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Carbohydrates_exam1
food sci
| Question | Answer |
|---|---|
| Carbohydrates are composed of? | carbon, hydrogen, and oxygen |
| Empirical formula of carbohydrates is | (CH_2_O)n |
| The two main classes of carbs are | simple sugars (soluble) and complex carbs or polysaccharides (large molecules like jelly and pectin) |
| Carbohydrates are composed of? | carbon, hydrogen, and oxygen |
| Empirical formula of carbohydrates is | (CH_2_O)n |
| The two main classes of carbs are | simple sugars (soluble) and complex carbs or polysaccharides (large molecules like jelly and pectin) |
| in plants simple sugars are a direct source of what? | energy which is formed by photosynthesis |
| photosynthesis | CO_2_ + H_2_O = (CH_2_O)n |
| complex carbs are used for | either storage forms of energy or structural components |
| Sugar is not based on sweetness but | structure |
| Monosaccharides | - are made up of 5 or 6 carbons - contains a functional carbonyl group C=O - and hydroxyl groups -OH |
| What are some important Monosaccharides? | Glucose (GLU), Galactose (GAL), Mannose (MAN), and Fructose (FRU). |
| These monosaccharides have different structures and functions but the same | number of atoms |
| Disaccharides | sucrose, lactose, maltose |
| Sucrose | glu-fru (table sugar 99.5% pure) |
| Lactose | gal-glu (found in milk) |
| Maltose | glu-glu |
| Tri/tetrassacharides | raffinose, stachyose (found in plants and beans) |
| Raffinose | gal-glu-fru |
| stachyose | gal-gal-glu-fru |
| linkages of sugars | sugar units in oligo- or polysaccharides are linked by a condensation between hydroxyls |
| digestibility depends on | the chemistry of the linkage between sugars and the presence of enzymes in the intestine which can break that linkage |
| Indigestible polysaccharides constitute | dietary fiber |
| Properties of sugars | soluble in water, crystallize easily, sometimes sweet, react with proteins and amino acids to give brown colors and flabors (when heated like baking) |
| Sweetness is related to | the 3d structure and depends on the position of oxygen atoms and hydroxyl groups |
| Sweetness level | fructose > glucose > galactose > mantose (most bitter) |
| Corn syrup | natural sweetener made from corn starch (a polymer of glucose) |
| High fructose corn syrup is made by | isomerization of glucose |
| Artificial and non-nutritive sweeteners | Saccharin, Aspartame - a dipeptide, acesulfame K |
| Saccharin | 1st artificial sweetener |
| Aspartame - A dipeptide | nutersweet / can't be used in heat process or it'll lose sweetness |
| Acesulfame K | example: Splenda Chemical derivative |
| Polysaccharides | polymer of sugar units n(s) --> (S)n |
| n is usually | very large > 100 |
| Starch | provides the most calorie (designed to be synthesized and broken down) |
| Polysaccharides exist in two forms | amylose (linear) and amylopectin (branched) |
| Is starch digestible | yes, it can form gels on cooling if the concentration is high |
| Cellulose | all plants contain cellulose (resistant to digestion because of linkage) |
| Pectin | is found in plant cell walls |
| Pectins are polymers of | galacturonic acid which is indigestible |
| Pectins can be strengthened by | cross linking with calcium |
Created by:
lindarim
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