MILKMILK

Def:Def:

►It is the secretion of mammary It is the secretion of mammary glands in human and animals glands in human and animals after labour.after labour.

► It is the only food for newborn for a It is the only food for newborn for a

long period till weaning time.long period till weaning time.

►Before birth the fetus receives its Before birth the fetus receives its

nutrition through the placenta.nutrition through the placenta.

►Milk secretion is stimulated byMilk secretion is stimulated by ProlactinProlactin..►Milk flow is decreased by Milk flow is decreased by EstrogenEstrogen and and

ProgesteroneProgesterone while increased by while increased by ThyroxinThyroxin. Also . Also SqualeneSqualene present in present in HELBA increase milk flow.HELBA increase milk flow.

►Initiation of lactation may result from Initiation of lactation may result from sudden removal of the placenta and sudden removal of the placenta and other factors.other factors.

►OxytocinOxytocin (posterior pituitary hormone) (posterior pituitary hormone) responsible for milk ejection.responsible for milk ejection.

Milk is considered as a complete diet as:-Milk is considered as a complete diet as:-

It contains all of the components necessary for It contains all of the components necessary for

growth, maintenance of life and reproduction.growth, maintenance of life and reproduction.

e.g:e.g:

Carbohydrates, Lipid, Protein, Some minerals and Carbohydrates, Lipid, Protein, Some minerals and

Vitamins.Vitamins.

ButBut it is deficient in: it is deficient in:

Vitamin C, Vitamin D, Vitamin K, Iron, Copper.Vitamin C, Vitamin D, Vitamin K, Iron, Copper.

Physical Properties of MilkPhysical Properties of Milk

1- Color:1- Color:

White color White color → due to presence of:→ due to presence of:► Fat globules in emulsion form.Fat globules in emulsion form.► Protein in colloidal form.Protein in colloidal form.► Ca. phosphate and Ca. Casinate.Ca. phosphate and Ca. Casinate.

* * Yellowish (creamy) colorYellowish (creamy) color →→ due to: due to:

► Presence of Carotene and Xanthophyll pigments Presence of Carotene and Xanthophyll pigments

specially in cow's milk and colostrums.specially in cow's milk and colostrums.

2- Reaction:2- Reaction: Fresh milk is amphoteric in reaction as it Fresh milk is amphoteric in reaction as it

contains acid and base.contains acid and base.Milk is an excellent buffer as it contain:

Protein.Protein. Phosphate.Phosphate. Bicarbonate.Bicarbonate. Citrate.Citrate.

** PH of fresh milk:** PH of fresh milk: 6.6 – 6.8 Cow's milk.6.6 – 6.8 Cow's milk. 6.8 – 7.4 Human's milk6.8 – 7.4 Human's milk

Milk pHMilk pH changed to alkaline in case of:changed to alkaline in case of:MastitisMastitis Late period of lactation.Late period of lactation.

If the milkIf the milk left to stand for a long period left to stand for a long period specially in warm temperature, lactose is specially in warm temperature, lactose is fermented to lactic acid by bacteria present fermented to lactic acid by bacteria present normally in milk as:normally in milk as:

* Streptococcus Lactis.* Streptococcus Lactis. * Lactobacillus Lactis.* Lactobacillus Lactis.Result inResult in decrease in milk PH and milk Souring.decrease in milk PH and milk Souring.

3- Specific Gravity:3- Specific Gravity:

It is the ratio between weight of a given It is the ratio between weight of a given

volume of milk compared with the same volume of volume of milk compared with the same volume of

water at a specific temperature.water at a specific temperature.

It measure total solids of milkIt measure total solids of milk, and determine if , and determine if

any constituent added or removed from milk.any constituent added or removed from milk... Measured by Lactometer.Measured by Lactometer. Normal specific gravity:Normal specific gravity:

1020 – 1030 Cow's milk.1020 – 1030 Cow's milk. 1030 – 1035 Human's milk.1030 – 1035 Human's milk.

FatFat is the only constituent in milk with specific is the only constituent in milk with specific gravity lower than 1000, so, when fat present gravity lower than 1000, so, when fat present in milk in high amount, specific gravity in milk in high amount, specific gravity decrease than normal values.decrease than normal values.

WhenWhen milk is skimmed (removal of fat milk is skimmed (removal of fat

content), the specific gravity increased content), the specific gravity increased due to:due to:

Removal of light constituents of milk.Removal of light constituents of milk.

WhenWhen water is added to milk (adulteration) water is added to milk (adulteration)

the specific gravity decreased due to dilution the specific gravity decreased due to dilution

of total solids.of total solids.

4- Taste:4- Taste: Normal characteristic milky taste.Normal characteristic milky taste. Milk taste changed in case of :Milk taste changed in case of :

Souring:Souring: due to increased acidity. due to increased acidity. Boiling:Boiling: due to certain biochemical changes due to certain biochemical changes

and evaporation of volatile fatty acids.and evaporation of volatile fatty acids. Late stage of lactation:Late stage of lactation: due to increase due to increase

chloride percent.chloride percent. Mastitis: Mastitis: inflammation of udder.inflammation of udder.

5- Odor:5- Odor: Characteristic milky odor.Characteristic milky odor.

6- Freezing point of milk:6- Freezing point of milk:► It is the temperature at which the liquid milk It is the temperature at which the liquid milk

freeze or crystallize.freeze or crystallize.

► The freezing point of cow or buffalo milk The freezing point of cow or buffalo milk ranges from (-0.53) to (-0.57) °C with average ranges from (-0.53) to (-0.57) °C with average (-0.55) °C(-0.55) °C

► Milk freezes at a temperature slightly lower Milk freezes at a temperature slightly lower than that of water due to the soluble than that of water due to the soluble constituents in milk such as lactose, minerals constituents in milk such as lactose, minerals which lower the freezing point.which lower the freezing point.

►This test is important for detection This test is important for detection of the amount of water added to of the amount of water added to milkmilk

►The addition of 9% water to milk The addition of 9% water to milk will raise the freezing point by 0.05 will raise the freezing point by 0.05 °C. °C.

i.e., if milk freezing point is -0.45 °C, i.e., if milk freezing point is -0.45 °C, it means addition of 18% water. it means addition of 18% water.

-0.45 – (-0.55) = -0.45 + 0.55 = +0.10-0.45 – (-0.55) = -0.45 + 0.55 = +0.10

0.05 → 9 %0.05 → 9 %

0.10 → X0.10 → X

X = = 18 % X = = 18 %

9x0.19x0.1

0.050.05

7- Boiling Point:7- Boiling Point:

► Milk boiling point is 100.5 °C , more than Milk boiling point is 100.5 °C , more than water due to presence of dissolving water due to presence of dissolving substancessubstances

8- Cream Line Formation:8- Cream Line Formation:

► When milk left at room temperature the When milk left at room temperature the fat globules coalesce, clumped at surface fat globules coalesce, clumped at surface of the container and form cream line. of the container and form cream line.

Normal Normal Chemical composition Chemical composition

of milkof milk

Milk is formed of:Milk is formed of:1)1) Water: form 87%.Water: form 87%.2)2) Solids: form 13%.Solids: form 13%. A-A- Organic constituents of milk.Organic constituents of milk.

