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Fermenting your Food

This article appeared in the July 22, 2011 edition of the Davis Enterprise.

Fermenting your Food

A local cow demonstrating the first stage in the digestive process

By Edward Thomas
Special to the Enterprise

As a young child I visited Explorit, as an adolescent I volunteered, and today I work there. My interest in studying science and going into a scientific career evolved through experiences at Explorit as well as other science centers, and a couple of great teachers.  Choosing to major in Animal Science at UC Davis was a natural extension of these interests and curiosity.

One common, and utterly fascinating, science 'fact' I remember hearing often as a child was that cows have four stomachs.  Although often said, it is a common misconception.

They instead have one large stomach with four compartments.  Named in order, they are the reticulum, rumen, omasum, and abomasum.  Ruminants, the category of animals with this stomach type, at times regurgitate boluses of food in a process called rumination.

These boluses are formed in the reticulum and passed back to the cow's mouth, allowing it to better break apart swallowed food through further mastication .  From the reticulum food moves into the rumen, the largest compartment and the site of fermentation, where a diverse population of microbes break down the consumed plant matter into digestible components.  The partially digested food is then sorted through the omasum and sent to the abomasum, their ‘true stomach’ for acidic digestion. 

Although humans cannot ferment food in their stomach, you can construct a home-made ‘rumen’ out of a jar to make concentrated, all natural fertilizer. 

Find a large jar or comparable container for the experiment, a matching lid is not necessary.  Gather enough plant matter to fill the jar 2/3 to 3/4 way full when gently packed in.  Chop up, but do not wash what is put in.  It is best to use fruits, succulent greens and buds.  Some examples include: over ripe fruit, trimmings from the vegetable garden, and old salad. 

After placing the plant matter in the jar add approximately 1/3 its weight in raw sugar or molasses.  Stir the concoction and add just enough water to cover the ingredients.  The goal is to dissolve any granular sugar and to remove air from around the plant matter. Find a cool dark place for the jar and cover it with a loose fitting lid or paper with a rubber band. Leave it to ferment for 1 to 2 weeks.

The microbes that lived naturally on the plant matter will explode in growth with the anaerobic, sugar rich, and dark environment.  As they grow and thrive, their metabolic processes break down the plants into basic nutrients and can even produce some alcohol.  Imagine that happening in your stomach! 

When it comes time to check on the jar, its contents should have become yellow or brown and smell sweet and sour.  There may be some mold growing on the surface too.  Don’t worry, this means the fermentation was a success!  Filter the juice to keep and put the solids into the compost bin.  To use, add one cup of the fermented plant juice to one gallon of water as an all natural home brew fertilizer.

Explorit’s coming events:

Summer Camp through Aug 19:  For information please visit or call (530) 756-0191 Monday-Friday from 9-4:30. 

Explorit Science Center’s 3141 5th St. site is the location for field trips, programs for groups, astronomy club meetings, and Summer Science Camp.  It is also the hub for Explorit’s traveling programs that reach an 18-county region.  The site is open to the public for special events and to groups by reservation. For more information call (530) 756-0191 or visit

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