Can't get jQuery UI autocomplete working
Adding drupal behaviours, as suggested by @2pha, did the trick:

(function ($) {
    Drupal.behaviors.infiniteScrollAddClass = {
        attach: function (context, settings) {

            $( "#business_category" ).autocomplete({
                source: [ "cat1", "cat2", "cat3" ]
            });
        }
    }

})(jQuery);