1.1. Protein.Protein.2.2. Lipid.Lipid.3.3. Carbohydrate.Carbohydrate.

B-B- Inorganic constituents of milk:Inorganic constituents of milk:1.1. Minerals.Minerals.2.2. Vitamins.Vitamins.

A- Organic Constituents of MilkA- Organic Constituents of Milk

1- Protein:1- Protein:► Milk protein less in human than in cow's milk.Milk protein less in human than in cow's milk.► All milk protein synthesized in the mammary gland.All milk protein synthesized in the mammary gland.► Milk protein of high coefficient digestibility (85 – Milk protein of high coefficient digestibility (85 –

95%)95%)Amount of NAmount of N22 absorbed absorbed

X 100X 100Total NTotal N22 in the protein in the protein

Characterized by:Characterized by:1-1- Protein of high biological value as: Protein of high biological value as:

►It contains all essential amino acids.It contains all essential amino acids.►Easily digested.Easily digested.►Easily absorbed.Easily absorbed.►Easily metabolized.Easily metabolized.

2- 2- Contain moderate amount of non essential Contain moderate amount of non essential amino acids to decrease stress on body cells.amino acids to decrease stress on body cells.

3-3- Essential to keep positive nitrogen balance Essential to keep positive nitrogen balance (nitrogen intake more than nitrogen output).(nitrogen intake more than nitrogen output).

5-5- Essential to maintain growth of newborn.Essential to maintain growth of newborn.

6.6. Total amount of protein differ according to Total amount of protein differ according to species and affect rate of growth of young:species and affect rate of growth of young:

e.g:e.g:► Young rabbit reach double weight in Young rabbit reach double weight in 5 days5 days as as

milk protein milk protein 10 gm/dl10 gm/dl..► Young calf reaches double weight in Young calf reaches double weight in 50 days50 days

as milk protein as milk protein 3.7 gm/dl.3.7 gm/dl.► Young child reach double weight in Young child reach double weight in 5 - 8 5 - 8

monthsmonths as milk protein as milk protein 1.5 gm/dl1.5 gm/dl..

Types of Milk Proteins are:Types of Milk Proteins are:

1.1. Casein.Casein.

2.2. Lactalbumin.Lactalbumin.

3.3. Lactglobulin.Lactglobulin.

4.4. Milk enzymes.Milk enzymes.

1) Casein1) Casein► ItIt is the main and most dominant milk is the main and most dominant milk

protein.protein.► It represents 25% in human's milk and 83% in It represents 25% in human's milk and 83% in

cow's milk.cow's milk.► It is a compound protein (Phospho-protein) It is a compound protein (Phospho-protein)

of high biological value.of high biological value.►The high phosphate content of casein allows The high phosphate content of casein allows

it to associate with calcium and form calcium it to associate with calcium and form calcium phosphate salts.phosphate salts. So, at normal PH of fresh milk (6.6 PH) So, at normal PH of fresh milk (6.6 PH)

casein present as insoluble Ca. caseinate casein present as insoluble Ca. caseinate phosphate complex.phosphate complex.

►Casein contains 0.7% phosphorous and 0.7% Casein contains 0.7% phosphorous and 0.7% sulpher, but it is Phospho-protein Not Sulpho-sulpher, but it is Phospho-protein Not Sulpho-protein. Why??protein. Why??

1) Phosphorous:1) Phosphorous: Attached to (OH) group of serine to form Attached to (OH) group of serine to form

phospho-serine.phospho-serine. Attached to (OH) group of therionine to Attached to (OH) group of therionine to

form phospho-therionine.form phospho-therionine.2) Sulpher:2) Sulpher: Found in methionineFound in methionine (But masked by the (But masked by the

methyl group) So, act as Lipotropic factor methyl group) So, act as Lipotropic factor that prevent accumulation of fats on liver.that prevent accumulation of fats on liver.

►Casein is suspended in milk in colloidal Casein is suspended in milk in colloidal

suspension complex of casein micelles that are suspension complex of casein micelles that are

dispersed in the water phase of milk.dispersed in the water phase of milk.

►Casein micelles are spherical in shape and Casein micelles are spherical in shape and

much smaller in diameter than fat globules, much smaller in diameter than fat globules,

and consists of a network of casein sub-and consists of a network of casein sub-

micelles, each one micelle contains 400-500 micelles, each one micelle contains 400-500

submicelles, bonded by calcium phosphate submicelles, bonded by calcium phosphate

bridges.bridges.

► Casein is Casein is deficientdeficient in cystiene and cystin so give in cystiene and cystin so give negative result with sulpher test.negative result with sulpher test.

► Casein : (Lactalbumin - Lactglobulin) ratio is 1:3 Casein : (Lactalbumin - Lactglobulin) ratio is 1:3 which facilitate its digestion.which facilitate its digestion.

► According to molecular weight and electrophoresis According to molecular weight and electrophoresis process, casein is separated in to 3 fractions, each process, casein is separated in to 3 fractions, each one of them has its own amino acid composition :one of them has its own amino acid composition : αα Casein → 75%. Casein → 75%. β β Casein → 22%.Casein → 22%. γγ Casein → 3%. Casein → 3%.

Casein Casein ==

11

Lactalbumin + Lactglobulin Lactalbumin + Lactglobulin 33

►Casein is the only milk protein that not Casein is the only milk protein that not coagulated on boiling.coagulated on boiling.

►The net charge of milk protein is negative The net charge of milk protein is negative charge, so protein molecules remain charge, so protein molecules remain separated from each others due to repulsion separated from each others due to repulsion forces.forces. Isoelectric point of casein:Isoelectric point of casein: It is the point of It is the point of

absence of net electrical charge on protein absence of net electrical charge on protein molecules (So, protein PPT and not affected molecules (So, protein PPT and not affected

by the electric field).by the electric field).

Milk Souring (Milk Curdling – Zabadi):Milk Souring (Milk Curdling – Zabadi):► The principle of coagulation, or curd formation, at The principle of coagulation, or curd formation, at

acidic pH is the basis for Yoghurt (Zabadi) acidic pH is the basis for Yoghurt (Zabadi) formation. How?formation. How?

► Fermentation of lactose to lactic acid by:Fermentation of lactose to lactic acid by: Lactic acid producing bacteria present normally in milk.Lactic acid producing bacteria present normally in milk. Addition of acid (acetic acid). Addition of acid (acetic acid). Addition of starter culture (yoghurt).Addition of starter culture (yoghurt).

Lactose + lactic acid bacteria Lactic acid Lactose + lactic acid bacteria Lactic acid ↓↓ pH pHWorm tempWorm temp..

FermentationFermentation

► Leading to decrease milk pH to 4.6 (Isoelectric Leading to decrease milk pH to 4.6 (Isoelectric point of casein) leads to PPT of casein as:point of casein) leads to PPT of casein as:

1)1) By souring and lactic acid production: some By souring and lactic acid production: some protein molecules gain the hydrogen ion with its protein molecules gain the hydrogen ion with its (+Ve) charge.(+Ve) charge.

2)2) Calcium and phosphate are dissolved and Calcium and phosphate are dissolved and separated from casein.separated from casein.

3)3) The (+Ve) charge protein attract to the (-Ve) The (+Ve) charge protein attract to the (-Ve) charge protein at 4.6 pH, leading to PPT of casein.charge protein at 4.6 pH, leading to PPT of casein.

