| dc.description.abstract | Attempts have been made to modify textural characteristics of sweetpotato by chemical and
physical treatments but no studies on the effect of lactic fermentation on its properties have
been carried out. Lactic fermentation has been reported to change textural properties of several
starchy substrates, including cassava. The sausages commonly available in the local market are
deficient in sensory properties especially texture. This study was carried out with the aim of
investigating a) the effect of lactic fermentation on the rheological characteristics of
sweetpotato flour and b) the suitability of fermented sweetpotato flour as sausage filler,
especially in improving sensory quality of sausages.
Nonfermented sweetpotato flour (NSPF) and naturally fermented sweetpotato flour (FSPF)
were prepared by drying a fresh sweetpotato roots' pulp before fermentation and after natural
fermentation, respectively, followed by comminution in a disc mill. The fermentation process
was characterized by taking lactic acid bacteria count, viable count, pH and titratable acidity
measurements after every 12 h. Brabender amylograph pasting properties of 7% fermented
sweetpotato flour (FSPF) were investigated with non-fermented swcctpotatc flour (NSPf) as
acid, citric acid, orthophosphoric acid and Hel were investigated. The effects of inhibition of
of 7%FSPF slurry to 6 using NaOH on the Brabender p~::;tinbproperties. Also, 30% FSpr and
a boiling water bath for 30 min. Evaluation of the performance of FSPF as sausage filler was
an experiment with NSPF and sausage rusks as controls. The lean beef solids of a typical fresh
beef sausage formulation were substituted with a) FSPF, b) NSPF and c) rusks solids at the
rates of 20, 30, 40 and 50%. The sausage batters were evaluated for pH, water holding
capacity, emulsion stability and cooking loss. Penetrometer firmness and sensory attributes of
the sausages after deep-flying were also determined.
The results indicated that natural fermentation of sweetpotato pulp is typical of that of other
starchy substrates with a marked increase in LAB count and acidity. FSPF exhibited higher
viscosity than NSPF and had a peak while the latter did not show any thermopasting behaviour.
Direct acidulation and inhibition of inherent amylase system of NSPF yielded typical
thermopasting curves but with peak viscosities and viscosity at 86°C lower than that of FSPF.
Generally, FSPF gave better results than NSPF for emulsion stability and cooking loss. The
water holding capacity of FSPF batters was comparable to that of both controls. Sensory
analysis indicated that 30%FSPF gave sausages that were superior to all the controls. There
was a strong correlation (r = -0.99) between penetrometer firmness and filler level and between
penetrometer firmness and sensory texture (r = 0.933) of cooked sausages.
This study concluded that fermentation affects viscopasting properties of sweetpotato flour and
that FSPF can be used to effectively substitute sausage rusks as sausage filler. | en |
