Lab 8

Introduction
In this lab period, we began the process of brewing our own beer. Intervals between "cooking" periods, consisted of lectures by Drs. Ebbole and Shaw on biochemistry, yeast and fermentation, and the history of beer.

LAB ACTIVITY

Let the Brewing Commence!
Before lab, 2 gallons of water were heated to 66.1C and the heat was then turned off (Fig. 1). The actual brewing process was started by placing 8 oz. 2-Row Malt, 8 0z. Crystal 90L Malt, and 8 oz. Crystal 10L Malt into a grain sack. This grain sack was then soaked in the 2 gallons of heated water for 25 minutes.

Fig. 1
20 gallons of boiling water in a fashionable ceramic pot

After this time period, the grain sack was lifter out of the water in order to drain. The bag was not squeezed as this would cause cloudiness in the brew. After most of the water had dripped out of the bag, the grain bag was discarded, one gallon of water was added to the pot, and the pot was again heated to a boil.

After the boil has commenced, the pot was removed from heat. At this point the malt extract and the following sugars were added: 1 lb Extra Light DME, 3 lb Munich Extract, 3 lb Extra Pale Extract (Figs. 2-4)

Fig. 2
Malt extracts and sugars

Fig. 3
Adding the extracts

Fig. 4
Adding the extracts

This mixture was stirred constantly (by Sheila, Fig. 5) in order to dissolve the extract. Heat was again returned to the mixture once everything had dissolved. Constant stirring was applied in order to prevent the sugars from burning.

Fig. 5
Sheila stirring the mixture

Once a rolling boil was achieved, the bittering hops (1 oz Galena, Fig 6) were added and boiled for 60 minutes (Fig. 7).

Fig. 6
Galena hops

Fig. 7
Adding Galena hops to mixture

After this time period, the flavor hops (0.5 oz Centennial ) were added and boiled for 15 minutes. Lastly, the aroma hops  (0.5 oz. Centennial) were added for the last 5 minutes (Fig. 8).

Fig. 8
Centennial hops

After all ingredients were added, the pot containing the mixture (wort) was removed from heat and placed in an ice bath. After the wort cooled, the mixture was decanted into a 6 gallon fermenter (Figs. 9-11), which had been previously sanitized.

Fig. 9
6 gallon fermenter, previously sterilized

Fig. 10
Chris decanting the wort into the fermenter

Fig. 11
Fermenter containing the wort

A sample was taken from the wort (Fig. 12) in order to determine the specific gravity. This was determined by using a hydrometer, which determines the alcohol content of the beer (Fig. 13). This ideal specific gravity should be 1.052.

Fig. 12
Taking a sample of the wort

Fig. 13
Determining the specific gravity of the wort sample

We all tried our brew before the yeast was added (Figs. 14-16).

Fig. 14
Sheila taking a swig

Fig. 15
Bitter beer face?

Fig. 16
Not too bad...?

Pitchable Liquid Yeast was then added to the concoction and stirred (Video 1). A lid with an airlock was then placed on the fermenter (Fig. 17). The airlock was filled approximately 1/3 with ethanol.

Video 1

Adding the pitchable yeast

Fig. 17
Wort with yeast added and airlock lid

The wort was then placed in Dr. Ebbole's secret lair, which I assume looks something like Fig 18.

Fig. 18
Dr. Ebbole's secret lair

LECTURE

Biochemistry

Dr. Ebbole lectured on biochemistry during this lab period. This included topics that I had come to know very well as an undergraduate but very eagerly to dumped out of my brain after my year of biochemistry. The KEGG website was mentioned as being a collection of metabolic pathways which represent the current knowledge of molecular interactions.

We first defined physiology as the function of an organism or tissue, and metabolism as the sum of all chemical reactions in the body. 

The first part of the the lecture covered glycoloysis, which is the metabolic pathway that converts glucose to pyruvate (Fig. 19).

Fig. 19
The Glycolysis pathway
http://www.accessexcellence.org

Naturally, the discussion on glycolysis lead into a discussion on gluconeogenesis, which is the generation of glucose from pyruvate (Fig. 20). 

Fig. 20
The Gluconeogenesis Pathway
http://themedicalbiochemistrypage.org

The very relevant topic of fermentation, the process of converting glucose to ethanol and carbon dioxide,  was discussed (Fig. 21).

Fig. 21
The Fermentation Pathway
http://www.emc.maricopa.edu

This was followed by a discussion of the TCA (tricarboxylic acid cycle, Krebs cycle, citric acid cycle) which is a pathway for the breakdown of glucose and other metabolites, such as amino acids, fatty acids, and other sugars (Fig. 22). 

Fig. 22
The TCA cycle
http://www.kmph.matrik.edu.my

We also discussed the topics of carbon regulation of gene expression and glucose sensing and signaling. Particularly, gene expression was discussed. The following terms were defined:

Gene expression: amount of expression, synthesis of a product

Basal expression: condition-specific: at this condition, this is the level of expression

Constituitive expression: no regulation

Repression: basal level of expression decreased by interaction of protein at the promoter

Uninduced: absence of activator

Induced: Increases basel level of expression

**De-repressed + uninduced = basal level

Conclusion

We covered a lot of information in this lab period. I will definitely have to go back and study my old biochemistry notes. However, I am very excited about our beer!

All for now,

C