In this experiment, the main objective is to extract lactose from milk. It is isolated by the addition of ethanol and thereafter crystallization of the resulting filtrate from previous procedures that were carried out to remove proteins from milk. After a step by step experiment, 2.23grams lactose crystals were obtained using a one-step extraction process under optimal conditions. This was 4% of the carbohydrate initially present in milk.
Among different demographics, milk is an essential part of a majority of dishes. Its nutritional value cannot be overlooked. Examples of these nutrients include fats stored in countless small globules and proteins that have hydrophobic and hydrophilic regions. In addition, phospholipids are also essential milk constituents. Besides the above, lactose is another fundamental nutrient in milk. It is a disaccharide formed from two simple sugars. It readily dissolved in water but is less soluble in a water-ethanol mixture. In this solution, it crystalizes. It is broken down by an enzyme called lactase which is produced by cells in the small intestine. The decreased ability to digest lactose due to lactase deficiency is called lactose intolerance. Although the people affected react differently to varying levels of lactose, the symptoms from one person to another are closely related. They include diarrhea in babies who react to lactose in breast milk and baby formula, and other individuals as well, nausea, abdominal pain and blotting among others.
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Materials:
Non-fat powdered milk
Weighing boat
Warm water
Ethanol
250 ml beaker
Source of heat
Stirrer.
1.0 M acetic acid.
Powdered calcium carbonate.
Procedure:
10 grams of free-fat powdered milk was weighed in a weighing boat. It was then dissolved in 100 ml of warm water in a 250 ml beaker.
The milk solution was heated to a temperature of 40 degrees Celsius.
Casein was precipitated out by the addition of 10 ml of 1.0 M acetic acid and the mixed components were given a slow stir for a short period of time. The Casein was made into a mass, after which, a stirring rod was used to remove it.
2-5 grams of powdered calcium carbonate were added immediately and the mixture was stirred thoroughly.
The remaining proteins were precipitated out when the mixture was heated to an almost boiling point for about 10 minutes. During heating, the mixture was continuously stirred.
Filtration of the hot mixture was carried out and the filtrate was collected in a 250 ml beaker.
The filtrate was boiled down to 10 ml and 50 ml and 95% ethanol was added.
The solution was carefully heated to 70 degrees Celsius.
The warm ethanol solution was filtered, and collected in a 125 ml Erlenmeyer flask which was stopped and placed in the lab drawer.
Lactose crystals were filtered off.
The filtered crystals were allowed to dry for one hour.
The crystals obtained were weighed.
Results:
On weighing the lactose crystals obtained, they were found to be 2.23g. This was 4 % of the carbohydrate that was present in the powdered milk. A supersaturated solution that resulted from the contact of nonfat powdered milk with aqueous ethanol was unstable and rapidly approached equilibrium conditions by the crystallization of lactose. The time course of these events was dictated by the processing conditions.
Key Uses for Lactase
Lactase supplements are used in the treatment of lactase intolerance.
It is used for commercial purposes. This particular type of lactase is extracted from yeast and molds and its primary commercial use is the making of supplements such as lacteeze and lactoid.
Also, it is utilized in the screening for blue-white colonies in different cloning sites of varied plasmid vectors or other bacteria. Lactose intolerance reflects the inheritance of different lactase gene alleles. It is a result of being homozygous for the recessive lactase allele. This allele is usually predisposed to poor expression after early childhood. Being homozygous or heterozygous for the persistent allele creates room for lactase expression, a phenomenon whose expression is expressed downwards. In some cases, heterozygotes can have partial intolerance, an indication of the presence of an incomplete dominant gene.
