Functional and pizza bake properties of Mozzarella cheese made with konjac glucomannan as a fat replacer

Konjac glucomannan (KGM) is a dietary fibre with potential to be used as a fat-replacer in Mozzarella cheese. The functional properties (texture, free oil, meltability and stretch performance) of full-fat cheese control (FFC), low-fat cheese control (LFC), skimmed cheese control (SKC), low-fat cheese with KGM (LF-KGM) and skimmed cheese with KGM (SK-KGM) after 0, 7, 14, 21 and 28 days of storage at 4 degrees C were measured. The pizza bake properties (appearance for pizza bake and browning) and microstructure were evaluated. Generally, LF-KGM and SK-KGM had lower firmness but higher meltability than LFC and SKC, respectively. The firmness and meltability of LF-KGM were similar to those of FFC. Both the stickiness and free oil content of LF-KGM and SK-KGM were similar to LFC and SKC, respectively. The LF-KGM and SK-KGM showed more complete shred melt, less scorching and lower browning (higher L* value after baking) on the cheese surface than LFC and SKC, respectively, when they were baked as a pizza topping. Microstructure of FFC, LFC and SKC showed that fat globules filled the serum pores/channels in the protein matrix. LF-KGM and SK-KGM showed more dense protein matrix with more coalesced fat globules distributed in the matrix. The stickiness, free oil content and meltability of all the cheeses increased but firmness decreased during storage. We show that KGM may be useful as a fat replacer in manufacturing fat-reduced Mozzarella cheeses to improve functionality and pizza bake characteristics.