DIGESTING LACTOSE WITH LACTASE
Lab Conclusions
Background Information
Part A Directions
• Fill each clean test tube with 1 mL of the
sample to be tested.
Test tube 1: 1ml glucose solution
Test tube 2: 1ml milk
Test tube 3: 1ml lactase solution
Test tube 4: 1ml milk plus 3 drops lactase
solution (swirl gently to mix)
Part B Directions
• Perform a Glucose test on each test tube
using Benedict ’s reagent
• Add 5-7 drops of Benedict’s Solution.
• Heat test tube in a hot water bath for 3-5
minutes.
• Check/Record color change.
• A positive result will be orange.
TABLE 1: RESULTS OF TEST FOR GLUCOSE
Test tube
Contents
Benedict’s Test Color
BEFORE
1
Glucose
2
Milk
3
4
blue
AFTER
Is it positive (+) or
negative (-) for
glucose?
orange
+
blue
purple
_
Lactase
blue
Light blue
_
Lactase +
Milk
blue
orange
+
Conclusions
• Lactose in milk can be broken down into glucose
and galactose.
• We tested to see if the lactose in milk was broken
down by detecting glucose
• We used Benedicts’ reagent to detect glucose
• The milk tested positive for glucose with lactase
added in test tube 4 but was negative for glucose
with out the lactase in test tube 2
• We can conclude that the added lactase caused
lactose to be broken down because of the
positive glucose test