http://bs-wiki.de/mediawiki/index.php?action=history&feed=atom&title=Diskussion%3ABenedict-ReagenzDiskussion:Benedict-Reagenz - Versionsgeschichte2026-05-12T17:16:31ZVersionsgeschichte dieser Seite in BS-Wiki: Wissen teilenMediaWiki 1.29.0http://bs-wiki.de/mediawiki/index.php?title=Diskussion:Benedict-Reagenz&diff=67478&oldid=prevDg: Die Seite wurde neu angelegt: „wp:e: ==Chemical test== To test for the presence of monosaccharides and reducing disaccharide sugars in food, the food sample is dissolved in water, and a …“2014-08-12T14:04:30Z<p>Die Seite wurde neu angelegt: „wp:e: ==Chemical test== To test for the presence of <a href="/mediawiki/index.php?title=Monosaccharides&action=edit&redlink=1" class="new" title="Monosaccharides (Seite nicht vorhanden)">monosaccharides</a> and reducing disaccharide sugars in food, the food sample is dissolved in water, and a …“</p>
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==Chemical test==<br />
To test for the presence of [[monosaccharides]] and reducing disaccharide sugars in food, the food sample is dissolved in water, and a small amount of Benedict's reagent is added. During a [[heated bath|water bath]], which is usually 4–10 minutes, the solution should progress in the colors of blue (with no glucose present), green, yellow, orange, red, and then brick red or brown (with high glucose present). A colour change would signify the presence of glucose.<br />
A greenish precipitate indicates about 0.5 g% concentration; yellow precipitate indicates 1 g% concentration; orange indicates 1.5 g% and red indicates 2 g% or higher concentration.<br />
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[[Sucrose]] (table [[sugar]]) contains two sugars (fructose and glucose) joined by their [[glycosidic bond]] in such a way as to prevent the glucose [[isomerizing]] to aldehyde, or the fructose to alpha-hydroxy-ketone form. Sucrose is thus a non-reducing sugar which does not react with Benedict's reagent. Sucrose indirectly produces a positive result with Benedict's reagent if heated with dilute hydrochloric acid prior to the test, although after this treatment it is no longer sucrose. The acidic conditions and heat break the [[glycosidic bond]] in sucrose through [[hydrolysis]]. The products of sucrose decomposition are glucose and fructose, both of which can be detected by Benedict's reagent, as described above.</div>Dg