how would you test for the presence of a lipid in a sample of food
Emulsion test Add ethanol to the solution you want to test, and add water. A colour change to cloudy white shows that lipids are present.
Benedict's reagent 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 water bath, which is usually 4â€“10 minutes, the solution should progress in the colors of blue (with no reducing sugar present), orange, yellow, green, red, and then brick red precipitate or brown (with high reducing sugar present). A color change would signify the presence of a reducing sugar.[3] The common disaccharides lactose and maltose are directly detected by Benedict's reagent because each contains a glucose with a free reducing aldehyde moiety, after isomerization.