Lab Report Experiment Determination of crude fiber PDF

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FST556 EXPERIMENT 5 DETERMINATION OF CRUDE FIBRE

NAME: STUDENT ID: GROUP: DATE OF EXPERIMENT IS DONE: 24th NOVEMBER 2020 DATE OF LAB REPORT IS SUBMITTED: 01th DECEMBER 2020 LECTURER’S NAME:

INTRODUCTION As a class of compounds, dietary fibre includes a mixture of polymers from plant carbohydrates. Both oligosaccharides and polysaccharides may be associated with lignin and other non-carbohydrate components, such as cellulose, hemicellulose, pectic substances, gums, resistant starch, inulin. For example, polyphenols, waxes, saponins, cutin, phytates, and resistant protein. Non-digestible carbohydrates, lignin and other related substances of plant origin, animal fibers and modified or synthetic non-digestible carbohydrate polymers are composed of dietary fibres. Cereals are the main source of cellulose, lignin and hemicellulose, while pectin, gums and mucilage are the primary sources of fruits and vegetables (Yangilar, 2013). Crude fiber is known as a part of carbohydrate in food called insoluble carbohydrates, which is not digested by digestive juices and does not degrade at treatment by diluted (acids and bases) and is limited in specific concentrations over a period of time. Treatment of certain foods, including legumes, grains and seeds soluble is soluble in weak acid and weak base results, for instance, sugars and protein that leave the composition behind the non-dissolved part such as cellulose and hemicellulose and lignin, name this crude fiber. The determination of the crude fibre is misleading, since the fraction obtained does not have any definite relation to the material's structural components. Cellulose is partly attacked, with substantial removal of lignin. In the lignin content of crude-fibre fractions, significant variation is found. A crude fibre rich in lignin does not generally yield extremely lignified materials (Norman, 1935). Thus, the aim of this experiment is to determine the crude fibre content of popcorn kernel and chickpeas using acid and alkali digestion method.

OBJECTIVE The objective of this experiment is to determine the crude fibre content of popcorn kernel and chickpeas using acid and alkali digestion method.

MATERIALS The materials used in this experiment are 0.255 N sulphuric acid, 0.313 N sodium hydroxide, 1% hydrochloric acid beaker, crude fibre apparatus, analytical balance, oven, muffle furnace, desiccator and measuring cylinder.

PROCEDURES First, 2 g

±

0.0001 (W1) of dried ground sample was weighed into a 600 ml beaker

fitted with a reflux condenser. 200 ml warm 0.255 N H 2SO4 was added and boiled for 30 minutes exactly from the onset of boiling heated using hotplate where watch glass used to prevent loss of solvent during digestion. The weight of filter paper used throughout the experiment was recorded. After that, the contents were filtered while hot through with ashless filter paper Whatman No 541 or equivalent and the residue was washed with hot water until free from acid that checked with litmus paper. The insoluble material was transferred quantitatively into original beaker and 200 ml warm 0.313 N NaOH was added and boiled for exactly 30 minutes. Three until five drops of n-octanol was added as antifoam agent. Next, the contents were filtered and the residue was washed with hot water, then with 15 ml of 1% hydrochloric acid twice. It is been washed again using hot water until neutral or free from acid and the insoluble material transferred into a weighed crucible and dried in oven at 105 oC overnight to a constant weight. The weight of residue and crucible (W2) was recorded and the dried sample was burned gently over a Bunsen burner until smoke is no longer evolved when heated strongly. The residue was ignited in a muffle furnace at 550oC for 3 hours. Lastly, the crucible was cooled in dessicator and weighed. The weight of ash and crucible (W3) was recorded and the loss in weight on ignition represents the weight of crude fibre.

RESULTS Table 1.1: Data for crude fibre analysis using acid-alkali digestion method.

Sample: Popcorn kernel Replicate

1 2 3

Weight of

Weight of

Weight of

Weight of

Weight of

% crude fibre

sample (g)

filter paper

empty

crucible +

crucible +

content

(g)

crucible (g)

dried

ash (g)

2.2493 2.3073 2.3311

62.4706 72.1662 65.8866

Weight of

Weight of

Weight of

Weight of

Weight of

% crude fibre

sample (g)

filter paper

empty

crucible +

crucible +

content

(g)

crucible (g)

dried

ash (g)

2.0036 2.0022 2.0028

residue (g) 63.2611 63.2033 72.9802 72.9206 66.6915 66.6323 Average ± SD

2.88 2.98 2.96 2.94 ± 0.05

Sample: Chickpeas Replicate

1 2 3

2.0012 2.0016 2.0007

CALCULATION

2.1935 2.2985 2.3018

72.0087 65.9743 71.9874

residue (g) 72.4093 72.3833 66.3537 66.3268 72.4102 72.3827 Average ± SD

1.30 1.34 1.37 1.34 ± 0.04

g crude fibre per 100 g sample =

W 2−W 3 W1

X 100

where, W1 = weigh in gram of sample taken W2 = weigh in gram of weigh of crucible + dried residue W3 = weigh in gram of weigh of crucible + ash

