A novel cheese made of Gracilaria edulis proteases and its characterisation

A milk clotting protease was isolated from the red marine macroalga Gracilaria edulis in a previous study of ours. In the current study, the protease was used to make a Cheddar style cheese and the chemical, physical, textural and sensory properties of the cheese were investigated. The algal cheese had a higher yield and moisture content but lower total solids, compared to calf rennet cheese. The colour of the algal cheese was lighter and less yellow than the calf rennet cheese. The microstructure parameters of algal and calf rennet cheeses were similar. SDS-PAGE showed that the algal protease digested all proteins in the milk continuously during ripening and produced many low molecular weight peptides. RP-HPLC showed that the algal cheese displayed a greater number of peptide peaks than calf rennet cheese. Sensory analysis revealed that the algal cheese generally had lower scores in several categories including overall flavour, which was mainly due to its stronger bitter taste. Overall, this study found that the G. edulis proteases are probably not very suitable for making cheese with a long ripening period such as Cheddar style cheese, due to excessive proteolysis and resultant development of bitter taste, but may have potential as a calf rennet substitute in making fresh cheeses, such as white cheese. •The novel proteases from Gracilaria edulis were applied to cheesemaking.•Physicochemical, biochemical and sensory properties of algal cheese were studied.•Some of the algal cheese properties were comparable to calf rennet cheese.•Algal cheese had had greater bitterness than calf rennet cheese.•G. edulis proteases may not be suitable for making aged cheese types.