Table 2.
Total plate count for probiotic yogurt on MRS agar at different pH values over 3 h period
| pH value | Yogurt | Total plate count (log CFU/mL) | ||||
|---|---|---|---|---|---|---|
| 0 h | 1.5 h | 2 h | 2.5 h | 3 h | ||
| 1.0 | C1 | 3.01 ± 0.71 (37.1) | – | – | – | – |
| T1 | 3.51 ± 0.19 (47.9) | – | – | – | – | |
| T2 | 3.63 ± 1.81(44.3) | – | – | – | – | |
| T3 | 3.51 ± 1.0 (50.6) | – | – | – | ||
| T4 | 3.59 ± 0.71 (47.5) | – | – | – | ||
| T5 | 4.12 ± 0.01 (45.1) | – | – | – | ||
| T6 | 3.61 ± 0.18 (47.6) | – | – | – | ||
| 1.5 | C1 | 4.01 ± 2.03 (49.4) | – | – | – | – |
| T1 | 4.52 ± 0.15 (61.7) | 1.14 ± 1.34 (15.2) | 0.88 ± 0.61 (11.7) | 0.41 ± 0.04 (5.6) | – | |
| T2 | 4.03 ± 0.66 (49.2) | 0.93 ± 0.02 (11.6) | 0.63 ± 0.93 (7.7) | 0.21 ± 0.02 (2.6) | – | |
| T3 | 4.16 ± 0.28 (60.0) | 2.13 ± 1.11 (29.8) | 1.01 ± 0.63 (14.4) | – | – | |
| T4 | 4.44 ± 0.71(58.8) | 0.86 ± 0.23 (11.4) | 0.73 ± 0.20 (10.0) | – | – | |
| T5 | 5.24 ± 0.14 (57.4) | 2.68 ± 1.87 (29.6) | 2.01 ± 1.47 (26.2) | 1.01 ± 0.56 (11.1) | – | |
| T6 | 4.12 ± 0.64 (54.4) | 2.01 ± 0.13 (26.7) | 1.98 ± 0.67 (21.9) | – | – | |
| 2.0 | C1 | 5.91 ± 1.16 (72.8) | 2.35 ± 0.01 (27.1) | – | – | |
| T1 | 4.86 ± 1.05 (66.3) | 3.16 ± 0.07 (42.3) | 2.99 ± 0.82 (39.8) | 2.22 ± 0.17 (30.4) | 2.03 ± 0.68 (28.0) | |
| T2 | 4.01 ± 1.01 (48.9) | 2.94 ± 0.81 (36.7) | 2.16 ± 0.65 (26.6) | 1.98 ± 0.12 (24.9) | 1.72 ± 0.36 (21.4) | |
| T3 | 4.42 ± 0.93 (63.7) | 3.30 ± 0.51 (46.2) | 2.86 ± 0.16 (40.7) | 2.84 ± 1.03 (40.5) | 2.27 ± 0.49 (34.0) | |
| T4 | 4.47 ± 0.86 (59.2) | 3.56 ± 0.16 (47.4) | 2.55 ± 0.53 (35.0) | 2.01 ± 0.61 (28.4) | 1.96 ± 0.13 (26.6) | |
| T5 | 5.01 ± 0.51 (54.9) | 4.18 ± 0.85 (46.1) | 4.06 ± 0.16 (44.9) | 4.01 ± 0.09 (44.4) | 4.91 ± 0.25 (54.4) | |
| T6 | 4.49 ± 0.21 (59.3) | 3.31 ± 0.07 (44.0) | 3.10 ± 0.91 (41.5) | 3.17 ± 0.17 (42.6) | 3.19 ± 1.12 (44.6) | |
| 3.0 | C1 | 5.11 ± 0.07 (63.0) | 2.37 ± 0.81 (27.4) | – | – | – |
| T1 | 5.28 ± 0.33 (72.1) | 4.81 ± 0.92 (65.0) | 4.03 ± 1.52 (53.7) | 3.63 ± 1.41 (49.7) | 3.52 ± 0.82 (48.5) | |
| T2 | 4.83 ± 0.36 (58.9) | 4.01 ± 1.25 (50.1) | 4.12 ± 1.83 (50.5) | 3.68 ± 1.30 (50.4) | 3.43 ± 0.77 (42.8) | |
| T3 | 4.62 ± 1.27 (66.6) | 4.42 ± 1.27 (61.9) | 4.16 ± 0.73 (59.3) | 3.81 ± 0.62 (54.4) | 3.53 ± 0.41 (53.0) | |
