Experiment 8: Tests for Nutrients in Food Michelle Magno, Dawnie Dawnie Jamaca, Queenie Queenie Pontejos, Pontejos, and Leslei Potutan Locker no.:3
Chemistry Department, Xavier University-Ateneo de Cagayan, Cagayan de Oro City Date Performed: January 11, 2013 Date Submitted: January 25, 2013 ABSTRACT
Food contains nutrients that are very significant to the body. The basic essential nutrients, vitamins, and minerals play very significant functions in the different metabolic processes. In order for the nutrients to be known, several tests were performed to qualitatively analyze nutrients for the different food samples. Reagents were used as indicators to test common food substances for the presence of specific nutrients. Fruit juice, raw egg yolk, peanuts tested negative for mineral matter; margarine, raw egg yolk, peanuts tested positive for the presence of fat; fruit juice, raw egg yolk, peanuts, cooked rice, tested positive for carbohydrates; raw egg white, peanuts, cooked rice, anchovy, tested positive for the presence of proteins.
INTRODUCTION
Food is any substance consumed to provide nutritional support for the body. It is usually such of plant or animal origin, and contains essential nutrients, such as carbohydrates, fats, proteins, vitamins, or minerals. Dietary habits play a significant role in the health and mortality of all humans. Imbalances between the consumed fuels and expended energy results in either: starvation or excessive reserves of adipose tissue, known as body fat. Poor intake of various vitamins and minerals can lead to diseases that can have far-reaching effects on health. The basic essential nutrients, vitamins, and minerals play very significant functions in the different metabolic processes. Historically, people secured food through two methods: hunting and gathering, and agriculture. Most food has always been obtained through agriculture. Most food has its origin in plants. Some food is obtained directly from plants; but even animals that are used as food sources are raised by feeding them food derived from plants. A nutrient is a chemical that an organism needs to live and grow or a substance used in an organism's metabolism which must be taken in from its environment; this is usually found in food. Carbohydrates are one of the main types of nutrients. They are the most important source of energy for the body. The digestive system s ystem changes carbohydrates into . Carbohydrates are called simple or complex, depending on their chemical structure. Simple carbohydrates include sugars found naturally in foods such as fruits, vegetables, milk, and milk products. Complex carbohydrates include whole grain breads and cereals, starchy vegetables and legumes. Every living cell in the body contains proteins. Protein is needed by the body to build and maintain bones, muscles, and skin. Proteins can be obtained in our diet from meat, dairy products, nuts, and certain grains and beans. However, the proteins in plant are incomplete compared to the proteins from meat which is complete. complete. Proteins supply all of the essential amino acids. acids. Oils and fats are lipids, and it contains more than twice the amount of energy found in carbohydrates.
This experiment is an application of all the analytical tests conducted on the different macrobiomolecules like carbohydrates, lipids, proteins and nucleic acids which can be detected in food. This is to qualitatively analyze nutrients for the different samples. MATERIALS AND METHODS
The following tests were performed using the following food samples: fruit juice — fresh extracts of any fruit, margarine, raw egg white, raw egg yolk, peanuts-uncooked, dried anchovyground. A. Test for Mineral Matter Samples such as fruit juice, raw egg yolk, peanuts, and dried anchovy were used in this test. Small amount of each sample were placed in a crucible and was burnt to test the presence of mineral matter. White powdery residue ind icates the presence of mineral matter. The ashes that were obtained from the dried anchovy, 5mL of hot distilled water which was acidified with HNO3 was added. The solution was divided into two portions. Few drops of 0.1N (NH4)2C2O4 was added to the first and 0.1N AgNO3 was added to the second. a.) Extraction of Fat from food sample 5mL of ether was added to the small portion of food sample to a 30mL test tube. The mixture was covered with a stopper and was shaken vigorously for several minutes. The ether extract was separated from the aqueous layer. The ether extract was used for the tests for vitamin A, cholesterol, and fats. The aqueous layer was used for tests on carbohydrates and proteins. B. Test for Fat A portion of the ether was placed on a brown paper. The ether was evaporated without heating; the paper was warmed carefully and was observed. Translucent on paper indicates the presence of fat. C. Vitamin A content Carr-Price reaction was performed on the following samples: fruit juice, margarine, raw egg yolk, peanuts, and ether extract obtained from extraction of fat. D. Liebermann-Burchard Test Lieberman-Burchard was performed to the egg yolk to test for cholesterol presence. a.) Preparation of sample for Carbohydrate and Protein Tests Saturated aqueous solutions of the sample were prepared to the aqueous layer from the extraction of fat. The sample was boiled in a little amount of distilled water until it was dissolved. The prepared aqueous solutions were used for the tests of carbohydrates and for proteins.
