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Generally, Benedict's test detects the presence of aldehyde groups, alpha-hydroxy-ketones, and hemiacetals, including those that occur in certain ketoses. In example, although the ketose fructose is not strictly a reducing sugar, it is an alpha-hydroxy-ketone which results to a positive test because the base component of Benedict converts it ...
Bifidobacterium in the human intestine have been found to contain type I chain lacto-N-biosidases capable of cleaving lacto-N-tetraose to lactose-N-biose and lactose. [ 11 ] Lacto- N -tetraose is a non-competitive food source for B. infantis with other enteric bacteria lacking the required proteins and incapable of degrading the sugar into ...
Reducing disaccharides like lactose and maltose have only one of their two anomeric carbons involved in the glycosidic bond, while the other is free and can convert to an open-chain form with an aldehyde group. The aldehyde functional group allows the sugar to act as a reducing agent, for example, in the Tollens' test or Benedict's test.
Ketoses and aldoses can be chemically differentiated through Seliwanoff's test, where the sample is heated with acid and resorcinol. [4] The test relies on the dehydration reaction which occurs more quickly in ketoses, so that while aldoses react slowly, producing a light pink color, ketoses react more quickly and strongly to produce a dark red color.
Since its discovery in 1904 until the 1960s, the Wöhlk test has mainly been used to detect the reducing disaccharide lactose in urine in medical laboratories. Although there were already a number of wet-chemical detection methods to identify sugars, such as the Fehling or Benedict test , those analyses could only differentiate between reducing ...
The patient is then given a small amount of pure lactose (typically 20 to 25 g), and then required to take readings every 15, 30 or 60 minutes for two to three hours. If the level of hydrogen rises above 20 ppm (parts per million) over the lowest preceding value within the test period, the patient is typically diagnosed as a lactose malabsorber ...
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The result can be detected with high levels of lactate and low levels of bicarbonate. This is usually considered the result of illness but also results from strenuous exercise. The effect on pH is moderated by the presence of respiratory compensation. Lactic acidosis is usually the result of tissue hypoxia which is not the same as arterial hypoxia.