I thought this would be an easy one, until I tried it. If you want to learn perl here is a good example of lots of perl idioms, half documented, but perltidy-ed) code.

use strict;
$_ = <DATA>;    #get first line
my @times = /(\S+\s+)/g;
my @widths = map length, @times;
$widths[-1] = -1;    # get rid of last width
s/\s//g for @times;  # get rid of spaces
my $food;
my %hash;

while ( my $line = <DATA> ) {
    my $newfood = substr $line, 0, $widths[0], "";
    $newfood =~ s/\s//g;
    $food = $newfood if length $newfood;
    for ( 1 .. $#times ) {
        my $name = substr $line, 0, $widths[$_], "";
        $name =~ s/\s//g;
        $hash{$food}{ $times[$_] } = []
          unless defined $hash{$food}{ $times[$_] };
        push @{ $hash{$food}{ $times[$_] } }, $name if length $name;
    }
}
shift @times;    #get rid of location
for my $food ( sort keys %hash ) {
    print "$food\n", "-" x length($food), "\n";
    for my $time (@times) {
        print "$time ", join( " ", @{ $hash{$food}{$time} } ), "\n";
    }
    print "\n";
}
__DATA__
LoCATION   10:00  10:30  11:00  11:30   12:00
PiZZA      SAM    MARY   LARRY  ED
           LUSI   RICK          SUE
                  DON
SEAFOOD    KIN    KHAN                  DANNY
                  MIKE    YOUND  TK     MONK
[download]

outputs

PiZZA
-----
10:00 SAM LUSI
10:30 MARY RICK DON
11:00 LARRY
11:30 ED SUE
12:00

SEAFOOD
-------
10:00 KIN
10:30 KHAN MIKE
11:00 YOUND
11:30 TK
12:00 DANNY MONK
[download]