According to Official Guinness Records,
The longest mozzarella (Fior di Latte) was 106 m 16 cm (348 ft 4 in) and was prepared by Ente Provinciale Turismo Avellino (Italy) in Avellino, Italy, on 13 June 2010.
Fior di Latte mozzarella is prepared using cow's milk rather than the better known buffalo mozzarella, which is made from buffalo milk.
For a complete list of 2010 records, please visit 2010 Guinness Records in Italy.