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Effect of
stabilizers on the physico-chemical and sensory attributes
of thermized yoghurt
Alakali, J. S.1*,
Okonkwo, T. M.2 and Iordye, E. M.1
1Department
of Food Science and Technology, University of Agriculture,
Makurdi, Nigeria.
2Department
of Food Science and Technology, University of Nigeria,
Nsukka, Nigeria.
*Corresponding author. E-mail:
josephalakali@yahoo.co.uk.
Accepted 27 September, 2007 |
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Stabilized thermized yoghurt was produced by the
addition of gelatin, carboxyl methyl cellulose (CMC) and
corn starch, into yoghurt mix as stabilizers, each at 0,
0.5, 0.75 and 1.0% concentrations. The yoghurt samples
produced after pasteurization of the mix, cooling,
inoculation of starter culture and incubation for about 16 h
were thermized at 75oC for 60 s followed by
immediate cooling. Results show that titratable acidity
value of the control samples (0% stabilizer) was 0.92 ±
0.03. CMC, when added to yoghurt mix at levels of 0.5% and
above, depressed lactic acid production (compare 0.92 ± 0.03
of the control with 0.90 ± 0.01 of samples containing 0.5
and 0.75% CMC). This observation is in contrast to effects
of corn starch and gelatin which enhanced lactic acid
production (at least up to 0.75% concentration). This was
also mirrored (in reverse order) in the pH values; as
samples with higher titratable acidity had, expectedly,
lower pH values. Addition of stabilizers decreased percent
protein and ash contents due to dilution effect but
increased total solids and specific gravity of the thermized
yoghurt samples. Sensory results showed that addition of
corn starch produced the most desirable flavour and taste
which differed significantly (p < 0.05) from flavour and
taste produced by gelatin but did not differ significantly
(p ≥ 0.050) from that produced by CMC at 0.5 and 0.75%
concentrations. Yoghurt containing CMC had the best mouth
feel/consistency as well as appearance which did not differ
significantly (p ≥ 0.05) from the mouth feel and appearance
of yoghurt containing corn starch but differed significantly
from yoghurt containing gelatin. Yoghurt containing CMC at
0.75% concentration was the most generally accepted.
Key words:
Stabilizers, thermized yoghurt, sensory attribute,
physco-chemical. |
