my $category;
my $decoded_text = decode('UTF-8', $_);
#my $latin1_html = encode('iso-latin-1', $decoded_text );
my $latin1_html = encode('iso-8859-1', $decoded_text );
if ($latin1_html =~ /behälter/i) {
    $category = 'Behälter';
}

##</code><code>##

use open IN  => ':encoding(UTF-8)';
use open OUT => ':encoding(iso-8859-1)';

##</code><code>##

my $category;
if ($_=~ /behälter/i) {
    $category = 'Behälter';
}

##</code><code>##

my $category;
if ($_=~ /beh\xE4lter/i) {
    $category = 'Behälter';
}