Michelle Rose Ann Braceros
Date submitted: January 26,2011 Date performed: January 11-19, 2011
Exercise 1.1.4 Determination of Crude fiber of Swift Corned Beef (175g)
Using AOAC Official Official Method 984.04
I.
Introduction
Crude fiber is a measure if the quantity of indigestible cellulose, pentosans, lignin, and other components of this type in present foods. These components have little food value but provide the bulk necessary for proper peristaltic action in the intestinal tract[1]. Crude Fiber is the loss on ignition of the the oven dried residue remaining remaining after sequential digestion of a sample with H2SO4 and NaOH solutions under specific conditions. This method is applicable to all dry samples; such as grains, meals, flours, pet foods, forages, oilseeds, meat products and fibrous materials; provided samples are fat extracted and a workable residue is left to be analyzed. The range of analysis is 0.2 to 70% fibre[2]. This exercise aims to determine the crude fiber of corned beef and to compare it with the theoretica theoreticall value. It also aims to know the principles of crude fiber determination and the significance of fiber in the human diet.
II.
Procedure
1. Hydrolysi Hydrolysiss of carbohydrate carbohydrates, s, protein proteinss and minerals minerals
2. Digestion (minerals) and saponification (lipids)
3. Drying
4. Ashing
III.
Discussion
The term fiber refers to carbohydrates that cannot be digested. Fiber is present in all plants that are eaten for food, including fruits, vegetables, grains, and legumes. However, not all fiber is the same, and there are a number of ways to categorize it[3]. In this exercise, the food sample that was analyzed for fiber content was corned beef. Theoretically, corned beef does not
contain fiber since it is made form 100% pure beef. The purpose of this exercise is to validate that corned beef has 0 % fiber. The official method of AOAC in determining the crude fiber of a food sample is called Wendee method. Its first step is boiling of carbohydrates, proteins and minerals in concentrated sulfuric acid. This is necessary in order to hydrolyze the components mentioned above. Next is the digestion of remaining minerals and saponification of lipids which is then followed by filtering, drying and weighing. The residue after weighing is the crude fiber of the sample. The percent crude fiber of the food sample was calculated using the following formula: %crude fiber =
x 100
In this exercise, the calculate fiber content was 7.97% but ideally there must be no fiber in the corned beef sample since it does not contain any plant ingredient. The possible sources of this error are the weighing of sample and the digestion and hydrolysis which cause some sample to stick along the sides of the beaker thus, making the analysis erroneous. The current trend in foods nowadays is health awareness. People are now interested in dietary fiber content of food products. Consistent intake of fiber through foods like whole grains, berries and other fresh fruit, vegetables, seeds and nuts is now associated with reduced risk of some of the world's most prevalent diseases including several types of cancer, obesity and high blood cholesterol. It also improves absorption of calcium, magnesium, and iron, reduction of blood cholesterol and triglyceride levels and stabilization of blood glucose levels after a meal[4]. It is indeed necessary to eat foods that are rich in fiber in order to have a healthy body. Unfortunately, the corned beef sample that was analyzed in this experiment does not contain fiber. IV.
Conclusion
In this experiment, the calculated value of crude fiber which is 7.97% is far from the theoretical value which is 0% fiber. It was therefore concluded that the conducted analysis was erroneous. However, it was found out that the fiber content of foods is good for the body and it reduces the risk of having diseases. This experiment would have been successful if the weighing process was done accurately and 100% of the sample was recovered from the digestion and hydrolysis process.
V. References
1. Crude fiber. Food Science Avenue. Retrieved January 21, 2011 from http://www.foodscienceavenue.com/2008/04/crude-fiber.html 2. Crude fiber. Retrieved january 21, 2011 from http://www.exova.ca/index.php? option=com_content&view=article&id=1477&Itemid=&lang=en 3. The Nutrition Source: Fiber. Harvard School of Public Health. Retrieved January 24,2011 from http://www.hsph.harvard.edu/nutritionsource/what-should-you-eat/fiber-fullstory/index.html 4. Fantastic Fibers: The Health Benefits of Fiber in the Diet A 2 Z of Health Beauty and Fitness. Retrieved January 24,2011 from http://health.learninginfo.org/fiber.htm
VI. Appendix
Calculations Loss in weight after ashing = crucible and cover – (weight of residue + crucible) – filter paper Loss in weight after ashing = 41.3164 -39.0312 – 1.7207 = 0.5645
% Crude fiber =
% Crude fiber =
x 100
x 100 = 7.97%
Raw Data Weight of watch glass Weight of sample Weight of filter paper Weight of crucible and cover Weight if filter paper with sample Crucible and sample After ashing ( dry weight) Weight of residue + crucible
44.4086 0.4478 1.7207 41.3164 1.7795 43.0945 41.9166 39.0312
