A PROJECT
WORK SUBMITTED TO THE DEPARTMENT OF FOOD SCIENCE AND TECHNOLOGY
FACULTY OF
AGRICULTURE AND NATURAL RESOURCES MANAGEMENT
IN THE
PARTIAL FULFILLMENT OF THE REQUIREMENT FOR THE AWARD OF THE DEGREE (B.Sc.) IN
FOOD SCIENCE AND TECHNOLOGY
ABSTRACT
Studies
were conducted to determine the effect of long storage time of palm kernel on
the physiochemical properties of palm kernel oil. In this work, palm kernels
stored at various length of time were used to produce palm kernel oil (p k o)
by solvent extraction using n-hexane as solvent. The physiochemical properties
of the oil determined includes: the specific gravity, the refractive index, the
freezing point, the acid value, iodine value, saponification value, the
moisture content and free fatty acid. The result obtained from the analysis
show that for storage time up to 22 months, the specific gravity of palm kernel
oil increased form 0.88 to 0.94, the freezing point increased from 17.3 to
22.330c, the refractive index did not noticeably changed with
storage time, the moisture content decreased from 5.5% to 2.04 and later
increased to 4.7%. On the chemical properties, the results obtained shows that
the iodine value increased from 5.094g/100g to 25.078.9/100g, the peroxide
value increased from 4.73 mEq/kg to 17.66 mEq/kg, the acid value increased form
49.38 mgKOH/g to 78.56 mgKOH/g, the saponification value increased from 185.14
mgKOH/g to 802.25 mgKOH/g while the free fatty acid increased from 24.83 to
39.40 mgKOH/g. however, the storage time of palm kernel heavily affected the
palm kernel oil characteristics. Generally, specific gravity, increased
slightly with storage time of the palm kernel the freezing point decreased with
storage time and later increased. The iodine value, peroxide value,
saponification value and Acid value/free fatty acid (FFA) increased with
storage time of palm kernel. The findings in this work, therefore recommends
that palm kernel oil (pko) should be produced from fresh palm kernel, but if
palm kernel oil was produced from stored palm kernel, the oil should be
refined.
CHAPTER THREE
MATERIALS AND METHODS
3.0 SOURCE OF SAMPLE
The sample (palm kernel) was obtained from palm fruits
gotten from palm trees in Enugu, Enugu state. The palm kernel was obtained from
the palm fruits after the production of palm oil from the fruits using the,
solven (by soaking) process. The palm kernel has been stored for one year and
seven months.
3.1 SAMPLE PREPARATION
200g of the sample (palm kernel) will be measured
using mettler balance model (P 1210), in the chemistry laboratory of food
science and technology of Ebonyi state university, Abakaliki, Ebonyi State. The
weighted sample will be crushed at Eke market Ezzangbo. The sample will be
reduced to smaller sizes to easy the oil extraction. After size reduction of
the sample, it will be soaked in 600m1 of n- Hexane in the food science and
technology chemistry laboratory for 24 hours.
3.2
FLOW PROCESS OF THE OIL
EXTRACTION
Raw material
Weigh
Crushing
Soaking (600ml
hexane)
Filtering - Palm
kernel cake (meal)
Oil in Hexane -
(Mixture)
Pour into Soxhlet
apparatus
Hexane - Heat at 700C
(using heating mantle)
Crude palm kernel
oil
Packaging
3.3
METHOD OF OIL EXTRACTION
Soxhlet method of oil extraction will be used to extract the oil. The oil extracted will be subjected to the following analysis:
Soxhlet method of oil extraction will be used to extract the oil. The oil extracted will be subjected to the following analysis:
1. Specific gravity/density;
2. Moisture content;
3. Acid / F.F.A;
4. Saponification value;
5. Peroxide value;
6. Iodine value;
7. Freezing point;
8. Refractive index;
9. Viscosity;
2. Moisture content;
3. Acid / F.F.A;
4. Saponification value;
5. Peroxide value;
6. Iodine value;
7. Freezing point;
8. Refractive index;
9. Viscosity;
3.3.1 SPECIFIC GRAVITY/DENSITY
The method described by G.I Onwuka (2005) will be used
for the determination of density. The pycometer bottle (5Oml) will be
washed with detergent, water and Detroleum ether, dry.and /
re weigh. After drying the bottle,it will be felled with Hgo & weigh, then day and fill it with the oil sample and weigh.
