Food Chemistry Quiz 2

Front 1

Carbohydrate

Back 1

any of a large group of organic compounds occurring in foods and living tissues and including sugars, starch, and cellulose. They contain hydrogen and oxygen in the same ratio as water and typically can be broken down to release energy in the animal body.

•Sweetening agent•Texture or structure•Energy source•Thickener or stabilizer

Front 2

Aldose

Back 2

An aldose is a monosaccharide (a simple sugar) that contains only one aldehyde (−CH=O) group per molecule. An example is galactose.

Front 3

Ketone

Back 3

In chemistry, a ketone (alkanone) /ˈkiːtoʊn/ is anorganic compound with the structure RC(=O)R', where R and R'.

An example is frustose

Front 4

Glycosidic bond

Back 4

a glycosidic bond or glycosidic linkage is a type of covalent bond that joins a carbohydrate (sugar) molecule to another group, which may or may not be another carbohydrate.

- Alpha-1-2- bond in surcrose

Front 5

Reducing sugar

Back 5

A reducing sugar is any sugar that is capable of acting as a reducing agent because it has a free aldehyde group or a free ketone group. IT has a free carbonyl.

Front 6

Amylose

Back 6

•Primarily linear•D-glucose units connected by a-1-4 linkages (flexible links)

Front 7

Amylopectin

Back 7

Branched. soluble polysaccharide and highly branched polymer of glucose found in plants. •D-glucose units connected by a-1-4 linkages and ~5% a-1-6 linkages at branch points

Front 8

Sugar Alcohol

Back 8

Polyols. •The reduction of the carbonyl group in monosaccharides produces sugar alcohols

Front 9

Caramelization reaction. What must be present for it to occur?

Back 9

Heat and sugar must be present for the reaction to occur.

•Melting a sugar (especially sucrose),heating for prolonged times below the melting temperature, or heating sugarsyrup in the presence of acidic (pH<3) and/or alkaline (pH>9) catalystsproduces brown colored products with a typical caramel aroma

Front 10

Descrie maillard browning. What must be present to occur? Under what temperature and water activity conditions does this reaction occur fastest?

Back 10

•Requirements:–Amino-bearingcompound (protein, amino acid)–Reducingsugar–Somewater (mobility)

»Reactionoccurs faster with:»Highertemperature»IntermediateaW»Longerstorage time

The Maillard reaction is a chemical reaction between amine and reducing sugars that gives browned foods their desirable flavor

Front 11

Describe structure of native starch granule. Is it digestible, why/why not?

Back 11

It is typically 25% amylose, 75% amylopectin. It is digestible because it is namely made of amylopectin.

Front 12

Define gelatinization and describe what happensto the starch granule during gelatinization. Compare and contrast gelation andgelatinization.

Back 12

Gelatinization – “disruption of molecular order withinstarch granules as they are heated in the presence of water

–Irreversiblegranule swelling–Lossof birefringence–Lossof crystallinity

Gelation is hardening, while gelatinization is loss of structure.

Front 13

Define retrogradation and describe what happensto starch structure during retrogradation. How does this relate to breadstaling?

Back 13

a process which occurs when the moleculescomprising gelatinized starch begin to reassociate in an ordered structure.

In its initial phases, two or more starchchains may form a simple juncture point which then may develop into moreextensively ordered regions. Ultimately,under favorable conditions, a crystalline order appears.”

•Staling of bread is largely caused by retrogradation of starch–Amyloseretrogrades quickly and gives elastic and tender crumb structure

Front 14

Define carbohydrates.

Back 14

any of a large group of organic compounds occurring in foods and living tissues and including sugars, starch, and cellulose. They contain hydrogen and oxygen in the same ratio as water (2:1) and typically can be broken down to release energy in the animal body.

Front 15

What functions do carbohydrates provide in foods?

Back 15

•Carbon source for fermented foods•Required for normal pectin gel formation•Principal ingredient (candy)•Participant in browning reactions (Maillardbrowning and Caramelization)•Sweetening agent •Texture or structure •Energy source •Thickener or stabilizer

Front 16

Defineand give examples of aldoses; define and give examples of ketoses.

Back 16

An aldose is a monosaccharide (a simple sugar) that contains only one aldehyde (−CH=O) group per molecule. The chemical formula takes the form Cn(H2O)n. The simplest possible aldose is the diose glycolaldehyde.

Ketoses are a type of monosaccharide, which are important fuel molecules and nucleic acid building blocks. The simplest example of a ketose is dihydroxyacetone.

