Case Study: Sylvester’s Milk for Cats
Case Study: Sylvester’s Milk for Cats
Does your human know that cats get gas and cramps from drinking untreated cow’s milk? Get your
human to buy Sylvester’s Milk for Cats which is 98% lactose reduced.
Most humans are unaware that cats are lactose intolerant. Jane Dyke’s tabby recently formed a company
called Sylvester’s Milk for Cats  to produce lactose-free milk for cats. As lab technicians new to the
business, you will have to prove that you understand your role in the lab before you can pass the
probationary period and get hired permanently.
Here is some background information.
 Milk contains lactose.
 Lactose is digested by lactase (beta galactosidase), an enzyme, to form glucose and galactose.
 Cats do not produce lactose and get abdominal cramps, gas, and diarrhea if they drink cow’s
milk.
 Lactase activity is inhibited by galactose and glucose.
 Enzymes are reusable.
Your job is to work with the prototype equipment provided to develop an effective and efficient system
for digesting the lactose in cow’s milk. First you will embed the lactase enzyme molecules in gel beads.
Next you will run milk through a column of beads. The embedded enzymes will digest the lactose
molecules as the milk flows past the beads in a column. Thus the enzymes are not lost in the product but
are constantly being reused. However, lactase is affected by endpoint inhibition. Glucose and galactose
inhibit lactase. Thus, if you have the milk flow through the syringe barrel too slowly and the beads get
prolonged exposure to glucose and galactose, the enzyme will no longer digest the lactose. You must
come up with a flow rate that maximizes contact of all the lactose molecules in the milk with the
embedded lactase molecules, but not saturate the enzyme molecules with glucose and galactose. It is
your job to determine the ideal flow rate of milk so that the production line can be set up based on the
calculations of your team.
106737121
1
Research conducted at
Case Study: Sylvester’s Milk for Cats
Equipment per group:
Lab (retort) stand with supporting base
Lab (retort) stand clamp to hold 10 ml syringe
Rubber hose (3/16”) about 10 cm long
Hoffman hose clamp
2x10 ml syringe without needle
3/16th “ circle of nylon gauze
tea strainer
2 x 250 ml beaker
distilled water bottle
Materials List (consumables) per group:
2 ml of Lactaid lactase enzyme
8 ml of Gaviscon liquid
5 x Diastix Reagent Strips for Urinalysis (cut each one lengthwise)
25 ml of Milk
about 100 ml of 1.5% calcium chloride solution
distilled water
Method
Step 1: Embedding the lactase into gel balls
1. Draw up 2 ml of Lactaid using a 10 ml syringe
2. Add 8 ml of Gaviscon liquid to the same syringe.
3. Rock the syringe back and forth until the two liquids mix completely. This may take about 5
minutes.
4. Get a 250 ml beaker and add about 100 ml of calcium chloride solution.
5. Add the Gaviscon-lactase mixture to the calcium chloride one drop at a time. Leave the beads
in the calcium chloride for 3-5 minutes to allow them to set.
6. Filter the gel beads and calcium chloride solution through a sieve and then rinse the beads with
distilled water.
106737121
2
Research conducted at
Case Study: Sylvester’s Milk for Cats
Step 2. Setting up a continuous flow system
7. Place a small circle of nylon gauze at the base of an 80 ml syringe. Attach a rubber hose about 10
cm long to the end of the syringe and place a Hoffman clamp on the hose close to the end of the
syringe.
8. Place the beads into the syringe barrel.
9. Collect 25 ml of milk in a small beaker.
10. Test the glucose content of the milk using Diastix. Record your result.
11. Slowly add the milk to the 10 ml syringe and alter opening of the Hoffman clamp so that the
milk passes through at a slow but steady rate. Record the rate of drops leaving the tube. Collect
the enzyme treated milk in a small beaker.
12. Test the glucose content of the lactase treated milk coming out of the hose after 2 minutes. If the
maximum level of glucose is not reached, slow the rate of milk leaving the hose and test again
after 2 minutes. Try to set the rate so that the glucose level in the milk is at the maximum testable
using the test strips.
13. Record your results and describe the changes to flow rates to get the different results. Continue
the tests until the entire milk sample has passed through the syringe or you run out of test strips.
14. Analyze your data and state generalizations concerning the ideal flow rate of milk to digest most
of the lactose.
15. Evaluate the procedure used and suggest how improvements could be made to the prototype
used.
16. Submit your results, analysis and evaluation to determine if Sylvester will hire you.
Author: J. Dyke
The Alberta Ingenuity Fund supports science and engineering research of the highest calibre, to create a prosperous future for
the province. This support includes programs designed to engage the public and encourage young people to pursue careers in
science. It draws funding from a $1 billion endowment established and managed by the Government of Alberta to build the
capacity for innovation, especially in areas with long lasting social and economic impact.
106737121
3
Research conducted at