Molecules controlling sensory properties
Quiz yourself by thinking what should be in
each of the black spaces below before clicking
on it to display the answer.
Help!
|
|
||||
---|---|---|---|---|---|
What's the common name applied to the group of reactions that occur when sugars are exposed to high temperatures? | Caramelisation
🗑
|
||||
Why does caramelisation differ from other browning reactions? | No amino groups are used
🗑
|
||||
What do the reactions of caramelisation form? | Volatiles (caramel aroma) and Brown - coloured products
🗑
|
||||
An example of caramelisation in foods is... | When food surfaces are heated strongly
Processing of food with high sugar content
In wine production
In the preparation of sucrose syrups
🗑
|
||||
At what temperature does caramelisation occur? | >120 degrees for prolonged periods in the presence or absence of a catalyst
🗑
|
||||
What are the 4 stages of caramelisation? | Enolisation, Dehydration, Fragmentation and Polymerisation
🗑
|
||||
What occurs during Enolisation? | A reversible isomerisation of the aldose/ketose sugar (via the open chain forms) to a 1,2-enediol intermediate (Initiates the chain of events)
🗑
|
||||
What occurs during Dehydration? (Caramelisation) | The high temperature dehydrates the intermediate, causing it to loose a water molecule. Further dehydration is responsible for the formation of compounds such as 5-hydroxymethylfurfural (HMF)
🗑
|
||||
What occurs during Fragmentation? (Caramelisation) | Products such as HMF can be degraded to molecules such as furfural via fragmentation
🗑
|
||||
What occurs during Polymerisation? (Caramelisation) | The typical brown colour is produced, and is attributed to polymeric products such as HMF and furfal
🗑
|
||||
What effects the rate of colour development in the sugar? | The structural stability of the sugars
🗑
|
||||
Alongside the production of HMF in caramelisation, what other products are produced? | Dicarbonyl compounds give rise to some flavours (aldeydes and pyrazines), 'Burnt sugar smell' is produced by large variety of intermediates
🗑
|
||||
Define Ascorbic Acid browning. | The thermal decomposition of ascorbic acid under both aerobic and anaerobic conditions, thus losing the nutritional value of the ascorbic acid
🗑
|
||||
Does Ascorbic Acid browning always occur following ascorbic acid degradation? | No.
🗑
|
||||
What is the first step of ascorbic acid browning? | The degradation of A.A. to dehydroascorbic acid in the presence of Oxygen
🗑
|
||||
What reactions follow the initial stage of ascorbic acid browning? | DHA isn't stable, and spontaneously converts to 2,3-diketo-L-gulonic acid. If there's no Oxygen to start with, DHA isnt formed (instead, A.A. is converted to the above molecule via its keto tautomer)
🗑
|
||||
Depending on the conditions, different intermediates are formed in A.A. degradation. What do/could the reduction products form/do next? | Enter into reactions with other reactants to form brown prodcuts
🗑
|
||||
What are the conditions for A.A. browning? | Temperature dependent, but can occur at low temps. Occurs at low pH levels in the presence of amino acids or proteins
🗑
|
||||
Name two molecules that could be effective at suppressing A.A. browning | Sulphites, L-cysteine, Sugars, Sorbitol
🗑
|
||||
The interaction of ________ with _______ causes lipid browning | Oxidised fatty acids and amino groups
🗑
|
||||
Unsaturated fatty acids are very susceptible to oxidation. This leads to the formation of _____ and ______ | Free Radicals and Lipid Hydroperoxides
🗑
|
Review the information in the table. When you are ready to quiz yourself you can hide individual columns or the entire table. Then you can click on the empty cells to reveal the answer. Try to recall what will be displayed before clicking the empty cell.
To hide a column, click on the column name.
To hide the entire table, click on the "Hide All" button.
You may also shuffle the rows of the table by clicking on the "Shuffle" button.
Or sort by any of the columns using the down arrow next to any column heading.
If you know all the data on any row, you can temporarily remove it by tapping the trash can to the right of the row.
To hide a column, click on the column name.
To hide the entire table, click on the "Hide All" button.
You may also shuffle the rows of the table by clicking on the "Shuffle" button.
Or sort by any of the columns using the down arrow next to any column heading.
If you know all the data on any row, you can temporarily remove it by tapping the trash can to the right of the row.
Embed Code - If you would like this activity on your web page, copy the script below and paste it into your web page.
Normal Size Small Size show me how
Normal Size Small Size show me how
Created by:
runwindmc
Popular Science sets