Calculation:
The density will be calculated as follows:
washed with detergent, water and Detroleum ether, dry.and /
re weigh. After drying the bottle,it will be felled with Hgo & weigh, then day and fill it with the oil sample and weigh.
Calculation:
The density will be calculated as follows:
Density = Weight of oil
Volume
Kirk (1965 developed a formular for calculating
density of fat using other fatty indices).
3.3.2 MOISTURE CONTENT
The moisture content of the oil will be determined
using the AOAC (1984) hot air oven method.
A petri-dish will be washed, dried, cooled and weighed
as w1.
5g of the sample (oil) will be weighed into the dried petri-dish as w2. The dish with the oil will be transferred into the electric oven and set at a temperature of 100°C-105°C and allow for one to two hours.
The dish and the oil will be transferred into dessicator to cool as w3 (w3 will be maintained at constant weight).
5g of the sample (oil) will be weighed into the dried petri-dish as w2. The dish with the oil will be transferred into the electric oven and set at a temperature of 100°C-105°C and allow for one to two hours.
The dish and the oil will be transferred into dessicator to cool as w3 (w3 will be maintained at constant weight).
% moisture = w2-w3 x 100
W2-w1 1
Where
w1 = weight of petri-dish,
w2 = weight of dish an4oil,
w3 = weight of petri-dish and dried oil.
w2 = weight of dish an4oil,
w3 = weight of petri-dish and dried oil.
3.3.3 ACID VALUE/FREE FATTY ACID (F.F.A)
G.I Onwuka’s procedure (2005) will be used to
determine the acid value:
25m1 (diethyl ether will be mixed with 25ml alcohol
and imi phenolphthalein solution (1%) and carefully neutralized with 0.lm NaOH.
Dissolve 1-lOg of the oil in the mixed neutral solvent and titrate with aqueous O.lm NaOH shaking constantly until a pink colour which persists for 15 second is obtained.
Dissolve 1-lOg of the oil in the mixed neutral solvent and titrate with aqueous O.lm NaOH shaking constantly until a pink colour which persists for 15 second is obtained.
Calculation:
Acid value = titre value (ml) x 5.61
Acid value = titre value (ml) x 5.61
Weight of
sample used
3.3.4 SAPONIFICATION VALUE
The G.I Onwuka procedure (2005) will be employ to
determine the saponification value. 2g of the oil will be weighed into a
conical flask and add exactly 25m1 of the alcoholic potassium hydroxide
solution. Attach a reflux condenser and heat the flask in boiling water for 1
hour, shaking frequently. Add 1ml of phenolphthalein (1%) solution and titrate
both the excess alkali with 0.5m hydrochloric acid (titration = aml).
Carry out a blank at the same time (titration = bml).
Calculation:
Saponification value = (b-a) x 28.05
Wt (g) of sample
3.3.5 PEROXID VALUE
The method of G.I Onwuka (2005) will be used.
ig of oil will be weighed into a clean dry boiling tube, while still liquid, ig of powdered potassium iodine and 2ml of solvent mixture (2 vol. flacial acetic acid + 1 vol chloroform will be added.
ig of oil will be weighed into a clean dry boiling tube, while still liquid, ig of powdered potassium iodine and 2ml of solvent mixture (2 vol. flacial acetic acid + 1 vol chloroform will be added.
The tube will be placed in boiling water so that the
liquid boils within 30secs. And allow to boil vigorously for not more that than
30 seconds. Pour the contents quickly into a flask containing 20m1 of potassium
iodine solution (5%), wash out the tube twice with 25m1 water and titrate with
0.002N sodium thiosuiphate solution using starch. Perform a blank at the same
time
3.36 IODINE
VALUE
G.I Onwuka (2005) will be used to determine the iodine
value.