POPCORN KERNEL Replicate 1 g crude fibre per 100 g sample = =

W 2−W 3 W1

X 100

63.2611 −63.2033 2.0036

X 100

= 2.88 % Replicate 2 g crude fibre per 100 g sample = =

W 2−W 3 W1

X 100

72.9802 −72.9206 2.0022

X 100

= 2.98 % Replicate 3 g crude fibre per 100 g sample = =

W 2−W 3 W1

X 100

66.6915 −66.6323 2.0028

= 2.96 % Mean 2.88 + 2.98 + 2.96 3

= 2.94

Standard deviation SD =

√

( 2.88 −2.94 ) 2+( 2.98− 2.94 ) 2+( 2.96− 2.94 ) 2 2

= 0.05

X 100

CHICKPEAS Replicate 1 g crude fibre per 100 g sample = =

W 2−W 3 W1

X 100

72.4093 −72.3833 2.0012

X 100

= 1.30 % Replicate 2 g crude fibre per 100 g sample = =

W 2−W 3 W1

X 100

66.3537 −66.3268 2.0016

X 100

= 1.34 % Replicate 3 g crude fibre per 100 g sample = =

W 2−W 3 W1

X 100

72.4102 −72.3827 2.0007

= 1.37 % Mean 1.30 +1.34 + 1.37 3

= 1.34

Standard deviation SD =

√

( 1.30 −1.34 ) 2+( 1.34 −1.34 ) 2+( 1.37−1.34 ) 2 2

= 0.04

X 100

DISCUSSION In this experiment popcorn kernel and chickpeas was used as a food sample. As shown in Table 1.1, the percent of crude fibre content for popcorn kernel are 2.88% for replicate 1, 2.98% for replicate 2 and 2.96% for replicate 3. The average of popcorn kernel crude fibre content is 2.94 ± 0.05 . On the other hand, the percent of crude fibre content for chickpeas are 1.30% for replicate 1, 1.34% for replicate 2 and 1.37% for replicate 3. The average of chickpeas crude fibre content is

1.34 ± 0.04 . Thus, it shows that the crude fibre content is high in popcorn kernel

compared to chickpeas. In order to divide carbohydrates into digestible and indigestible fractions, this method was used. The energy content of the feed is low when the crude fibre content is high, because crude fiber is considered indigestible. Sample digested by H2SO4 to hydrolyze CHO and protein and NaOH will saponify fatty acid. Insoluble residue was collected by filtration then dried and weighed. Ashing conducted, cooled and weighed to correct mineral contamination. Crude fibre determined consist mainly of cellulose and lignin while pectin and hemicellulose are solubilized which cannot be detected. As the sample is subjected to acid and alkali digestion, the collected residue includes the sample's ash (mineral matter) and the resistant carbohydrate fraction. The organic matter is oxidized when the residue is ignited, leaving the inorganic residue or ash. Therefore, the difference in residue weight before and after ashing gives the crude fiber weight (Yangilar, 2013).

QUESTIONS 1. Differentiate between crude fibre and dietary fibre. Dietary fiber is the part of plant-based food that mostly passes through digestive system without breaking down or being digested meanwhile crude fiber refers to one type of dietary fiber, the type that remains as residue after food receives a standardized laboratory treatment with dilute acid and alkali.

2. What are the factors that greatly affect the accuracy of crude fibre analysis? Foods with a significant amount of resistant starch and lignin will have a high fiber content, thus overestimating the fiber content. Fiber-measured resistant starch. If sugar is

not extracted prior to fiber analysis from sugar-rich foods, the fiber content will be overestimated. The incorporation of proteolytic enzymes into the protein digestion processes of both AOAC and Englyst-Cummings allows some fiber to be solubilized, which transfers some of the insoluble fiber fraction to the soluble fiber fraction.

CONCLUSION The experiment was achieved because able to determine the crude fibre content of popcorn kernel and chickpeas using acid and alkali digestion method. The crude fiber content for popcorn kernel is

2.94 ± 0.05 and 1.34 ± 0.04

for chickpeas.

REFERENCES Norman, A. G. (1935). The composition of crude fibre. The Journal of Agricultural Science, 25(4), 529-540. Retrieved from https://www.cambridge.org/core/journals/journal-ofagricultural-science/article/composition-of-crudefibre/D06E5F0CF97A607CC68B8A3B3178B78B Yangilar, F. (2013). The application of dietary fibre in food industry: structural features, effects on health and definition, obtaining and analysis of dietary fibre: a review. Journal of Food and Nutrition Research, 1(3), 13-23. Retrieved from http://article.foodnutritionresearch.com/pdf/JFNR-1-3-1.pdf...