Lecture 10: Di and Complex CBOH Flashcards
Glucose
- Monosaccharide
- Hexose
- Sweet taste
Maltose
- “malt sugar”
- Prepared by yeasts or enzymes acting upon starches
- A disaccharide of 2 glucose parts
Lactose
- Disaccharide from mammalian milk
- Composed of glucose and galactose
- Commercially prepared from whey
- 1/6 sweetness of sucrose
- Low solubility
Lactose intolerant
- Decrease and lose production of lactase and can’t digest lactose
- At least half of the world’s adults cannot effectively digest lactose
Starch
- Polysaccharide (polymer of many sugar moieties)
- Composed of 2 polymers (amylose and amylopectin)
Swelling of starch
- Upon heating, starch granules swell (fill with water) –> sol (solution) is formed
- Upon cooling, a gel is formed from starch granules trapping water
What’s the difference between regular chocolate pudding and instant?
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
Gel
- Mostly solvent (water) entrapped in a network of polymer
- With sugar –> jelly or jam
- Ex) pudding = 95% water (solvent)
Retrogradation
- Realignment of the starch polymers that causes the expulsion of water
- Causing the staling of bread (and other foods)
How is retrogradation inhibited or slowed?
- 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”
Staling
- Bread becomes tough and gritty
- Mold can accompany the staling of bread, but is not staling per se
Does bread stale more quickly being left on the counter or when put in the freezer or refrigerator?
- In the freezer/refrigerator
- Refrigeration causes evaporation of water and retrogradation to proceed more quickly due to ice crystal formation
Amylase
Enzymes used to breakdown starch
Describe the 2 major types of amylases
- Alpha = a random attack to release sugar
- Beta = cleaves of maltose
Dietary fiber
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
How does fiber regulate the GI tract?
- 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
Insoluble fiber
- Undigestible
- Ex) cellulose, lignin
- Acts as a bowel irritant
- Draws water out into lumen
- Cleans out lower GI (correlated with less colon cancer)
Soluble fiber
- Partially digestible
- Ex) gums, pectins
- Lowers cholesterol concentration
- More cholesterol covered to bile salts
- Cholesterol pulled from bloodstream
Cellulose
- 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
Pectins
- 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
