Would this (untested!) not work?

use 5.14.2;
use strict;
use warnings;

use XML::RSSLite;
use LWP::Simple;

my @keywords = qw(approach);

my @URLlist = ( 
 'http://www.theguardian.com/theguardian/mainsection/rss',
 'http://www.theguardian.com/theguardian/mainsection/rss1', 
);

foreach my $URL ( @URLlist ) {
  my $content = get($URL);

  my %result;
  parseRSS(\%result, \$content);

  my $re = join "|", @keywords;
  $re = qr/\b(?:$re)\b/i;

  foreach my $item (@{ $result{items} }) {
    my $title = $item->{title};
    $title =~ s{\s+}{ };  
    $title =~ s{^\s+}{  }; 
    $title =~ s{\s+$}{  };

    if ($title =~ /$re/) {
      print "$title\n\t$item->{link}\n\n";
    }
  }
}
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