Grains Flashcards
What is the process of food turning brown due to chemical reactions called?
Browning
Browning is significant in food chemistry and research related to health, nutrition, and food technology.
What are the two main categories of browning processes?
- Enzymatic
- Non-enzymatic
What is enzymatic browning?
A chemical reaction involving enzymes like polyphenol oxidase that creates melanin and benzoquinone from natural phenols
Enzymatic browning requires exposure to oxygen.
What factors can affect the taste, color, and value of fruits and vegetables during enzymatic browning?
- Polyphenol oxidase
- Catechol oxidase
- Other enzymes
Give two examples of foods that undergo enzymatic browning.
- Coffee
- Dried fruits like figs and raisins
What is non-enzymatic browning?
A process that produces brown pigmentation in foods without enzyme activity
Includes caramelization and the Maillard reaction.
What is caramelization?
The oxidation of sugar that produces a nutty flavor and brown color
It is a type of non-enzymatic browning.
At what temperature does sucrose and glucose begin to caramelize?
Around 160°C (320°F)
Fructose caramelizes at a lower temperature of 110°C (230°F).
What is the Maillard reaction?
A chemical reaction between an amino acid and a reducing sugar that occurs above 140°C (285°F)
It produces flavors and colors in food.
What conditions affect the rate of the Maillard reaction?
- Temperature
- pH
- Water activity
What are some methods to prevent enzymatic browning?
- Treatment with antioxidant agents
- Treatment with agents of firmness (calcium salts)
- Treatment with acidifying agents
- Blanching
- Freezing
- Conservation in modified atmosphere
- Coating
What is the purpose of blanching in food preservation?
To inactivate enzymatic systems responsible for sensory and vitaminic alterations
Blanching can enhance the colors of plants for better presentation.
How does freezing help in preventing browning?
It decreases the available water for enzymatic reactions.
What is modified atmosphere packaging?
A method that changes the oxygen content of the storage atmosphere to control enzymatic browning
It delays enzymatic systems without altering product quality.
What is the role of coating agents in fruit storage?
To extend shelf-life by decreasing moisture and aroma losses, delaying color changes, and improving appearance.
