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Thursday, January 15, 2009

Fermentable Facts: Lactobacillus

With all the news about bad bacteria (Salmonella, Listeria, E.coli) in the press, I thought it was time to talk about some good bacteria. Today’s helpful bacteria is Lactobacillus. Lactobacillus are, (in microbiology speak), regular, non-spore forming, gram positive rods. They are found naturally on plants, in our bodies (and those of other warm blooded animals), and in foods – fermented foods. As is you may guess by their name, they produce lactic acid as a by-product of fermentation.

Fermentation is not new – it has been around for ages. It happened naturally, unaided but not unnoticed by man, who saw that some foods underwent a transformation which affected both the appearance and flavor. They also noticed that this change kept food safe to eat for longer periods of time as compared to fresh food; thus it became a preservation method. The definition of fermentation is the breakdown of carbohydrates or carbohydrate-like materials, under anaerobic (lack of oxygen) conditions. And Lactobacillus species are among some of the most common fermenters used in foods.

Lactobacillus changes cucumbers into pickles, cabbage into sauerkraut, meat into salami and milk into sour cream, yogurt and cheese. But in addition to making these tasty treats, they have the ability to inhibit the growth of food spoilage and pathogenic bacteria that may also be present in the food (this is called lactic antagonism). While not fully understood, it is likely to be due to a combination of lowered pH, the production of lactase and other inhibitory compounds and by outcompeting pathogens for nutrition.

These bugs and the compounds they produce during fermentation have some other great benefits as well:

1) improved digestive tract health – some species are used as probiotics (like L. casei, L. acidolphilus)
2) synthesize vitamins (Vitamin B12, folic acid)
3) enhanced immune system (link)
4) may help reduce the risk of colon cancer (link)
5) enhance the bioavailability of nutrients by breaking down indigestible plant materials

Too bad the helpful bacteria in our world get so little press. I’ll be discussing some other favorite fermenters in my next post – the kind that make alcohol, so please come back!

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