Incidentally, you might consider enclosing things that should be in "text mode" instead of "math mode" in dollar-signs. Note that this is not how it would work if you were composing a LaTeX document (it'd be the inverse), but because the way this thing is set up, everything is in math mode by default.
Example:
[tex]\displaystyle C_{12}H_{22}O_{11} \begin{matrix}
\beta-$galactosidase$ \\
\longrightarrow \\
H_{2}O
\end{matrix}
C_{6}H_{12}O_{6} ($Galactose$) + C_{6}H_{12}O_{6} ($Glucose$)[/tex]