332 Gelatin and pectin Gels

%Sag =

(depth in container-depth on plate)/(Depth in container) x 100

What is required in order for pectin to form a gel?

A delicate balance of pectin, water, sugar, and acid.

What does pectin form when it disperses into water?

A sol, and under right conditions a gel

What are the functional properties of pectins?

Gelling agent, thickening agent, stablizers

Pectins are available either as ______ or as a _____. Which has the longer shelf life?

Granular; Liquid (sol) and granular has the longer shelf life

What pectins chemically?

Partially demethylated

As little at ____ part gelatin can set or immobilize _____ parts of water by weight.

one; 99

What happens to the gel if it is super cool very quickly?

rapid drop in temperature results in the formation of numerous crystal nuclei (Crystallites) - Results in a gel with a lower melting point - Discontinuous network

What is the final concentration of sugar in a pectin gel?

65% ---- 40%-70% can form a gel but it effects the firmness. High sugar is soft and sticky, low sugar is tough gel

What must the concentration of pectin and acid in order for the product to be a jelly?

0.5%-1.0%

What is the next two steps in the production of gelatin after it has been pretreated from its source?

1). The gelatin sol is then filtered clarified and concentrated. 2). Gelled in thin layer and then is dried -- Marketed as coarse particles or fine powder.

What are all the steps in the production of Gelatin?

1. Hydrolysis of pretreated cooked meats (Pig skin cow hide or demineralized bone) 2. The gelatin sol is then filtered clarified and concentrated 3. the gelled in thin layers and then is dried

What percentage of carboxyl groups are esterified with methanol in Low methoxyl pectins?

20%

What is the effect of acids on gels? (gelatin) And What does this do?

Acids weaken gels by protein hydrolysis (Lowers melting point, lowers temperature of gel formation, improves clarity)

What are the two sources of pectin?

Apple pomace (Core and skin) Albedo of citrus fruits (inner white of the peel)

When do you add acid to pectin to form a gel?

At the end of the boiling period to prevent pectin hydrolysis

What is significant about the isoelectric point in gelatins and the effect of swelling, and why?

At the isoelectric point it is the least soluble except in the presence of added salts, this is because like charges repel keeping the proteins in solution (as a sol)

why is the Isoelectric point of gelatin variable?

Because it is heterogenous nature of gelatin, and because of the effect of production methods.

What is protopectinases?

Catalyzes the hydrolysis of protopectin forming the shorter chain pectic substances. this creates positive and negative results.

What are pectin esterases?

Cause demethylation and diminishes gel forming ability of the pectin, complete demethylation yields pectic acid.

How is gelatin Marketed as? So what does it look like?

Coarse particles or fine powder.

How do you make pectin?

Cut apples, retaining seeds and core. Cover with water and simmer 20 minutes, then mash and continue simmering. Strain through a jelly bag.

What is the purpose of water in pectin gel?

Dissolves acids, sucrose, and salts. and disperses pectins as a colloidal sol

How does Salt effect the swelling of the Gelatin?

Divalent ions increase protein bonding, and aides in swelling when gelatin at the isoelectric point.

During slow cooling with does the most rapid increase in firmness occur?

During the first day?

What happens to the gel if it is super cooled slowly?

Formation of more heat-stable junction zones. - gel rigidity increases with time. Most rapid increase in firmness occurs during the first day.

Where are pectic substances found?

Found in and between the primary cell wall, an contributes to the plant's firmness and structure.

What are the three classes of Pectins?

High methoxyl pectins, Low Methoxyl pectins, and intermediate methoxyl pectins. The degree of methylation ranges from about 10-60%

What are pectins?

Important polysaccharides, Constituents of plant tissue, large complex molecules.

Where is protopectin found?

In immature fruit

Where are junction zones formed?

In regions that do not have other sugars; rhamnose, galaxies, arabinose, xylose. Results in bending and kinking, preventing alignment. The spaces between the chains trap water.

Where is pectic acid found?

In very very ripe fruit, which is completely demethylated, and cannot form a gel.

What is Grading of pectin evaluation?

Indicates the sugar-carrying capacity. Indicates the weight of sucrose that when combined with a unit weight of pectin will yield jelly of a specified rigidity as measured by its SAG when turned from a mold.

How does sugar effect gel formation in pectin?

It acts as a dehydrating agent, and competes for water allowing for interactions between pectin chains also bacterial control. It is a dehydrating agent because it binds water to pectin network prevents free water from leaving the gel.

What is the effect of adding hot water to gelatin after cold water has already been added?

It completes the process of dissociation of the gelatin by breaking the hydrogen bonds, which results in a formation of a sol.

