Apparatus: Soxhlet apparatus and accessories, oven, desiccator and analytical
balance.
Determination : 1gm of each dried sample was weighed into fat free extraction thimble
and pug lightly with cotton wool. The thimble was placed in the extractor and
fitted up with reflux condenser and a 250ml soxhlet flask which has been
previously dried in the oven, cooled in the desiccators and weighed. The
soxhlet flask is the filled to 3/4 of its volume with
petroleum ether (b.pt 400- 600), and the soxhlet flask.
Extractor plus condenser set was placed on the heater. The heater was put on
for six hours with constant running water from the tap for condensation of
ether vapor. The set was constantly watched for ether leaks and the heat source
was adjusted appropriately for the ether to boil gently. The ether was left to
siphon over several times say over at least 10 – 12 times until it is short
siphoning. It is after this is noticed that any ether content of the extractor
was carefully drained on a clock glass on the bench top. The extractor, flask
and condenser were replaced and the distillation continues until the flask is
practically dry. The flask which now contains the fat or oil was detached, it’s
exterior cleaned and dried to a constant weight in the oven. The initial weight
of dry soxhlet flask is W0 and the final weight of oven dried flask
+ oil is W1, percentage
fat/oil is obtained by the formula:
W1 – W0 X 100
Wt. of sample 1
Taken
ECONOMIC ANALYSIS
DRY MATTER AND MOISTURE DETERMINATION (AOAC OFFICIAL METHOD 967.08)
Apparatus: Oven, crucibles, desiccator and balance.
Reagents: Silical gel, grease.
Determination: 2g of the sample was weighed into a previously weighed crucible. The
crucible plus the sample taken was then transferred into the oven set at 1000c
to dry to a constant weight for 24 hours overnight. At the end of the 24 hours,
the crucible plus sample was removed from the oven and transferred to
desiccator, cooled for ten minutes and weighed.
If the weight of empty crucible is W0
Weight of crucible plus
sample is W1
Weight of crucible plus
oven-dried sample W3
(% DM) % Dry Matter = W3 – W0 X 100
W1
---- W0 1
% Moisture = W1 --- W3 X
100
W1
--- W0 1
0r % Moisture = 100 -- % DM.
DETERMINATION OF ASH (AOAC OFFICIAL METHOD 942.05)
Apparatus: Porcelain crucibles, a Desiccator, Analytical Balances
and a Furnace.
Determination: 2.0gm of the sample was weighed into a porcelain
crucible. This was transferred into the muffle furnace set at 5500C and
left for 4 hours. About this time it had turned to white ash. The crucible and
its content were cooled to about 1000C in air, then room temperature
in a desiccator and weighed. This was done in duplicate. The percentage ash was
calculated from the formula below :
Ash
content = Wt. of ash x
100
Original Wt. of sample 1
FIBER DETERMINATION (AOAC 958.06)
Apparatus : Heating mantle, crucible, furnace, sieve cloth, fiber
flask, funnel, analytical weighing balance, a desiccator.
Reagents : 0.255N H2SO4, 0.313N NaOH and
Acetone.
Determination :2.gm of the sample was accurately transferred into the fiber flask
and 100ml of 0.255N H2SO4 added. The mixture was heated
under reflux for 1 hour with the heating mantle. The hot mixture was filtered
through a fiber sieve cloth. The filtrate obtained was thrown off and the
residue was returned to the fiber flask to which 100ml of (0.313N NaOH) was
added and heated under reflux for
another 1 hour. The mixture was filtered through a fiber sieve cloth and 10ml
of acetone added to dissolve any organic constituent. The residue was washed
with about 50ml hot water on the sieve cloth before it was finally transferred
into the crucible. The crucible and the residue were oven –dried at 1050C
overnight to drive off moisture. The oven-dried crucible containing the residue
was cooled in a desiccator and later weighed to obtain the weight W1.
The crucible with weight W1 was transferred to the muffle furnace
for Ashing at 5500C for 4 hours.
The crucible containing white or grey ash (free
of carbonaceous material) was cooled in the desiccator and weight to obtain W2.
The difference W1 ----- W2 gives the weight of fiber. The
percentage fiber was obtained by the formula:
% Fiber = W1 ---- W2 X 100
Wt. Of sample
NITROGEN –FREE EXTRACT (NFE)
DETERMINATION
The NFE was determined by difference.
This was done by subtracting SUM of (Moisture % + % Crude Protein + % Ether
Extract + % Crude Fiber + % Ash ) from 100 i.e. (100 – ( % M + % CP + % EE + CF
+ Ash ).
GROSS ENERGY DETERMINATION
Gross energy was calculated using the
following factors: Crude Protein = 23.9kj/g, Crude Lipids = 39.8kj/g and NFE =
17.6kj/g, (Schulz et al.,2008).
Economic analysis was carried out to determine
the cost implication and benefit of maggot production .Thus the cost of
producing per kg of maggot was estimated. Gross margin model according to Ezike
et al., (2009),
was used to estimate cost of maggot production.
Gross-Margin
= Gross output – total variable cost
Gross
output = Total product multiplied by the unit price of the product
Cost
per unit= Total variable cost / total output