Carbohydrate reactions Flashcards
How are aldonic acids formed?
the aldehyde group of aldoses is oxidized into carboxyl resulting in carboxylic acid group
what is is it called when the carboxylic acid is on an aldose? and what is the complemntary base, the salt called?
- aldonic acid
- aldonate
aldonates have many applications what are some of them and why?
The why: gluconate salts from at a higher PH
- sodium-D-gluconate is uses as a persavative that is allowed to be a food additive
- calcium-D-gluconate is used for calcium fortification
- Copper, zinc, iron-D-GLuconates are used for nutritional supplemnets
why are Copper, zinc, iron-D-GLuconates used for nutritional supplments?
because they are more soluble than other salts
why is calcium-d-gluconate used for calcium fortification?
because there is no taste, no odor and is very bioavailable. It is also not irratating to the gastrointestinal tract.
How do redox reactions help in quantative determination of sugars like glucose and lactose?
In the redox reaction, the aldehyde group of a reducing sugar (like glucose or lactose) is oxidized to a carboxylic acid, reducing another reagent (like copper in Fehling’s solution and silver in tollens) which changes color, indicating the presence of the reducing suga
What distinguishes aldoses from ketoses in the context of reducing sugars?
Aldoses have an aldehyde group that can directly participate in redox reactions, making them reducing sugars. Ketoses, which have a ketone group, generally do not participate unless they undergo isomerization to form an aldose.
How can ketoses show a positive result in tests for reducing sugars?
Ketoses like fructose can isomerize to aldoses under alkaline conditions, which then allows them to participate in redox reactions as reducing sugars.
Example of a ketose that can act as a reducing sugar under specific conditions.
Fructose is a ketose that can tautomerize into an aldose such as glucose or mannose in alkaline conditions, allowing it to show a positive result in tests for reducing sugars.
What are uronic acids/how do they form?
they are formed from selective oxidation of primary alcohols of monosachrides. A primary alcohol is the alcohol attached to a carbon atom at the end of the carbon chain that is only bonded to one other carbon atom.
What are aldaric acids/how do they form?
They form from the oxidation of both aldehyde groups and primary alcohols on monosachrides resulting in both ends of the molecule being oxidized
in what conditions are aldaric acids fromed?
- in the presence of hot nitric acid
- formed by special enzymes as well
How are lactones formed?
They are formed from aldonic acids undergoing an esterfiactin reaction in wich an ester is formed from an alcohol and carboxyl. This is a intramolecular reaction that forms a cyclic ester, hence the name lactone. This reaction is catalyzed by glucose oxidase or hexose oxidase
What type of rings can be formed
- 6 membered ring (1,5 or δ)
- 5 membered ring (1,4 or γ) which is more often stable
what are the uses of lactones D-glucono-δ-lactone (GDL)
- used in industrial baking for leaving agent in refigerdated/frozen doughs since during baking there will be reversion to D-gluconic acid which is a leavening agent since it reacts with bicarbonate and releases CO2
- Used in the manufacturing of some cheeses since it has the same effect as lactic acid but lowers the cost since no fermenation
- Used in fish products to lower pH and then increase antimicrobial effect of perseving agent
- used in canning of frozen fruits and veggies since it can interact and remove iron that catalyzes enzymatic browning reaction so color remains good
- Used for bread dough improvment because adding enzymes will make GDL and hydrogen peroxide which is a powerful oxidant which can replaced oxidants that shouldnt be used