4)4) Part of lactic acid combines of with Ca. of casein to Part of lactic acid combines of with Ca. of casein to form Ca. lactate and free casein which PPT with fat form Ca. lactate and free casein which PPT with fat and fat soluble vitamins.and fat soluble vitamins.

Ca. Caseinate + lactic acid Casein (pure) + calcium lactateCa. Caseinate + lactic acid Casein (pure) + calcium lactate PPT PPT ↓↓ (soluble) (soluble)

Whey of milk curd:Whey of milk curd:It is the residual clear fluid which formed after removal It is the residual clear fluid which formed after removal

of casein and contain:of casein and contain:►Water. Water. ►Lactic acid. Lactic acid. ►Lactalbumin & lactglobulin Lactalbumin & lactglobulin (whey protein)(whey protein) ►Minerals. Minerals. ►Water soluble vitamins.Water soluble vitamins.

The greenish yellow color of whey is due to The greenish yellow color of whey is due to riboflavin (vitamin Briboflavin (vitamin B22))

Milk Clotting (Cheese Manufacturing)Milk Clotting (Cheese Manufacturing)During digestion (in new born):During digestion (in new born):► Rennin enzyme acts on casein, converting it to Rennin enzyme acts on casein, converting it to

soluble Paracaseinate which is bounded to Ca and soluble Paracaseinate which is bounded to Ca and form insoluble Ca. paracaseinate (milk clot).form insoluble Ca. paracaseinate (milk clot).

► Rennin enzyme:Rennin enzyme: Derived from 4Derived from 4thth stomach of calves and used stomach of calves and used

externally in cheese manufacture.externally in cheese manufacture. It is secreted inactive as pro-rennin.It is secreted inactive as pro-rennin. Its optimum PH 4.Its optimum PH 4. It is absent in adult stomach.It is absent in adult stomach.

► Formation of milk clot:Formation of milk clot: prevents rapid passage of prevents rapid passage of milk from stomach to intestine so give the sense of milk from stomach to intestine so give the sense of fullness to newborn.fullness to newborn.

Whey of milk clot:Whey of milk clot:Residual clear fluid after removal of casein which Residual clear fluid after removal of casein which

contain:contain:►Water. Water. ►Lactose. Lactose. ►Lactalbumin & lactglobulin Lactalbumin & lactglobulin (whey (whey

protein)protein) ►Minerals except Ca. Minerals except Ca. ►Water soluble vitamins.Water soluble vitamins.

B- Lactalbumin:B- Lactalbumin:► Represent 87% of whey protein.Represent 87% of whey protein.► PPT by full saturation with ammonium PPT by full saturation with ammonium

sulphate.sulphate.► Rich in cystein and cystin Rich in cystein and cystin soso give +ve result give +ve result

with sulpher test.with sulpher test.► Simple protein.Simple protein.► Soluble protein.Soluble protein.► Easily digested.Easily digested.

►Consists of two fractions:Consists of two fractions: α Lactalbumin 32% of whey protein.α Lactalbumin 32% of whey protein. β lactglobulin 55% of whey protein.β lactglobulin 55% of whey protein.

N.B:N.B:

β lactglobulin called globulin because it need β lactglobulin called globulin because it need small amount of NaCl to be dissolved but it is small amount of NaCl to be dissolved but it is not PPT by half saturation as albumin.not PPT by half saturation as albumin.

3- Lactglobulin:3- Lactglobulin:► Represent 13% of whey protein.Represent 13% of whey protein.► PPT by half saturation with ammonium PPT by half saturation with ammonium

sulphate solution.sulphate solution.► Rich in cystein and cystinRich in cystein and cystin so so give +ve result give +ve result

with sulpher test.with sulpher test.► Simple protein.Simple protein.► Soluble protein.Soluble protein.► Easily digested.Easily digested.

►Consists of two fractions:Consists of two fractions: True globulin (Euglobulin) 50%.True globulin (Euglobulin) 50%. False globulin (Pseudoglobulin) 50%.False globulin (Pseudoglobulin) 50%.

►They carry antibodies causing immunity so They carry antibodies causing immunity so called called immunoglobulins.immunoglobulins.

►They present in higher concentration in They present in higher concentration in colostrum.colostrum.

4- Milk enzymes:4- Milk enzymes:

1.1. Catalase.Catalase.

2.2. Peroxidase.Peroxidase.

3.3. Xanthin oxidase.Xanthin oxidase.

4.4. Alkaline phophatase.Alkaline phophatase.

5.5. Amylase.Amylase.

6.6. Lipase.Lipase.

7.7. Aldehyde oxidase.Aldehyde oxidase.

1- Catalase:1- Catalase:► Carried by Carried by fat globulesfat globules..

► Act on hydrogen peroxide (HAct on hydrogen peroxide (H22OO22) producing ) producing

water and oxygen.water and oxygen.► Increased in case of mastitis.Increased in case of mastitis.

2- Peroxidase:2- Peroxidase:► Carried by Carried by lactalbuminlactalbumin..► Act on hydrogen peroxide (HAct on hydrogen peroxide (H22OO22).).► It is heat stable enzyme (resist destruction by heat).It is heat stable enzyme (resist destruction by heat).► It is destroyed by milk sterilization.It is destroyed by milk sterilization.Milk sterilization:Milk sterilization: Heating of milk to 116Heating of milk to 116◦◦C for 15 minutes which destroy C for 15 minutes which destroy

all harmful and non harmful microorganisms.all harmful and non harmful microorganisms.► Milk sterilization leads to alteration in milk taste and Milk sterilization leads to alteration in milk taste and

destruction of vitamin C and vitamin Bdestruction of vitamin C and vitamin B22.. N.B:N.B: Absence of peroxidase enzyme indicates milk Absence of peroxidase enzyme indicates milk

sterilization. sterilization.

3- Xanthin oxidase:3- Xanthin oxidase:► Carried by Carried by fat globulesfat globules..► Act on hypoxanthin and xanthin to produce Act on hypoxanthin and xanthin to produce

uric acid.uric acid.

4- Alkaline phophatase:4- Alkaline phophatase:► Carried by Carried by fat globulesfat globules..► Catalyze hydrolysis of phosphate ester.Catalyze hydrolysis of phosphate ester.► Destroyed by the same temperature that destroys the Destroyed by the same temperature that destroys the

harmful bacteria.harmful bacteria. e.g:e.g: Tubercle bacilli.Tubercle bacilli.► Absence of Alkaline phophatase enzyme indicates Absence of Alkaline phophatase enzyme indicates

milk pasteurization. milk pasteurization. ► Milk pasteurization:Milk pasteurization: Heating of milk to 60Heating of milk to 60◦◦C for 30 minutes or 70◦C for 15 C for 30 minutes or 70◦C for 15

minutesminutes followed by sudden cooling which destroy followed by sudden cooling which destroy the harmful microorganisms only.the harmful microorganisms only.

5- Amylase:5- Amylase:► Carried by Carried by lactalbuminlactalbumin..► Catalyze hydrolysis of α 1, 4 glycosidic Catalyze hydrolysis of α 1, 4 glycosidic

linkage of starch and glycogen.linkage of starch and glycogen.► Increased in case of mastitis.Increased in case of mastitis.

