1. Why does milk bother me? And other lactose-related fables Scott MacLean CHEE 450 – January 23,2004

2. Lactose Intolerance Inability to digest milk protein lactose Symptoms include nausea, cramps, bloating, gas, and diarrhea 30-50 million Americans are lactose intolerant 75% of African Americans, 90% of Asian Americans are lactose intolerant

3. What’s the Deal? Lactose is broken down by lactase into glucose and galactose If a patient is deficient in the enzyme lactase and demonstrate symptoms, they are considered lactose intolerant

4. Treatment Dietary control Lactase tablets/liquid (Aspergillus oryzae- produced lactase is functional in GI-Tract) Lactose-reduced products

5. Lactose-Reduced Milk Addition of lactase enzyme before pasteurization 70-100% Lactose reduction, available in skim, 1%, 2%, whole, and chocolate, as well as calcium fortified! (May be UHT pasteurized)

6. The Microorganism Kluyveromyces lactis Yeast Has also been GM to produce rennin

7. The Enzyme Lactase, a.k.a. β-galactosidase Optimum pH=7, T=3-25 o C (K. lactis) Competitively inhibited by galactose

8. The Process Growth (Submerged liquid, solid-state) Harvesting Cells Extraction of Enzyme (Lysis, mechanical disintegration, electric field pulses) Purification (Chromatography) Ready for use!

9. The Process Liquid lactase is commercially available Added to milk, 25mL/100L milk 99% lactose reduction in 24h at 4 o C

10. The Economics Problem: Milk Spoils! UHT Pasteurization helps extend shelf life Enzyme available commercially, 7mL for $7US Lacteeze: $3.49, 2L, Food Basics

11. Summary Enzyme selection dependent on type of process, administration and use Different organisms produce similar enzymes, active under different conditions! Lactose Intolerance is a big problem, but with the help of a little bug, can be helped!

12. Reference National Centre for Biotechnology Education, http://www.ncbe.reading.ac.ukhttp://www.ncbe.reading.ac.uk