## 2 Results
### Viscosity and WHC during Fermentation  
Changes in the viscosity and WHC of all samples and the control during fermentation are shown in Table 2. At the end of fermentation, the viscosities of the yogurt in all samples and the control were 580 (A1), 590 (A2), 615 (A3), 560 (A4), 580 (A5) and 590 (control) mPa-s. There were significant differences in the viscosity of the samples, indicating that the ratio of _L. delbrueckii_ subsp. _bulgaricus_ IMAU20312 and _S. thermophilus_ IMAU80809 in the starter culture had a clear influence on the viscosity of the yogurt.  
The WHC of all samples and the control had significantly decreased by the end of fermentation (\(p<0.05\)). Higher WHC values indicated a strong tissue state and improved retention of aromas. At the end of fermentation, the WHC was highest in the A1, A2 and A3 samples, and lowest in the A4 sample (Table 2). These results confirmed that the ratio of _L. delbrueckii_ subsp. _bulgaricus_ IMAU20312 and _S. thermophilus_ IMAU80809 in the starter culture affected yogurt consistency.  
\begin{table}
\begin{tabular}{c c c c c c c c c c c c c} \hline \hline \multirow{2}{*}{
\begin{tabular}{c} **Time** \\ **(h)** \\ \end{tabular} } & \multicolumn{8}{c}{**Viscosity (mPa-s)**} & \multicolumn{8}{c}{**Water Holding Capacity (\%)**} \\ \cline{2-13}  & **A1** & **A2** & **A3** & **A4** & **A5** & **JD** & **A1** & **A2** & **A3** & **A4** & **A5** & **JD** \\ \hline
0 & \(175\pm 13^{\circ}\) & \(225\pm 1^{\circ}\) & \(210\pm 1^{\circ}\) & \(212\pm 1^{\circ}\) & \(140\pm 1^{\circ}\) & \(180\pm 5^{\circ}\) & \(21\pm 0.5^{\circ}\) & \(28\pm 3.5^{\circ}\) & \(15\pm 0^{\circ}\) & \(14\pm 1.5^{\circ}\) & \(17\pm 2.5^{\circ}\) & \(15\pm 0.5^{\circ}\) \\
2 & \(220\pm 2^{\circ}\) & \(320\pm 3^{\circ}\) & \(310\pm 8^{\circ}\) & \(315\pm 6^{\circ}\) & \(160\pm 24^{\circ}\) & \(380\pm 3^{\circ}\) & \(34\pm 0.3^{\circ}\) & \(30\pm 25^{\circ}\) & \(22\pm 1^{\circ}\) & \(39\pm 45^{\circ}\) & \(22\pm 0.5^{\circ}\) & \(20\pm 3^{\circ}\) \\
4 & \(340\pm 2^{\circ}\) & \(420\pm 2^{\circ}\) & \(440\pm 3^{\circ}\) & \(300\pm 1^{\circ}\) & \(336\pm 1^{\circ}\) & \(470\pm 3^{\circ}\) & \(47\pm 0.5^{\circ}\) & \(47\pm 25^{\circ}\) & \(36\pm 25^{\circ}\) & \(25\pm 0.5^{\circ}\) & \(30\pm 0.5^{\circ}\) \\
6 & \(470\pm 28^{\circ}\) & \(510\pm 7^{\circ}\) & \(485\pm 10^{\circ}\) & \(370\pm 1^{\circ}\) & \(470\pm 13^{\circ}\) & \(525\pm 1^{\circ}\) & \(48\pm 25^{\circ}\) & \(44\pm 0.5^{\circ}\) & \(42\pm 3^{\circ}\) & \(45\pm 1^{\circ}\) & \(42\pm 0.5^{\circ}\) \\
8 & \(580\pm 3^{\circ}\) & \(590\pm 3^{\circ}\) & \(615\pm 1^{\circ}\) & \(560\pm 2^{\circ}\) & \(580\pm 3^{\circ}\) & \(590\pm 4^{\circ}\) & \(49\pm 0.5^{\circ}\) & \(49\pm 0.5^{\circ}\) & \(57\pm 0.5^{\circ}\) & \(43\pm 1^{\circ}\) & \(46\pm 0.5^{\circ}\) & \(47\pm 0.2^{\circ}\) \\ \hline \hline \end{tabular} Note: Data are represented as means \(\pm\) SD; figures in the same row followed by different lowercase letters indicate that they are significantly different from each other (\(p<0.05\)).  
\end{table}
Table 2: Differences in water holding capacity and viscosity of yogurts produced through fermentation using different ratios of _L. delbrueckii_ subsp. _bulgaricus_ IMAU20312 and _S. thermophilus_ IMAU80809 in starter culture compared with the commercial starter culture.  
Figure 1: Changes in pH and TA during fermentation. The black and red lines represent pH and TA of the samples, respectively.