6- Lipase:6- Lipase:► Carried by Carried by caseincasein..► Catalyze hydrolysis of primary ester linkage in Catalyze hydrolysis of primary ester linkage in

triacylglycerol.triacylglycerol.► Act on milk fat producing free fatty acids and Act on milk fat producing free fatty acids and

undesirable taste (Rancidity).undesirable taste (Rancidity).

7- Aldehyde oxidase (Schardinger's enzyme):7- Aldehyde oxidase (Schardinger's enzyme):► Its absence indicates milk boiling.Its absence indicates milk boiling.► Schardinger's test:Schardinger's test:

Milk + Methyl blue + FormaldehydeMilk + Methyl blue + Formaldehyde Blue color appeared in case of boiled milk.Blue color appeared in case of boiled milk. Colorless in case of unboiled milk.Colorless in case of unboiled milk.

N.B:N.B:Beside milk proteins milk also contains:Beside milk proteins milk also contains:

A) Lactoferrin binding protein:A) Lactoferrin binding protein: It contains iron which is bounded to a glycoprotein.It contains iron which is bounded to a glycoprotein. It facilitates iron transport and storage.It facilitates iron transport and storage. Found in high concentration in human colostrums Found in high concentration in human colostrums

and milk.and milk.

B) Vitamin BB) Vitamin B1212 binding protein: binding protein: It carries vitamin BIt carries vitamin B1212..

Lactoferrin and vitamin BLactoferrin and vitamin B1212 binding protein binding protein deprive pathogenic intestinal bacteria from iron deprive pathogenic intestinal bacteria from iron and vitamin Band vitamin B1212 so they have bacteriostatic so they have bacteriostatic action.action.

2- Lipid:2- Lipid:► Human's and cow's milk contain the same Human's and cow's milk contain the same

amount 3.5 gm/dl amount 3.5 gm/dl butbut buffalo's milk is a little buffalo's milk is a little higher 7 gm/dl.higher 7 gm/dl.

► Easily separated on standing.Easily separated on standing.► Responsible for white color of milk Responsible for white color of milk

► It consists mainly of It consists mainly of triacylglyceroltriacylglycerol distributed as coarse emulsion which contains distributed as coarse emulsion which contains oleic, myristic, palmitic and stearic fatty acids.oleic, myristic, palmitic and stearic fatty acids.

Also contain small amounts of:Also contain small amounts of:►phospholipids phospholipids 0.1%.0.1%.

Milk phospholipids are lecithin, cephalin, Milk phospholipids are lecithin, cephalin, sphingomyelin (9:5:1).sphingomyelin (9:5:1).

Phospholipids in cow's milk twice that of Phospholipids in cow's milk twice that of human milk.human milk.

►Cholesterol 0.01%.Cholesterol 0.01%.

Cow's milk contains higher proportion (mainly free Cow's milk contains higher proportion (mainly free form) than human milk mainly (ester form)form) than human milk mainly (ester form)

► Milk contain fat soluble substance:Milk contain fat soluble substance:

e.g:e.g:

►Fat soluble vitamins (vitamin A)Fat soluble vitamins (vitamin A) which is which is higher in human milk than cow's milk.higher in human milk than cow's milk.

► Milk fat is formed mainly in lactating mammary gland Milk fat is formed mainly in lactating mammary gland from:from:

Active acetate.Active acetate. Glycerol: derived from glucose Glycerol: derived from glucose

(dihydroxyaceton phosphate).(dihydroxyaceton phosphate).► Milk fat may be derived from blood triacylglycerol but Milk fat may be derived from blood triacylglycerol but

to a limited extent.to a limited extent.

Cow's milkCow's milk Human's milkHuman's milk

Contain short chain fatty Contain short chain fatty acids 10%. acids 10%.

Contain no short chain fatty Contain no short chain fatty acids.acids.

Contain 0.05% essential Contain 0.05% essential (polyunsaturated) fatty (polyunsaturated) fatty acids.acids.

Contain 10% essential Contain 10% essential (polyunsaturated) fatty acids (polyunsaturated) fatty acids specially linoleic fatty acids.specially linoleic fatty acids.

Saturated fatty acids 58%. Saturated fatty acids 58%. Saturated fatty acids 48%.Saturated fatty acids 48%.

Unsaturated fatty acids Unsaturated fatty acids 42%. 42%.

Unsaturated fatty acids Unsaturated fatty acids 52%. 52%.

3- Carbohydrates:3- Carbohydrates:► Lactose (milk sugar) is the only carbohydrate Lactose (milk sugar) is the only carbohydrate

of milk.of milk.► It is a reducing disaccharide consists of It is a reducing disaccharide consists of

glucose and galactose.glucose and galactose.► Human's milk contains 7% lactose while cow's Human's milk contains 7% lactose while cow's

milk contains 5% lactose.milk contains 5% lactose.► Lactose may be excreted in urine during last Lactose may be excreted in urine during last

third of pregnancy physiologically so it should third of pregnancy physiologically so it should be differentiated from glucose by osazon test.be differentiated from glucose by osazon test.

Importance of lactose:Importance of lactose:1.1. It is less sweet than sucrose so allow the baby It is less sweet than sucrose so allow the baby

to take large amount of milk without causing to take large amount of milk without causing nausea.nausea.

2.2. It is non fermentable carbohydrate so it doesn't It is non fermentable carbohydrate so it doesn't produce COproduce CO22 in GIT and the baby doesn't in GIT and the baby doesn't suffer from abdominal colic or distention.suffer from abdominal colic or distention.

3.3. Lactose help growth of lactic acid producing Lactose help growth of lactic acid producing bacteria so help in absorption of Ca, P, Fe, Cu bacteria so help in absorption of Ca, P, Fe, Cu which prefer acidic medium for their which prefer acidic medium for their absorption.absorption.

4.4. Lactose inhibits growth of putrefactive bacteria Lactose inhibits growth of putrefactive bacteria which cause abdominal distention by which cause abdominal distention by increasing the acidity of the intestine.increasing the acidity of the intestine.

Lactose synthesis:Lactose synthesis:Lactose is synthesized in mammary gland from α Lactose is synthesized in mammary gland from α

D glucose and β D galactose.D glucose and β D galactose. Galactose converted to galactose -1- Galactose converted to galactose -1-

phosphate by phosphate by galactokinase enzymegalactokinase enzyme.. Galactose -1- phosphate and UDP glucose are Galactose -1- phosphate and UDP glucose are

converted to UDP galactose and glucose -1- converted to UDP galactose and glucose -1- phosphate by phosphate by uridyle tranferase enzymeuridyle tranferase enzyme..

UDP galactose bounded to glucose by UDP galactose bounded to glucose by lactose lactose synthase enzymesynthase enzyme forming lactose. forming lactose.

Galactosemia:Galactosemia:►It is a condition occurs due to deficiency of It is a condition occurs due to deficiency of

galactose -1- phosphate uridyle transferase.galactose -1- phosphate uridyle transferase.►Characterized by accumulation of galactose and Characterized by accumulation of galactose and

galactose -1- phosphate in blood.galactose -1- phosphate in blood.

