Pectins and Gums

WHat is the chemical make-up of pectin?

Galacturonic acid units joined by alpha glycosidic linkages

_____ is the most common monosaccharide found

Galctose

What are 3 uses of pectin in the food commercial industry?

Gelling agent-jelly 2. Thickeners 3. Stabilizer

Examples of seed gums?

Guar gum, locaust bean gum

rapid set (70-85%) pectins have what?

High amount of HM pectin

Pectins are classified as what according to the degree of esterification?

High methoxyl pectins or low methoxyl pectins

Characteristics of pectic acid

overripe,soluble, no gel, almost no methyl, mushy

HM pectin gels under what condition?

pH of 3.5 or less and acid

Why are synthetic gums used in diabetic tailored food?

provides bulk, body and mouthfeel normally supplied by sucrose

carrageenan=

red seaweed

Gums are classified as insoluble/soluble fiber b/c they undergo very little digestion

soluble

Gum arabic is used to _____emulsions and control crystal size in ice and glazes

stabilize

HM pectins gel when there is sufficient ____ and ____ present?

sugar and acid

Pectins have the unique quality to form spreadable gels in the presence of ____,_____ or _____

sugar, acid, calcium

Pectic acid=???

Overripe fruit

Describe pectins?

1. High molecular weight polysaccharides 2. Found in the lamellae of plant wall 3. Important in firmness and softening of fruits

Gums are obtained from the plants of what five categories?

1. Seed gums 2. Plant Exudates 3. Microbial exudates 4. Seaweed extracts 5. Synthetic gums made from extract

What affects the composition and properties of pectin in a food matrix?

1. source of pectin 2. Processes used during preparation of pectin 3. Subsequent treatment of pectin

What are the functional roles of gums?

1.Thickeners 2. Stabilizers 3. Control crystal size 4. Suspending agents 5. Gelling agents 6. Coating agents 7. Bulking agents 8.Fat replacers 9. Starch replacers 10. Source of fiber

Guar gum contains _:_ ration mannose;galactose and is _____ in cold water

2:1 ; soluble

_____ chemically district pectic substances have been identified?

3

Locust bean contains __:__ mannose; galactose and must be dispersed in ___water

4:1 ; hot water

WHat are seed gums?

Branched polymers, contained only MANNOSE and Galactose

gums do/don't gel- highly branched structure

DO NOT!!!!!! DO NOT!!!!! DO NOT!!!!!

Protopectin= immature fruit; what is happening chemically?

Enzymatic hydrolysis

High and low methoxyl pectins have the same properties and gel under the same conditions?

False

gum trangacanth is not expensive and is used alot?

False; expensive and is used alot

Glucose is usually present in gums?

False; it is usually absent

WHat happens to gums when added to water?

Form stable aqueous colloidal dispersions or SOLS

Where are the highest quality pectins found?

In lemon and lime peel

_______ bilking agents, binders, thickeners- increase viscosity of foods

Non metabolizable

Characteristics of pectinic acid?

Ripe, collodial, gel, less methyl, optimum

what is pectic acid

Short-chain demethylated derivative of pectinic acid associated with overripe fruit

What happens to the chemical make-up of pectins when fruits and veggies are ripening?

The acids groups along the galacturonic acid chains become methylated

Ex of seaweed exudates?

alginates, carrageenan, agar

Synthetic gums are used to coat food before/after frying to limit amount of fat absorbed?

before

Iota seaweed gum forms gels with ___ ions

ca+

Most commercially available pectin omes from _____ peel or apple ______

citrus; pomace

Gum trangacanth is used for?

creamy textures, suspend particles and act as stabilizer in salad dressing, ice cream and confections

Pectinic acid= ripe fruit; what is happening chemically

depolymerization and demethylation

LM pectin is present in what found items?

diabetic jellies, jams, preserves and marmalades----- natural fruit preserves

LM's gel only in the presence of ______ that provide cross bridges?

divalent cations

Pectins can be deliberately ____ during extraction or processing

esterified

The methylation of some of the carboxylic acid groups on the galacturonic acid untis are chemically considered ______

esters

kappa carrageenan- smallest # sulfate esters

form gels with K ions

Ex of plant exudates?

gum arabic, gum trangacanth

______ are made from thousands of monosaccharide units?

gums

HM is found in what founds?

high-sugar, jellies, jams, preserves, acidic milk drinks, milk gels

Gums: due to thier affinity for water and their size they are often referred to as ______

hydrocolloids

Carboxymethyl cellulose is formed from the ______ of cellose with acid

hydrolysis

Plant exudates are highly branched polysacharides and are _____ in cold water

insoluble

Characteristics of protopectin?

insoluble, underripe,no gel, lots of methyl, hard

WHat three factions does carrageenan occur in ?

kappa, iota and lambda differentiated by varying amounts of negatively charged sulfate esters

Lambda seaweed has a ___ # of sulfate groups and is too highly charged to form a gel

large

WHat is the easiest pectin variety to isolate?

lemon or lime peel is the easier to isolate

What is pectinic acid

less methylated galacturonic acid polymer produce during ripening

Xanthan gum does not form gel unless used in combination with _______

locust bean

What is protopectin-

methylated galacturonic acid polymers found in immature fruits

Synthetic gums?

microcrystalline cellulose, carboxylmethyl cellulose

When the pH is lowered in HM what happen?

the highly hydrated and charged carboxylate groups are convered into uncharged and slightly hydrated and charged carbosylate group (ALLOWING GELLING)

Degree of esterification is the term used for ____

the proportion of methyl esters in a pectic substance

How are microbial exudates produced?

through fermentation

Gums form what kind of gels?

viscous

Xanthan gum form ____ sols that are stable over wide range of pH and temperature

viscous

Ex of microbial exudates?

xanthum. gellan, dextranginates, carrageenan, agar