carbohydrates Flashcards
What is raffinose ?
trisaccharide : galactose, glucose and fructose
What is stachyose ?
glucose, fructose and two galactose
When you want to make a caramel flavor, you use a ___ solution
sucrose
When you want to make a caramel color, you use a ___ solution
glucose
2 aminoketones will give a ___
pyrazine
the more a sugar is ____ the more it will be sweet
soluble
how can you mix prevent the crystallization
mix the sugars
****what can you do if you want to minimize the browning you use ____ in your maillard reaction
sucrose
T or F : the sugar alcohol are more sweet than sucrose or glucose
false, they are less sweet
what is the only sugar alcohol with a sweetness comparable to sucrose
xylitol
the ____ is hydrogenated to form xylitol
xylose
___ is the polymer of xylose
xylan
In amylopectine, every ____ glucoses molecules, there will be a a glucose that has two glycosidic bonds (one in the 1-4 and one in the 1-6)
12-20
____ (starch) is more soluble in water
amylopectin
Loss of granular integrity generally occurs between _____ gelatinization temperature is a function of the starch source.
60˚C and 70˚C
why is the invert sugar called inverted sugar
because of the rotation of the solution from +66 to -39˚C.
What is the general formula of carbohydrates
Cx(H2O)x
What are the two optical isomers of glucose
glucose-D and L-glucose
what is the only carbon at which isomers are not considered to be different sugars ?
the n-1 carbon
fructose has a hemiketal or a hemiacetal
hemiketal
glucose has a hemiketal or a hemiacetal?
hemiacetal
T or F : in the pyranose form, the fructose has a hemiacetal
false
Beta and alpha glucose are two ____
anomers
the crystaline form of thre sugars is always ____
cyclical
In solutions, there is a dynamic equilibrium between ___ ___and __
alpha, beta, open chain.
the alpha-glucopyranose has an optical roation of _____
112˚
the beta glucopyranose has an optical rotation of ____
19˚
the active aldehyde form is the _____ form
open-chain
T or F : all aldehydes are reducing sugars
true, because they have a free ketone or a free aldehyde
What is the most common test of reducing sugars
the fehling’s test (cuII in copper tartate (blue) to cuI oxide (red))
What are the two ways water can be eliminated from a sugar molecule
- by forming a glycosidic bond with another sugar (random polymerization)
- Elimination of water from within a sugar molecule leading to unsaturated molecule.
how many water molecules are lost to make HMF
3
what is the key intermidiate in the following reactions :
Caramelization
Maillard Reaction
Caramelization : HMF
Maillard reaction : amadori compound
How are sugar alcohol produced?
produced by reducing the aldehyde group by an hydroxyl group (hydrogenation).
what is the effect of the presence of sugars in the gel formation
retard the gel formation and retrogradation because they compete for available water and interfere with starch to starch.
surfactants forms complex with starch, it is more noticeable for _____
amylose