Lactose synthase enzyme:Lactose synthase enzyme:Consists of two subunits:Consists of two subunits:1.1. Catalytic subunit:Catalytic subunit:

Can't synthesize lactose.Can't synthesize lactose. It catalyze the attachment of galactose to protein to It catalyze the attachment of galactose to protein to

form glycoprotein.form glycoprotein.2.2. Modifier subunit:Modifier subunit:

Alter the specificity of the catalytic subunite which Alter the specificity of the catalytic subunite which make galactose bounded to glucose to form lactose.make galactose bounded to glucose to form lactose.

► During pregnancy little modifier subunite is formed in During pregnancy little modifier subunite is formed in the mammary gland so no lactose synthesized But at the mammary gland so no lactose synthesized But at birth large amount of modifier is formed helping the birth large amount of modifier is formed helping the synthesis of lactose in mammary gland.synthesis of lactose in mammary gland.

Importance of lactose:Importance of lactose:1.1. It is less sweet than sucrose so allow the baby It is less sweet than sucrose so allow the baby

to take large amount of milk without causing to take large amount of milk without causing nausea.nausea.

2.2. It is non fermentable carbohydrate so it doesn't It is non fermentable carbohydrate so it doesn't produce produce COCO22 in GIT and the baby doesn't in GIT and the baby doesn't suffer from abdominal colic or distention.suffer from abdominal colic or distention.

3.3. Lactose help growth of lactic acid producing Lactose help growth of lactic acid producing bacteria so help in absorption of Ca, P, Fe, Cu bacteria so help in absorption of Ca, P, Fe, Cu which prefer acidic medium for their which prefer acidic medium for their absorption.absorption.

4.4. Lactose inhibits growth of putrefactive Lactose inhibits growth of putrefactive bacteria which cause abdominal bacteria which cause abdominal disturbance by increasing the acidity of disturbance by increasing the acidity of the intestine.the intestine.

5.5. On hydrolysis it produce glucose and On hydrolysis it produce glucose and galactose:galactose:

Glucose act as source of energy.Glucose act as source of energy. Galactose used for synthesis of Galactose used for synthesis of

galactolipids so help in development of galactolipids so help in development of nerve tissues.nerve tissues.

N.B:N.B:

Lactose level in milk tend to vary directly with the Lactose level in milk tend to vary directly with the weight of the adult brain:weight of the adult brain:

Man has the largest brain in proportion to the Man has the largest brain in proportion to the body weight of all animals this may be related body weight of all animals this may be related to the galactolipids of the brain which contains to the galactolipids of the brain which contains galactose.galactose.

6.6. Lactose has a laxative effect as some of Lactose has a laxative effect as some of glucose is fermented by the intestinal glucose is fermented by the intestinal bacteria producing bacteria producing COCO22 which stimulate which stimulate

the intestinal movement.the intestinal movement.

N.B:N.B:

IfIf the milk is taken by the adult in large the milk is taken by the adult in large amount result in amount result in diarrheadiarrhea due to decrease due to decrease in in lactase enzymelactase enzyme so lactose is hydrolyzed so lactose is hydrolyzed by intestinal bacteria to glucose and by intestinal bacteria to glucose and galactose. galactose. Glucose is fermented producing Glucose is fermented producing COCO22 and and

abdominal distention. abdominal distention. Non fermentable galactose and Non fermentable galactose and

unhydrolyzed lactose increase osmotic unhydrolyzed lactose increase osmotic pressure of the intestine leads to diarrhea.pressure of the intestine leads to diarrhea.

B-InorganicB-Inorganic constituents of constituents of milkmilk

1- Minerals:1- Minerals:► Human milk contain less mineral elements Human milk contain less mineral elements

(0.4%) than cow's milk (0.8%).(0.4%) than cow's milk (0.8%).► Milk rich in Milk rich in CaCa and and PP which are present in which are present in

their proper ratio for absorption their proper ratio for absorption (2:1)(2:1) in human in human milk while in cow's milk milk while in cow's milk (1:2)(1:2) which is not which is not suitable for their maximum absorptionsuitable for their maximum absorption ..

► CaCa and and PP are essential for: are essential for:

1.1. Growth of bone and teeth.Growth of bone and teeth.

2.2. Stability of casein.Stability of casein.

►Milk is deficient in Milk is deficient in FeFe and and CuCu which are which are supplied by their storage in liver during prenatal supplied by their storage in liver during prenatal life life (this store is sufficient till weaning time).(this store is sufficient till weaning time).

N.B:N.B:

Milk is deficient in Milk is deficient in IronIron but it is more in human but it is more in human milk than cow's milk milk than cow's milk ThusThus anaemia in breast anaemia in breast feeding is less common. feeding is less common.

►Milk contain adequate amount of Milk contain adequate amount of NaNa, , KK, , MgMg..►Human milk contains Human milk contains Na:KNa:K (1:2) which is (1:2) which is

suitable for the optimal growth of newborn.suitable for the optimal growth of newborn.

2- Vitamins:2- Vitamins:► Milk is deficient in:Milk is deficient in:

► Vitamin C.Vitamin C.► Vitamin D.Vitamin D.► Vitamin K.Vitamin K.

► Milk contain adequate amount of vitamin B complex Milk contain adequate amount of vitamin B complex which are sufficient for first week of lifewhich are sufficient for first week of life

e.g:e.g:► Pantothenic acid.Pantothenic acid.► Riboflavin (gives the whey the greenish tint in Riboflavin (gives the whey the greenish tint in

sunlight).sunlight).

N.B:N.B:►Vitamin C must be supplied to the growing baby Vitamin C must be supplied to the growing baby

in the form of fruit juices to withstand infection.in the form of fruit juices to withstand infection.►Fortified vitamin D milk is used in order to Fortified vitamin D milk is used in order to

supply the baby with vitamin D requirement supply the baby with vitamin D requirement which is added from cod liver oil.which is added from cod liver oil.

►Exposure to sunlight in the early morning or Exposure to sunlight in the early morning or before sunset help in formation of active vitamin before sunset help in formation of active vitamin D from cholesterol.D from cholesterol.

Milk is an adequate diet for Milk is an adequate diet for childrenchildren

Although milk is deficient in Although milk is deficient in Fe, Cu, vitamin C, Fe, Cu, vitamin C, vitamin D, and vitamin Kvitamin D, and vitamin K it is complete natural it is complete natural food for the following reasons:food for the following reasons:

1.1. Easily digested absorbed and metabolized.Easily digested absorbed and metabolized.

2.2. Contain all the nutrients required for the Contain all the nutrients required for the newborn at early stage of life.newborn at early stage of life.

3.3. Balanced ratio between carbohydrates, lipid Balanced ratio between carbohydrates, lipid and protein.and protein.

4.4. Milk protein:Milk protein:

Protein of high biological value as:Protein of high biological value as: It contains all essential amino acids.It contains all essential amino acids. Easily digested.Easily digested. Easily absorbed.Easily absorbed. Easily metabolized.Easily metabolized.

5.5. Milk lipid:Milk lipid: Milk contain essential fatty acidsMilk contain essential fatty acids e.g:e.g:

Linoleic acid.Linoleic acid. Linolenic acid.Linolenic acid.

