MadSci Network: Biochemistry

Re: what is the test for lactose digestion?

Date: Wed Sep 29 12:35:20 1999
Posted By: Dick van Wassenaar, Analytical PROTEIN Biochemist, Unilever Research Laboratory
Area of science: Biochemistry
ID: 938218237.Bc

Your questions: 
1) i am looking for resources with information on measuring lactose 
digestion. my 
experiment will compare the efficiency of non-prescription lactase 
2) i would like to know if the benedict test for sucrose digestion will 
work with 
lactose? can i simply measure ph changes?

Some answers:
1) To determine the lactose digestion - assuming you use lactase - one 
of the possibilities would be to use chromatographic techniques [thin-layer 
or high performance liquid chromatography] and determine the decrease in 
lactose and increase in both galactose and glucose. Another method would 
possibly be to use the optical differences of the system. The use of the 
Benedict test would not give you the right information as the test is 
specific for reducing sugars and that includes both lactose and glucose, as 
both have their reducing sites available for reaction with Benedict so one 
cannot differentiate between the two.

2) Sucrose is non-reducing because the potential reducing carbonyl groups 
are involved in the linkage between the glucose and fructose moiety. Upon 
hydrolysis this will release glucose that can be detected by Benedicts. 
Measurement of pH is not useful as it is not likely that this will change
UNLESS you use a microbial hydrolysis procedure [lactic acid bacteria e.g. 
yoghurt culture] in a non-buffered system to hydrolyse the lactose such 
that it will yield lactic acid and thereby lowering the pH.

[The Benedict's solution contains copper (II) sulfate, a mild oxidizing 
agent, which reacts with an available oxygen atom on sugar molecules known 
as reducing sugars. The resulting compound is copper (I) oxide, a red 
compound. Nonreducing sugars and complex carbohydrates do not produce a 
positive Benedict's test ]

Current Queue | Current Queue for Biochemistry | Biochemistry archives

Try the links in the MadSci Library for more information on Biochemistry.

MadSci Home | Information | Search | Random Knowledge Generator | MadSci Archives | Mad Library | MAD Labs | MAD FAQs | Ask a ? | Join Us! | Help Support MadSci

MadSci Network,
© 1995-1999. All rights reserved.