Bioscience Methods 2017, Vol.8, No.2, 18-30
20
give 23 v/v concentration while equal volume of
Vernonia amygdalina
and
Ocimum
gratissimum
extract mixed
together was diluted to give 45.5 v/v concentration. 8 grams of salt was added to
Vernonia amygdalina
extract, 6
gms of salt to
Ocimum gratissimum
extract and eight gms of salt into mixture of
Vernonia amygdalina
and
Ocimum
gratissimum
extract for brining. A five man taste panelists was used to determine the acceptable level of
extract and salt concentration.
1.4 Preparation of fish snack
The fish samples were washed in jet of tap water to remove dirt and thereafter, allowed to drain. The fish were
scaled, gutted and washed clean again after gutting to prevent contamination of the muscle. Thereafter, they were
filleted, and the weight of the fillets taken. The fillets were cut into smaller pieces (2.5 cm x 6 cm), and the pieces
were staked on sterilized palm frond sticks. Staked fillets pieces were weighed and soaked in brine and mixture of
plant extracts and brine for two minutes, the brined/ brine plus extracts stakes were hung to drain excess solution
after which oil and spice was applied. Smouldering fire from wood and charcoal combustion was used to cook dry
the snacks.
1.5 Keeping quality assessment
The snacks were packaged in three different sterilized packaging materials (Polythene bag, Aluminum Foil and
Brown Paper). Snacks were kept under ambient condition after packaging to determine the shelf life and
appropriate packaging material for a period of ten (10) days based on the shelf life of some commercial snacks
such as sausage roll e.g.
Gala, Beefy
etc. Each of the packaged snacks was wrapped with brown paper and the
untreated sample was kept in a brown paper without either of the other packaging material. A representative
sample of the snack was checked/ examined daily for microbial or sensory loss during the period of storage.
1.6 pH determination
One gram of each sample was ground and poured into 9 mls of distilled water. The mixture was homogenized by
gently shaking the container of mixture (sample and distilled water). SURGIFIELD
®
hand held pH meter (Model;
SM-602A) was dipped into the mixture for 3 minutes and the pH value determined in triplicate.
1.7 Microbial analysis
1.7.1 Sterilization of materials
The test tube bottles, conical flasks and all glassware used for this work were thoroughly washed with household
detergent, rinsed with clean water, air dried and sterilized in the hot air oven at 170°C for 2hours.
1.7.2 Media preparation
Nutrient Agar and Potato Dextrose Agar were prepared according to the manufacturer`s (Oxoid
®
) specification by
weighing (2.8 gms of Nutrient Agar and 3.9 gms of Potato Dextrose Agar into 100 mls of water). 8.4 gms of
Nutrient Agar and 11.7 gms of Potato Dextrose Agar were weighed and poured into two conical flasks, 300 mls of
distilled water was poured into each of the flasks and mixed by shaking the flasks with the opening corked with
cotton wool and sealed with foil paper, after shaking the flasks, the flask containing the mixture were autoclaved
at 121°C for 15 mins after which the autoclave was allowed to cool down, the flasks containing the media
mixtures were then removed and allowed to cool to about 45°C before pouring into plate.
1.7.3 Innoculation of samples
One gram each of the snack sample in powdered form was serially diluted in three test tubes containing 9 mls of
sterile distilled water to give dilution 10
-2
and 10
-3
respectively. Hands and work table were sterilized with ethanol;
0.5 mls of the 10
-2
dilution sample was poured into the petridishes in triplicate and labeled accordingly. After
pouring, the petridishes were manually rocked gently both clockwise and anti-clockwise for the media to form a
uniform layer. The petridishes were allowed to cool for one hour for the media to solidify, taped and kept in the
incubator at a temperature of 37°C and observed after 24 hours.
