Unit 4 : Food Chemistry - Carbohydrates Flashcards
How many sugar molecules are in each of Monosaccharides , Disaccharides , Oligosaccharides and Polysaccharides ?
- Monosaccharides : 1 sugar molecule
- Disaccharides : 2 sugar molecules
- Oligosaccharides : 3-10 sugar molecules
- Polysaccharides : 100s of sugar molecules
What are some examples of Monosaccharides ?
- Glucose
- Fructose
- Galactose
What area some example of Disaccharides and what enzymes are used for digesting each of them?
- Sucrose - enzyme sucrase helps to digest it
- Maltose - enzyme maltase helps to digest it
- Lactose - enzyme lactase helps to digest it
Compare Lactose Intolerance with Milk allergy
- name what they are classified as and where they occur and what the reaction it is to
- Lactose intolerance : A sensitivity, occurs in gastrointestinal system and its a sensitivity to lactose
- Milk allergy : An allergy , triggered by immune system , reaction to milk protein
Sugars are hygroscopic and what does that mean ?
- It means they attract water and absorb water
Sugars are Humectants, and what does that mean?
- It means that they hold moisture in food
How does caramelization occur with sugar ?
- its dry heated at high temp, sugars melt and turn brown
How does the Maillard reaction occur with sugar?
- A non enzymatic reaction between reducing sugar and an amino acid, when they are heated the sugar and amino acids undergo a series of reaction which lead to the production of a complex mixture of brown compounds called melanoidins
How does sugar affect the freezing point?
- The higher the concentration of sugar, the lower the freezing point
How does Crystallization occur in sugars?
- When the supersaturated sugar solution is cooled , the sugar starts to separate from the water and starts to recrystallize.
- this is how candy is made
What are some examples of Oligosaccharides ?
- Raffinose
- Stachyose
- Verbascose
How are Oligosaccharides digested ?
- Humans do not have enzymes to digest oligosaccharides
- so the normal intestinal bacteria ferments them to produces gases (methane, CO2, hydrogen)
What are some examples of Polysaccharides ?
- Starches
- Fibres
- Glycogen
What are some properties of Starch and how does the digestion work ?
- pure starch is a white, tasteless, and odourless powder that is insoluble in cold water
- Enzymes are produced to digest starch and when digest it is broken down into monomers of glucose
What are 3 ways starch is used in foods
- as a thickener in foods
- as an excellent binder
- To form the gel like soft texture of baked goods
How does Dextrinization occur in starch?
- Starch is heated in the absence of water, it turns brown and breaks down a little.
How can starch be used as a sweetener ?
- Since starch is tasteless, it needs to be hydrolzued so the glucose molecules start to become free and can bind to our taste receptors , thus taste sweet.
Where is glycogen stored in humans and what is it the storage form of and how is it digested ?
- Its stored in liver and muscles
- storage form of carbohydrates in human beings
- the human body produces enzymes to breakdown glycogen
Do dietary fibre get broken down by enzymatic reaction?
- No , dietary fibre is resistant to it , as the. digestive system does not produce enzymes to break down fibres
What is another name for water soluble fibres and what do they do ?
- Viscous fibres
- They dissolve in water and increase the viscosity of the water
How do water soluble fibres impact our digestive system when consumed ?
- They increase the viscosity of chyme in our digestive system which leads to slow movement of chyme in the digestive system - aka peristalsis
How is peristalsis impacting the body ?
- It keeps the stomach full for a longer period of time and slows down the absorption of nutrients through the wall
What is another name for water insoluble fibres and what do they do ?
- Non viscous fibres
- They do not dissolve in water and thus have no impact on the viscosity of water
What do water insoluble fibres help with?
- they bind minerals. phytochemical and some vitamin
What are some ways the food industry uses fibres?
- For improving texture
- as a bulking agent in reduce sugar applications
- To manage moisture in the replacement of fat
- To add colour
What are the two main types of pectic substances that are also soluble fibres and at what pH and how much sugar is needed for them to form gels ?
- High methoxy (HM) pectins and they form gels below 3.5 pH and at least 55% sugar
- Low methoxy (LM) pectins and they form gels between 2-7 pH and without sugar
