slightly refactored version of the same code less side effects.

combo2.pl

#!/usr/bin/env perl

use strict;
use warnings;
use Data::Dumper;
use Math::BigInt;
use List::Util qw(first max maxstr min minstr reduce shuffle sum);
use List::MoreUtils qw( pairwise );

my $t    = 10; 
my %d    = ("apple"=>3, "pear"=>2, "pineapple"=>9, "strawberry"=>1, 
            "kiwi"=>-5, "lime"=>15, "lemon"=>5, "orange"=>-1, "banana"=>5);
my $n    = scalar(keys %d);
my $l    = sprintf("%d", $n);
my $x    = Math::BigInt->new("2");
$x->bpow(sprintf("%d", $n));
$x->bdec();

sub xdump($) {
    my $arr = shift;
    my $p; 
    print "[";
    foreach $p (@$arr) {
        print $p."(".$d{$p}."), ";
    }   
    print "]\n";
}


while( $x->is_pos() ) { 
  my @by   = split(//,substr('0' x $l . substr($x->as_bin(), 2),-1*$l));
  my @k    = keys %d; 
  my @z    = pairwise {[$a,$b]} @k, @by;
  my $k    = (reduce { if(@$b[1] eq '1') {push($a,@$b[0]);$a} else {$a}} [], @z)[0]; 
  my $sum  = reduce { $a + $d{$b} } 0, @$k;
  
  if( $sum == $t ) { 
    print $x.". .".$x->as_hex()." ";
    xdump($k);
  }
  $x->bdec(); 
}

# __END__