Carbohydrates Flashcards
Define a carbohydrate.
Polyhydroxy aldehydes, polyhydroxy ketons, and compounds derived from simple carbohydrates through reduction, oxidation, substitution, and condensation
T or F. All carbohydrates are sweet.
False
T or F. Monosaccharides are the simplest carbohydrates.
True.
T or F. All aldohexoses are reducing sugars.
True
A uronic acid id produced when hydroxyl group in a hexose is oxidized at what carbon?
C6
The Fehling’s test is used to determine what?
reducing sugars
Polyols are produced from sugars by what process?
reduction
Required substrate(s) for caramelization reactions is?
only carbohydrates
Carbohydrates that may serve as substrate in Maillard reactions are:
reducing sugars
The molecule for sucrose is:
aGlucose (1-2)BFructose
The molecule for lactose is:
BGalactose(1-4)Glucose
Which of these is a tetrasaccharide?
a. sucrose
b. maltotriose
c. manitol
d. raffinose
e. stachyose
e. stachyose
If all solutions were prepared with the same concentration of sugars and amino acids and were heated 2 hrs at 100 degree C, which one will have the most Maillard reaction product:
a. glucose, lysine, pH 9, in water
b. maltose, tyrosine, pH 7, in water with sulfites
c. lactose, proline, pH 4, in water
d. fructose, glycine, pH 9, in water
e. sucrose, cysteine, pH 11, in water
a. glucose, lysine, pH 9, in water
What is a reducing power of maltotetrose compared to reducing power of glucose?
25%
T or F. Addition of ammonia compounds is allowed in production of certain types of caramels.
True
T or F. When sugar caramelizes, its caloric value decreases.
True
Caramelization reactions include:
melting, dehydration, fragmentation, and condensation
T or F. Glycosidic bond is more susceptible to acid hydrolysis than peptide bonds.
True
Which sweetener will provide cooling effect while being dissolved?
some polyols - xylitol
T or F. If two polysaccharides, one linear and one highly branched, have the same molecular weight and make solutions of the same concentration, solutions of the linear polysaccharide will be more viscous.
True
Oxidation of monosaccharaides results in formation of:
polyhydroxy alcohols
High amylose starch contains:
50-70% amylose
Diameter of starch granules is:
2-100 micrometer
In waxy starches, amylose content is:
< 2%
What is the reducing power of maltopentose compared to reducing power of glucose?
1/5 (20%)
The largest starch granule is what?
potato
Consider two corn syrups with DE of 25 and 85. The corn syrup that has thicker texture (more viscous) and less sweetness is which one?
DE ~ 25
Define gelatinization.
The irreversible swelling of starch granules under the influence of heat in an aqueous medium to give a starch paste
The last enzyme used in production of HFCS is:
isomerase
B-amylase hydrolyzes amylopectin at:
a 1-4 bonds, two glucose from non-reducing end
Maltodextrins have a DE of:
5-25
