Course:FNH200/Lessons/Lesson 05/Page 05.7

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5.7 Summary

  • Food deterioration can occur as a result of physical, chemical or biological causes.
  • The primary objectives of food preservation are to minimize deterioration and eliminate potential microbiological harm to the consumer, and to maintain quality and nutritional value while producing a safe food product.
  • A number of methods can be used to achieve these objectives. However, it should be noted that no method can completely eliminate spoilage phenomena indefinitely. For example, although canned foods will not undergo microbial or enzymatic spoilage as long as the physical integrity of the can is maintained, the foods may spoil as a consequence of chemical reactions such as Maillard browning which can proceed slowly even at ambient temperature.
  • As mentioned in the video, "old" preservation technologies such as smoking or fermentation cause noticeable changes in the food (i.e. fresh salmon vs. smoked salmon, grapes vs. wine, milk vs. cheese); whereas "new" preservation technologies such as pasteurization or freezing change very little the starting food material. We should remember however, that without these "old" preservation methods we wouldn't have the variety of desirable food products such as: cheese, bread, wine, smoked meats, etc.


Authorship:

FNH 200 Course content on this wiki page and associated lesson pages was originally authored by Drs. Brent Skura, Andrea Liceaga, and Eunice Li-Chan. Ongoing edits and updates are contributed by past and current instructors including Drs. Andrea Liceaga, Azita Madadi-Noei, Nooshin Alizadeh-Pasdar, and Judy Chan.

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1. Name of the enzyme responsible for the browning of apple after it’s cut.


2. Choose all the correct ways to prevent apple slices from enzymatic browning:

Dipping apple slices in hot water.
Dipping apple slices in water.
Dipping apple slices in water with lemon juice.
Applying sulfur dioxide.


3. There are factors that influence the extent of spoilage. Which of the following statement is true about heat?

Excessive heat denatures enzymes but promotes microbial growth.
Low heat denatures enzymes but promotes microbial growth.
Excessive heat denatures enzymes and can destroy microbes.
Low heat denatures enzymes and can destroy microbes.


4. There are factors that influence the extent of spoilage. Which of the following statement is true about moisture?

Changes in free water influences enzymatic, microbiological and chemical spoilage.
Changes in free water only influence chemical spoilage and not enzymatic or microbiological.
Changes in free water influences enzymatic and microbiological spoilage and not chemical.
Changes in free water only influence enzymatic and not chemical spoilage or microbiological.


5. What is true about enzymes and microorganisms?

Enzymes are found in plants like vegetables and in meats but not in microorganisms like bacteria.
Both enzymes and microorganisms are considered living things.
Enzymes present in microorganisms only cause food spoilage as none are present in food items like vegetables or meats.
Enzymes are found naturally in all living things including plants and microorganisms.