E. Test for Carbohydrates a.) Molisch test was perfomed on all food samples except raw egg white. b.) Osazone test was performed from the fruit juice. The crystals that formed from the said test were carefully examined under a microscope. F. Test for Proteins a.) Biuret test was performed on the following samples: raw egg white, peanuts, cooked rice, and dried anchovy. Two mL of the aqueous food solutions of the said samples were used for this test.
RESULTS AND DISCUSSION
Summary of results of the tests conducted Food Sample Mineral Matter
Fruit Juice Margarine Raw Egg White Raw Egg Yolk Peanuts Cooked Rice Dried Dilis
Fat
N/A N/A
+ N/A
Carbohydrates (Molisch) + N/A
Proteins (Biuret) N/A N/A +
_
+
+
N/A
N/A +AgNO3 +(NH4)2C2O4
+ N/A -
+ + -
+ + +
Vitamin A (Carr-Price)
N/A
N/A N/A
Out of the tests that were performed, it is seen that there is a presence of fat in margarine, raw egg yolk, and peanuts. Because carbohydrates are one of the main types of nutrients, and one of the most common, all of the samples except margarine and dried anchovy were positively tested. For proteins, raw egg white, peanuts, cooked rice, and dried anchovy were positive in the presence of proteins. For the vitamin A testing, the samples deem to be negative. Results for Carr-Price test were all cloudy-transparent white except raw egg yolk which yielded a purple color. However, there are many statements in literature that the blue tint of the Carr-Price reaction depends on the percentage of vitamin A present. Mineral matter Fats Molisch test was used to test the presence of carbohydrates. Molisch test is a sensitive chemical test for the presence of carbohydrates, based on the dehydration of the carbohydrate by sulfuric acid to produce an aldehyde, which condenses with two molecules of phenol, resulting in a red- or purple-colored compound. Fruit juice and peanuts yielded a dark purple color. Raw egg yolk and cooked rice yielded a normal purple color. Anchovy yielded a purplebrownish color. Margarine, on the other hand, yielded a cloudy yellowish color indicating that it is negative for the test.
For vitamin A, Carr-Price reaction was performed. Carr-Price reaction is a reaction of antimony trichloride and vitamin A in chloroform solution that gives a blue color and is used for the identification and assessment of vitamin A. In the experiment done, it was shown that all the samples seem to be negative in this test.
CONCLUSION
The different nutrients that are acquired from food are very much important to the body. The basic essential nutrients, vitamins, and minerals play very significant functions in the different metabolic processes. Carbohydrates are found in a wide array of foods — bread, beans, milk, popcorn, potatoes, cookies, spaghetti, whole grain breads and cereals. They also come in a variety of forms. The most common and abundant forms are sugars, fibers, and starches. Proteins are essential nutrients for the human body. They are one of the building blocks of body tissue, and can also serve as a fuel source. Some of the protein eaten contains all the amino acids needed to build new proteins. This kind is called complete protein. Animal sources of protein tend to be complete. Other protein sources lack one or more “essential” amino acids. Incomplete proteins usually come from fruits, vegetables, grains, and nuts. REFERENCES 1.) 2.) 3.)
