The Fresh Loaf

News & Information for Amateur Bakers and Artisan Bread Enthusiasts

Back to Uni. First Lecture

mwilson's picture
mwilson

Back to Uni. First Lecture

Yeast metabolism. And you thought sugar just got converted to CO2 and Alcohol...

Mini Oven's picture
Mini Oven

If only all our crap could be recycled.  No wonder we love the little beasties!  :)

So this is what happens during the life cycle of a yeast cell.  

What happens when we build up a mass of these and cut their lives short as when we bake their cute little cells bottoms?  Everything less or just some of the end products?

mwilson's picture
mwilson

90+ % is just a simple conversion of sugar to CO2 and alcohol but sometimes the yeast need to utilise energy to look after themselves. The diagram shows all possible routes of creating energy.

Baked yeast will explode and release their products and some of these help to create flavour compounds..

mwilson's picture
mwilson

Plating microbes (specifically wine yeast) today in agar.,,

Mini Oven's picture
Mini Oven

in the agar-agar?  

mwilson's picture
mwilson

ok, ok, It's not just agar, It does contain nutrients. I have the recipe on file and will come back to you on that...

There are different "media". In the photo the blue looking agar is designed to create an anaerobic environment while the burnt-orange looking one is just the standard one.

Mini Oven's picture
Mini Oven

correspond to the colors in the metabolism diagram???  Different by-products?

mwilson's picture
mwilson

Good guess but no sorry. The different colours of the agar represent their type (ingredients) for the purpose of growing different microbes (yeast or bacteria) under different conditions.


Yeast growth.


The black marks are from counting the cells which were diluted many times before plating.

PS. I'm not sure of the relevance of the colours in the yeast diagram...