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Milk. Objectives. Formation of milk (lactation) Nutritional Value of milk Composition of milk Human milk and animal milk The colostrum. Lactation. Preparation of breast during pregnancy : carried out by the ovarian and placental hormones (estrogen & progesterone mainly ) - PowerPoint PPT Presentation
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MilkMilk
ObjectivesObjectives
• Formation of milk (lactation)
• Nutritional Value of milk
• Composition of milk
• Human milk and animal milk
• The colostrum
LactationLactation• Preparation of breast during pregnancy: carried out by the ovarian and placental hormones (estrogen &
progesterone mainly)
• Initiation of milk secretion :Under the effect of lactogenic hormone (from ant. Pituitary), starts at the
last days of pregnancy due to lowering of hormones (where prev. hormones inhibit releasing of the lactogenic hr.)
• Milk letting:Flow of milk from breasts occurs after delivery by the suckling
reflex and release of oxytocin (post. Pituitary)
Nutritional Value of Milk :Nutritional Value of Milk :
• Almost complete diet for infant • Deficient in : vit K , C + Fe , Cu
3 3 rd rd m citrus fruitm citrus fruit
66th th m soup ,egg yolkm soup ,egg yolk
ColorColor
• White ± yellowishyellowish ,opaque
carotenescarotenes( colostrum + cow’s milk)
• Emulsion of fat + colloidal state of proteins & Ca phosphate
ReactionReaction
• pH cow’s 6.66.6 ,human milk 7.07.0
• Good buffer( proteins ,HCO3-, PO4,)
• Used for hyperacidity
• Lipids
• Proteins
• Carbohydrate
• Minerals and vitamins
Composition of milkComposition of milk
• Human & cows about 3.5%
• Present in form of emulsion emulsion surrounded by a thin coat layer of (PL, cholesterol and proteins)
• TAG: 99 %,99 %, main palmitic, oleic, stearic acids
• Human milk 10% essential. F.A.
• Cow’s milk 10% butyric acid
Milk FatMilk Fat
Other lipids :
• Small amount of cholesterol, phospholipids, fat soluble vit. & carotenes
• RichRich in vit. A
• PoorPoor in vit. K fairfair in E
• Cow’s milk poor in D but human fair
Milk ProteinsMilk Proteins
• Human 1.2%1.2% , cow’s 3.5%3.5%
• Casien : 80% (cow’s),40% (human) ,
phosphoproteinphosphoprotein,
• Rich in methionine,
• Poor in cystine & cysteine
• Ppt at its pI (4.6)
• Not coagulable
Lactalbumin & Lactoglobulin (whey Lactalbumin & Lactoglobulin (whey protein)protein)
• Human 60% , Cow 20 %
• Separate in whey
• Heat coagulable
• High biological value
• Can’t ppt at pH 4.6
• Include Ɣ –globulin (ab.)
Other proteins
• Lactoferrin:
↑↑↑↑ absorption of iron in intestine
Contain enzymes e.g.
proteinases,
amylase,
peroxidase, catalase,
alkaline phosphatase
Lactose (most suitable sugar)Lactose (most suitable sugar)
• Only CHO in milk
• Human 7.4% , cow’s 4.7%
• Digestion : gives glucose + galactose for E
• Galactose can form glycolipids
• Less sweet: not nausea
• Helps growth of lactic acid- producing bacteria in the intestine
• BacteriaBacteria
• Lactose Lactic acid ↓pH
• ↑ solubility & absorption of Ca , Mg 2, PO4 , Fe, Cu
• Inhibits growth of putrefactive bacteria
Milk Minerals & VitaminsMilk Minerals & Vitamins
• Human less in minerals than cow’s• RichRich in Ca , PO4 , K, Cl• FairFair amn. of Na & Mg• Both milk poorpoor in Fe & Cu but
human is richer• RichRich in vit A & B2
• PoorPoor in C & K• FairFair in others
Comparison Between Human & Comparison Between Human & Animal MilkAnimal Milk
Hman Milk Animal Milk
1- Proteins:• Amount of curds•Types of curds
• small•fine and thin
•Large•Thick and tough
2-Fats:•Fat globules•Volatile acids
•Small size•Absent
•Large• High amounts
3- Carbohydrate •Lactose •Lactose
4-Minerals:• Ca: P content•Ca:P ratio •Iron
•Smaller• Suitable 2:1•Deficient
•Higher•Not suitable •More deficient
5- Reaction •Alkaline(7.0) •More acidic (6.6)
6- Digestion • Easy • Difficult
7-Growth promotion
• More •Less
ColostrumColostrum• Yellowish secreted during the first
week
• Differs from mature in:
• Higher protein with less casein & more whey protein
• Esp rich in IgA which prevents gastroenteritis
• Minerals are higher
• Vitamins are higher
• Fats are lower but with higherhigher fat soluble vitamins, carotenes (yellowish coloryellowish color )
• Easier to digest
• Lower lactose , less sweet & more suitable for new born
Some Milk ProductsSome Milk Products• Full cream milk :milk containing all of its fat
e.g. nestogen, SMA and SIMILAC
• Acidified milk: milk with pH lower than ordinary milk and is used in infants suffering from diarrhea or vomiting e.g. Pelargon and prodieton
• Fortified milk: milk to which concentrated forms of vitamins or minerals are added
Milk ClottingMilk Clotting RenninRennin
• Casein paracasein (sol) +peptone –like
• Paracasein + Ca 2+ insoluble Ca para.
ppts entangling fat + fat soluble vit.
milk clot or cheesemilk clot or cheese
WheyWhey :
• greenish yellow (riboflavin) in color contains
water &
water soluble vitamins,
lactalbumin, lactaglobulins,
lactose,
minerals,
reduced Ca content
Milk CurdlingMilk Curdling• It is the precipitation of casein
at its isoelectric pH, (pH =4.6)
• Produced by the action of action of lactobacillus acidophiluslactobacillus acidophilus
• Fermenting lactose
• Casein ppts + fats + fat soluble vit. to form curds or yogurt
WheyWhey of the milk curds
contains
less less lactoselactose
moremore B- vitamins( produced by bact.)
moremore calcium (not ppt with casein)
Advantages of colostrum for Advantages of colostrum for babybaby
• Highly nutrititve: high proteins and minerals
• High antibody contents; mainly gamma globulins which give immunity
• Laxative effect : which prevents constipation