LABORATORY 3

LABORATORY REPORT

SBK3033 FOOD SCIENCE

TITLE OF EXPERIMENT :LABORATORY 3 LIPID ANALYSIS

LECTURER : DR HASIMAH ALIMON

GROUP : A

GROUP MEMBERS:

MOHAMAD HARITH BIN SULAIMAN	D20141067083
SHARIFAH AWANIS BINTI SYED MOHD ASWAD	D20141067053
MAUREEN SANTIH ANAK AMBANG	D20141067070

RESULTS

EXPERIMENT 1 : TEST FOR LIPID

		Result when added water
1	Oil dissolved in water	3	A layer of cloudy white suspension forms at the top of solution.
2	Alcohol alone	4	Solution remains colorless

EXPERIMENT 2:CHARACTERISTICS OF LIPID IN FOOD- VISUAL OBSERVATIONS

Sunflower seeds

Potato chips

Chocolate chips

Table 1 : Visual observations of fat

Food	Describe what you see on the paper towel
Chocolate chips	A lot of grease spot found on the paper towel.
Potato chips	Little grease spot found on the paper towel.
Sunflower seeds	Very little grease spot found on the paper towel.

Table 2: extraction of lipids

food	Weight of beaker	Weight of beaker with raw food	Weight of raw food	Weight of beaker with dried food	Weight loss of food	% lipid extraction
Chocolate chips	28.89 g	33.89 g	5 g	33.79 g	0.10 g	2%
Potato chips	28.93 g	33.93 g	5 g	33.59 g	0.34 g	6.8%
Sunflower seeds	29.74 g	34.74 g	5 g	33.95 g	0.74 g	15.8 %

Table 3: description of fats

food	color	texture	odor	Viscosity
Chocolate chips	Brown	Waxy	chocolate	Hard, dry
Potato chips	Light yellow	Oily	Corn	Thick oil
Sunflower seeds	Yellow	Oily	Sunflower seed	Thick oil

QUESTIONS

Experiment 1. Test for lipid

1. What was the only difference between the contents of tubes 1 and 2 ?

    Tube 1 has vegetable oil while Tube 2 do not has vegetable oil

2. What was the visible difference between tubes 3 and 4 after adding the contents of tubes 1 and 2 to the water in them?

For tube 3, there are layer of cloudy white suspension forms at the top of solution which are emulsion. For test tube 4, there is no change in color.

3.How would you attempt to explain the appearance of the liquid in tube 3?

Emulsion which are layer of cloudy white suspension forms at the top of solution. This shows that the lipids is present in the solution. Food(example : vegetable oil) with high lipid content have a higher layer than foods with less lipid contenT

4.What difficulties can you foresee in using this test with samples which contain both lipids and water?

When water react with vegetable oil(lipid), they will not mix. The oil always floats to the top because it is less dense than water. Oil and water don’t mix because water molecules are more attracted to each other than to oil molecules. So the mixture will form two layers so this might be acceptable evidence for the presence of lipid.

5.Water and alcohol mix in all proportions. What precautions must be taken in selecting the alcohol for use in this experiment and why is this precaution necessary?

The vegetable oil must be mixed with alcohol first. The alcohol needs to be free from water otherwise an emulsion will form on attempting the extraction.

6.How would you design an experiment to find out the sensitivity of this test for fats?

   A serial dilution, e.g. 1 cm³ oil dissolved in 100 cm³ alcohol, diluted with alcohol to 0.1%, .01 % etc. Equal volumes of the diluted extracts to be poured into equal volumes of water.

Experiment 2: Characteristics of lipid in food – visual observation

1. How can you tell that the dark wet spot on the paper towel is fat and not water?

-  Fat has waxy texture. After touching the paper towel, greasy texture can be felt.

2.Rank form most to least the percentage of lipid extracted from all three food. Look at the nutrition facts label on the packages of all three foods and rank them. Did your ranking agree with the ranking of the product labels?

- Sunflower seeds, potato chips, chocolate chips. According to Nutrition facts labels, 28 gram of sunflower seed contain 15 gram of fats, 28 gram of potato chips contains 10 gram fats and 28 gram chocolate chips contains 8 gram of fats. So the result that getting from the experiment are consistent.

3.Determine which lipids contained saturated and unsaturated fatty acids in this experiment, based on your descriptions of the fats in the petri dishes.

-  Lipid extracted from chocolate contain saturated fatty acids. While both lipid extracted from sunflower seeds and potato chips contains unsaturated fatty acids.

CONCLUSION

A layer of cloudy white suspension which is emulsion forms at the top of solution when oil is dissolved in water and alcohol. This shows the presence of lipid. A lot of grease spot found on the paper towel of chocolate chips followed by potato chips and lastly sunflower seeds. Sunflower seed has higher percentage of lipid extraction then followed by potato chips and lastly chocolate chips. Chocolate chips have waxy structure while potato chips and sunflower seeds have oily structure. The viscosity of chocolate chips is hard and dry while for the potato chips and sunflower seeds both are thick oil Lipid extracted from chocolate contained saturated fatty acids. While both lipid extracted from sunflower seeds and potato chips contains unsaturated fatty acids.