6.6. Milk sugar (lactose):Milk sugar (lactose):A.A. It is less sweet than sucrose so allow the baby to It is less sweet than sucrose so allow the baby to

take large amount of milk without causing nausea.take large amount of milk without causing nausea.B.B. It is non fermentable carbohydrate so it doesn't It is non fermentable carbohydrate so it doesn't

produce COproduce CO22 in GIT and the baby doesn't suffer in GIT and the baby doesn't suffer from abdominal colic or distention.from abdominal colic or distention.

C.C. Lactose help growth of lactic acid producing Lactose help growth of lactic acid producing bacteria so help in absorption of Ca, P, Fe, Cu bacteria so help in absorption of Ca, P, Fe, Cu which prefer acidic medium for their absorption.which prefer acidic medium for their absorption.

D.D. Lactose inhibits growth of putrefactive bacteria Lactose inhibits growth of putrefactive bacteria which cause abdominal distention.which cause abdominal distention.

E.E. On hydrolysis it produce glucose and galactose.On hydrolysis it produce glucose and galactose.

F.F. Lactose has a laxative effect.Lactose has a laxative effect.

7.7. Provide Ca and P in proper ratio for absorption (2:1) Provide Ca and P in proper ratio for absorption (2:1) which are essential for:which are essential for:

1.1. Growth of bone and teeth.Growth of bone and teeth.

2.2. Stability of casein.Stability of casein.

8.8. Good source of vitamins.Good source of vitamins.

9.9. Contain antibodies specially in colostrums which Contain antibodies specially in colostrums which provide immunity to the newborn.provide immunity to the newborn.

10.10. Cheep in price and of good caloric value.Cheep in price and of good caloric value.

N.B:N.B:►Certain foreign substance in the blood Certain foreign substance in the blood

plasma may enter the milk as:plasma may enter the milk as:►Volatile oils of certain foods (onions – Volatile oils of certain foods (onions –

garlic).garlic).►Drugs (sulphonamids – salicylate – Drugs (sulphonamids – salicylate –

morphin – alcohol).morphin – alcohol).►Inorganic elements (iorn – iodin – lead – Inorganic elements (iorn – iodin – lead –

mercury).mercury).

Factors affecting milk compositionFactors affecting milk composition

1.1. Species:Species:►Milk protein:Milk protein:

Rabbit's milk 10% while cow' milk 3.7%.Rabbit's milk 10% while cow' milk 3.7%.

►Milk fat:Milk fat:

Cow's milk 3.5% while buffaloe's milk 7%.Cow's milk 3.5% while buffaloe's milk 7%.

2.2. Age:Age:►Old age decrease fat contents of milk.Old age decrease fat contents of milk.

3.3. Seasonal variation:Seasonal variation:►In winter increase in fat, protein and mineral In winter increase in fat, protein and mineral

contents of milk.contents of milk.

4.4. Nutritional variation:Nutritional variation:► Overfeeding has no effect on milk composition.Overfeeding has no effect on milk composition.

► Underfeeding decrease in milk volume and protein Underfeeding decrease in milk volume and protein and lactose contents of milk while fat contents of and lactose contents of milk while fat contents of milk increased.milk increased.

5.5. Infection of mammary gland:Infection of mammary gland:► Mastitis decrease fat, lactose and casein contents of Mastitis decrease fat, lactose and casein contents of

milk while whey protein and chloride ions milk while whey protein and chloride ions increased.increased.

6.6. Stage of lactation:Stage of lactation:► Colostrum Colostrum secreted during 1secreted during 1stst week of week of

lactation.lactation.► Intermediate milkIntermediate milk secreted during 1 secreted during 1stst month of month of

lactation except 1lactation except 1stst week. week.► Mature milkMature milk secreted during 1 secreted during 1stst year of year of

lactation except 1lactation except 1stst month. month.► Late milkLate milk secreted after 1 secreted after 1st st year of lactation.year of lactation.

Watery in consistancy.Watery in consistancy. Contains less protein, lipid, lactose and Contains less protein, lipid, lactose and

vitamins.vitamins. Contains more minerals than mature milk Contains more minerals than mature milk

(less sweet to help weaning).(less sweet to help weaning).

N.B:N.B:

Witch's milk:Witch's milk:

Fluid secreted by mammary gland of Fluid secreted by mammary gland of infants during first few days of life due to infants during first few days of life due to the effect of placental hormones on the effect of placental hormones on mammary gland of infants.mammary gland of infants.

A- Colostrum:A- Colostrum:► Yellowish fluid secreted by mammary gland during Yellowish fluid secreted by mammary gland during

1st week of lactation.1st week of lactation.► Volume of colostrum in human Volume of colostrum in human (150 – 300 ml/day).(150 – 300 ml/day).► Specific gravitySpecific gravity (1.040 – 1.060)(1.040 – 1.060)

Colostrum is very important for survival of new born due Colostrum is very important for survival of new born due to:to:

1.1. High level of protein (20%):High level of protein (20%): 40 – 55% globulin specially γ globulin 40 – 55% globulin specially γ globulin

(immunoglobulin) which provide immunity for (immunoglobulin) which provide immunity for newborn up to 6 monthsnewborn up to 6 months ..

Globulin is a coagulable protein by heat.Globulin is a coagulable protein by heat.

Absorbed without digestion due to its low Absorbed without digestion due to its low molecular weight.molecular weight.

Globulin contain prolin which enter in Hb Globulin contain prolin which enter in Hb synthesis.synthesis.

2.2. Low fat (3 g%) and carbohydrate (4 g%) content.Low fat (3 g%) and carbohydrate (4 g%) content.► Easily digested.Easily digested.► Contains higher content of cholesterol and Contains higher content of cholesterol and

lecithin.lecithin.3.3. High mineral content.High mineral content.

► Iron found in higher concentration than mature Iron found in higher concentration than mature milk.milk.

4.4. High fat soluble vitamins (E, D, A, K) and water High fat soluble vitamins (E, D, A, K) and water soluble vitamins (riboflavin, nicotinic acid).soluble vitamins (riboflavin, nicotinic acid).

5.5. Trypsin inhibitor:Trypsin inhibitor: Inhibit action of trypsin enzyme so: Inhibit action of trypsin enzyme so:

immunoglobulins absorbed as such.immunoglobulins absorbed as such.

6.6. Yellowish color of colostrum is due to high Yellowish color of colostrum is due to high level of level of β caroteneβ carotene which is present 50 – 100 which is present 50 – 100 times as much as in mature milk.times as much as in mature milk.

► Colostrum contains large granular bodies Colostrum contains large granular bodies (colostrum corpuscles):(colostrum corpuscles):

Alveolar cells of mammary gland and Alveolar cells of mammary gland and leukocytes baded with fat.leukocytes baded with fat.

FunctionFunction::

1.1. Has a laxative effect so help excretion of Has a laxative effect so help excretion of meconium.meconium.

2.2. Contain high level of immunoglobulins which Contain high level of immunoglobulins which provide immunity for newborn.provide immunity for newborn.

3.3. Easily digested, absorbed and metabolized.Easily digested, absorbed and metabolized.

4.4. Has high nutritive value (rich in protein, Has high nutritive value (rich in protein, minerals and vitamins).minerals and vitamins).

