FOOD STUDIES - CARBOHYDRATES

What are polysaccharides?

carbohydrates of high molecular weight, which differ from sugars.

Describe the structure of beta glucose.

first - OH up, H down second - H up, OH down third - OH up, H down fourth- H up, OH down fifth - CH2OH up, H down ending with O

Structure of Alpha fructose.

first- CH2OH up, OH down second- H up, OH down third- H up, OH down fourth- H up, OH down fifth - H up, H down ending with O

Structure of Beta fructose

first- OH up, CH2OH down second - H up, OH down third - H up, OH down Fourth - H up, OH down fifth - H up, H down ending with O

What is the molecular formula of polysaccharide?

(C6H10O5)n

Example of a formation of a disaccharide?

(C6H11O5) OH + HO (C6H11O5) --> (C6H11O5)-O- (the glycosidic bond) - (C6H11O5) + H2O

Properties of disaccharides

1. Dissolve in water forming sweet solutions. 2. During digestion they are hydrolysed (broken down) to give monosaccharides from which they were built eg: sucrose gives glucose and fructose.

What are the properties of monosaccharides?

1. Dissolve in water to give sweet solutions eg glucose, galactose, fructose 2.end products of digestion 3. can be absorbed into the bloodstream

State the properties of cellulose

1. Insoluble in water 2. cannot be digested by human cause enzymes present in intestine cannot break the glucose bond.

what are the properties of polysaccharides?

1. Non crystalline 2. insoluble in water 3. tasteless unless hydrolyzed by amylase. ​

Name the properties of fructose.

1. Twice as sweet as sucrose 2. Readily converted to triglyceride than glucose in the liver. 3. Found in honey and nectars. ​

What are the properties of sucrose?

1. White crystalline solid 2. Dissolve in water 3. Sweet to taste 4. made of glucose and fructose 5. obtained from cane sugar or sugar beet

What is the formula of glucose, sucrose and starch?

1. glucose -C6H12O6 2. sucrose -C12H22O11 3. starch -(C6H10O5)n

what are the properties of glucose?

1. white solid 2. sweet tasting sugar

what is oligosaccharides?

Are carbohydrates with 3 to 10 monosaccharides units.

What are monosaccharides?

Basic units of carbohydrates

Give some examples of gelatinisation based sauces.

Bechamel, bordelaise,espagnole sauce.

How is a polysaccharide formed?

By the union between monosaccharide molecules with the elimination of water

General formula of carbohydrates?

Cx(H20)y. (x and y are whole numbers)

What is the other name of glucose?

Dextrose

Define formation of disaccharide.

Formed by the union of two monosaccharides with the loss of a water molecule ( condensation reaction) bond in the middle is known as glycosidic bond.

Where is pectin found and describe its structure.

Found in soft fruits and cell walls of all plants. exists as protopectin in unripe fruits and d vegetables. made up of long chain like molecules of alpha( the alphabet) D galacturonic acid.

Describe the structure of alpha glucose.

It is a hexagon (start from right) first - H up , OH down second- H up, OH down third- OH up, H down fifth- CH2OH up, H down ending with an O. ​

What is lactose and what is it made up of?

It is the principal sugar present in milk. made up of glucose and galactose ​

What is maltose and where is it obtained?

Made up of two glucose units. Obtained when starchy materials are hydrolyzed by the enzyme diastase.

what are extrinsic sugars?

Not part of the cell structure. They include non - milk extrinsic sugars eg refined sugars, extracted sugars in honey and fruit juice added to foods and milk sugars.

What are intrinsic sugars?

Sugars that form part of the cell structure of plants eg in fruits.

What happens during overcooking of starch?

The cell walls disintegrate and produce an unpalatable mush.

Describe the structure of cellulose and state where it is found.

They are long chains made of beta glucose. The bundle of chains lie side by side linked together by hydrogen bond giving cellulose fibres. Found in almost all food of vegetable origin.

What happens to NSP that is attacked and broken down by harmless bacteria?

This is caused by bacterias that live in the bowels. Converted to short chain fatty acids( that is absorbed into the bloodstream and contribute to energy intake) ,carbon dioxide and methane. (may be a source of embarrassment due to gas production. fart.) hydrogen is absorbed and expired in breath.

what are disaccharide? give examples.

Two connected monosaccharides unit. Sucrose,maltose, lactose

what is difference between amylose and amylopectin?

amylopectin is 3,4 times more in amount than amylose. Amylose 1,4 alpha glucose and amylopectin 1,4 and 1,6 alpha glucose. amylopectin more complex than amylose.

What is starch made up of?

amylose and amylopectin

How can starch resist cold water?

because amylose and amylopectin closely packed together in an orderly crystaline manner. hydrogen bonding (between hydrogen and oxygen) help hold molecules together giving cohesion to the starch particles.

what elements carbohydrates contain?

carbon, Hydrogen, oxygen

where is NSP found?

cereals, fruits and vegetables.

What happens during ripening?

enzymes present in plants convert protopectin to pectin.

Why can't we digest uncooked starchy foods?

granules contained within the cells walls thus digestive juices cannot penetrate.

