Lecture 10: Di and Complex CBOH

Question 1

Glucose

Answer 1

• Monosaccharide
• Hexose
• Sweet taste

Question 2

Maltose

Answer 2

• “malt sugar”
• Prepared by yeasts or enzymes acting upon starches
• A disaccharide of 2 glucose parts

Question 3

Lactose

Answer 3

• Disaccharide from mammalian milk
• Composed of glucose and galactose
• Commercially prepared from whey
• 1/6 sweetness of sucrose
• Low solubility

Question 4

Lactose intolerant

Answer 4

• Decrease and lose production of lactase and can’t digest lactose
• At least half of the world’s adults cannot effectively digest lactose

Question 5

Starch

Answer 5

• Polysaccharide (polymer of many sugar moieties)

- Composed of 2 polymers (amylose and amylopectin)

Question 6

Swelling of starch

Answer 6

• Upon heating, starch granules swell (fill with water) –> sol (solution) is formed
• Upon cooling, a gel is formed from starch granules trapping water

Question 7

What’s the difference between regular chocolate pudding and instant?

Answer 7

REGULAR
-smoother and has better texture
-must be heated to gelatinize the starch
INSTANT
-doesn't have as good a texture
-just needs milk added, then mixed
-thickens without heating b/c it has pre-gelatinized starch

Question 8

Gel

Answer 8

• Mostly solvent (water) entrapped in a network of polymer
• With sugar –> jelly or jam
• Ex) pudding = 95% water (solvent)

Question 9

Retrogradation

Answer 9

• Realignment of the starch polymers that causes the expulsion of water
• Causing the staling of bread (and other foods)

Question 10

How is retrogradation inhibited or slowed?

Answer 10

• The more amylopectin, the less retrogradation
• Starches with high amylopectin percentages are called “waxy” starches
• To prevent retrogradation, manufacturers chemically modify starches –> must be label as “modified starch”

Question 11

Staling

Answer 11

• Bread becomes tough and gritty

- Mold can accompany the staling of bread, but is not staling per se

Question 12

Does bread stale more quickly being left on the counter or when put in the freezer or refrigerator?

Answer 12

• In the freezer/refrigerator

- Refrigeration causes evaporation of water and retrogradation to proceed more quickly due to ice crystal formation

Question 13

Amylase

Answer 13

Enzymes used to breakdown starch

Question 14

Describe the 2 major types of amylases

Answer 14

• Alpha = a random attack to release sugar

- Beta = cleaves of maltose

Question 15

Dietary fiber

Answer 15

Edible parts of plants or analogous carbs that are resistant to digestion and absorption in the human small intestine with complete or partial fermentation in the large intestine

Question 16

How does fiber regulate the GI tract?

Answer 16

• Fiber provides bulk to help move materials through the GI tract
• Poop is 75% water, 25% solids
• Of the solids, 30% is dietary fiber that is either insoluble or soluble

Question 17

Insoluble fiber

Answer 17

• Undigestible
• Ex) cellulose, lignin
• Acts as a bowel irritant
• Draws water out into lumen
• Cleans out lower GI (correlated with less colon cancer)

Question 18

Soluble fiber

Answer 18

• Partially digestible
• Ex) gums, pectins
• Lowers cholesterol concentration
• More cholesterol covered to bile salts
• Cholesterol pulled from bloodstream

Question 19

Cellulose

Answer 19

• Wood and paper CHO
• Starch-like, but with a different biochemical linkage
• Indigestible by mammals except ruminants where microorganisms actually break down the cellulose into simple glucose sugars

Question 20

Pectins

Answer 20

• What nature uses to cement plant cell walls together
• When plants are heated, they release broken “chunks” of the cell wall pectin to form smaller molecules that we call ordinary pectin