1 / 28

Food Enzymes: Friend or Foe? A Great Teaching Topic

Food Enzymes: Friend or Foe? A Great Teaching Topic. Dr. S. Suzanne Nielsen, Purdue University, Dept. Food Science, nielsens@purdue.edu. Enzymes in the Food Industry - - Friend or Foe?. What are enzymes? What controls the action of enzymes? Why are enzymes important in the food industry?

meir
Télécharger la présentation

Food Enzymes: Friend or Foe? A Great Teaching Topic

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Food Enzymes: Friend or Foe? A Great Teaching Topic Dr. S. Suzanne Nielsen, Purdue University, Dept. Food Science, nielsens@purdue.edu

  2. Enzymes in the Food Industry - - Friend or Foe? • What are enzymes? • What controls the action of enzymes? • Why are enzymes important in the food industry? • Examples of enzymes used in the food industry.

  3. What are enzymes? • Enzymes are highly specialized proteins that catalyze specific biochemical reactions • Proteins are chains of individual amino acids

  4. Enzymes catalyze reactions such as these: Starch  Glucose   -----   Sucrose  Glucose + Fructose  Proteins  Amino Acids 

  5. What controls the action of enzymes? • Temperature • Water Content • pH • Chemicals • Alteration of Substrates • Alteration of Products

  6. Why are enzymes important in the food industry? • Added or used to cause particular reaction • Advantages • Natural, Nontoxic • Catalyze specific reactions • Active under mild conditions • Active at low concentrations • Can control rate of reaction • Can be inactivated

  7. Why are enzymes important in the food industry? • Naturally present – may want to inactivate them • Naturally present – may want them to act • Used as indicators of proper processing • Used to measure another compound in the food

  8. Experiments with Food Enzymes • Enzymatic Browning of Fruits and Vegetables • Coagulation of Milk by Rennet Addition

  9. Enzymatic Browning of Fruits and Vegetables • Apple (or potato, banana, etc.) slice is put in each of the following solutions. The browning is observed at 5, 10 , and 20 minutes. • Control (no solution; open to air) • Water Only • 0.1% acetic acid • 0.1% citric acid • 0.1% ascorbic acid

  10. Samples at 5 minutes Control

  11. Samples at 10 minutes Control

  12. Samples at 20 minutes Control

  13. Control

  14. Water

  15. 0.1% Acetic Acid

  16. 0.1% Citric Acid

  17. 0.1% Ascorbic Acid

  18. Why? • Ascorbic acid – Acts as antioxidant; Oxygen preferentially oxidized the ascorbate and not the phenolic compounds • Citric acid – Acts as a chelating agent; Complexes copper ions that are necessary for enzyme activity • Acetic acid – a strong organic acid; Reduces the pH below 3.0 and irreversibly inactivates the enzyme • H2O – Oxygen is necessary for the browning reaction; Immersion in H2O restricts the available oxygen

  19. Experiments with Food Enzymes • Enzymatic Browning of Fruits and Vegetables • Coagulation of Milk by Rennet Addition

  20. Coagulation of Milk by Rennet Addition • Pipette 10 ml of milk into each of 3 test tubes. • To two of the tubes, add ~1.5 ml of a 1% rennet solution. • Mix. (The 3rd tube will serve as a control. It contains no rennet). • Place one of the two tubes with rennet into water at ~37C • Observe the coagulation.

  21. Coagulation of Sample • Control

  22. Coagulation of Sample • 1% Rennet Solution, No Heat 5 minutes 10 minutes 20 minutes

  23. Coagulation of Sample • 1% Rennet Solution, 37C 5 minutes 10 minutes 20 minutes

  24. Why? • Rennet • An enzyme obtained from fourth stomach of ruminant animals, and from some microorganisms • Cleaves particular bond in K-casein of milk to initiate milk coagulation • Coagulates milk protein in cheese making • Aids in development of flavor and texture in ripened cheese. • Mild heat speeds up the enzyme reaction.

  25. Other Examples of Enzymes in Foods • Milk • Lactase • Alkaline phosphatase • Lipases • Plasmin • Fresh vs. canned pineapple • Bromelain breaks down gelatin in “Jello” • Meat tenderizer – uses bromelain, ficin, or papain • Blanching of vegetables – catalase and peroxidase • Cloudy vs. clear apple juice • Mandarin oranges • Onions – enzyme alliinase acts on sulfur cmpds.

  26. Enzymes in the Food Industry - - Friend or Foe? • What are enzymes? • What controls the action of enzymes? • Why are enzymes important in the food industry? • Examples of enzymes used in the food industry.

  27. Food Enzymes: Friend or Foe? A Great Teaching Topic Dr. S. Suzanne Nielsen, Purdue University, Dept. Food Science, nielsens@purdue.edu

  28. Questions?

More Related