Genomics and Applied Biology, 2017, Vol.8, No.3, 17-25
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The decrease in the pH values of all the treatments was an indication that more acid was released or produced in
the process of fermentation. This can be traced to the nature of the isolates used for the fermentation. Several
researchers have been reported that these microbial isolates can thrive well in acidic media, especially when pH is
not less than 4 (Abba-kareem and Okagbue, 1999; Oboh, 2005). The rapid degradation of the linamarin may also
be facilitated by the indigenous enzymes; linamarase which has been reported to be concentrated at the peels of
the cassava tuber (Kojima et al., 1983). More so, the pH range recorded during the experiment might have added
the optimum activity of the enzymes. Owuamanam et al. (2010) and Yeoh (1989) have earlier reported a
maximum activity of 85% for linamarase at pH between 8 and 5.
The study has shown that cassava peels (waste) is rich in protein, this may be linked to the fact that linamarase is
protein in nature and it is more at the peels than the pulp of the cassava tuber (Kojima et al., 1983). Fermenting
cassava peels increased the crude protein present in the cassava peels. The high protein content of the control after
the period of fermentation is an indication that activity of the cassava peels’ enzymes. Although, the ability of the
organisms to convert carbohydrate to protein during fermentation process may also contribute to the increase in
the protein content as reported earlier (Gregory et al
.
, 1976). The high protein values in the samples fermented by
the isolates could also be as a result of the growth and multiplication of the microorganisms. Hence, the high
amount of protein obtained from the proximate analysis of the cassava peels may be justified.
However, the
carbohydrate content of the raw cassava peels before fermentation was higher than the values obtained from the
treatments, which validates the carbohydrate utilization of the fermenting microbes. The oil content of all the
treatments were more than the initial oil content as it were in the case of crude protein, this may be due to the
abundant availability of carbohydrate for energy production and the need for sourcing energy in other food
material like oil may be useless. The high fibre content of the control experiment after fermentation may be due to
the absence of fermenting organisms. This concurs with the findings of Srinorakutara et al
.
(2006) which revealed
that soluble fibre is utilized by the organisms during fermentation.
Finally, since the crude protein and lipid content of the cassava peels after fermentation increased considerably,
and cyanide content reduced significantly, hence, fermented cassava peels can be used as alternative source of
protein for animals instead of discarding it as waste in cassava processing industries as it is done in Nigeria. More
so, fermentation can be an essential way of improving the nutritional value of the peels.
3 Materials and Methodology
The cassava peels used for the study were obtained from Igbatoro cassava processing industry while the cassava
was obtained from Agricultural Development Programme Farm, Akure, Ondo state Nigeria. The cassava peels
were washed, drained and dipped in 70% ethanol for 5min. for surface sterilization. Working in a sterile top the
peels were rapidly milled into a sterile container with a sterile Muchang grinder model No. 9FZ-300. The milled
peels were then stored in a refrigerator at 4°C.
3.1 Microbial isolates
Microorganisms used for fermentation were isolated from liquid extract obtained from fermented cassava pulp in
press at Igbatoro garri processing factory. One milliliter each of the extract was cultured separately on Potato
Dextrose Agar (PDA) and Nutrient Agar (NA) prepared according to manufactural description. Pure cultures were
obtained through sub culturing. The pure cultures were then identified and preserved in agar slant pending when
they were needed.
3.2 Extraction of linamarase
Two hundred grams (200 g) of fresh cassava peels were homogenized in 1600 ml of 0.1 M acetate in a blender for
3 min. The homogenate was centrifuged at 10000 xg for 30 min. The supernatant liquid was brought to 60%
saturation of (NH
4
)
2
SO
4
by adding 724 g of (NH
4
)
2
SO
4
in 1600 ml supernatant. The salt was added slowly with
continuous gentle agitation. The precipitate was collected by centrifugation at 10000 rpm for 1h. The supernatant
was discarded. The precipitate was dissolved in 150 ml of phosphate buffer (pH 6.0) and stored frozen.
