Summary
Carbohydrates summary Food Chemistry (FCH20806)
- Course
- Institution
Complete summary of the information needed to understand carbohydrates during this course.
[Show more]
Seller
Follow
Alisongeorgala
Content preview
CarbohydratesIntroduction to carbohydrates
- one of the macromolecules in food
Classification
- carbohydrates have a ring structure (no double bonds) consisting of C-, H- and O- atoms
- carbohydrates contain different residues (glucose, galactose, fructose)
Roles of carbohydrates in food
1. Sweetener (sugar)
2. Humectant: lowers water activity
3. Energy supplier (glucose, lactose)
4. Texture: cell wall, thickeners, gelling agents
5. Colour: browning reactions
Monosaccharides
- Glucose and fructose (main monosaccharides in food)
- Other monosaccharides: galactose, mannose etc
Structural differences in monosaccharides
1. Aldose vs ketose
Double bonded oxygen becomes an OH-group
in the ring structure
,How to recognize an aldose/ketose by looking at the ring structure?
- anomeric carbon: a carbon between two oxygen atoms
- If the anomeric carbon has another Carbon bonded to it =
KETOSE
- No extra Carbon bonded to the anomeric carbon = ALDOSE
Pyranose vs furanose
Pyranose = 6-membered ring
furanose = 5-membered ring
Pentose vs Hexose
Hexose: 6 Carbon atoms
Pentose: 5 Carbon atoms
Alpha vs Beta
Alpha: OH-group points down
Beta: OH-group points upwards
QUESTIONS from slides
To understand why fructose unit in
sucrose is Beta-configurated you
need to look at the structure of the
whole sucrose molecule
(knowledge clip)
N-glycoside
O-glycoside
, When a carbohydrate reacts with another type of molecule, often a link at the anomeric
carbon is formed with the other molecule. This results in a glycoside, such as O-, N- or S-
glycosides. Glycosides are often better soluble than the molecule without the sugar unit, so
this is a way for molecules to increase their solubility.
Reducing properties
- One of the most important properties of carbohydrates
- When a saccharide is a reducing sugar, the ring structure can open at the anomeric carbon if
it has a FREE OH-group
- In the open form, the double bonded oxygen on the saccharide can now react with another
compound.
- However, this is only possible when the anomeric carbon is not involved in a glycosidic
linkage.
- This can also be represented with a double bonded oxygen on the first carbon in the open
line structure
Why is it called a reducing sugar?
The carbonyl group (C=O) of a sugar can reduce Cu2+ (blue colour) to a red colour
This property is used for the quantification of carbohydrates
- All monosaccharides and some oligo- and polysaccharides are reducing sugars.
- Cyclic carbohydrates are NOT reducing sugars
- A saccharide with a reducing end is reactive at elevated temperatures in for example
browning reactions (Maillard and caramelization)
Mutarotation: monomers in solution can convert from the alpha-anomer into the Beta-anomer and
vise-versa. ONLY reducing sugars have this property.
Glycosidic bonds – systematic name
Definition: glycosidic bond is a bond within the carbohydrate connecting the monosaccharides
The benefits of buying summaries with Stuvia:
Guaranteed quality through customer reviews
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through credit card or Stuvia-credit for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying these notes from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller Alisongeorgala. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for $3.77. You're not tied to anything after your purchase.
Can Stuvia be trusted?
4.6 stars on Google & Trustpilot (+1000 reviews)
56326 documents were sold in the last 30 days
Founded in 2010, the go-to place to buy study notes for 14 years now