Enzymes Lab – the Cheese

Factory

Chapter 5Please sign field trip form

Lab #4 EnzymesLearning Objectives

• Understand the chemical and biological properties and importance of enzymes.

• Experience the application of two different enzymes (one digests proteins and the other digests lipids).

Review what is protein denaturation (shape change).

Understand why lipid digestion requires more steps.

Lab #4 Enzymespp. 43-50

Work in Groups of 8 and Set up cheese experiment first. This will take the entire lab time.

Work in Groups of 4 – group lab report (4 students per group)

• Set up bile and fat digestion experiment

• Incubate for 1 hours at 4 C, room temp., 37 C, or 80 C (**turn on water baths).

• Enzymes are catalytic proteins

• Enzymes are highly specific.

• Enzyme activity is regulated.

What is an Enzyme?

This is how an enzyme works.

The Activity of Enzymes is Influenced by their Environment

• Temperature • Salt concentration• pH• Presence of other

molecules, e.g., coenzymes like vitamins; and inhibitors

Fat Digestion

• Why bile salt/juice is helpful in complete fat digestion?

• What happens if one person’s bile or gallbladder (where bile juice is stored) does not function?

• Is fat digestion faster or slower or not at all if digestion happens at 4C, 25C, 37C, or 80C?

Bile and Fat Digestion

• What is litmus cream?– Cream is rich in neutral fat

– Litmus: pH indicator – • Turns blue in alkaline

• Turns Red in acidic

• 4 test tubes to be set up

The fat/grease you eat

Nothing happens in mouth

In small intestine

Can be absorbed

• 4 tubes, one test tube brush, one pencil, one rack.

• Please be careful when transferring solutions from flasks into tubes

• Please clean the beaker used for making cheese in the metal sink only.

• Use test tube brushes to clean tubes and invert all tubes at the end.

• Use a wet paper towel to clean lab benches

To 3 ml of Litmus Cream• Tube 1 – 6 ml of dH2O

• Tube 2 – 3 ml of dH2O and 3 ml of bile solution

• Tube 3 – 3 ml of dH2O and 3 ml of lipase solution

• Tube 4 – 3 ml of bile solution and 3 ml of lipase solution

• Which group is control?

To 3 ml of Litmus Cream• Tube 1 – 6 ml of dH2O

• Tube 2 – 3 ml of dH2O and 3 ml of bile solution

• Tube 3 – 3 ml of dH2O and 3 ml of lipase solution

• Tube 4 – 3 ml of bile solution and 3 ml of lipase solution

• Record color of your tubes before and after expt. For comparison. Also, record the time.

Incubate all tubes at designated temperature (4 C, room temperature, 37 C, or 80 C water bath) for one hour. (label your group’s)

Remove tubes and record your results.

Before

After

Which group will have no digestion, partial digestion, or complete digestion?

What will be the difference of temperature in which the tubes are incubated?

Control, bile only; lipase only; bile + lipase

One ingredient added

Enzyme added

How to make cheese?

Acidification20 ml of buttermilk per liter of milk for >4 h at 20 C.

Coagulation: slowly heat the mixture to 32 C. Setting: mid range (~15 min). Also label tubes

Monitor the temp. Thermometer not touch the bottom. StirRemove beaker from hotplate.

Add 1 ml of rennet. Stir for 1 min. Let sit for 30 min.

Cutting: stir the curd gently for 15 min whey released.

Cooking: heat slowly to 37-38C (do not overshoot). Hold for 30 min (on/off). and stir every 3-5 min.

Acidification20 ml of buttermilk per liter of milk for >4 h at 20 C.

Quiz 3 (Ch 5 6)Coagulation: slowly heat the mixture to 32 C. Setting: mid range

(~15 min). Monitor the temp. Thermometer not touch the bottom. Stir

Remove beaker from hotplate.

Add 1 ml of rennet. Stir for 1 min. Let sit for 30 min.Set up Lipase Experiment after instruction

Cutting: stir the curd gently for 15 min whey released. Go over Quiz 3 answers

Cooking: heat slowly to 37-38C (do not overshoot). Hold for 30 min (on/off). and stir every 3-5 min.

Firming: Let beaker sit for 1 hr. Stir every 5-10 min.

Draining: Pour through cheesecloth (over a sink). Squeeze.

Pressing: Press. air dry at RT.

Aging:

• What is whey: The watery part of milk that separates from the curds, as in the process of making cheese.

• Catalyst: A substance, usually used in small amounts relative to the reactants, that modifies and increases the rate of a reaction without being consumed in the process.

• Enzyme: any of several complex proteins that are produced by cells and act as catalysts in specific biochemical reactions

A few words about Good vs. Bad Cholesterol

LDL Cholesterol:  Less than 130 mg/dL is near optimal for most people.  More than 160 mg/dL or 130 mg/dL or above if you have two or more risk factors for cardiovascular disease

About one-third of blood cholesterol is carried by high-density lipoprotein (HDL). HDL cholesterol is known as the "good" cholesterol because it gets rid of the bad cholesterol. Low HDL cholesterol levels (< 40 mg/dL) increase the risk for heart disease.)

Patient’s Lipid Profile

• Total Cholesterol: 214 mg/dl

• LDL Cholesterol: 134 mg/dl

• HDL Chelesterol: 72 mg/dl

• Glucose: 86 mg/dl

• What does it mean?