacteria propionibacterium shermanii in order for holes to form, whereas Limburger's brevibacterium linens gives the cheese its notorious smell.
Many of the harmful bacteria in food can cause stomach-related problems. The bacteria in yoghurt does the opposite and helps the digestive process. Yoghurt, one of the most common fermented milk products, contains lactobacilli bacteria, which break down lactose into lactic acid. People with lactose intolerances can experience painful stomach problems if they eat regular dairy products, but lactic acid is much easier to digest, and it can help regulate metabolism.
A key ingredient in most bread products is yeast. The bacteria in baker's yeast, saccharomyces cerevisiae, breaks down enzymes and creates carbon dioxide, which in turn causes dough to rise and gives it its texture. In sourdough bread especially, the bacteria gives it its characteristic sour taste. Yeast bacteria are also elemental in the fermentation of beer and wine.
Pickled foods such as sauerkraut require lactic acid bacteria. Dill pickles, for example, are fermented cucumbers. Fermentation begins with the streptococci bacteria. As the process continues, other types of bacteria carry on the fermentation. The vinegar used in most pickling recipes is also a product of bacterial fermentation. Other non-pickled foods, such as olives, also need to ferment with help from bacteria before they are edible.
Bacteria in meat can cause serious illnesses, though some products use them in small amounts of fermentation. Salami, bologna and sausages need lactic acid, Pediococcus and other types of bacteria for fermentation. Sushi also requires lactobacilli bacteria for fermentation. The lactic acid bacteria can actually prevent some food-borne illnesses because it kills listeria in cured meats.