Humanization of cow's Humanization of cow's milkmilk

Def:Def: It is a process by which cow's milk is made to be It is a process by which cow's milk is made to be

as near as human's milk.as near as human's milk.Aim:Aim: Protein of human's milk (casein) form 25% of Protein of human's milk (casein) form 25% of

milk protein while casein in cow's milk form 5/6 milk protein while casein in cow's milk form 5/6 of milk protein so it form dense clot in newborn of milk protein so it form dense clot in newborn stomach which can't be digested leading to stomach which can't be digested leading to vomition.vomition.

Lactose in human's milk higher than that in Lactose in human's milk higher than that in cow's milk (7:5).cow's milk (7:5).

Steps:Steps:1.1. Pasteurization of milk:Pasteurization of milk:

Heating of milk to 60 Heating of milk to 60 ◦◦C for 30 minutes followed by C for 30 minutes followed by sudden cooling then the pasteurized milk left in sudden cooling then the pasteurized milk left in cool place for 4 hours to allow separation of cream.cool place for 4 hours to allow separation of cream.

2.2. Separate the cream and the residual milk called Separate the cream and the residual milk called Skimmed milk.Skimmed milk.

3.3. Skimmed milk is divided to two halves.Skimmed milk is divided to two halves. To one half add:To one half add:

Separated cream.Separated cream. Equal amount of water.Equal amount of water. Complete lactose to 7%.Complete lactose to 7%. Iron, vitamin C, vitamin D may be added.Iron, vitamin C, vitamin D may be added.

4.4. Mix well then sterilize the milk:Mix well then sterilize the milk: Heating of milk to 116 Heating of milk to 116 ◦◦C for 15 minutes.C for 15 minutes.

N.B:N.B:1.1. The humanized milk still differs from human milk in The humanized milk still differs from human milk in

containing containing less iron and copperless iron and copper..2.2. The protein in diluted cow's milk is usually still higher The protein in diluted cow's milk is usually still higher

than that of human milk so:than that of human milk so:Bottle fed babies store greater quantities of Bottle fed babies store greater quantities of

nitrogen than do breast fed babies. This nitrogen than do breast fed babies. This nitrogen retention result in a nitrogen retention result in a muscle mass muscle mass 25%25% greater in bottle fed babies. greater in bottle fed babies.

Cow's milk Cow's milk digested more slowlydigested more slowly than human milk. than human milk. The faeces of bottle fed babies are The faeces of bottle fed babies are more abundant more abundant

and of a harder consistencyand of a harder consistency than those of breast fed than those of breast fed babies.babies.

3.3. High mineral content of cow's milk High mineral content of cow's milk may bemay be a a load to cardiovascular system due to high Naload to cardiovascular system due to high Na++ content.content.

4.4. High phosphate content of cow's milk High phosphate content of cow's milk may may produceproduce hyperphosphatemia and hypocalcemia hyperphosphatemia and hypocalcemia with convulsions in the infants.with convulsions in the infants.

Advantages of human milk (Breast Feeding):Advantages of human milk (Breast Feeding):

1.1. Psychological effect on both child and Psychological effect on both child and mother.mother.

2.2. Breast milk is supplied in suitable Breast milk is supplied in suitable temperature.temperature.

3.3. Sterile and not liable to be contaminated.Sterile and not liable to be contaminated.

4.4. Cheaper than animal milk.Cheaper than animal milk.

5.5. Not liable to adulteration.Not liable to adulteration.

6.6. Lactation may act as a contraceptive Lactation may act as a contraceptive measure.measure.

7.7. Lactation minimize the risk of breast tumors.Lactation minimize the risk of breast tumors.

8.8. Lactation help involution of the uterus.Lactation help involution of the uterus.

ESTIMATION OF LACTOSE ESTIMATION OF LACTOSE IN MILKIN MILK

Principle:Principle: Lactose in milk is estimated in the clear filtrate Lactose in milk is estimated in the clear filtrate

after precipitating proteins. Tungestic acid, and after precipitating proteins. Tungestic acid, and Trichloroacetic acid can be used to precipitate Trichloroacetic acid can be used to precipitate milk proteins.milk proteins.

Instrument:Instrument:1.1. Estimated pipette.Estimated pipette.2.2. Volumetric flask.Volumetric flask.3.3. Funnel.Funnel.4.4. Beaker. Beaker. 5.5. Burette.Burette.6.6. Burette holder.Burette holder.7.7. Porcelain dish.Porcelain dish.

Procedures:Procedures:a) PPT of casein:a) PPT of casein:►In a clean dry volumetric flask add:In a clean dry volumetric flask add:

5ml5ml of milk of milk 5ml5ml of 10% sodium tungstate solution of 10% sodium tungstate solution 5ml5ml of 2/3 N sulphuric acid drop by drop. of 2/3 N sulphuric acid drop by drop.

►Shake gently after each addition .Shake gently after each addition .►Complete to the Complete to the 100-ml100-ml mark by distilled mark by distilled

water.water.►Left for sometime (1/4 – 1/2 hr) until the Left for sometime (1/4 – 1/2 hr) until the

precipitate of casein settles down.precipitate of casein settles down.

b) Filteration:b) Filteration:►Filter into a dry clean beaker. Filter into a dry clean beaker.

N.B:N.B:

The filtrate must be clear, The filtrate must be clear, ifif not refilter again. not refilter again.

c) Reduction:c) Reduction:► When about half the volume is filtered, wash the burette When about half the volume is filtered, wash the burette

with little of the filtrate.with little of the filtrate.► ThenThen fill the burette with the filtrate. fill the burette with the filtrate.► In a porcelain dish place:In a porcelain dish place:

10 ml10 ml of Fehling’s solution. of Fehling’s solution. 20 ml20 ml of distilled water. of distilled water.

Heat the Fehling’s solution until it gently boils and Heat the Fehling’s solution until it gently boils and ► Begin the reduction adding the filtrate slowly and Begin the reduction adding the filtrate slowly and

regularly in order to keep Fehling’s solution boiling all regularly in order to keep Fehling’s solution boiling all the time.the time.

► Continue the reduction until the last trace of blue color Continue the reduction until the last trace of blue color is just discharged.is just discharged.

►Using an external indicator near the end point Using an external indicator near the end point (Potassium Ferrocyanide solution acidified with (Potassium Ferrocyanide solution acidified with Glacial Acetic acid) Glacial Acetic acid) to ensure the complete to ensure the complete reduction of Fehling's solution:reduction of Fehling's solution:The end point is reached when no brown color or The end point is reached when no brown color or

precipitate is formed on the addition of one drop of precipitate is formed on the addition of one drop of the solution to the external indicator. 10-ml Fehling’s the solution to the external indicator. 10-ml Fehling’s solution are reduced by 0.0678-gram lactose.solution are reduced by 0.0678-gram lactose.

