on the other hand increasing the concentration to lead to syneresis
during the fermentation period (data not shown).
The results of the evaluation of rank sums by using critical tables
(Newell & MacFarlane, 1987) were agreed with the results of the
evaluation method using significant differences obtained by multiple
comparison tests, except overall acceptability (Table 6). The
consistency of control samples was evaluated as significantly
higher than apple juice added samples (P < 0.05) while no difference
was found between the beverages with 15% and 25% apple
juice (P > 0.05). Panelists suggested that acidity of the control
samples was lowest, and the beverage with 15% apple juice was
more acidic. This promoted that the best proper medium for
L. acidophilus was the soy milk with 15% apple juice. When apple
flavor and color in the beverage was compared between the samples,
members evaluated that the sample containing 25% apple
juice had the best (P < 0.05).
The sums of ranks for overall acceptability were not significantly
different for the evaluation method using the critical value tables
(P < 0.05). The overall acceptability rank sums obtained by multiple
comparison tests (Duncan) showed that the fermented soymilk
beverages with 25% apple juice were preferred by panelists
compared to with 15% apple juice and control beverages without
apple juice (P < 0.05) (Table 6). The multiple comparison evaluation
method could have distinguished the difference between overall
acceptability in detail.
4. Conclusion
According to the results of this study, soy milk with or without
added apple juice could support the growth of L. acidophilus and
L. acidophilus could survive at higher numbers during the storage
period of 21 days at 4 C. The pH values of the fermented soy milk
beverages with or without added apple juice changed little during
the storage period of 21 days at 4 C.
The fermented soy milk beverage with added apple juice samples
was found to be having pseudoplastic shear-thinning nature. It
was obtained that the addition of the apple juice decreased the
consistency coefficient of the fermented beverage. The consistency
of the control group increased up to the value of 71.60 ± 4.73 Pa.sn
(rheological measurements) in the 1st week of the storage at 4 C.
Similarly, the consistency of control samples was found as significantly
higher than apple juice added samples in the sensory tests
by the panelists.
Fermented soymilk beverage with apple juice presented good
sensory acceptance and provided its microbiological stability for at
least 21 days at 4 C with acceptable survival rates of the probiotic
bacteria. Since this fermented soy milk beverage is new and going
to be possible commercial product, the data obtained in this study
could serve valuable information for the design of pumping systems
for the fermented soy milk beverages and development of
novel fermented drinks.
Acknowledgment
The authors are grateful for financial support provided for the
project entitled “Investigation of rheological and microbiological
characteristics of fermented soy milk beverage with added apple
juice” under Ege University BAP project no: 2013-MUH-073 Turkey.