Fermentable Facts: Saccharomyces

Like last week's fermenting friend Lactobacillus, Saccharomyces is a very helpful little bug. Saccharomyces is a eukarotic, osmophillic yeast. And while there are many species in this genus, the most studied, and most used species is S. cerevisiae.

Fermentation using yeasts has been around for some 4000 years with evidence of breads and beer being found in Egyptian tombs. Yeasts are what turn dough into bread, malt into beer, molasses into rum, grapes into wine and rice into sake.

While the actual definition of fermentation, as I stated previously, is the breakdown of carbohydrates under anaerobic conditions, a common definition is the breakdown of sugars into carbon dioxide and alcohol under aerobic conditions. Saccharomyces species multiply better under aerobic conditions (which was used to great advantage by Charles Fleischmann in 1868 to produce the first commercially available yeast) but ferment better under anaerobic conditions like in a dough.

Obviously alcohol is not the by-product of fermentation we are looking for in bread; its the carbon dioxide that we want for leavening. However, the alcohol produced helps extract flavor compounds that are not water soluble and creates some of the characteristic flavors associated with baked bread. Saccharomyces cerevisiae is also known as baker's yeast and it is what you buy in those little envelopes at the grocery store.

Alcohol is what we want when making wine and beer, with the carbon dioxide adding a nice fizz. Saccaromyces ellipsoideus is used to ferment grape juice into wine. while two different species are used in beer manufacturing depending on what you are brewing. Saccharomyces cerevisiae is a top fermenter (top of the vessel) and produces ales while Saccharomyces pastorianus is a bottom fermenter and produces lagers. Yeasts are also used in the production of industrial ethanol for fuel.

So, what to take away from all of this? Well, how about that microorganisms can be your friend as well as your enemy and that they can make what we eat more fun to eat.

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!

2008 Recap

Happy New Year! Sorry for the extended absence - the Christmas holiday always is busy for me and I found I had too few hours in my day, so something had to give. I decided that today's post would be on three interesting topics from 2008 headlines.


Melamine

Wow - was this ever a topic in 2008; the Chinese milk scandal was covered around the world. Melamine, for those still wondering exactly the newscasters were talking about, is a chemical compound used in the making of plastics that contains nitrogen (C3H6N6) and that's important. You see, many high protein foods are priced by the quantity of protein present; the higher the protein levels the higher the price and the way we test for protein content is my measuring nitrogen levels. But the Chinese manufacturers wanted to sell protein they didn't have and bumped up their nitrogen levels with the addition of melamine. Not good - when used as a plasticizer, even for food contact surfaces, melamine is fine (although you should never put melamine in the microwave - it can melt and enter your food). But ingesting melamine is tough on your organs - especially for infants who's systems cannot handle toxins. The Chinese government has now stepped up inspections and testing and our own FDA and FSIS have increased the number of samples pulled and tested as well.

COOL

Mandatory Country of Origin Labeling (technically the: Food, Conservation, and Energy Act of 2008 expanded list of commodities). This new USDA/AMS regulation took effect on September 30, 2008. It is intended to provide consumers with information about the source of their: beef, veal, pork, lamb, goat, chicken, fish and shellfish (wild & farmed), perishable (fresh & frozen) fruits and vegetables, peanuts, pecans, macadamia nuts and ginseng. Whew! This information can be placed on a placard, sticker, twist tie, sign, band or pin tag as long as it is legible and conspicously located for the consumer. Of course there are always exceptions. All processed foods are excluded, so any food "that has undergone specific processing resulting in a change of character (e.g. cooking, curing, smoking, restructuring); or that has been combined with another food component" will not be subject to this rule. So roasted peanuts = no COOL, peanuts in shell = COOL; plain pork loin = COOL, teriyaki pork loin = no COOL. So while some are still not happy with the workings of this act, it should provide those concerned with the origins of some of the foods they eat with valuable information about the food source.

Stevia

I talked a bit about this back on my March 16th post, so for those who want to know more about this sweetener please click on that link. As of December 17, 2008, Rebaudioside A (a highly purified derivative of one of the two primary sweet glycoside compounds contained in the Stevia plant) was granted GRAS approval by the FDA for use in foods and beverages. This is great news for those seeking a natural high-intensity sweetener (200 - 300 times sweeter than sugar) that does not induce a glycemic response (no increased blood sugar levels). Cargill's tradename is Truvia and is working with Coke for the use of its product in Sprite, Odwalla and Glaceau Vitaminwaters. Whole Earth Sweetener's tradename is Purevia and they are working with Pepsi to add the sweetener to SoBe Lifewater, and Trop50. These beverages, and probably many others, should hit the market in the begining of 2009. This won't be an inexpensive sweetener given that Rebaudioside A is only 2-4% of the stevia plant (stevioside - the other sweet glycoside is 5 -10% of the plant), but its low usage rate (due both to its intensity & slight licorice taste) will make it desirable to manufacturers.

So, that is my look back at 2008. This new year looks to be just as interesting as the last and I should have plenty of topics upon which to opine. As always, send me your questions, concerns or just topics you'd like to know more about!