The oil sample will be poured into a small beaker add a small rod and weigh out a suitable quantity of the sample by difference into a dry glass — stopped bottle of about 250m1 capacity. The approximate weigh in g of the oil to be taken can be calculated by diving 20 by the highest expected iodine value. lOmI of carbon tetrachloride will be added to the oil and dissolve.
The oil sample will be poured into a small beaker add a small rod and weigh out a suitable quantity of the sample by difference into a dry glass — stopped bottle of about 250m1 capacity. The approximate weigh in g of the oil to be taken can be calculated by diving 20 by the highest expected iodine value. lOmI of carbon tetrachloride will be added to the oil and dissolve.
Add 20m of Wiji’s solution, insert the stopper
(previously moistened with potassium iodine solution) and allow to stand in the
dark for 30 minutes.
15ml of potassium iodine solution (10%) and lOOmI
water, mix and titrate with O.lm thiosulphate solution using starch as
indicator just before the end-point (titration = aml).
Carry out a blank at the same time commencing with lOmI of carbon tetrachloride (titration = bml)
Iodine value = (b-a) x j.26g
Wt (g) of sample
3.3.7 FREEZING POINT
The oil will be poured into the bottle and placed in
the refrigerator and monitor closely from time to time. The temperature of the
oil will be noted immediately it start to freezing.
3.3.8 REFRACTIVE INDEX
The method of G.I Onwuka (2005) will be used to
determine the refractive index.
The refractometer will be rested with a light
compensator (water at
20°C). Smear the oil sample on the lower prism of the instrument and close. Light will be passed by means of the angled minor; the rejected light appears in a form of a dark background. Using the fine adjustment move the telescope tube until the black shadow appears central in the cross wire indicator read off the refractive index.
20°C). Smear the oil sample on the lower prism of the instrument and close. Light will be passed by means of the angled minor; the rejected light appears in a form of a dark background. Using the fine adjustment move the telescope tube until the black shadow appears central in the cross wire indicator read off the refractive index.
3.3.9 VISCOSITY
The oil will be poured into the l00 mI beaker. The
viscometer spindle speed will be set at 65r.p.m after 5 seconds the spindle
will be immersed in the oil at temperature of 25°C. The viscometer reading will
be recorded when it will be steady for 5 seconds.
3.3.10 STATISTICAL ANALYSIS
The data collected will be tested using product —
moment formula for the linear correlation coefficient from Schaum’s out lines
third edition (1998).
The data generated will be, analyzed using analysis of
variance (ANOVA) (Steel and Torrie, 1980).
REFERENCES
- Malaysain palm oil council
- Malaysain palm oil council
- Mayochilinc corn.
- USDA national nutrient database for standard
reference
- American palm oil council.
Sron, B. (2005) palm oil’s track record global oil and
fats 2: 24: 25
Tang, S.T and Teoh, P.K (1995). Palm kernel oil extraction.
Tang, S.T and Teoh, P.K (1995). Palm kernel oil extraction.
The Malaysian experience paper, presented to the world
conference on processing of palm, palm kernel and coconut oils, Kuala Lumpur,
Malaysia. Journal of the American oil chemist society 62 (2) 255.
Onwuka, G.I., (2005). Food analysis and
instrumentation theory
and practice Naphtli prints A division of HG support Nig. Ltd 6 Adeniyi Jones close Surulere, Lagos, Nigeria. 102-103.
and practice Naphtli prints A division of HG support Nig. Ltd 6 Adeniyi Jones close Surulere, Lagos, Nigeria. 102-103.
Leong W.L (1992). The refining and fractionation of
palm oil.
Palm oil mill Engineers- Executives training course 14th semester 1. PORIM.
Palm oil mill Engineers- Executives training course 14th semester 1. PORIM.