IfIf brown color or PPT appeared it indicates: brown color or PPT appeared it indicates: Incomplete reduction of fehling’s solution.Incomplete reduction of fehling’s solution. Complete reduction till the yellow color of the Complete reduction till the yellow color of the

indicator doesn’t change.indicator doesn’t change.

d) Calculation:d) Calculation:► R = number of mls of the filterate used for complete R = number of mls of the filterate used for complete

reduction of fehling’s solution.reduction of fehling’s solution.► 10 ml Fehling’s solution are completely reduced by 0.0678 gm 10 ml Fehling’s solution are completely reduced by 0.0678 gm

lactose.lactose.► Total dilution of milk (T.D):Total dilution of milk (T.D):

► Lactose in milk (g%):Lactose in milk (g%):

2020= = 100100

55

Lactose in milk =Lactose in milk =0.0678 x 20 x 1000.0678 x 20 x 100

RR

Estimation of glucose or lactose in Estimation of glucose or lactose in solutionsolution::

Principle of the test:Principle of the test: The quantitative determination of glucose or lactose in The quantitative determination of glucose or lactose in

gm/dl in the solution depends upon their reducing gm/dl in the solution depends upon their reducing property to Fehling’s solution.property to Fehling’s solution.

Instruments used in the estimation:Instruments used in the estimation:► Pipette 5 and 10-ml capacity.Pipette 5 and 10-ml capacity.► Conical flask of 100 cc capacity.Conical flask of 100 cc capacity.► Burette 50 ml capacityBurette 50 ml capacity► Burette holder.Burette holder.► Porcelain dish.Porcelain dish.► Beaker.Beaker.

Reagents and solutions required:Reagents and solutions required:► Glucose or lactose, solution under estimation.Glucose or lactose, solution under estimation.► Fehling quantitative reagent.Fehling quantitative reagent.► Potassium ferrocyanide acidified with glacial acetic Potassium ferrocyanide acidified with glacial acetic

acid (external indicator).acid (external indicator).

Significance of the test:Significance of the test:► This test considered the bases of tests used for the This test considered the bases of tests used for the

determination of blood glucose.determination of blood glucose.► Used for estimation of lactose in milk, for detection of Used for estimation of lactose in milk, for detection of

adulteration of milk by the addition of water.adulteration of milk by the addition of water.

procedures:procedures:(A) Rough estimation:(A) Rough estimation:► Fill the burette with glucose or lactose solution after its Fill the burette with glucose or lactose solution after its

careful rinsing with water.careful rinsing with water.► Put in the porcelain dishPut in the porcelain dish

10-ml of Fehling quantitative reagent. 10-ml of Fehling quantitative reagent. 20 ml of distilled.20 ml of distilled.

Heat until the Fehling boils in the dish.Heat until the Fehling boils in the dish.

► Begin the reduction by slow addition of solution in Begin the reduction by slow addition of solution in order to keep the Fehling boiling all the time.order to keep the Fehling boiling all the time.

► Continue reduction till the last trace of the blue color of Continue reduction till the last trace of the blue color of the Fehling’s reagent turn to red brown PPT of Cuthe Fehling’s reagent turn to red brown PPT of Cu22O.O.

► Record the rough reading Record the rough reading RR (number of mls of glucose (number of mls of glucose or lactose descended from the burette).or lactose descended from the burette).

►If If the the (R)(R) rough reading is rough reading is below 5mlbelow 5ml make make dilution to the glucose or the lactose solution dilution to the glucose or the lactose solution under the estimation.under the estimation.

►If If the the (R)(R) rough reading is rough reading is above 5mlabove 5ml calculate the percentage of glucose or the lactose calculate the percentage of glucose or the lactose solution under the estimation.solution under the estimation.

(B) Preparation of diluted sugar solution:(B) Preparation of diluted sugar solution:► Mutiply the (R) by 4.Mutiply the (R) by 4.► The result is equaled to 5, 10 or 20.The result is equaled to 5, 10 or 20.► In 100 ml volumetric flask add:In 100 ml volumetric flask add:

? ml of the glucose or lactose sugar solution. ? ml of the glucose or lactose sugar solution. Completed with distilled water to 100 ml mark Completed with distilled water to 100 ml mark

and well mixed.and well mixed.► In this case the sugar solution is diluted 5, 10 or 20 In this case the sugar solution is diluted 5, 10 or 20

times.times.

(C) Accurate estimation:(C) Accurate estimation:► Wash the burette with distilled water and rinse it with Wash the burette with distilled water and rinse it with

little of diluted sugar, little of diluted sugar, ► fill it again with the diluted sugar. fill it again with the diluted sugar. ► In the porcelain dish add:In the porcelain dish add:

10 ml of Fehling’s quantitative solution.10 ml of Fehling’s quantitative solution. 20 ml of distilled water. 20 ml of distilled water.

Heat till gentile boiling.Heat till gentile boiling.► BeginBegin the reduction by slow addition of the diluted the reduction by slow addition of the diluted

sugar solution drop by drop in order to keep the sugar solution drop by drop in order to keep the Fehling’s solution boiling all the time.Fehling’s solution boiling all the time.

► ContinueContinue reduction till the last trace of the blue color reduction till the last trace of the blue color disappeared and changed to red brown PPT of Cudisappeared and changed to red brown PPT of Cu22OO

► Using an external indicator near the end point Using an external indicator near the end point (Potassium Ferrocyanide solution acidified with Glacial (Potassium Ferrocyanide solution acidified with Glacial Acetic acid) Acetic acid) to ensure the complete reduction of to ensure the complete reduction of Fehling's solution:Fehling's solution:If If no brown color or PPT is formed on the addition no brown color or PPT is formed on the addition

of one drop of the solution to the external indicator it of one drop of the solution to the external indicator it indicates:indicates: complete reduction of Fehling's solution.complete reduction of Fehling's solution.

IfIf brown color or PPT appeared it indicates: brown color or PPT appeared it indicates: Incomplete reduction of Fehling's solution.Incomplete reduction of Fehling's solution. Complete reduction till the yellow color of the Complete reduction till the yellow color of the

indicator doesn’t change.indicator doesn’t change.► Record the number of mls used for reduction of 10 ml Record the number of mls used for reduction of 10 ml

Fehling’s quantitative solution and give it symbol Fehling’s quantitative solution and give it symbol (V)(V) ml.ml.

D) Calculation:D) Calculation:► 10 ml Fehling’s solution are completely reduced by 10 ml Fehling’s solution are completely reduced by

0.0678 gm lactose.0.0678 gm lactose.

Lactose in solution =Lactose in solution =0.0678 x 1000.0678 x 100

g/dlg/dlRR

Lactose in solution =Lactose in solution =0.0678 x T.D x 1000.0678 x T.D x 100

g/dlg/dlVV

► 10 ml Fehling’s solution are completely reduced by 10 ml Fehling’s solution are completely reduced by 0.05 gm glucose.0.05 gm glucose.

Glucose in solution =Glucose in solution =0.05 x 1000.05 x 100

g/dlg/dlRR

Glucose in solution =Glucose in solution =0.05 x T.D x 1000.05 x T.D x 100

g/dlg/dlVV

N.B.:N.B.:► Fehling’s solution should boil gently all the Fehling’s solution should boil gently all the

time.time.► Never stir by glass rod.Never stir by glass rod.► The rate of addition of sugar solution from the The rate of addition of sugar solution from the

burette should be equal to the rate of burette should be equal to the rate of evaporation of Fehling in the dish.evaporation of Fehling in the dish.

► Do not use the external indicator as long as Do not use the external indicator as long as there is blue coloration seen by naked eye.there is blue coloration seen by naked eye.

► The external indicator should be present in The external indicator should be present in white, clean porcelain slab.white, clean porcelain slab.

الله بحمد الله تم بحمد تم