|MadSci Network: Biochemistry|
Your questions: 1) i am looking for resources with information on measuring lactose digestion. my experiment will compare the efficiency of non-prescription lactase replacements. 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 ]
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