What is the chemical properties of low methyl pectin?

It has most carboxyl group available to form cross-links with divalent ions such as calcium

What are the properties of low methoxyl pectins?

It has sufficient cross-links that are formed so it forms a 3D network that can obtained which traps liquid, thus forming a GEL without the use of sugar or acid.

What is pectic acid?

It is a short chain derivative of pectin which is formed as fruit ripens.

How are Gelatin made?

Made during the hydrolysis of cooked meat

What are protopectins chemically?

Methylated galaturonic acid polymer

Used in what type of products?

Molded desserts, aspics, whips, sponges and creams

The percentage of methylation of pectins determine the what?

Name and properties.

Which one of these can form a gel? Pectin, pectic acid, or protopectin

Only pectin

What are two types of fruit ripening enzymes?

Pectin (methyl) esterases and protopectinases

What pectins have the best jelly forming ability?

Pectins with a high molecular weight (long-chain) and high proportion of methyl ester group.

What are the commercial sources?

Pig skin (pretreated with with acid) Cow Hide (Pretreated with base) Demineralized bone (pretreated with base)

What are pectic substances molecularly?

Polysaccharides, long thread-like chain which under the right conditions in able to trap liquid and form a gel. They are linear and sometimes branched polymer of D-galacturonic acid joined by alpha 1,4 glylcosidic linkages (((Some of the COOOH groups esterified with the methanol))))

What do the pretreatments of the demineralized bone do?

Pretreatments remove impurities and disrupts covalent bonds that cross-link collagen monomers.

What are Pectic substances?

Protopectin, Pectin (pectin acid), pectic acid

What factors effect the swelling of the gelatin?

Salt, pH, Water Temperature,Isoelectric point

What is a sol?

Solids that are dispersed in a liquid.

What are junction zones?

Specific regions where two molecules of pectin align and H-bond; D-glacturonic acid.

What do Intermidiate MP's require?

Sugar, acid and divalent ions (30%-40%) methylated.

What needs to be reduced in order for pectin gel formation?

The separating forces must be reduced, so the attraction for water must be decreased, and the attraction for self must be increased.

Pectin concentration varies with the plant tissue Give two examples

The skin and core of the apple have greater amount of pectin than the pericarp, and the maturity of the fruit also affects the type of pectin present.

How are pectins formed?

They are formed from protopectins as fruit ripens

What are the properties of high methoxyl pectins?

They are gel formers by the addition of sugar and acid, the most common procedure for making pectin jellies. `

What are some of the properties of pectins?

They can forma gel, and are dispersible in cold water.

What are High methoxyl pectins proportions?

They contain high proportions of esterified carboxyl group (25-50%) (The degree dependent on fruit ripeness: just under ripe to just ripe)

What is the effect of cold water on gelatin?

They hydrate in cold water, because it initiates separation of gelatin molecules.

What are the functions of gelatin?

Thickening agent, gelling agent, and stabilizer (like gums and pectins)

Through what method do HMP's form?

Though Junction zones

What are crystallites in the gelatin?

Three gelatin molecules reunite to form a triple helix Creates pockets that trap liquid Cutting or spooning of a gel will result in syneresis

What is the definition of pectin gel formation?

Water (juice) held in a 3-D network of pectin molecules

What is the chemical reason for the sol formation of pectin?

When the pectin is despersed into water some of acid groups ionize and water hydrogen bonds to pectin structure, the negative charge on the pectin molecules, coupled with their attraction for water keeps them apart that they form a stable sol.

When does gelation take place in gelatin?

When the sol is super cooled. Must be cooled to a minimum of 35 C.

When can pectin be extracted form certain fruit?

When they are heated in a limited volume of water.

Is gelatin an effective gelling agent?

Yes

What is the maximum hydration pH of gelatin?

between 3.2-3.5 or 9.0 (bimodal)

What is the pI of Alkaline processed gelatins?

between 4.75 and 5.2

What is the pI of Acid processed gelatins?

between 5.5 and 6.5

How is the 3-d network obtained in gel formation of pectin?

by the addition of acid or sugar.

What are some of the properties of protopectin?

insoluble in water, and cannot form a gel. although they can be converted to a water dispersible pectin by heat in boiling water.

What occurs as the gelatin cools in the sol state?

it becomes more viscous and elastic

What is the purpose of acid on a pectin gel?

lowers the pH to a level of conductive for gel formation which is <3.5. Provides protons to keep more carboxyl gourds uncharged, which makes the pectin molecules unable to repel each other,

Through what method do LMP's form?

thought divalent ions.