Sources of raw material
Live matured healthy chickens for this study was procured from Orie Ugba market in Umuahia North Local Government area, Abia state. All the analyses was carried out at National Root Crop Research Laboratory.
3.2. Raw material preparation
The live matured chicken was slaughtered in a cleaned environment with a clean stainless knife, and a preheated water was used to defeather the chicken. The chicken meat was eviscerated to remove the unwanted parts after which it was washed thoroughly with a clean tap water to remove sands and other foreign materials. It was then be cut into small sizes and divided into three different portions before subjecting it to three different processing methods.
3.3. Proximate analysis
The proximate properties that was determined include moisture content, crude fibre content, ash content, crude protein, fat and carbohydrates content and it was carried out using the method described by Onwuka (2018).
3.3.1 Moisture content determination
Moisture content was determined according to the method of Onwuka, (2018). Porcelain dishes was cleaned and dried in the oven at 100˚C for 1 hour to achieve a constant weight. Thereafter, they were cooled in a desiccator and then weighed (W1). Two grams of sample was placed in each dish (W2) and dried in oven at 100˚C until constant weight was achieved. The dishes together with the samples was cooled in a desiccator and weighed (W3).
% moisture = weight loss x 100
Weight of sample
That is,
% moisture content = (W2-W3) (g) x 100
(W2-W1)1
Where:
W1 = weight of dish
W2 = weight of dish + sample before drying
W3 = weight of dish + sample after drying
3.3.2 Determination of crude fibre
Crude fiber was determined using the method described by Onwuka, (2018). About 2 g of each sample was defatted The resulting solution was filtered through linen on a fluted funnel. And then washed with boiling water at 100oC, 3 times. The residue was then transferred to a beaker and boiled at 100oC for 30 minutes with 200 mL of a solution containing 1.25 g of carbonate free NaOH per 100 mL. And then dried at 120oC for 1 hour in an electric oven and weighed. It was also incinerated at 500oC in a muffle furnace, cooled at 27oC in a desiccator and weighed. The loss in weight after incineration multiplied by 100 is the percentage of crude fibre.
% Crude Fibre = W2 – W3 X 100
W1
Where;
W2 = weight of crucible + sample after washing, boiling and drying
W3 = weight of crucible + residue
W1 = weight of sample
3.3.3 Determination of crude protein
The micro Kjeldahl method as described by Onwuka (2018) was used to determine crude protein. Ten grams of copper sulphate and sodium sulphate (catalyst) in the ratio 5:1, respectively and 25 mL concentrated sulphuric acid was also added to the digestion flask. The flask was placed into the digestion block in the fume cupboard and heated until frothing ceases giving clear and light blue green coloration. The mixture was then allowed to cool and diluted with distilled water until it reaches 250 mL of volumetric flask. Distillation apparatus was connected, and 10 mL of the mixture was poured into the receiver of the distillation apparatus, also 10 mL of 40% sodium hydroxide was added. The released ammonia by boric acid was treated with 0.02 molar of hydrochloric acid until the green color changes to purple.
Nitrogen (%) = (Titre – Blank) × 14.008 × Normality × 100
Weight of sample
% Crude protein = % Nitrogen X 6.25
3.3.4 Determination of fat
The Soxhlet extraction method described by Onwuka (2018) was used in determining the fat content of the samples. It was carried out (boiling point 40-60oC). The thimble was plugged with cotton wool. At completion of extraction which lasted for 8 hours, the solvent was removed by evaporation on a water bath and the remaining part in the flask was dried at 800C for 30 minutes in the air oven to dry the fat and then cooled to room temperature in a desiccator. The flask was reweighed and percentage fat was calculated as:
% Fat = weight loss × 100
weight of sample
3.3.5 Determination of ash content
Ash content was determined using the method of Onwuka (2018). About 2 g of sample was weighed into a crucible, and then the sample was incinerated in a muffle and was weighed to obtain ash content.
Ash (%) =
3.3.6 Carbohydrate determination
Carbohydrate content was determined by difference.
Carbohydrate = 100 – (%M + % P+ %F + % A + %Cf)
Where:
M = % moisture
P = % protein
F = % fat
A = % ash
Cf = % crude fibre
3.4. analysis of heavy metals
The presence of the heavy metals was determined using the method described by Nagwa (2015). The standard solutions were analyzed for Arsenic, lead, mercury and chromium by Atomic Absorption Spectrophotometer (Sens AA; GBC scientific EQUIPMENT Spectrophotometer) at the pre-adjusted conditions specific to each heavy metal.
The calculation of residual levels (μg/g wet weight) using the following equation:
Element, (ppm, mg/kg) = R × D/W
Where:
R= Reading of element concentration, ppm from the digital scale of AAS.
D= Dilution of the prepared sample.
W= Weight of the sample.
3.5. Microbial load determination
The total viable count, total fungi count, total coliform count and total salmonella count will be determine by the method described by Ezeama (2007). Exactly 5 grams of each sample dissolved in 45 ml of distilled water. Therefore 1 ml of the sample suspension diluted using a six fold serial dilution inoculating them on a nutrient agar, MacConkey agar and potato dextrose Agar respectively. The dilution used is 106. The organisms inoculated on nutrient agar were incubated for 24 h at 37. The plates were observed for growth after the incubation period and were purified and the microbial load counted and calculated. The purified cultures were then transferred onto MacConkey agar (a selective media) and incubated for 24h at 37. The samples were equally plated on potato dextrose agar (PDA) for isolation of fungi. Thereafter the organisms (bacteria) were characterized biochemically. The fungi isolates were characterized with the microscope and with reference to mycological manuals
Calculation: Microbial loads = x dilution
3.6. Sensory evaluation
The method described by Iwe (2014) was used to ascertain the appearance, taste, aroma, texture, and general acceptability of the chicken meat samples using 9-point hedonic scale. Twenty five (25) semi-trained panelist was randomly selected from the College of Applied Food Science and Tourism, of Michael Okpara University of Agriculture, Umudike. The samples were presented to the semi-trained panellist in a white clean flat plate with three random digit codes. Water was provided to the semi-trained panellist to rinse their mouth after each tasting to prevent masking of successive tasting.
3.7. statistical analysis and EXPERIMENTAL design
Data obtained from the proximate, heavy metals, microbial loads, dietary and sensory analyses was subjected to one-way analysis of variance (ANOVA) using the SPSS software version 21.0 of a completely randomized design (CRD) while the Duncan multiple range test was used to separate the means at 95% confidence level.