======Lactase Breakdown of Lactose======


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**Alternative titles:** Testing Lactase Using Milk Sugar
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====Summary====                   
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====Procedure====  
  - Prepare a 2 to 4 percent lactose solution in tap water or use lactose-containing milk diluted 1 to 1 with tap water to reduce opacity.
  - Label two test tubes: Enzyme and No Enzyme.
  - Add 5 mL of lactose solution to each tube.
  - Crush a lactase tablet and dissolve a small portion in 5 mL of tap water to make a lactase solution.
  - Add 1 mL of lactase solution to the Enzyme tube and 1 mL of plain tap water to the No Enzyme tube.
  - Mix gently and incubate both tubes at about 37 degrees C for 5 to 10 minutes. If no water bath is available, hold the tubes in warm hands for several minutes and extend the time.
  - Dip a glucose test strip into each tube for the time specified by the strip instructions. Remove, wait the indicated development time, and compare to the color chart.
  - Record whether glucose is detected in each tube and note the relative intensity of color.
  - Interpret results: appearance of glucose in the Enzyme tube but not in the No Enzyme tube indicates that lactase converted lactose into glucose and galactose.



====Links==== 
Lactose Enzyme Examination - Dan Rott: 
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📄 Explore enzymes and the science of lactose intolerance using lactase tablets - Science in School: [[https://scienceinschool.org/article/2024/science-of-lactose-intolerance/]]\\

====Variations====
  * Test different incubation temperatures, such as room temperature versus 37 degrees C, to explore temperature effects on enzyme rate.
  * Compare different lactase tablet brands or doses to see how enzyme amount changes the readout.
  * Use lactose-free milk as an additional control; it should already contain glucose and give a positive strip without added enzyme.
  * Extend incubation time and take multiple readings to create a simple time course of glucose formation.



====Safety Precautions====
  * Do not ingest any reagents or solutions; treat all student-handled samples as not food.
  * Wear eye protection when crushing tablets and handling warm water baths.
  * Avoid hot water above 45 degrees C to prevent burns and to avoid denaturing the enzyme unintentionally unless testing temperature as a variable.
  * Wash hands after the activity and clean the workspace; dispose of used strips and solutions according to classroom guidelines.




====Questions to Consider====
  * Why is a No Enzyme tube included as a control? (It shows that any glucose detected comes from enzyme action, not from the lactose solution itself.)
  * What products are formed when lactase acts on lactose? (Glucose and galactose.)
  * Why do we incubate near 37 degrees C? (It approximates the optimal temperature for many human-use enzymes, increasing reaction rate without denaturation.)
  * If the glucose strip is positive in both tubes, what could explain this? (The starting solution already contained glucose, the lactose source was lactose-free, strips were contaminated, or instructions were not followed.)
  * How would very hot water affect your results? (Heat can denature lactase, reducing or eliminating glucose formation and giving a weaker or negative strip.)