How can macromolecules be detected in foods?

Answer 1

We just did this in class and I am working on the lab write-upright now, haha. Ok, to detect macromolecules in foods you use chemical indicators. An indicator is a substance that changes to indicate the presence of a particular compound or type of compound. The indicator may change color or temperature, or produce some other substance, such as, bubbles or a distinctive odor. The change in the indicator is due to a chemical reaction between the indicator and the tested substance. Indicators are very specific and work based on the chemical composition of the indicator and of the substance being detected. Some indicators are sensitive to temperature, pH, and other environmental conditions so it is necessary to know the optimal conditions for using each indicator. Generally, the easiest indicators to use are ones that change color to indicate the presence of a substance. Here are some different tests: Benedict's solution is an indicator that can be used to test for monosaccharides (simple sugars). Benedict's solution is light blue in color. However, when it is heated in the presence of simple sugars, it turns from blue to green or yellow/orange or even to red. The final color depends on the amount and type of monosaccharide. Benedict's solution needs to be heated to work properly.(Or you can use a glucose strip, its much easier, its a piece of paper and you put the end with the colored square in the substance and if it changes color then it has sugar in it) Lugol's Iodine can be used as an indicator for starch. Lugol's Iodine is yellow or light brown in color; in the presence of starch, it turns dark purple or even black. Biuret solution is a protein indicator. Biuret solution is a light blue color; in the presence of protein, the color changes to violet or purple. The shade or darkness of the color depends on the type and concentration of the protein, and can range from a very light violet to a deep purple. Fats and lipids leave a translucent mark on brown paper. Translucent means light can pass through, although distinct images may not be seen through it. Moist foods can be applied directly to brown paper to test for lipids; dry foods can be tested once they are made into an alcohol extract. This is done by grinding the food and placing it in alcohol, and applying samples of the liquid extract to the paper.