et al. (2008) also reported that L. acidophilus La5 showed growth insoymilk with the fermentation time reaching to 12e17 h.In this study, the addition of apple juice to soymilk increasedthe number of L. acidophilus slightly of about 0.25 and 0.35 logunits for the apple juice concentrations of 15 and 25%, respectively.On the other hand, the increase in the numbers ofL. acidophilus for these samples were not significantly differentfrom the control samples (P > 0.05). Bozanic et al. (2008) reportedthat the addition of sugar (5% glucose or sucrose) tosoymilk before fermentation did not influence the fermentationtime and the number of L. acidophilus.The survival of L. acidophilus in the fermented soymilk drinksduring storage at 4 C for 21 days was given in Table 2. No significantdifferences between the numbers of L. acidophilus duringdifferent storage days were obtained (P > 0.05). During the storageperiod of 21 days, the numbers of L. acidophilus were in the range of8.73e9.11 log cfu/g. According to Turkish Food Codex Communiqueon Fermented Milk (No: 2009/25), acidophilus milk must contain atleast a minimum of 6 log cfu/g total specific microorganisms(Anonymous, 2009). In our study, acidified soymilk beverage withor without added apple juice met this criterion with a minimumL. acidophilus count of about 8.73 log cfu/g. Other studies alsoconfirmed the higher survival rates of probiotic bacteria in fermentedsoymilk products. €Ozbey, Topçu, and Saldamlı (2007)
reported that the number of L. acidophilus in yogurts containing 15%
soymilk increased significantly about 0.65 log cfu/g after 14 days of
storage. Beasley, Tuorila, and Saris (2003) observed that Lactococcus
lactis (LL3) survived at levels of over 8 log cfu/ml in the fermented
soy milk products containing strawberry (3%) and glucose (2%) for 3
weeks. Wang et al. (2002) reported that regardless of whether or
not sucrose (15 Bx) was added, no marked changes in the numbers
of L. acidophilus (about 8 log cfu/ml) were observed during 10 days
of storage at 5 C. Lin et al. (2004) also reported that supplementation
of milk-soymilk mixture with different amounts of Lycium
chinense Miller juice did not affect the growth of Lactobacillus
paracasei subsp. paracasei and Bifidobacterium longum; the cell
numbers for both starters were about the same. On the contrary to
the findings of this study, it was indicated that, L. acidophilus survived
poorly during 21 days of cold storage and the viable cell count
was under the 106 cfu/ml as soon as after the first week of storage
(Bozanic et al., (2011).
Yeasts and mold growths were not detected (<10 cfu/g) during
the storage period of 21 days at 4 C for each sample. Similar to this
study, Beasley et al. (2003) also reported that they could not detect
the growth of yeast or mold in the fermented soymilk products
(<10 cfu/ml).
The incubation temperatures of 37 C (Wang et al., 2002) and
42e43 C (Ashraf & Shah, 2011) were used for the fermented
products with L. acidophilus. In the present study, fermentation
temperature of 37 C was used. Bozanic et al. (2008) reported that
37 C was more appropriated than 43 C for all tested probiotic
bacteria.
3.3. Rheological properties of fermented soy milk beverages
Most of the studies related to the fermented beverages have
been focused on the fermentation process in terms of microbiota
while the determination of rheological parameters and sensory
properties can devote the additional quality characteristics of fermented
foods.
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