How to change the color of the oxidation numbers in chemmacros?

Question

I would like to change the color of the oxidation numbers in some reactions like:

\documentclass{article}

\usepackage{chemformula}
\usepackage{chemmacros}
\usepackage[spanish]{babel}
\usepackage[version=3]{mhchem}

\let\chold\ch % necesario para que ch ponga bien las flechas
\renewcommand\ch[1]{%
    \catcode`<=12
    \catcode`>=12
    \chold{#1}%
    \catcode`<=\active
    \catcode`>=\active
}
\chemsetup{
  formula = {chemformula} ,
  modules = {redox} 
}
\chemsetup[redox]{
roman = false ,
explicit-sign = true ,
pos = top
}
\begin{document}
\ch{"\ox{5,N}" O3^- + 1 e- + 2 H+ <=> "\ox{4,N}" O2 + H2O}
\end{document}

I use chemmacros (ox) to write the oxidation numbers, but there is no color option. Is there any way to change only the oxidations numbers? Thanks in advance

Answer 1

update 2020/03/09

Using the newest versions of chemmacros and chemformula you

1. can use the option redox/format to add the color and
2. don't need your workaround any more:

\documentclass{article}
\usepackage[spanish]{babel}

\usepackage{chemmacros}[2020/03/07]
\usepackage{chemformula}[2020/03/07]

\chemsetup{
  formula = chemformula ,
  modules = redox ,
  redox/roman = false ,
  redox/explicit-sign = true ,
  redox/pos = top ,
  redox/format = \textcolor{red}
}
\begin{document}

\ch{"\ox{5,N}" O3^- + 1 e- + 2 H+ <=> "\ox{4,N}" O2 + H2O}

<<Test>>

\end{document}

Original Answer, 2020/03/06

For the time being the only viable possibility is to disable the parsing of the oxidation numbers (note that then the option redox/roman and redox/explicit-sign don't have any effect…). When the parsing is disabled you can just use \textcolor:

\documentclass{article}
\usepackage{chemmacros}

\chemsetup{
  formula = chemformula ,
  modules = redox ,
  redox/parse = false ,
  redox/pos = top
}

\begin{document}

\ch{"\ox{\textcolor{red}{+5},N}" O3^-}

\end{document}