Can't get the literal 'de' from dateFormat. Example: 8 de Enero de 2016

I'm trying to get a date with the following format using the jquery ui datepicker: d de MM de yy. Example: 8 de Enero de 2016

I've try with: dateFormat: 'd \de MM \de yy' dateFormat: 'd 'de' MM 'de' yy' but it's not working as I expected, it displays 8 8e Enero 8e 2016 instead of 8 de Enero de 2016. I have the code in the folling fiddle: http://jsfiddle.net/yewnu9jL/1/

<input type="text" id="datepicker">

$(function(){
  $.datepicker.regional["es"] = {
        closeText: "Cerrar",
        prevText: "<Ant",
        nextText: "Sig>",
        currentText: "Hoy",
        monthNames: ["Enero", "Febrero", "Marzo", "Abril", "Mayo", "Junio", "Julio", "Agosto", "Septiembre", "Octubre", "Noviembre", "Diciembre"],
        monthNamesShort: ["Ene","Feb","Mar","Abr", "May","Jun","Jul","Ago","Sep", "Oct","Nov","Dic"],
        dayNames: ["Domingo", "Lunes", "Martes", "Miércoles", "Jueves", "Viernes", "Sábado"],
        dayNamesShort: ["Dom","Lun","Mar","Mié","Juv","Vie","Sáb"],
        dayNamesMin: ["Do","Lu","Ma","Mi","Ju","Vi","Sá"],
        weekHeader: "Sm",
        dateFormat: "dd/mm/yy",
        firstDay: 1,
        isRTL: false,
        showMonthAfterYear: false,
        yearSuffix: ""
    };
    $.datepicker.setDefaults($.datepicker.regional["es"]);

    $('#datepicker').datepicker({
        dateFormat: 'd de MM de yy',
        maxDate: 0,
        onSelect: function() {
            $('#form-fecha').submit();
        }
    }).datepicker('setDate', new Date());    
});

How can I do it?