Microbiology of Beer, Bread and Cheese
Review Questions for Test 2, Fall, 2015
History and Culture of Bread
1. Where and when was bread first made?
2. Which grains were used to make bread in Ethiopia vs. Iran vs. Sudan vs.
India? Why were these grains used?
3. Be able to discuss how culture has influenced how breads are made, and
which grains are used.
4. Be able to discuss how the grains used determine (at least initially) the
predominant bread-making techniques of a region.
5. Be able to tell the roles of the following individuals (or groups of individuals)
in bread baking: Dutch Distillers, Viennese Brewers, Charles Flieschmann
6. Hexaploid wheat has a higher gluten content than durham and emmer wheat
(both tetraploid). All three have higher gluten contents than the wild grasses
from which they evolved. Give two other differences between domesticated
wheats and wild wheats, and tell how these differences are important to
bread production.
Biochemistry of Fermented Breads
1. Be able to describe why heterofermentative lactic acid fermentation is such
an important part of the generation of sourdough flavor and characteristics.
2. How does the metabolism of glucose differ in heterofermentative lactic acid
bacteria as compared to that in yeast? Be able to name the reaction that is
used in both cases.
3. Be able to describe the structure of a starch molecule. How do amylose and
amylopectin differ in structure?
4. What happens to starch as you heat it and hydrate it? What impact does this
have on bread?
5. Be able to describe how gluten forms. How does kneading aid the process?
How did the ‘no-knead’ process we used for the pizza dough form gluten?
6. Be able to describe the foam formation in bread…from fermentation to
baking. Make sure you describe the roles that the fermenters, starch,
proteins, kneading, heat and water play in the process.
7. Be able to describe how fermentation changes grain texture, flavor, aroma
and nutrition.
8. Be able to apply concepts from questions 3, 4 and 5 to the production of idli,
teff and kisra.
Microbiology of Fermented Breads
1. When you viewed your sourdough starters, what types of microorganisms
did you think you saw? What type (s) of fermentation process (es) were
these microbes most likely carrying out?
2. What endogenous factors impacted the types of microbes that ended up in
your sourdough starters? Which of these factors was likely to vary from one
starter to the next?
3. What exogenous factors impacted the types of microbes that ended up in
your sourdough starters? Which of these factors was likely to vary from one
starter to the next?
4. Which genus of LAB is the most common in sourdough starters? Be able to
name it, as well as 3 others that can also be found.
5. Which genus of yeast is the most common in sourdough starters? Be able to
name it, and to give 3 other examples of yeast that are found in fermented
breads (not necessarily sourdough).
6. What is ‘backslopping’?
7. In order to survive long term in sourdough starters, LAB must have many
adaptations. Describe 3.
8. What is a microbial consortium, and what does that term have to do with
fermented breads?
9. When you all brought your sourdough starters to class, I was relatively
unworried about pathogens. I did look for evidence of them, but did not
really expect to see any. Why not? Give 3 reasons.
10. Be able to describe the mutualistic relationship between S. exiguous and L.
sanfranciscensis.
Flavor and Aroma of Sourdough Breads
1. Be able to list 4 important volatile and non-volatile products of yeast
fermentation and lactic acid bacterial fermentation. Be able to give examples
of at least 1 compound that is unique to each type of fermenter, and to tell
how that product impacts the bread’s flavor/aroma.
2. How do Maillard and Carmelization reactions impact bread flavor, aroma and
appearance?
Chemistry of Beer
1. I will provide all of the formulas. You need to be able to calculate the correct
value, using the appropriate formula (for example, if I ask for Real Extract, you
should be able to pick out and use the formula RE = (0.1808 × °Pi) + (0.8192 × °Pf) )