How to extract value from a messy text file?

I would like to extract the mass value that is in the file. I did not figure out a way to do this using textscan.

Answer 1

[Walter Roberson]

S = fileread('Massa.txt');
mass = str2double( regexp(S, '(?<=''mass'':\s*)[^, ]+', 'match', 'once') );

[Matheus]

Thank you, but I already solved my problem