FOOD TESTS AND DIGESTIVE ENZYME PRACTICAL

Nutrition Practical: Food Tests and Digestive Enzyme Practical



Nutrition Practical: Food Tests and Digestive Enzyme Practical

Introduction

Humans need to consume food compounds such as carbohydrates, proteins, fats, and vitamins to meet their energy requirements. In this lab, reagents were used as indicators to test common food substances for the presence of specific nutrients. Milk, Potato, and Bread tested positively for fat, protein, starch and glucose (Lawley 2008, 12-17). Meats and oils had a high fat content, and potato and frozen pizza had high sodium content. None of the foods tested in this lab would individually be able to meet all of our body's requirements for essential food compounds. Therefore, it is important to eat a variety of foods that provide just the right balance between fat, protein, starch and glucose (Knight 2002, 35-39).

Food substance

Reagent

Nutrient

Indicator Response

Gelatin suspension

Biuret solution

Protein

Light lavender (4)

Glucose solution

Benedict's solution

Sugar

Bright yellow (3)

Starch solution

Lugol's iodine solution

Starch

Dark blue (4)

Ascorbic acid solution

Indophenol solution

Vitamin C

Colorless (5)

NaCl solution

Silver nitrate solution

Chloride

3 drops*

Butter

None

Fat

Level 5 greasy spot* *

Vegetable oil

None

Fat

Level 5 greasy spot* *

Discussion

Reagent tests of the foods selected for this lab show that each food tests positive for at least three of the nutrients described above. Potato were the only food tested that contained all six compounds (Jones 2005, 16-18). Both milk and potato contained all the food compounds except fats. Sugar was found in all substances except. All food substances except the milk contained starch. All of the food substances tested positively for protein except cheerios, the orange, and the carrot (Hutton 2003, 20-29). Glucose was found in the milk, potato only. All food substances contained proteins except the potato. Fats were found in bread, potato with trace amounts in the milk (Hutton 2002, 24-29).

Analysis of Compounds in Common Foods Using Known Reagents

Compound

Food Substance

Protein

Starch

Fat

Glucose

Milk

1

3

0

0

Potato

1

5

3

4

Bread

1

3

0

2

Results indicate that potato, milk, are good sources of protein necessary for cell replication and the structure and growth of the cell. Starch and glucose are indicators of foods high in carbohydrate, a good energy source (Hutton 2001, 12-18). All foods, except the potato tested positively for these carbohydrates, indicating they are good sources ...