Nutrients & their Metabolism
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What are the important dietary CHO categorised into?
Monosaccharides Disaccharides + oligosaccharides Polysaccharides
How many carbons can monosaccharides have?
3 to 7
What are the most important monosaccharides?
The 6C hexoses: • Glucose • Galactose • Fructose
What is the most important monosaccharide
alpha-D-glucose
What is the sweetest monosaccharide?
Fructose
How is high fructose corn syrup manufactured enzymatically?
By changing the glucose in cornstarch to fructose.
What does evidence suggest about high fructose corn syrup?
That high diets of this may contribute to obesity + other health conditions i.e metabolic syndrome.
Where are galactose + fructose metabolised?
Liver
What do infants have when they are born with inability to metabolise galactose?
Galactosemia
What are the 3 most important disaccharides
Sucrose Lactose Maltose
How are disaccharides formed?
By glycosidic linked monosaccharides between the active aldehyde or ketone carbon + a specific hydroxyl on another sugar.
Describe what an invert sugar is
A natural form of sugar An unlinked glucose + fructose in a 1:1 ratio
Why is invert sugar used commercially?
Sweeter than the equal conc. of sucrose.
Give an example of an invert sugar
Honey
What are oligosaccharides
Small 3-10 monosaccharide Readily H20 soluble Often sweet
Define a polysaccharide
CHO w/ 10+ monosaccharide units
Why is amylopectin more abundant in the food supply than amylose?
Due to its larger size
What causes different starches to have their own unique taste, texture + absorbability?
The rel. no. of glucose units in straight (amylase) and branched configurations (amylopectin) + The degree of accessibility to digestive enzymes.
What does moist cooking cause for the starch granules?
Causes them to swell = Gelatinises the starch, softens + ruptures the cell wall = Making starch more digestible by pancreatic amylase.
Define dietary fibre
Intact plant components GI enzymes can’t digest
Define functional fibres
Nondigestible CHO that have been extracted or manufactured from plants
List some of the less soluble fibres
Cellulose Hemicellulose Lignin
Major function of cellulose as a less soluble fibre
⬆️ H20-holding capacity = ⬆️ fecal volume + ⬇️ gut transit time.
Major function of lignin as a less soluble fibre
Fermentation produces short-chain FAs associated w/ ⬇️ risk of tumor formation