It wouldn't do  'item' => 'bread' but it would do bread =>. This was as close as I could get:

#!/usr/bin/perl

use strict;
use warnings;

use Data::Rmap qw(:all);

my @item = ('bread', 'butter', 'beans');

my $initial =
  [
    note =>
      [
         shopping =>
           [ 
             $item[0] =>
             $item[1] =>
             $item[2] =>
           ],
      ],
];

use Data::Dumper;
my ($dump) = rmap_array {
  
  if ($_->[0] eq 'shopping') {
    my @item;
    for my $item qw(bread butter beans) {
      push @item, [ item => $item ];
    }
    my $newdata = [ shopping => \@item ];
    cut($newdata)
  } else {
    $_;
  }

  } my @item ;

warn Dumper($initial, $dump);
[download]

Updated: fixed typo