What happens when starch is shaken with cold water?

it forms a milky suspension

What happens when hydrated gelatin is heated with water above 35°?

it liquifies and form a sol. on cooling the sol set to become solid, known as gelation.

What are carbohydrates?

macronutrients that occur in food as sugars and starches.

How is jam made?

made by boiling fruit with sugar solution and is essentially a gel or a semi-solid mass containing puped or whole fruit.

describe the structure of pectin and where is it found?

made of long chain like molecules of alpha (the symbol)-D- galacturonic acid found in soft fruits and in cell walls of plants. found as protopectin in unripe fruits and vegetables. ​

Function of cellulose?

main component of cell walls of plants, thus providing structural support.

Function of starch?

main energy reserve of most plants stored in tubers and elsewhere.

What is the function of carbohydrates?

major source of energy in the diet and as cellulose which is the main NSP (non starch polysaccharide)

What is the role of starch in plants and where is it found?

major source of energy reserve in plants. converted to sugars in plants. found in stems, tubers,unripe fruits,seeds.

Identify plant NSP and animal NSP

plant NSP - cellulose and pectin animal NSP- glycogen

How is glucose formed in plants and animals?

plant- main product of photosynthesis animal- Produced during digestion of starch and other carbohydrates.

What are the properties of a perfect jam and factors affecting jam making

quantity of pectin and acid because gel formation only occurs when the concentration of sugar, pectin and pH of the mixture lie within certain limits fruit such as current, lemon etc... Little pectin affect jam making. fruits also Matter. Raw and too ripe fruit will not give a firm gel whereas unripe will give a firm one. PH is also important for eg pH of unripe fruit is 3.5 which gives a firm gel. protopectin is present in maximum amount in just ripe fruits, thus giving more pectin upon conversion.

What are granules?

small particles that make up starch. vary in shape and size from which they come from. Very small, cannot be seen by naked eyes.

What happens to starch granules when cooking?

softens the cell wall so the digestive juices can penetrate causing them to disintegrate and gelatinise. retrograding occurs (structural change in starch)

What happens when retrograding occurs?

starch escapes digestion by amylase in the ileum, thus not absorbed as glucose and reaches the colon where it functions as NSP.

What is the use of glycogen in man?

store of carbohydrates in liver and muscles.

where is glycogen stored in the body and what does it give when broken down?

stored in the liver and muscles of man and animals. It is broken down to give glucose.

what is hemicellulose made up of?

sugar xylose

How is polysaccharide,starch and cellulose formed?

sugars formed by photosynthesis are transported within the plant as sucrose, which is soluble in water. sucrose is then converted into these.

what is the end product of photosynthesis?

sugars.

what is hemicellulose?

water soluble polysaccharide that accompanies cellulose in plant tissues.

How is gel formed by gelatin in protein?

when cold water is added to gelatin it swells due to absorption of water. functions like a sponge. just in protein it got a structure. the different protein molecules that contains gelatin are in the form of a zigzag polypeptide chain that are weakly lined together to form a three dimensional network. there's hydrogen bonding.

Where is fructose usually found?

with glucose in sucrose

Explain gelatinisation in cooking.

• Occurs when a suspension is heated. • molecules of water, amylose and amylopectin aquire vibrational energy. • weak bond between them breaks down and water molecules penetrate the granules. • The granules swells. • temp 55-70°c (varies) • During process granules swell increasing viscosity. • thermal energy of water molecules, amylopectin and amylose decreases and hydrogen bonds re-establish. • mixture thickens eg in roux sauce.

Describe maillard reaction

• Occurs whenever carbohydrates are heated with protein. • occurs between amino groups projecting from a protein chain or peptide or amino acid and the carboxyl group of a reducing substance such as glucose, lactose and galactose to form brown melanoidins. • Maillard reaction also produces changes in flavour,colour and aroma of food. • Roasting and toasting and baking. eg quality of bread during baking and toasting is improved.

what is the importance of NSP in the diet?

• Responsible for the absorption of water in the small intestine that leads to a speedier transit of food through the gut and form smoother and larger stool. • Help prevent diseases such as constipation, appendicitis,haemorrhoids. • Diet high in soluble NSP slows down the release of glucose in bloodstream thus helpful for thuse suffering diabetes mellitus. • Blood lipids reduce lowering risk of coronary heart disease. • High water soluble NSP help lower blood cholesterol. • Wheat that contains phytates and phytic acid form complex with minerals present in the diet that interfere with their absorption.

What are the properties of protopectin?

• insoluble in water • responsible for the hard texture of unripe fruits and vegetables.

What happens during dextrinisation?

• when starch is subjected to dry heat, breaks down to form dextrins also known as pyrodextrins. this is known as dextrinisation. pyrodextrins are yellow to brown in colour and soluble in water. Dextrinisation is partially responsible for Browning of toasted bread, quiche, Tarte etc...

Define caramelisation

•Process where sugar melts into a thick syrup. •As temp rises sugar change from clear to light yellow then brown. (caramelization) • In caramelization glucose and fructose breaks down which combines by loosing water molecules resulting into a molecule called sucrose anhydrid. • As heating continues caramelan is formed that is bitter tasting. • eventually caramelen which is a higher weight molecule. • Finally caramelin which is a dark insoluble molecule.