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Food Enzymes: Friend or Foe? A Great Teaching Topic. Dr. S. Suzanne Nielsen, Purdue University, Dept. Food Science, [email protected]. 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? - PowerPoint PPT Presentation
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Food Enzymes: Friend or Foe?
A Great Teaching TopicDr. S. Suzanne Nielsen, Purdue University, Dept. Food Science, [email protected]
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.
What are enzymes? Enzymes are highly specialized proteins
that catalyze specific biochemical reactions
Proteins are chains of individual amino acids
Enzymes catalyze reactions such as these:
Starch Glucose
-----
Sucrose Glucose + Fructose
Proteins Amino Acids
What controls the action of enzymes?TemperatureWater ContentpHChemicalsAlteration of SubstratesAlteration of Products
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
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
Experiments with Food Enzymes
Enzymatic Browning of Fruits and Vegetables
Coagulation of Milk by Rennet Addition
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
Samples at 5 minutesControl
Samples at 10 minutesControl
Samples at 20 minutesControl
Control
Water
0.1% Acetic Acid
0.1% Citric Acid
0.1% Ascorbic Acid
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
Experiments with Food Enzymes
Enzymatic Browning of Fruits and Vegetables
Coagulation of Milk by Rennet Addition
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 ~37C Observe the coagulation.
Coagulation of Sample Control
Coagulation of Sample 1% Rennet Solution, No Heat5 minutes 10 minutes 20 minutes
Coagulation of Sample 1% Rennet Solution, 37C5 minutes 10 minutes 20 minutes
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.
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.
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.
Food Enzymes: Friend or Foe?
A Great Teaching TopicDr. S. Suzanne Nielsen, Purdue University, Dept. Food Science, [email protected]
Questions?