FOOD CHEM pectins

42問 • 11ヶ月前

問題一覧

_______ and _____are polysaccharides widely used in food as gelling agents, thickeners, and stabilizers. They help maintain or enhance food texture and physical characteristics.

pectins,gums

A high-molecular-weight, methylated galacturonic acid polymer in immature fruits, insoluble in water.

protopectin

A methylated derivative of galacturonic acid, including pectins, which are water-dispersible and capable of gel formation.

pectinic acid

A shorter-chain, demethylated form of pectinic acid found in overripe fruits, incapable of gel formation.

pectic acid

_____ are high-molecular-weight pectinic acids with varying degrees of esterification

pectins

(20-40% esterified): Form gels with divalent ions like calcium, without sugar or acid.

Low-methoxyl pectins

(50-58% esterified): Require sugar and acid for gel formation.

High-methoxyl pectins

Pectin gels consist of water trapped in a __-dimensional network of pectin molecules

The process is called ________ is when carboxylic acids are esterified (combined with an alcohol to form an ester), the resulting esters are liquids with fruity flavors.

esterification

Key Factors in Gel Formation: - ______: Competes for water, reducing pectin-water interaction.

sugar

Key Factors in Gel Formation: - ______: Lowers pectin ionization, reducing charge and increasing pectin-pectin attraction.

acid

Key Factors in Gel Formation: - Pectin forms a ___-dimensional network, with pectin as the continuous phase and water trapped as the dispersed phase.

Principles of Making Jelly Jelly is made by combining ~fruit juice (water & acid source) ~pectin ~sucrose then heating until boiling. -Importance of Boiling Time: - Too long: Heat and acid break glycosidic bonds, depolymerizing pectin, weakening gel formation. - Too short: Not enough invert sugar forms, increasing the risk of sucrose crystallization during storage.

remember

complex hydrophilic carbohydrates with thousands of monosaccharide units, mainly galactos

gums

They are classified as _________ due to their strong water affinity.

hydrocolloids

In food, gums are used as thickeners, emulsifiers, and stabilizers.

remember!

Main Characteristics - Large, highly branched hydrophilic polymers. - Rich in galactose and classified as hydrocolloids. - Form viscous solutions but most do not gel. - Considered soluble fiber, contributing few calories due to minimal digestion and absorption.

remember!

Uses in Food - Found in salad dressings, sauces, soups, dairy products, baked goods, meat products, and fried foods. - Act as thickening agents, replacing starch. - Stabilize emulsions and maintain texture in frozen desserts. - Common in reduced-fat products to enhance viscosity and mouthfeel.

remember!

Sources and Types of Gums 1. _____ Gums(e.g., guar gum, locust bean gum)

seed

Sources and Types of Gums 2. _____ Exudates (e.g., gum arabic, gum tragacanth)

plant

Sources and Types of Gums 1. Seed Gums - ____ gum stabilizes ice cream and slows glucose absorption, potentially helping in diabetes management.

guar

Sources and Types of Gums 1. Seed Gums - ____ bean gum is used in dairy and meat products and can gel with xanthan gum.

locust

2. Plant Exudates (e.g., gum arabic, gum tragacanth) - Gum ______ dissolves in cold water and stabilizes emulsions, controlling crystal size in ices and glazes.

arabic

2. Plant Exudates (e.g., gum arabic, gum tragacanth) -Gum ________ forms viscous sols, providing a creamy texture and acting as a stabilizer in salad dressings, ice cream, and confections.

tragacanth

Guar gum, locust bean gum.

seed gum

Gum arabic, gum tragacanth.

plant exudates

Xanthan, gellan, dextran, curdlan.

microbial exudates

Alginates, carrageenan, agar.

seaweed polysaccharide

Microcrystalline cellulose, carboxymethyl cellulose, methyl cellulose.

synthetic gum

Microbial Exudates - ______ gum is the most common, forming viscous sols stable across pH and temperature ranges.

xanthan

Seaweed Polysaccharides - ________ is extracted from red seaweeds, especially Irish moss, and has three main types

carrageenan

Seaweed Polysaccharides Carrageenan - _____ carrageenan: Least negatively charged, forms strong gels with potassium ions.

kappa

Seaweed Polysaccharides Carrageenan - ____ carrageenan: Forms gels with calcium ions.

lota

Seaweed Polysaccharides Carrageenan - _____ carrageenan: Highly charged and does not form gels.

lambda

Properties and Uses of Agar - Extracted from red seaweeds. - Forms strong, transparent, heat-reversible gels that melt when heated and reform upon cooling. - Composed of agarose and agaropectin both polymers of galactose.

remember

Properties and Uses of Alginates - Obtained from brown seaweeds, composed mainly of D-mannuronic acid and L-guluronic acid. - Form calcium alginate gels, which remain stable even at boiling temperatures. - Used for making reconstituted fruit products by mixing fruit purees with sodium alginate and treating them with calcium. - Example: Synthetic cherries, apple, and apricot pieces for pie fillings.

remember

Functional Roles of Gums in Food Products 1. Thickeners 2. Stabilizers 3. Control Crystal Size 4. Suspending Agents 5.Gelling Agent 6. Coating Agents 7. Fat Replacers 8. Starch Replacers 9.Bulking Agents 10. Source of Fiber

remembz!

Synthetic Gums A natural plant component, insoluble in water, and classified as insoluble fiber.

Cellulose

Synthetic Gums Cellulose (Avicel)Used as a bulking agent in low-calorie foods.

Microcrystalline

Synthetic Gums Increases viscosity, used as a thickener and binder in pie fillings and puddings. It also controls ice and sugar crystal growth in ice cream and confections.

Carboxymethyl Cellulose

Synthetic gums Forms gels when heated, used to coat foods before deep-frying to reduce fat absorption.

Methyl Cellulose

Synthetic gums Also used as batters for coating fried foods.

Hydroxypropyl Cellulose & Hydroxypropylmethyl Cellulose

biochem

velante · 99問 · 1年前

biochem