# use binmode on the filehandle
open my $fh, '<', "file" or die "... $!";
binmode $fh, ':utf8';

# open $fh for reading UTF-8
open(my $fh, "<:encoding(UTF-8)", "file") or die "... $!";

# Use the open pragma to open all input files as UTF-8
# see http://perldoc.perl.org/open.html
use open IN => ':utf8';

# or you can manually use ...
$str = decode_utf8( $str );
# on each data item