| T4 | 4.95 ± 1.61 (65.5) | 4.41 ± 1.31 (58.7) | 3.91 ± 1.22 (53.7) | 3.01 ± 0.22 (42.0) | 3.33 ± 0.63 (45.2) | |
| T5 | 6.86 ± 0.45 (75.2) | 6.17 ± 0.23 (68.1) | 6.19 ± 0.72 (68.4) | 5.87 ± 1.45 (65.0) | 5.96 ± 0.41 (66.1) | |
| T6 | 5.12 ± 0.02 (67.6) | 5.13 ± 0.72 (68.3) | 5.26 ± 0.91 (70.5) | 4.30 ± 0.81 (57.7) | 3.19 ± 0.05 (44.6) | |
| 4.0 | C1 | 5.49 ± 1.65 (67.6) | 3.35 ± 0.05 (38.7) | 2.61 ± 1.40 (34.0) | – | – |
| T1 | 5.91 ± 1.41 (80.7) | 5.80 ± 1.61 (77.7) | 5.61 ± 1.4 (74.8) | 5.71 ± 0.59 (78.3) | 5.31 ± 1.82 (73.2) | |
| T2 | 5.50 ± 1.21 (67.1) | 5.42 ± 1.73 (67.7) | 5.11 ± 0.86 (62.6) | 4.72 ± 1.02 (59.5) | 4.16 ± 1.05 (51.9) | |
| T3 | 5.27 ± 1.04 (76.0) | 5.21 ± 0.93 (73.0) | 4.93 ± 2.01 (70.3) | 4.41 ± 0.83 (63.0) | 4.00 ± 1.26 (60.6) | |
| T4 | 5.00 ± 1.22 (66.2) | 4.83 ± 0.85 (64.3) | 4.44 ± 1.71 (61.0) | 4.12 ± 0.66 (57.4) | 4.12 ± 0.74 (55.9) | |
| T5 | 6.71 ± 0.34 (73.5) | 6.49 ± 0.14 (71.7) | 6.32 ± 0.61 (69.9) | 6.04 ± 0.14 (66.8) | 5.81 ± 0.23 (64.4) | |
| T6 | 5.81 ± 0.81 (76.7) | 5.17 ± 0.77 (68.8) | 4.73 ± 0.49 (63.4) | 4.12 ± 0.51 (55.3) | 3.61 ± 1.12 (50.4) | |
|
Control (pH 6.2) |
C1 | 8.11 ± 0.26 (100) | 8.64 ± 0.41 (100) | 7.67 ± 0.96 (100) | 8.42 ± 0.99 (100) | 7.41 ± 1.30 (100) |
| T1 | 7.32 ± 0.06 (100) | 7.46 ± 0.82 (100) | 7.50 ± 0.71 (100) | 7.29 ± 0.94 (100) | 7.25 ± 0.68 (100) | |
| T2 | 8.19 ± 0.31 (100) | 8.00 ± 0.93 (100) | 8.15 ± 0.61 (100) | 7.93 ± 0.15 (100) | 8.01 ± 0.52 (100) | |
| T3 | 6.93 ± 0.26 (100) | 7.13 ± 0.64 (100) | 7.01 ± 0.18 (100) | 7.00 ± 0.74 (100) | 6.66 ± 0.29 (100) | |
| T4 | 7.55 ± 0.23 (100) | 7.51 ± 0.33 (100) | 7.27 ± 0.18 (100) | 7.16 ± 0.39 (100) | 7.36 ± 0.72 (100) | |
| T5 | 9.12 ± 0.08 (100) | 9.05 ± 0.07 (100) | 9.04 ± 0.06 (100) | 9.03 ± 0.12 (100) | 9.01 ± 0.71 (100) | |
| T6 | 7.57 ± 0.05 (100) | 7.51 ± 0.06 (100) | 7.46 ± 0.08 (100) | 7.44 ± 0.03 (100) | 7.15 ± 0.05 (100) | |
Values in parenthesis show percent survivability. C1—containing yogurt starter culture (S. thermophilus + L. bulgaricus), T1—(yogurt starter culture + L. acidophilus), T2—(yogurt starter culture + Bifidobacterium bifidum), T3—(yogurt starter culture + L. plantarum), T4—(yogurt starter culture + L. casei), T5—(yogurt starter culture + L. acidophilus + Bifidobacterium bifidum), T6—(yogurt starter culture + L. plantarum + L. casei)