Lect 2 - Lactose, Maltose

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PHARM. D

Chemical Pharmacognosy- I

Lecture 2February 21, 2011

CARBOHYDRATESLACTOSE, MALTOSE

M.M. AhsanAhsan KhalidKhalid,, B.PharmB.Pharm, Pharm. D, Pharm. DM.PhilM.Phil Scholar (RIPS/RIU)Scholar (RIPS/RIU)

HIPSHIPS--HUKICHUKIC


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LACTOSE


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Lactose is made from galactose and glucose units:

Lactose or milk sugar occurs in the milk ofmammals - 4-6% in cow's milk and 5-8% in human

milk. It is also a by product in the manufacture of

cheese.

The galactose and glucose units are joined by anacetal oxygen bridge in the beta orientation


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Isolation of Lactose

Several million tons are produced annually as a by-product of the dairy industry.

Whey is made of up 6.5% solids of which 4.8% is

lactose that may be purified by crystallization.

Whey or milk plasma is the liquid remaining after

milk is curdled and strained, for example in the

production of cheese.

Lactose makes up about 2-8% of milk by weight.Lactose is purified from whey by adding ethanol.

Since it is insoluble in ethanol, lactose precipitates

in about 65% yield


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Lactose Intolerance

Lactose intolerance is the inability to metabolize

lactose, because of a lack of the required enzyme

lactase in the digestive system.

This inability results from a shortage of the

enzyme lactase, which is normally produced by the

cells that line the small intestine.


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Lactase breaks down the lactose, milk sugar, into

glucose and galactose that can then be absorbed intothe bloodstream.

When there is not enough lactase to digest the

amount of lactose consumed, produce some

uncomfortable symptoms.

The ingested lactose is not absorbed in the smallintestine, but instead is fermented by bacteria in the

large intestine, producing uncomfortable volumes of

carbon dioxide gas.


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Common symptoms include nausea, cramps,

bloating, gas, and diarrhea, which begin about30 minutes to 2 hours after eating or drinking

foods containing lactose.

The severity of symptoms varies depending on

the amount of lactose each individual can

tolerate.


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Diagnosis

To assess lactose intolerance, the intestinal

function is challenged by ingesting more dairy than

can be readily digested.

it is important to distinguish lactose intolerance

from a milk allergy, which is an abnormal immuneresponse to milk proteins.

This may be done by giving lactose-free milk to a

person displaying a reaction to milk. If thecondition is purely lactose intolerance, the

sufferer's symptoms will vanish, but if it is a milk

allergy, the person will have the same reaction to

the lactose-free milk as to normal milk.


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Diagnosis

Hydrogen breath test

Stool acidity test

Intestinal biopsy


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In a hydrogen breath test, after an overnight fast,

50g of lactose is swallowed.

If the lactose cannot be digested, enteric bacteriametabolize it and produce hydrogen. This, along

with methane, can be detected in the patient's breath

by a clinical gas chromatograph or a compact solid

state detector. The test takes about 2 to 3 hours.

In conjunction, measuring the blood glucose level

every 10-15 min after ingestion will show a "flat

curve" in individuals with lactose malabsorption,while the lactase persistent will have a significant

"top", with an elevation of typically 50 to 100%

within 1-2 hrs.


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Stool Acidity Test can be used to diagnose lactose

intolerance in infants, for whom other forms of

testing are risky or impractical

An Intestinal Biopsy can confirm lactase deficiency

following discovery of elevated hydrogen in thehydrogen breath test.

Modern techniques have enabled a test to be

performed at the patient's bedside which identifies

the presence/absence of the lactase enzyme in

conjunction with upper gastrointestinal endoscopy


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Managing Lactose Intolerance Fortunately, lactose intolerance is relatively easy to

treat by controlling the diet.

No cure or treatment exists to improve the body's

ability to produce lactase.

Young children with lactase deficiency should noteat any foods containing lactose.

Most older children and adults need not avoid

lactose completely, but individuals differ in the

amounts and types of foods they can handle.

Dietary control of lactose intolerance depends on

each person's learning through trial and error how

much lactose he or she can handle.


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MALTOSE


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Maltose or malt sugar is the least common

disaccharide in nature. It is present in germinating

grain, in a small proportion in corn syrup, and formson the partial hydrolysis of starch.

The two glucose units are joined by an acetal

oxygen bridge in the alpha orientation.


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Maltose can be broken down into two glucose

molecules by hydrolysis.

In living organisms, the enzyme maltase can achieve

this very rapidly.

In the laboratory, heating with a strong acid for

several minutes will produce the same result


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Malted Barley: Barley, a basic cereal grain, is low in gluten, and is not

particularly good for milling into flour for use in

products such as bread. Barley is the preferred grain to

make beer. The barley grains must be "malted" before

they can be used in the brewing process.

Malting is a process applied to cereal grains, in which

the grains are made to germinate by soaking in water

and are then quickly halted from germinating further by

drying with hot air. Malting grains develops enzymesthat are required to modify the grain's starches into

sugars including monosaccharides such as glucose or

fructose, and disaccharides such as sucrose or maltose.


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The production of maltose from germinating

cereals, such as barley, is an important part of thebrewing process.

When barley is malted, it is brought into a

condition in which the concentration of maltose-

producing amylases has been maximized.

Mashing is the process by which these amylases

convert the cereal's starches into maltose.

Metabolism of maltose by yeast duringfermentation then leads to the production of

ethanol and carbon dioxide.

Lect 2 - Lactose, Maltose

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