Front 17

Giveexamples of monosaccharides used in foods.

Back 17

Frutose, Glucose, Galactose

Front 18

Giveexamples of disaccharides, trisaccharides, and tetrasaccharides.

Back 18

Disaccharides - Sucrose, Maltose, Lactose

Trisaccharies- raffinose

Tetrasaccharides- Stachyose

Front 19

Describe the basicstructure of starch. Identify thedifferences between waxy, normal and high-amylose starches.

Back 19

The basic structure of starch is 25% amylose, 75% amylopectin

•Waxy starch (corn)–0 –8% amylose–Moreeasily dispersed, clear paste (no gel)–Moredigestible by humans than other starches

•Normal starch–20-30%amylose–Strongergel produced

•High-amylose starch–>50%amylose–Unusuallyhigh gelatinization temperature

Front 20

Name the carbohydrates used as sweeteners.

Back 20

Monosaccharides and Disaccharides

Front 21

Why are carbohydrates water-soluble? What makes a carbohydrate more or less soluble?

Back 21

Carbohydrates are very soluble because of their numerous hydroxyl groups.

Solubility increases as temperature increases.

Front 22

Describe the Maillard browning process. What must be present for the process to occur?

Back 22

The Maillard reaction is a chemical reaction between amine and reducing sugars that gives browned foods their desirable flavor

The Maillard reaction is a chemical reaction between amine and reducing sugars that gives browned foods their desirable flavor

Can speed up with higher temperature, intermediate water activity and longer storage. Can slow down with lower temperature and lower activity.

Front 23

What function(s) do polysaccharides perform in foods?`

Back 23

Polysaccharides make up starch (Amylose and Amylopectin)

Front 24

Describe what conditions are necessary for gelatinization to occur AND what happens to starch granule structure during gelatinization.

Back 24

Gelatinization – “disruption of molecular order within starch granules as they are heated in the presence of water –Irreversible granule swelling –Loss of birefringence –Loss of crystallinity - SWELLS - LEAKS AMYLOSE

Front 25

What is starch retrogradation? Name several benefits and several drawbacks.

Back 25

•Occurs when gelatinized starch moleculesbegin to reassociatein an ordered structure (form a gel or a precipitate)

•Initially 2 or more amylose oramylopectin polymers may form a simple juncture point which may then developinto more ordered regions

–As starch pastes are cooled and stored starch becomes less soluble

--•Staling of bread is largely caused by retrogradation of starch–Amyloseretrogrades quickly and gives elastic and tender crumb structure

Front 26

Compare and contrast amylose/amylopectin

Structure

Back 26

Amylose is primarily linear while amylopectin is branched.

Front 27

Compare and contrast amylose/amylopectin function

Back 27

Amylose is the preferred starch for storage in plants while amylopectin because it takes up less space but amylopectin is easier to digest.

Front 28

Compare and contrast amylose/amylopectin response to heating and cooling

Back 28

After heating and cooling, starch with more amylose will become more viscous compared to starch with almost no amylose.

Front 29

Compare and contrast amylose/amylopectin ratios and amounts in common commodities

Back 29

Amylose is on average 25% starch while amylopectin is 75%

Waxy starch(Corn) - 0-8% amylose

High amylose starch- >50% amylose

Front 30

Compare and contrast amylose/amylopectin influence on food product structure and texture

Back 30

More amylose typically makes a stronger gel and raises the gelatinization temperature, while making it harder to digest. No amylose leads to paste and easier to digest. Amylopectin leads to crystallization

Front 31

Isomer

Back 31

An isomer would be a chemical with the same empirical formula, but a different structural arrangement. This happens most often in organic chemistry, though it is possible with inorganic chemicals.

Front 32

How many enzymes are needed to hydrolyze starch down to glucose?

Back 32

More than 1!

Front 33

Pre gelatinized starch is cold water soluble. T/F?

Back 33

True

Front 34

Dif between cross-linked and substitute starch

Back 34

Substitute have big functional groups, making it swell up extremely large, not as much retrogradation.

- Cross links won't swell up as much, compact less, covalent bonds.q

Front 35

RVA curve is...

Back 35

Viscosity on y axis and temperature on the right.

Gelatinization is when it starts rising, regtrogradation is when it starts sinking and setback is when it sinks againq

Front 36

Lactose is

Back 36

Unique disaccharide made of glucose and galactose liked by alpha-1-4- glycosidic bond.