The Lipase-Bile Relationship in the Digestion of Fats & Oils (Lipids)

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Life Science

Grade Level

Middle/Junior High School (7-9)

Difficulty of Project 



$70.00 – Excluding the cost of the Tri-fold display board

Safety Issues
  1. Bile salt may cause eye and skin irritation. Avoid inhalation. If eye contact occurs, flush with copious amounts of water. Prolonged contact with its dust may cause respiratory irritation, allergic or asthmatic reaction. Harmful if swallowed. Use with adequate ventilation. Wash thoroughly after handling. Keep the bottle closed when not in use.
  2. Lipase may cause eye and skin irritation in some individuals. It is moisture sensitive keep the bottle closed when not in use. The toxicological properties of lipase have not been fully investigated.
  3. When the project is completed dispose the used materials in a manner consistent with applicable regulations as written on the lipase and bile bottle labels and/or the accompanying written package inserts.
  4. Always wash hands with soap and water immediately after completing the project. The supervising adult should discuss the warnings and safety information with the child or children before commencing the activity.
Material Availability

Readily available

Approximate Time Required to Complete the Project 

45 minutes to one hour after the materials are secured.


Bile is a digestive compound produced in the liver and stored in the gall bladder that causes lips (fats and oils) to break down or be emulsified into tiny, microscopic droplets. The research aspect of this science fair project is to determine if pancreatic lipase can break down lipids on its own or does it require the assistance of digestive bile salt.

Three plastic jars or bags will be filled with cooking oil and water. Bile salt and lipase will then be added. The first jar will be a control, bile will be added to the 2nd jar and bile and lipase will be added the 3rd jar. The contents will be thoroughly mixed and allowed to sit for a pre-set time. The oils will then be examined to determine if emulsification and digestion (lipid breakup) took place and under which circumstances. From the results of the tests a data table will be produced. 

Materials and Equipment / Ingredients

Three pint size jars or plastic bags, bile salt, powdered lipase, safety goggles, ¼ teaspoon, water, cooking oil, clock or watch, and coffee stirring (if jars are used) sticks.

With the exception of the bile salt and the powdered lipase all of the other materials are available from a major retail (Wal-Mart, Target, Dollar General, etc) discount department store. Bile salt and powdered lipase maybe purchased from the local pharmacy or online from Nasco Science ( 


The digestive system is made up of the digestive tract which is a series of hollow organs joined in a long, twisting tube from the mouth to the anus along with other organs that help the body break down and absorb food.  The body uses a two-step process to break down lipids (fat and oils). The first step begins when oils and/or fats entering the upper portion of the small intestine (duodenum), where bile salts from the gall bladder are secreted. The bile dissolve the oil into the watery contents much like detergents that dissolve grease from in a frying pan, splitting the oil into thousands of smaller droplets of oil. The second step takes place when the pancreas secretes the digestive enzyme lipase. Lipase breaks the smaller oil droplets into an easily absorbable form. 

Fats and oils are complex molecules and because they do not dissolve in water, these molecules enter the small intestine in a congealed mass, which makes it impossible for the pancreatic lipase enzymes to break them up, since lipase is a water soluble enzyme and can only attack the surface of the these molecules. To overcome this problem the digestive system uses a substance called bile, produced in the liver but stored in the gallbladder, which enters the duodenum via the bile duct. Bile emulsifies fats - meaning, it breaks it up into small droplets which then become suspended in the watery contents of the digestive tract. Emulsification allows lipase to gain easier access to these molecules and thus speeds up their breakdown and digestion.

Digital photos can be taken during the experimenting process and the following websites offer down loadable images of various cut-a-way views of the digestive organs where bile is made and stored and where lipase is made and released into the small intestines.

Research Questions
  • What is bile and where is it made?
  • What is lipase and where is it made?
  • What is the job of the gallbladder?
  • In which jar or bag did the oil begin to break up?
  • What was the control for this project? What was the variable?
  • Is bile an enzyme that chemically digests oil by itself?
  • Did lipase need bile in order to break-down oil?
  • Which digestive compound acts as an emulsify agent, bile or lipase? 
Terms, Concepts and Questions to Start Background Research

Bile, lipase, enzyme, lipid, gallbladder, bile duct, emulsify agent, pancreas, and the small intestine.

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